kevin/linux
1
Fork 0
Code
f4a1e8e369
linux/fs/netfs/write_issue.c

724 lines
20 KiB
C
Raw Normal View History

netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
// SPDX-License-Identifier: GPL-2.0-only
/* Network filesystem high-level (buffered) writeback.
*
* Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
*
* To support network filesystems with local caching, we manage a situation
* that can be envisioned like the following:
*
* +---+---+-----+-----+---+----------+
* Folios: | | | | | | |
* +---+---+-----+-----+---+----------+
*
* +------+------+ +----+----+
* Upload: | | |.....| | |
* (Stream 0) +------+------+ +----+----+
*
* +------+------+------+------+------+
* Cache: | | | | | |
* (Stream 1) +------+------+------+------+------+
*
* Where we have a sequence of folios of varying sizes that we need to overlay
* with multiple parallel streams of I/O requests, where the I/O requests in a
* stream may also be of various sizes (in cifs, for example, the sizes are
* negotiated with the server; in something like ceph, they may represent the
* sizes of storage objects).
*
* The sequence in each stream may contain gaps and noncontiguous subrequests
* may be glued together into single vectored write RPCs.
*/
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include "internal.h"
/*
* Kill all dirty folios in the event of an unrecoverable error, starting with
* a locked folio we've already obtained from writeback_iter().
*/
static void netfs_kill_dirty_pages(struct address_space *mapping,
struct writeback_control *wbc,
struct folio *folio)
{
int error = 0;
do {
enum netfs_folio_trace why = netfs_folio_trace_kill;
struct netfs_group *group = NULL;
struct netfs_folio *finfo = NULL;
void *priv;
priv = folio_detach_private(folio);
if (priv) {
finfo = __netfs_folio_info(priv);
if (finfo) {
/* Kill folio from streaming write. */
group = finfo->netfs_group;
why = netfs_folio_trace_kill_s;
} else {
group = priv;
if (group == NETFS_FOLIO_COPY_TO_CACHE) {
/* Kill copy-to-cache folio */
why = netfs_folio_trace_kill_cc;
group = NULL;
} else {
/* Kill folio with group */
why = netfs_folio_trace_kill_g;
}
}
}
trace_netfs_folio(folio, why);
folio_start_writeback(folio);
folio_unlock(folio);
folio_end_writeback(folio);
netfs_put_group(group);
kfree(finfo);
} while ((folio = writeback_iter(mapping, wbc, folio, &error)));
}
/*
* Create a write request and set it up appropriately for the origin type.
*/
struct netfs_io_request *netfs_create_write_req(struct address_space *mapping,
struct file *file,
loff_t start,
enum netfs_io_origin origin)
{
struct netfs_io_request *wreq;
struct netfs_inode *ictx;
netfs: Fix handling of USE_PGPRIV2 and WRITE_TO_CACHE flags The NETFS_RREQ_USE_PGPRIV2 and NETFS_RREQ_WRITE_TO_CACHE flags aren't used correctly. The problem is that we try to set them up in the request initialisation, but we the cache may be in the process of setting up still, and so the state may not be correct. Further, we secondarily sample the cache state and make contradictory decisions later. The issue arises because we set up the cache resources, which allows the cache's ->prepare_read() to switch on NETFS_SREQ_COPY_TO_CACHE - which triggers cache writing even if we didn't set the flags when allocating. Fix this in the following way: (1) Drop NETFS_ICTX_USE_PGPRIV2 and instead set NETFS_RREQ_USE_PGPRIV2 in ->init_request() rather than trying to juggle that in netfs_alloc_request(). (2) Repurpose NETFS_RREQ_USE_PGPRIV2 to merely indicate that if caching is to be done, then PG_private_2 is to be used rather than only setting it if we decide to cache and then having netfs_rreq_unlock_folios() set the non-PG_private_2 writeback-to-cache if it wasn't set. (3) Split netfs_rreq_unlock_folios() into two functions, one of which contains the deprecated code for using PG_private_2 to avoid accidentally doing the writeback path - and always use it if USE_PGPRIV2 is set. (4) As NETFS_ICTX_USE_PGPRIV2 is removed, make netfs_write_begin() always wait for PG_private_2. This function is deprecated and only used by ceph anyway, and so label it so. (5) Drop the NETFS_RREQ_WRITE_TO_CACHE flag and use fscache_operation_valid() on the cache_resources instead. This has the advantage of picking up the result of netfs_begin_cache_read() and fscache_begin_write_operation() - which are called after the object is initialised and will wait for the cache to come to a usable state. Just reverting ae678317b95e[1] isn't a sufficient fix, so this need to be applied on top of that. Without this as well, things like: rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { and: WARNING: CPU: 13 PID: 3621 at fs/ceph/caps.c:3386 may happen, along with some UAFs due to PG_private_2 not getting used to wait on writeback completion. Fixes: 2ff1e97587f4 ("netfs: Replace PG_fscache by setting folio->private and marking dirty") Reported-by: Max Kellermann <max.kellermann@ionos.com> Signed-off-by: David Howells <dhowells@redhat.com> cc: Ilya Dryomov <idryomov@gmail.com> cc: Xiubo Li <xiubli@redhat.com> cc: Hristo Venev <hristo@venev.name> cc: Jeff Layton <jlayton@kernel.org> cc: Matthew Wilcox <willy@infradead.org> cc: ceph-devel@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org Link: https://lore.kernel.org/r/3575457.1722355300@warthog.procyon.org.uk/ [1] Link: https://lore.kernel.org/r/1173209.1723152682@warthog.procyon.org.uk Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-07 11:38:46 -07:00
bool is_buffered = (origin == NETFS_WRITEBACK ||
netfs: Speed up buffered reading Improve the efficiency of buffered reads in a number of ways: (1) Overhaul the algorithm in general so that it's a lot more compact and split the read submission code between buffered and unbuffered versions. The unbuffered version can be vastly simplified. (2) Read-result collection is handed off to a work queue rather than being done in the I/O thread. Multiple subrequests can be processes simultaneously. (3) When a subrequest is collected, any folios it fully spans are collected and "spare" data on either side is donated to either the previous or the next subrequest in the sequence. Notes: (*) Readahead expansion is massively slows down fio, presumably because it causes a load of extra allocations, both folio and xarray, up front before RPC requests can be transmitted. (*) RDMA with cifs does appear to work, both with SIW and RXE. (*) PG_private_2-based reading and copy-to-cache is split out into its own file and altered to use folio_queue. Note that the copy to the cache now creates a new write transaction against the cache and adds the folios to be copied into it. This allows it to use part of the writeback I/O code. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-20-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-01 16:40:22 -07:00
origin == NETFS_WRITETHROUGH ||
origin == NETFS_PGPRIV2_COPY_TO_CACHE);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
wreq = netfs_alloc_request(mapping, file, start, 0, origin);
if (IS_ERR(wreq))
return wreq;
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_enter("R=%x", wreq->debug_id);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
ictx = netfs_inode(wreq->inode);
netfs: Fix handling of USE_PGPRIV2 and WRITE_TO_CACHE flags The NETFS_RREQ_USE_PGPRIV2 and NETFS_RREQ_WRITE_TO_CACHE flags aren't used correctly. The problem is that we try to set them up in the request initialisation, but we the cache may be in the process of setting up still, and so the state may not be correct. Further, we secondarily sample the cache state and make contradictory decisions later. The issue arises because we set up the cache resources, which allows the cache's ->prepare_read() to switch on NETFS_SREQ_COPY_TO_CACHE - which triggers cache writing even if we didn't set the flags when allocating. Fix this in the following way: (1) Drop NETFS_ICTX_USE_PGPRIV2 and instead set NETFS_RREQ_USE_PGPRIV2 in ->init_request() rather than trying to juggle that in netfs_alloc_request(). (2) Repurpose NETFS_RREQ_USE_PGPRIV2 to merely indicate that if caching is to be done, then PG_private_2 is to be used rather than only setting it if we decide to cache and then having netfs_rreq_unlock_folios() set the non-PG_private_2 writeback-to-cache if it wasn't set. (3) Split netfs_rreq_unlock_folios() into two functions, one of which contains the deprecated code for using PG_private_2 to avoid accidentally doing the writeback path - and always use it if USE_PGPRIV2 is set. (4) As NETFS_ICTX_USE_PGPRIV2 is removed, make netfs_write_begin() always wait for PG_private_2. This function is deprecated and only used by ceph anyway, and so label it so. (5) Drop the NETFS_RREQ_WRITE_TO_CACHE flag and use fscache_operation_valid() on the cache_resources instead. This has the advantage of picking up the result of netfs_begin_cache_read() and fscache_begin_write_operation() - which are called after the object is initialised and will wait for the cache to come to a usable state. Just reverting ae678317b95e[1] isn't a sufficient fix, so this need to be applied on top of that. Without this as well, things like: rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { and: WARNING: CPU: 13 PID: 3621 at fs/ceph/caps.c:3386 may happen, along with some UAFs due to PG_private_2 not getting used to wait on writeback completion. Fixes: 2ff1e97587f4 ("netfs: Replace PG_fscache by setting folio->private and marking dirty") Reported-by: Max Kellermann <max.kellermann@ionos.com> Signed-off-by: David Howells <dhowells@redhat.com> cc: Ilya Dryomov <idryomov@gmail.com> cc: Xiubo Li <xiubli@redhat.com> cc: Hristo Venev <hristo@venev.name> cc: Jeff Layton <jlayton@kernel.org> cc: Matthew Wilcox <willy@infradead.org> cc: ceph-devel@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org Link: https://lore.kernel.org/r/3575457.1722355300@warthog.procyon.org.uk/ [1] Link: https://lore.kernel.org/r/1173209.1723152682@warthog.procyon.org.uk Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-07 11:38:46 -07:00
if (is_buffered && netfs_is_cache_enabled(ictx))
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
fscache_begin_write_operation(&wreq->cache_resources, netfs_i_cookie(ictx));
wreq->cleaned_to = wreq->start;
wreq->io_streams[0].stream_nr = 0;
wreq->io_streams[0].source = NETFS_UPLOAD_TO_SERVER;
wreq->io_streams[0].prepare_write = ictx->ops->prepare_write;
wreq->io_streams[0].issue_write = ictx->ops->issue_write;
wreq->io_streams[0].collected_to = start;
wreq->io_streams[0].transferred = LONG_MAX;
wreq->io_streams[1].stream_nr = 1;
wreq->io_streams[1].source = NETFS_WRITE_TO_CACHE;
wreq->io_streams[1].collected_to = start;
wreq->io_streams[1].transferred = LONG_MAX;
if (fscache_resources_valid(&wreq->cache_resources)) {
wreq->io_streams[1].avail = true;
netfs: Fix writeback that needs to go to both server and cache When netfslib is performing writeback (ie. ->writepages), it maintains two parallel streams of writes, one to the server and one to the cache, but it doesn't mark either stream of writes as active until it gets some data that needs to be written to that stream. This is done because some folios will only be written to the cache (e.g. copying to the cache on read is done by marking the folios and letting writeback do the actual work) and sometimes we'll only be writing to the server (e.g. if there's no cache). Now, since we don't actually dispatch uploads and cache writes in parallel, but rather flip between the streams, depending on which has the lowest so-far-issued offset, and don't wait for the subreqs to finish before flipping, we can end up in a situation where, say, we issue a write to the server and this completes before we start the write to the cache. But because we only activate a stream when we first add a subreq to it, the result collection code may run before we manage to activate the stream - resulting in the folio being cleaned and having the writeback-in-progress mark removed. At this point, the folio no longer belongs to us. This is only really a problem for folios that need to be written to both streams - and in that case, the upload to the server is started first, followed by the write to the cache - and the cache write may see a bad folio. Fix this by activating the cache stream up front if there's a cache available. If there's a cache, then all data is going to be written to it. Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/1599053.1721398818@warthog.procyon.org.uk cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-19 07:20:18 -07:00
wreq->io_streams[1].active = true;
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
wreq->io_streams[1].prepare_write = wreq->cache_resources.ops->prepare_write_subreq;
wreq->io_streams[1].issue_write = wreq->cache_resources.ops->issue_write;
}
return wreq;
}
/**
* netfs_prepare_write_failed - Note write preparation failed
* @subreq: The subrequest to mark
*
* Mark a subrequest to note that preparation for write failed.
*/
void netfs_prepare_write_failed(struct netfs_io_subrequest *subreq)
{
__set_bit(NETFS_SREQ_FAILED, &subreq->flags);
trace_netfs_sreq(subreq, netfs_sreq_trace_prep_failed);
}
EXPORT_SYMBOL(netfs_prepare_write_failed);
/*
* Prepare a write subrequest. We need to allocate a new subrequest
* if we don't have one.
*/
static void netfs_prepare_write(struct netfs_io_request *wreq,
struct netfs_io_stream *stream,
loff_t start)
{
struct netfs_io_subrequest *subreq;
netfs: Fix write oops in generic/346 (9p) and generic/074 (cifs) In netfslib, a buffered writeback operation has a 'write queue' of folios that are being written, held in a linear sequence of folio_queue structs. The 'issuer' adds new folio_queues on the leading edge of the queue and populates each one progressively; the 'collector' pops them off the trailing edge and discards them and the folios they point to as they are consumed. The queue is required to always retain at least one folio_queue structure. This allows the queue to be accessed without locking and with just a bit of barriering. When a new subrequest is prepared, its ->io_iter iterator is pointed at the current end of the write queue and then the iterator is extended as more data is added to the queue until the subrequest is committed. Now, the problem is that the folio_queue at the leading edge of the write queue when a subrequest is prepared might have been entirely consumed - but not yet removed from the queue as it is the only remaining one and is preventing the queue from collapsing. So, what happens is that subreq->io_iter is pointed at the spent folio_queue, then a new folio_queue is added, and, at that point, the collector is at entirely at liberty to immediately delete the spent folio_queue. This leaves the subreq->io_iter pointing at a freed object. If the system is lucky, iterate_folioq() sees ->io_iter, sees the as-yet uncorrupted freed object and advances to the next folio_queue in the queue. In the case seen, however, the freed object gets recycled and put back onto the queue at the tail and filled to the end. This confuses iterate_folioq() and it tries to step ->next, which may be NULL - resulting in an oops. Fix this by the following means: (1) When preparing a write subrequest, make sure there's a folio_queue struct with space in it at the leading edge of the queue. A function to make space is split out of the function to append a folio so that it can be called for this purpose. (2) If the request struct iterator is pointing to a completely spent folio_queue when we make space, then advance the iterator to the newly allocated folio_queue. The subrequest's iterator will then be set from this. The oops could be triggered using the generic/346 xfstest with a filesystem on9P over TCP with cache=loose. The oops looked something like: BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page ... RIP: 0010:_copy_from_iter+0x2db/0x530 ... Call Trace: <TASK> ... p9pdu_vwritef+0x3d8/0x5d0 p9_client_prepare_req+0xa8/0x140 p9_client_rpc+0x81/0x280 p9_client_write+0xcf/0x1c0 v9fs_issue_write+0x87/0xc0 netfs_advance_write+0xa0/0xb0 netfs_write_folio.isra.0+0x42d/0x500 netfs_writepages+0x15a/0x1f0 do_writepages+0xd1/0x220 filemap_fdatawrite_wbc+0x5c/0x80 v9fs_mmap_vm_close+0x7d/0xb0 remove_vma+0x35/0x70 vms_complete_munmap_vmas+0x11a/0x170 do_vmi_align_munmap+0x17d/0x1c0 do_vmi_munmap+0x13e/0x150 __vm_munmap+0x92/0xd0 __x64_sys_munmap+0x17/0x20 do_syscall_64+0x80/0xe0 entry_SYSCALL_64_after_hwframe+0x71/0x79 This also fixed a similar-looking issue with cifs and generic/074. Fixes: cd0277ed0c18 ("netfs: Use new folio_queue data type and iterator instead of xarray iter") Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202409180928.f20b5a08-oliver.sang@intel.com Closes: https://lore.kernel.org/oe-lkp/202409131438.3f225fbf-oliver.sang@intel.com Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: kernel test robot <oliver.sang@intel.com> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Paulo Alcantara <pc@manguebit.com> cc: Jeff Layton <jlayton@kernel.org> cc: v9fs@lists.linux.dev cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Steve French <stfrench@microsoft.com>
2024-09-26 06:58:30 -07:00
struct iov_iter *wreq_iter = &wreq->io_iter;
/* Make sure we don't point the iterator at a used-up folio_queue
* struct being used as a placeholder to prevent the queue from
* collapsing. In such a case, extend the queue.
*/
if (iov_iter_is_folioq(wreq_iter) &&
wreq_iter->folioq_slot >= folioq_nr_slots(wreq_iter->folioq)) {
netfs_buffer_make_space(wreq);
}
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
subreq = netfs_alloc_subrequest(wreq);
subreq->source = stream->source;
subreq->start = start;
subreq->stream_nr = stream->stream_nr;
netfs: Fix write oops in generic/346 (9p) and generic/074 (cifs) In netfslib, a buffered writeback operation has a 'write queue' of folios that are being written, held in a linear sequence of folio_queue structs. The 'issuer' adds new folio_queues on the leading edge of the queue and populates each one progressively; the 'collector' pops them off the trailing edge and discards them and the folios they point to as they are consumed. The queue is required to always retain at least one folio_queue structure. This allows the queue to be accessed without locking and with just a bit of barriering. When a new subrequest is prepared, its ->io_iter iterator is pointed at the current end of the write queue and then the iterator is extended as more data is added to the queue until the subrequest is committed. Now, the problem is that the folio_queue at the leading edge of the write queue when a subrequest is prepared might have been entirely consumed - but not yet removed from the queue as it is the only remaining one and is preventing the queue from collapsing. So, what happens is that subreq->io_iter is pointed at the spent folio_queue, then a new folio_queue is added, and, at that point, the collector is at entirely at liberty to immediately delete the spent folio_queue. This leaves the subreq->io_iter pointing at a freed object. If the system is lucky, iterate_folioq() sees ->io_iter, sees the as-yet uncorrupted freed object and advances to the next folio_queue in the queue. In the case seen, however, the freed object gets recycled and put back onto the queue at the tail and filled to the end. This confuses iterate_folioq() and it tries to step ->next, which may be NULL - resulting in an oops. Fix this by the following means: (1) When preparing a write subrequest, make sure there's a folio_queue struct with space in it at the leading edge of the queue. A function to make space is split out of the function to append a folio so that it can be called for this purpose. (2) If the request struct iterator is pointing to a completely spent folio_queue when we make space, then advance the iterator to the newly allocated folio_queue. The subrequest's iterator will then be set from this. The oops could be triggered using the generic/346 xfstest with a filesystem on9P over TCP with cache=loose. The oops looked something like: BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page ... RIP: 0010:_copy_from_iter+0x2db/0x530 ... Call Trace: <TASK> ... p9pdu_vwritef+0x3d8/0x5d0 p9_client_prepare_req+0xa8/0x140 p9_client_rpc+0x81/0x280 p9_client_write+0xcf/0x1c0 v9fs_issue_write+0x87/0xc0 netfs_advance_write+0xa0/0xb0 netfs_write_folio.isra.0+0x42d/0x500 netfs_writepages+0x15a/0x1f0 do_writepages+0xd1/0x220 filemap_fdatawrite_wbc+0x5c/0x80 v9fs_mmap_vm_close+0x7d/0xb0 remove_vma+0x35/0x70 vms_complete_munmap_vmas+0x11a/0x170 do_vmi_align_munmap+0x17d/0x1c0 do_vmi_munmap+0x13e/0x150 __vm_munmap+0x92/0xd0 __x64_sys_munmap+0x17/0x20 do_syscall_64+0x80/0xe0 entry_SYSCALL_64_after_hwframe+0x71/0x79 This also fixed a similar-looking issue with cifs and generic/074. Fixes: cd0277ed0c18 ("netfs: Use new folio_queue data type and iterator instead of xarray iter") Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202409180928.f20b5a08-oliver.sang@intel.com Closes: https://lore.kernel.org/oe-lkp/202409131438.3f225fbf-oliver.sang@intel.com Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: kernel test robot <oliver.sang@intel.com> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Paulo Alcantara <pc@manguebit.com> cc: Jeff Layton <jlayton@kernel.org> cc: v9fs@lists.linux.dev cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Steve French <stfrench@microsoft.com>
2024-09-26 06:58:30 -07:00
subreq->io_iter = *wreq_iter;
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_enter("R=%x[%x]", wreq->debug_id, subreq->debug_index);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);
netfs: Move max_len/max_nr_segs from netfs_io_subrequest to netfs_io_stream Move max_len/max_nr_segs from struct netfs_io_subrequest to struct netfs_io_stream as we only issue one subreq at a time and then don't need these values again for that subreq unless and until we have to retry it - in which case we want to renegotiate them. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-8-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-07 01:02:58 -07:00
stream->sreq_max_len = UINT_MAX;
stream->sreq_max_segs = INT_MAX;
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
switch (stream->source) {
case NETFS_UPLOAD_TO_SERVER:
netfs_stat(&netfs_n_wh_upload);
netfs: Move max_len/max_nr_segs from netfs_io_subrequest to netfs_io_stream Move max_len/max_nr_segs from struct netfs_io_subrequest to struct netfs_io_stream as we only issue one subreq at a time and then don't need these values again for that subreq unless and until we have to retry it - in which case we want to renegotiate them. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-8-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-07 01:02:58 -07:00
stream->sreq_max_len = wreq->wsize;
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
break;
case NETFS_WRITE_TO_CACHE:
netfs_stat(&netfs_n_wh_write);
break;
default:
WARN_ON_ONCE(1);
break;
}
if (stream->prepare_write)
stream->prepare_write(subreq);
__set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
/* We add to the end of the list whilst the collector may be walking
* the list. The collector only goes nextwards and uses the lock to
* remove entries off of the front.
*/
netfs: Use bh-disabling spinlocks for rreq->lock Use bh-disabling spinlocks when accessing rreq->lock because, in the future, it may be twiddled from softirq context when cleanup is driven from cache backend DIO completion. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-12-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-12 03:54:11 -07:00
spin_lock_bh(&wreq->lock);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
list_add_tail(&subreq->rreq_link, &stream->subrequests);
if (list_is_first(&subreq->rreq_link, &stream->subrequests)) {
stream->front = subreq;
if (!stream->active) {
stream->collected_to = stream->front->start;
/* Write list pointers before active flag */
smp_store_release(&stream->active, true);
}
}
netfs: Use bh-disabling spinlocks for rreq->lock Use bh-disabling spinlocks when accessing rreq->lock because, in the future, it may be twiddled from softirq context when cleanup is driven from cache backend DIO completion. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-12-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-12 03:54:11 -07:00
spin_unlock_bh(&wreq->lock);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
stream->construct = subreq;
}
/*
* Set the I/O iterator for the filesystem/cache to use and dispatch the I/O
* operation. The operation may be asynchronous and should call
* netfs_write_subrequest_terminated() when complete.
*/
static void netfs_do_issue_write(struct netfs_io_stream *stream,
netfs: Simplify the writeback code Use the new folio_queue structures to simplify the writeback code. The problem with referring to the i_pages xarray directly is that we may have gaps in the sequence of folios we're writing from that we need to skip when we're removing the writeback mark from the folios we're writing back from. At the moment the code tries to deal with this by carefully tracking the gaps in each writeback stream (eg. write to server and write to cache) and divining when there's a gap that spans folios (something that's not helped by folios not being a consistent size). Instead, the folio_queue buffer contains pointers only the folios we're dealing with, has them in ascending order and indicates a gap by placing non-consequitive folios next to each other. This makes it possible to track where we need to clean up to by just keeping track of where we've processed to on each stream and taking the minimum. Note that the I/O iterator is always rounded up to the end of the folio, even if that is beyond the EOF position, so that the cache can do DIO from the page. The excess space is cleared, though mmapped writes clobber it. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-18-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-05 23:48:55 -07:00
struct netfs_io_subrequest *subreq)
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
{
struct netfs_io_request *wreq = subreq->rreq;
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_enter("R=%x[%x],%zx", wreq->debug_id, subreq->debug_index, subreq->len);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
if (test_bit(NETFS_SREQ_FAILED, &subreq->flags))
return netfs_write_subrequest_terminated(subreq, subreq->error, false);
trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
stream->issue_write(subreq);
}
void netfs_reissue_write(struct netfs_io_stream *stream,
netfs: Use new folio_queue data type and iterator instead of xarray iter Make the netfs write-side routines use the new folio_queue struct to hold a rolling buffer of folios, with the issuer adding folios at the tail and the collector removing them from the head as they're processed instead of using an xarray. This will allow a subsequent patch to simplify the write collector. The primary mark (as tested by folioq_is_marked()) is used to note if the corresponding folio needs putting. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-16-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:47:07 -07:00
struct netfs_io_subrequest *subreq,
struct iov_iter *source)
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
{
netfs: Simplify the writeback code Use the new folio_queue structures to simplify the writeback code. The problem with referring to the i_pages xarray directly is that we may have gaps in the sequence of folios we're writing from that we need to skip when we're removing the writeback mark from the folios we're writing back from. At the moment the code tries to deal with this by carefully tracking the gaps in each writeback stream (eg. write to server and write to cache) and divining when there's a gap that spans folios (something that's not helped by folios not being a consistent size). Instead, the folio_queue buffer contains pointers only the folios we're dealing with, has them in ascending order and indicates a gap by placing non-consequitive folios next to each other. This makes it possible to track where we need to clean up to by just keeping track of where we've processed to on each stream and taking the minimum. Note that the I/O iterator is always rounded up to the end of the folio, even if that is beyond the EOF position, so that the cache can do DIO from the page. The excess space is cleared, though mmapped writes clobber it. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-18-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-05 23:48:55 -07:00
size_t size = subreq->len - subreq->transferred;
// TODO: Use encrypted buffer
subreq->io_iter = *source;
iov_iter_advance(source, size);
iov_iter_truncate(&subreq->io_iter, size);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
__set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
netfs: Simplify the writeback code Use the new folio_queue structures to simplify the writeback code. The problem with referring to the i_pages xarray directly is that we may have gaps in the sequence of folios we're writing from that we need to skip when we're removing the writeback mark from the folios we're writing back from. At the moment the code tries to deal with this by carefully tracking the gaps in each writeback stream (eg. write to server and write to cache) and divining when there's a gap that spans folios (something that's not helped by folios not being a consistent size). Instead, the folio_queue buffer contains pointers only the folios we're dealing with, has them in ascending order and indicates a gap by placing non-consequitive folios next to each other. This makes it possible to track where we need to clean up to by just keeping track of where we've processed to on each stream and taking the minimum. Note that the I/O iterator is always rounded up to the end of the folio, even if that is beyond the EOF position, so that the cache can do DIO from the page. The excess space is cleared, though mmapped writes clobber it. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-18-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-05 23:48:55 -07:00
netfs_do_issue_write(stream, subreq);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
}
netfs: Speed up buffered reading Improve the efficiency of buffered reads in a number of ways: (1) Overhaul the algorithm in general so that it's a lot more compact and split the read submission code between buffered and unbuffered versions. The unbuffered version can be vastly simplified. (2) Read-result collection is handed off to a work queue rather than being done in the I/O thread. Multiple subrequests can be processes simultaneously. (3) When a subrequest is collected, any folios it fully spans are collected and "spare" data on either side is donated to either the previous or the next subrequest in the sequence. Notes: (*) Readahead expansion is massively slows down fio, presumably because it causes a load of extra allocations, both folio and xarray, up front before RPC requests can be transmitted. (*) RDMA with cifs does appear to work, both with SIW and RXE. (*) PG_private_2-based reading and copy-to-cache is split out into its own file and altered to use folio_queue. Note that the copy to the cache now creates a new write transaction against the cache and adds the folios to be copied into it. This allows it to use part of the writeback I/O code. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-20-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-01 16:40:22 -07:00
void netfs_issue_write(struct netfs_io_request *wreq,
struct netfs_io_stream *stream)
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
{
struct netfs_io_subrequest *subreq = stream->construct;
if (!subreq)
return;
stream->construct = NULL;
netfs: Simplify the writeback code Use the new folio_queue structures to simplify the writeback code. The problem with referring to the i_pages xarray directly is that we may have gaps in the sequence of folios we're writing from that we need to skip when we're removing the writeback mark from the folios we're writing back from. At the moment the code tries to deal with this by carefully tracking the gaps in each writeback stream (eg. write to server and write to cache) and divining when there's a gap that spans folios (something that's not helped by folios not being a consistent size). Instead, the folio_queue buffer contains pointers only the folios we're dealing with, has them in ascending order and indicates a gap by placing non-consequitive folios next to each other. This makes it possible to track where we need to clean up to by just keeping track of where we've processed to on each stream and taking the minimum. Note that the I/O iterator is always rounded up to the end of the folio, even if that is beyond the EOF position, so that the cache can do DIO from the page. The excess space is cleared, though mmapped writes clobber it. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-18-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-05 23:48:55 -07:00
subreq->io_iter.count = subreq->len;
netfs_do_issue_write(stream, subreq);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
}
/*
* Add data to the write subrequest, dispatching each as we fill it up or if it
* is discontiguous with the previous. We only fill one part at a time so that
* we can avoid overrunning the credits obtained (cifs) and try to parallelise
* content-crypto preparation with network writes.
*/
netfs: Speed up buffered reading Improve the efficiency of buffered reads in a number of ways: (1) Overhaul the algorithm in general so that it's a lot more compact and split the read submission code between buffered and unbuffered versions. The unbuffered version can be vastly simplified. (2) Read-result collection is handed off to a work queue rather than being done in the I/O thread. Multiple subrequests can be processes simultaneously. (3) When a subrequest is collected, any folios it fully spans are collected and "spare" data on either side is donated to either the previous or the next subrequest in the sequence. Notes: (*) Readahead expansion is massively slows down fio, presumably because it causes a load of extra allocations, both folio and xarray, up front before RPC requests can be transmitted. (*) RDMA with cifs does appear to work, both with SIW and RXE. (*) PG_private_2-based reading and copy-to-cache is split out into its own file and altered to use folio_queue. Note that the copy to the cache now creates a new write transaction against the cache and adds the folios to be copied into it. This allows it to use part of the writeback I/O code. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-20-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-01 16:40:22 -07:00
int netfs_advance_write(struct netfs_io_request *wreq,
struct netfs_io_stream *stream,
loff_t start, size_t len, bool to_eof)
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
{
struct netfs_io_subrequest *subreq = stream->construct;
size_t part;
if (!stream->avail) {
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_leave("no write");
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
return len;
}
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_enter("R=%x[%x]", wreq->debug_id, subreq ? subreq->debug_index : 0);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
if (subreq && start != subreq->start + subreq->len) {
netfs_issue_write(wreq, stream);
subreq = NULL;
}
if (!stream->construct)
netfs_prepare_write(wreq, stream, start);
subreq = stream->construct;
netfs: Move max_len/max_nr_segs from netfs_io_subrequest to netfs_io_stream Move max_len/max_nr_segs from struct netfs_io_subrequest to struct netfs_io_stream as we only issue one subreq at a time and then don't need these values again for that subreq unless and until we have to retry it - in which case we want to renegotiate them. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-8-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-07 01:02:58 -07:00
part = umin(stream->sreq_max_len - subreq->len, len);
_debug("part %zx/%zx %zx/%zx", subreq->len, stream->sreq_max_len, part, len);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
subreq->len += part;
subreq->nr_segs++;
cachefiles, netfs: Fix write to partial block at EOF Because it uses DIO writes, cachefiles is unable to make a write to the backing file if that write is not aligned to and sized according to the backing file's DIO block alignment. This makes it tricky to handle a write to the cache where the EOF on the network file is not correctly aligned. To get around this, netfslib attempts to tell the driver it is calling how much more data there is available beyond the EOF that it can use to pad the write (netfslib preclears the part of the folio above the EOF). However, it tries to tell the cache what the maximum length is, but doesn't calculate this correctly; and, in any case, cachefiles actually ignores the value and just skips the block. Fix this by: (1) Change the value passed to indicate the amount of extra data that can be added to the operation (now ->submit_extendable_to). This is much simpler to calculate as it's just the end of the folio minus the top of the data within the folio - rather than having to account for data spread over multiple folios. (2) Make cachefiles add some of this data if the subrequest it is given ends at the network file's i_size if the extra data is sufficient to pad out to a whole block. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-22-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-12 04:44:30 -07:00
stream->submit_extendable_to -= part;
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
netfs: Move max_len/max_nr_segs from netfs_io_subrequest to netfs_io_stream Move max_len/max_nr_segs from struct netfs_io_subrequest to struct netfs_io_stream as we only issue one subreq at a time and then don't need these values again for that subreq unless and until we have to retry it - in which case we want to renegotiate them. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-8-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-07 01:02:58 -07:00
if (subreq->len >= stream->sreq_max_len ||
subreq->nr_segs >= stream->sreq_max_segs ||
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
to_eof) {
netfs_issue_write(wreq, stream);
subreq = NULL;
}
return part;
}
/*
* Write some of a pending folio data back to the server.
*/
static int netfs_write_folio(struct netfs_io_request *wreq,
struct writeback_control *wbc,
struct folio *folio)
{
struct netfs_io_stream *upload = &wreq->io_streams[0];
struct netfs_io_stream *cache = &wreq->io_streams[1];
struct netfs_io_stream *stream;
struct netfs_group *fgroup; /* TODO: Use this with ceph */
struct netfs_folio *finfo;
netfs: Advance iterator correctly rather than jumping it In netfs_write_folio(), use iov_iter_advance() to advance the folio as we split bits of it off to subrequests rather than manually jumping the ->iov_offset value around. This becomes more problematic when we use a bounce buffer made out of single-page folios to cover a multipage pagecache folio. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/2238548.1727424522@warthog.procyon.org.uk cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-09-27 01:08:42 -07:00
size_t iter_off = 0;
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
size_t fsize = folio_size(folio), flen = fsize, foff = 0;
loff_t fpos = folio_pos(folio), i_size;
bool to_eof = false, streamw = false;
bool debug = false;
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_enter("");
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
/* netfs_perform_write() may shift i_size around the page or from out
* of the page to beyond it, but cannot move i_size into or through the
* page since we have it locked.
*/
i_size = i_size_read(wreq->inode);
if (fpos >= i_size) {
/* mmap beyond eof. */
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_debug("beyond eof");
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
folio_start_writeback(folio);
folio_unlock(folio);
wreq->nr_group_rel += netfs_folio_written_back(folio);
netfs_put_group_many(wreq->group, wreq->nr_group_rel);
wreq->nr_group_rel = 0;
return 0;
}
if (fpos + fsize > wreq->i_size)
wreq->i_size = i_size;
fgroup = netfs_folio_group(folio);
finfo = netfs_folio_info(folio);
if (finfo) {
foff = finfo->dirty_offset;
flen = foff + finfo->dirty_len;
streamw = true;
}
if (wreq->origin == NETFS_WRITETHROUGH) {
to_eof = false;
if (flen > i_size - fpos)
flen = i_size - fpos;
} else if (flen > i_size - fpos) {
flen = i_size - fpos;
if (!streamw)
folio_zero_segment(folio, flen, fsize);
to_eof = true;
} else if (flen == i_size - fpos) {
to_eof = true;
}
flen -= foff;
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_debug("folio %zx %zx %zx", foff, flen, fsize);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
/* Deal with discontinuities in the stream of dirty pages. These can
* arise from a number of sources:
*
* (1) Intervening non-dirty pages from random-access writes, multiple
* flushers writing back different parts simultaneously and manual
* syncing.
*
* (2) Partially-written pages from write-streaming.
*
* (3) Pages that belong to a different write-back group (eg. Ceph
* snapshots).
*
* (4) Actually-clean pages that were marked for write to the cache
* when they were read. Note that these appear as a special
* write-back group.
*/
if (fgroup == NETFS_FOLIO_COPY_TO_CACHE) {
netfs_issue_write(wreq, upload);
} else if (fgroup != wreq->group) {
/* We can't write this page to the server yet. */
kdebug("wrong group");
folio_redirty_for_writepage(wbc, folio);
folio_unlock(folio);
netfs_issue_write(wreq, upload);
netfs_issue_write(wreq, cache);
return 0;
}
if (foff > 0)
netfs_issue_write(wreq, upload);
if (streamw)
netfs_issue_write(wreq, cache);
/* Flip the page to the writeback state and unlock. If we're called
* from write-through, then the page has already been put into the wb
* state.
*/
if (wreq->origin == NETFS_WRITEBACK)
folio_start_writeback(folio);
folio_unlock(folio);
if (fgroup == NETFS_FOLIO_COPY_TO_CACHE) {
netfs: Cancel dirty folios that have no storage destination Kafs wants to be able to cache the contents of directories (and symlinks), but whilst these are downloaded from the server with the FS.FetchData RPC op and similar, the same as for regular files, they can't be updated by FS.StoreData, but rather have special operations (FS.MakeDir, etc.). Now, rather than redownloading a directory's content after each change made to that directory, kafs modifies the local blob. This blob can be saved out to the cache, and since it's using netfslib, kafs just marks the folios dirty and lets ->writepages() on the directory take care of it, as for an regular file. This is fine as long as there's a cache as although the upload stream is disabled, there's a cache stream to drive the procedure. But if the cache goes away in the meantime, suddenly there's no way do any writes and the code gets confused, complains "R=%x: No submit" to dmesg and leaves the dirty folio hanging. Fix this by just cancelling the store of the folio if neither stream is active. (If there's no cache at the time of dirtying, we should just not mark the folio dirty). Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-23-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-29 04:23:11 -07:00
if (!cache->avail) {
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
trace_netfs_folio(folio, netfs_folio_trace_cancel_copy);
netfs_issue_write(wreq, upload);
netfs_folio_written_back(folio);
return 0;
}
trace_netfs_folio(folio, netfs_folio_trace_store_copy);
netfs: Cancel dirty folios that have no storage destination Kafs wants to be able to cache the contents of directories (and symlinks), but whilst these are downloaded from the server with the FS.FetchData RPC op and similar, the same as for regular files, they can't be updated by FS.StoreData, but rather have special operations (FS.MakeDir, etc.). Now, rather than redownloading a directory's content after each change made to that directory, kafs modifies the local blob. This blob can be saved out to the cache, and since it's using netfslib, kafs just marks the folios dirty and lets ->writepages() on the directory take care of it, as for an regular file. This is fine as long as there's a cache as although the upload stream is disabled, there's a cache stream to drive the procedure. But if the cache goes away in the meantime, suddenly there's no way do any writes and the code gets confused, complains "R=%x: No submit" to dmesg and leaves the dirty folio hanging. Fix this by just cancelling the store of the folio if neither stream is active. (If there's no cache at the time of dirtying, we should just not mark the folio dirty). Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-23-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-29 04:23:11 -07:00
} else if (!upload->avail && !cache->avail) {
trace_netfs_folio(folio, netfs_folio_trace_cancel_store);
netfs_folio_written_back(folio);
return 0;
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
} else if (!upload->construct) {
trace_netfs_folio(folio, netfs_folio_trace_store);
} else {
trace_netfs_folio(folio, netfs_folio_trace_store_plus);
}
netfs: Use new folio_queue data type and iterator instead of xarray iter Make the netfs write-side routines use the new folio_queue struct to hold a rolling buffer of folios, with the issuer adding folios at the tail and the collector removing them from the head as they're processed instead of using an xarray. This will allow a subsequent patch to simplify the write collector. The primary mark (as tested by folioq_is_marked()) is used to note if the corresponding folio needs putting. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-16-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:47:07 -07:00
/* Attach the folio to the rolling buffer. */
netfs_buffer_append_folio(wreq, folio, false);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
/* Move the submission point forward to allow for write-streaming data
* not starting at the front of the page. We don't do write-streaming
* with the cache as the cache requires DIO alignment.
*
* Also skip uploading for data that's been read and just needs copying
* to the cache.
*/
for (int s = 0; s < NR_IO_STREAMS; s++) {
stream = &wreq->io_streams[s];
stream->submit_off = foff;
stream->submit_len = flen;
if ((stream->source == NETFS_WRITE_TO_CACHE && streamw) ||
(stream->source == NETFS_UPLOAD_TO_SERVER &&
fgroup == NETFS_FOLIO_COPY_TO_CACHE)) {
stream->submit_off = UINT_MAX;
stream->submit_len = 0;
}
}
/* Attach the folio to one or more subrequests. For a big folio, we
* could end up with thousands of subrequests if the wsize is small -
* but we might need to wait during the creation of subrequests for
* network resources (eg. SMB credits).
*/
for (;;) {
ssize_t part;
size_t lowest_off = ULONG_MAX;
int choose_s = -1;
/* Always add to the lowest-submitted stream first. */
for (int s = 0; s < NR_IO_STREAMS; s++) {
stream = &wreq->io_streams[s];
if (stream->submit_len > 0 &&
stream->submit_off < lowest_off) {
lowest_off = stream->submit_off;
choose_s = s;
}
}
if (choose_s < 0)
break;
stream = &wreq->io_streams[choose_s];
netfs: Advance iterator correctly rather than jumping it In netfs_write_folio(), use iov_iter_advance() to advance the folio as we split bits of it off to subrequests rather than manually jumping the ->iov_offset value around. This becomes more problematic when we use a bounce buffer made out of single-page folios to cover a multipage pagecache folio. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/2238548.1727424522@warthog.procyon.org.uk cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-09-27 01:08:42 -07:00
/* Advance the iterator(s). */
if (stream->submit_off > iter_off) {
iov_iter_advance(&wreq->io_iter, stream->submit_off - iter_off);
iter_off = stream->submit_off;
}
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
netfs: Simplify the writeback code Use the new folio_queue structures to simplify the writeback code. The problem with referring to the i_pages xarray directly is that we may have gaps in the sequence of folios we're writing from that we need to skip when we're removing the writeback mark from the folios we're writing back from. At the moment the code tries to deal with this by carefully tracking the gaps in each writeback stream (eg. write to server and write to cache) and divining when there's a gap that spans folios (something that's not helped by folios not being a consistent size). Instead, the folio_queue buffer contains pointers only the folios we're dealing with, has them in ascending order and indicates a gap by placing non-consequitive folios next to each other. This makes it possible to track where we need to clean up to by just keeping track of where we've processed to on each stream and taking the minimum. Note that the I/O iterator is always rounded up to the end of the folio, even if that is beyond the EOF position, so that the cache can do DIO from the page. The excess space is cleared, though mmapped writes clobber it. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-18-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-05 23:48:55 -07:00
atomic64_set(&wreq->issued_to, fpos + stream->submit_off);
cachefiles, netfs: Fix write to partial block at EOF Because it uses DIO writes, cachefiles is unable to make a write to the backing file if that write is not aligned to and sized according to the backing file's DIO block alignment. This makes it tricky to handle a write to the cache where the EOF on the network file is not correctly aligned. To get around this, netfslib attempts to tell the driver it is calling how much more data there is available beyond the EOF that it can use to pad the write (netfslib preclears the part of the folio above the EOF). However, it tries to tell the cache what the maximum length is, but doesn't calculate this correctly; and, in any case, cachefiles actually ignores the value and just skips the block. Fix this by: (1) Change the value passed to indicate the amount of extra data that can be added to the operation (now ->submit_extendable_to). This is much simpler to calculate as it's just the end of the folio minus the top of the data within the folio - rather than having to account for data spread over multiple folios. (2) Make cachefiles add some of this data if the subrequest it is given ends at the network file's i_size if the extra data is sufficient to pad out to a whole block. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-22-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-12 04:44:30 -07:00
stream->submit_extendable_to = fsize - stream->submit_off;
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
part = netfs_advance_write(wreq, stream, fpos + stream->submit_off,
stream->submit_len, to_eof);
stream->submit_off += part;
if (part > stream->submit_len)
stream->submit_len = 0;
else
stream->submit_len -= part;
if (part > 0)
debug = true;
}
netfs: Advance iterator correctly rather than jumping it In netfs_write_folio(), use iov_iter_advance() to advance the folio as we split bits of it off to subrequests rather than manually jumping the ->iov_offset value around. This becomes more problematic when we use a bounce buffer made out of single-page folios to cover a multipage pagecache folio. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/2238548.1727424522@warthog.procyon.org.uk cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-09-27 01:08:42 -07:00
if (fsize > iter_off)
iov_iter_advance(&wreq->io_iter, fsize - iter_off);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
atomic64_set(&wreq->issued_to, fpos + fsize);
if (!debug)
kdebug("R=%x: No submit", wreq->debug_id);
netfs: Fix early issue of write op on partial write to folio tail During the writeback procedure, at the end of netfs_write_folio(), pending write operations are flushed if the amount of write-streaming data stored in a page is less than the size of the folio because if we haven't modified a folio to the end, it cannot be contiguous with the following folio... except if the dirty region of the folio is right at the end of the folio space. Fix the test to take the offset into the folio into account as well, such that if the dirty region runs right up to the end of the folio, we leave the flushing for later. Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: Steve French <sfrench@samba.org> cc: Paulo Alcantara <pc@manguebit.com> (DFS, global name space) cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240620173137.610345-4-dhowells@redhat.com Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-05 14:18:04 -07:00
if (foff + flen < fsize)
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
for (int s = 0; s < NR_IO_STREAMS; s++)
netfs_issue_write(wreq, &wreq->io_streams[s]);
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_leave(" = 0");
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
return 0;
}
netfs: Fix missing wakeup after issuing writes After dividing up a proposed write into subrequests, netfslib sets NETFS_RREQ_ALL_QUEUED to indicate to the collector that it can move on to the final cleanup once it has emptied the subrequest queues. Now, whilst the collector will normally end up running at least once after this bit is set just because it takes a while to process all the write subrequests before the collector runs out of subrequests, there exists the possibility that the issuing thread will be forced to sleep and the collector thread will clean up all the subrequests before ALL_QUEUED gets set. In such a case, the collector thread will not get triggered again and will never clear NETFS_RREQ_IN_PROGRESS thus leaving a request uncompleted and causing a potential futute hang. Fix this by scheduling the write collector if all the subrequest queues are empty (and thus no writes pending issuance). Note that we'd do this ideally before queuing the subrequest, but in the case of buffered writeback, at least, we can't find out that we've run out of folios until after we've called writeback_iter() and it has returned NULL - at which point we might not actually have any subrequests still under construction. Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/3317784.1727880350@warthog.procyon.org.uk cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-02 07:45:50 -07:00
/*
* End the issuing of writes, letting the collector know we're done.
*/
static void netfs_end_issue_write(struct netfs_io_request *wreq)
{
bool needs_poke = true;
smp_wmb(); /* Write subreq lists before ALL_QUEUED. */
set_bit(NETFS_RREQ_ALL_QUEUED, &wreq->flags);
for (int s = 0; s < NR_IO_STREAMS; s++) {
struct netfs_io_stream *stream = &wreq->io_streams[s];
if (!stream->active)
continue;
if (!list_empty(&stream->subrequests))
needs_poke = false;
netfs_issue_write(wreq, stream);
}
if (needs_poke)
netfs_wake_write_collector(wreq, false);
}
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
/*
* Write some of the pending data back to the server
*/
netfs: Cut over to using new writeback code Cut over to using the new writeback code. The old code is #ifdef'd out or otherwise removed from compilation to avoid conflicts and will be removed in a future patch. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-08 05:36:05 -07:00
int netfs_writepages(struct address_space *mapping,
struct writeback_control *wbc)
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
{
struct netfs_inode *ictx = netfs_inode(mapping->host);
struct netfs_io_request *wreq = NULL;
struct folio *folio;
int error = 0;
netfs: Record contention stats for writeback lock Record statistics for contention upon the writeback serialisation lock that prevents racing writeback calls from causing each other to interleave their writebacks. These can be viewed in /proc/fs/netfs/stats on the WbLock line, with skip=N indicating the number of non-SYNC writebacks skipped and wait=N indicating the number of SYNC writebacks that waited. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: Steve French <sfrench@samba.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-5-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-31 07:48:29 -07:00
if (!mutex_trylock(&ictx->wb_lock)) {
if (wbc->sync_mode == WB_SYNC_NONE) {
netfs_stat(&netfs_n_wb_lock_skip);
return 0;
}
netfs_stat(&netfs_n_wb_lock_wait);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
mutex_lock(&ictx->wb_lock);
netfs: Record contention stats for writeback lock Record statistics for contention upon the writeback serialisation lock that prevents racing writeback calls from causing each other to interleave their writebacks. These can be viewed in /proc/fs/netfs/stats on the WbLock line, with skip=N indicating the number of non-SYNC writebacks skipped and wait=N indicating the number of SYNC writebacks that waited. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: Steve French <sfrench@samba.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-5-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-31 07:48:29 -07:00
}
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
/* Need the first folio to be able to set up the op. */
folio = writeback_iter(mapping, wbc, NULL, &error);
if (!folio)
goto out;
wreq = netfs_create_write_req(mapping, NULL, folio_pos(folio), NETFS_WRITEBACK);
if (IS_ERR(wreq)) {
error = PTR_ERR(wreq);
goto couldnt_start;
}
trace_netfs_write(wreq, netfs_write_trace_writeback);
netfs: Add some write-side stats and clean up some stat names Add some write-side stats to count buffered writes, buffered writethrough, and writepages calls. Whilst we're at it, clean up the naming on some of the existing stats counters and organise the output into two sets. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-26 01:48:44 -07:00
netfs_stat(&netfs_n_wh_writepages);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
do {
netfs: Simplify the writeback code Use the new folio_queue structures to simplify the writeback code. The problem with referring to the i_pages xarray directly is that we may have gaps in the sequence of folios we're writing from that we need to skip when we're removing the writeback mark from the folios we're writing back from. At the moment the code tries to deal with this by carefully tracking the gaps in each writeback stream (eg. write to server and write to cache) and divining when there's a gap that spans folios (something that's not helped by folios not being a consistent size). Instead, the folio_queue buffer contains pointers only the folios we're dealing with, has them in ascending order and indicates a gap by placing non-consequitive folios next to each other. This makes it possible to track where we need to clean up to by just keeping track of where we've processed to on each stream and taking the minimum. Note that the I/O iterator is always rounded up to the end of the folio, even if that is beyond the EOF position, so that the cache can do DIO from the page. The excess space is cleared, though mmapped writes clobber it. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-18-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-05 23:48:55 -07:00
_debug("wbiter %lx %llx", folio->index, atomic64_read(&wreq->issued_to));
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
/* It appears we don't have to handle cyclic writeback wrapping. */
netfs: Simplify the writeback code Use the new folio_queue structures to simplify the writeback code. The problem with referring to the i_pages xarray directly is that we may have gaps in the sequence of folios we're writing from that we need to skip when we're removing the writeback mark from the folios we're writing back from. At the moment the code tries to deal with this by carefully tracking the gaps in each writeback stream (eg. write to server and write to cache) and divining when there's a gap that spans folios (something that's not helped by folios not being a consistent size). Instead, the folio_queue buffer contains pointers only the folios we're dealing with, has them in ascending order and indicates a gap by placing non-consequitive folios next to each other. This makes it possible to track where we need to clean up to by just keeping track of where we've processed to on each stream and taking the minimum. Note that the I/O iterator is always rounded up to the end of the folio, even if that is beyond the EOF position, so that the cache can do DIO from the page. The excess space is cleared, though mmapped writes clobber it. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-18-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-05 23:48:55 -07:00
WARN_ON_ONCE(wreq && folio_pos(folio) < atomic64_read(&wreq->issued_to));
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
if (netfs_folio_group(folio) != NETFS_FOLIO_COPY_TO_CACHE &&
unlikely(!test_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags))) {
set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags);
wreq->netfs_ops->begin_writeback(wreq);
}
error = netfs_write_folio(wreq, wbc, folio);
if (error < 0)
break;
} while ((folio = writeback_iter(mapping, wbc, folio, &error)));
netfs: Fix missing wakeup after issuing writes After dividing up a proposed write into subrequests, netfslib sets NETFS_RREQ_ALL_QUEUED to indicate to the collector that it can move on to the final cleanup once it has emptied the subrequest queues. Now, whilst the collector will normally end up running at least once after this bit is set just because it takes a while to process all the write subrequests before the collector runs out of subrequests, there exists the possibility that the issuing thread will be forced to sleep and the collector thread will clean up all the subrequests before ALL_QUEUED gets set. In such a case, the collector thread will not get triggered again and will never clear NETFS_RREQ_IN_PROGRESS thus leaving a request uncompleted and causing a potential futute hang. Fix this by scheduling the write collector if all the subrequest queues are empty (and thus no writes pending issuance). Note that we'd do this ideally before queuing the subrequest, but in the case of buffered writeback, at least, we can't find out that we've run out of folios until after we've called writeback_iter() and it has returned NULL - at which point we might not actually have any subrequests still under construction. Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/3317784.1727880350@warthog.procyon.org.uk cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-02 07:45:50 -07:00
netfs_end_issue_write(wreq);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
mutex_unlock(&ictx->wb_lock);
netfs_put_request(wreq, false, netfs_rreq_trace_put_return);
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_leave(" = %d", error);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
return error;
couldnt_start:
netfs_kill_dirty_pages(mapping, wbc, folio);
out:
mutex_unlock(&ictx->wb_lock);
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_leave(" = %d", error);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
return error;
}
netfs: Cut over to using new writeback code Cut over to using the new writeback code. The old code is #ifdef'd out or otherwise removed from compilation to avoid conflicts and will be removed in a future patch. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-08 05:36:05 -07:00
EXPORT_SYMBOL(netfs_writepages);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
/*
* Begin a write operation for writing through the pagecache.
*/
netfs: Cut over to using new writeback code Cut over to using the new writeback code. The old code is #ifdef'd out or otherwise removed from compilation to avoid conflicts and will be removed in a future patch. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-08 05:36:05 -07:00
struct netfs_io_request *netfs_begin_writethrough(struct kiocb *iocb, size_t len)
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
{
struct netfs_io_request *wreq = NULL;
struct netfs_inode *ictx = netfs_inode(file_inode(iocb->ki_filp));
mutex_lock(&ictx->wb_lock);
wreq = netfs_create_write_req(iocb->ki_filp->f_mapping, iocb->ki_filp,
iocb->ki_pos, NETFS_WRITETHROUGH);
if (IS_ERR(wreq)) {
mutex_unlock(&ictx->wb_lock);
return wreq;
}
wreq->io_streams[0].avail = true;
trace_netfs_write(wreq, netfs_write_trace_writethrough);
return wreq;
}
/*
* Advance the state of the write operation used when writing through the
* pagecache. Data has been copied into the pagecache that we need to append
* to the request. If we've added more than wsize then we need to create a new
* subrequest.
*/
netfs: Cut over to using new writeback code Cut over to using the new writeback code. The old code is #ifdef'd out or otherwise removed from compilation to avoid conflicts and will be removed in a future patch. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-08 05:36:05 -07:00
int netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
struct folio *folio, size_t copied, bool to_page_end,
struct folio **writethrough_cache)
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
{
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_enter("R=%x ic=%zu ws=%u cp=%zu tp=%u",
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
wreq->debug_id, wreq->iter.count, wreq->wsize, copied, to_page_end);
if (!*writethrough_cache) {
if (folio_test_dirty(folio))
/* Sigh. mmap. */
folio_clear_dirty_for_io(folio);
/* We can make multiple writes to the folio... */
folio_start_writeback(folio);
if (wreq->len == 0)
trace_netfs_folio(folio, netfs_folio_trace_wthru);
else
trace_netfs_folio(folio, netfs_folio_trace_wthru_plus);
*writethrough_cache = folio;
}
wreq->len += copied;
if (!to_page_end)
return 0;
*writethrough_cache = NULL;
return netfs_write_folio(wreq, wbc, folio);
}
/*
* End a write operation used when writing through the pagecache.
*/
netfs: Cut over to using new writeback code Cut over to using the new writeback code. The old code is #ifdef'd out or otherwise removed from compilation to avoid conflicts and will be removed in a future patch. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-08 05:36:05 -07:00
int netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
struct folio *writethrough_cache)
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
{
struct netfs_inode *ictx = netfs_inode(wreq->inode);
int ret;
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_enter("R=%x", wreq->debug_id);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
if (writethrough_cache)
netfs_write_folio(wreq, wbc, writethrough_cache);
netfs: Fix missing wakeup after issuing writes After dividing up a proposed write into subrequests, netfslib sets NETFS_RREQ_ALL_QUEUED to indicate to the collector that it can move on to the final cleanup once it has emptied the subrequest queues. Now, whilst the collector will normally end up running at least once after this bit is set just because it takes a while to process all the write subrequests before the collector runs out of subrequests, there exists the possibility that the issuing thread will be forced to sleep and the collector thread will clean up all the subrequests before ALL_QUEUED gets set. In such a case, the collector thread will not get triggered again and will never clear NETFS_RREQ_IN_PROGRESS thus leaving a request uncompleted and causing a potential futute hang. Fix this by scheduling the write collector if all the subrequest queues are empty (and thus no writes pending issuance). Note that we'd do this ideally before queuing the subrequest, but in the case of buffered writeback, at least, we can't find out that we've run out of folios until after we've called writeback_iter() and it has returned NULL - at which point we might not actually have any subrequests still under construction. Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/3317784.1727880350@warthog.procyon.org.uk cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-02 07:45:50 -07:00
netfs_end_issue_write(wreq);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
mutex_unlock(&ictx->wb_lock);
netfs: Fix AIO error handling when doing write-through If an error occurs whilst we're doing an AIO write in write-through mode, we may end up calling ->ki_complete() *and* returning an error from ->write_iter(). This can result in either a UAF (the ->ki_complete() func pointer may get overwritten, for example) or a refcount underflow in io_submit() as ->ki_complete is called twice. Fix this by making netfs_end_writethrough() - and thus netfs_perform_write() - unconditionally return -EIOCBQUEUED if we're doing an AIO write and wait for completion if we're not. Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/295052.1716298587@warthog.procyon.org.uk cc: Jeff Layton <jlayton@kernel.org> cc: Enzo Matsumiya <ematsumiya@suse.de> cc: netfs@lists.linux.dev cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-21 06:36:27 -07:00
if (wreq->iocb) {
ret = -EIOCBQUEUED;
} else {
wait_on_bit(&wreq->flags, NETFS_RREQ_IN_PROGRESS, TASK_UNINTERRUPTIBLE);
ret = wreq->error;
}
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
netfs_put_request(wreq, false, netfs_rreq_trace_put_return);
return ret;
}
/*
* Write data to the server without going through the pagecache and without
* writing it to the local cache.
*/
int netfs_unbuffered_write(struct netfs_io_request *wreq, bool may_wait, size_t len)
{
struct netfs_io_stream *upload = &wreq->io_streams[0];
ssize_t part;
loff_t start = wreq->start;
int error = 0;
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_enter("%zx", len);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
if (wreq->origin == NETFS_DIO_WRITE)
inode_dio_begin(wreq->inode);
while (len) {
// TODO: Prepare content encryption
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_debug("unbuffered %zx", len);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
part = netfs_advance_write(wreq, upload, start, len, false);
start += part;
len -= part;
netfs: Simplify the writeback code Use the new folio_queue structures to simplify the writeback code. The problem with referring to the i_pages xarray directly is that we may have gaps in the sequence of folios we're writing from that we need to skip when we're removing the writeback mark from the folios we're writing back from. At the moment the code tries to deal with this by carefully tracking the gaps in each writeback stream (eg. write to server and write to cache) and divining when there's a gap that spans folios (something that's not helped by folios not being a consistent size). Instead, the folio_queue buffer contains pointers only the folios we're dealing with, has them in ascending order and indicates a gap by placing non-consequitive folios next to each other. This makes it possible to track where we need to clean up to by just keeping track of where we've processed to on each stream and taking the minimum. Note that the I/O iterator is always rounded up to the end of the folio, even if that is beyond the EOF position, so that the cache can do DIO from the page. The excess space is cleared, though mmapped writes clobber it. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/20240814203850.2240469-18-dhowells@redhat.com/ # v2 Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-05 23:48:55 -07:00
iov_iter_advance(&wreq->io_iter, part);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
if (test_bit(NETFS_RREQ_PAUSE, &wreq->flags)) {
trace_netfs_rreq(wreq, netfs_rreq_trace_wait_pause);
wait_on_bit(&wreq->flags, NETFS_RREQ_PAUSE, TASK_UNINTERRUPTIBLE);
}
if (test_bit(NETFS_RREQ_FAILED, &wreq->flags))
break;
}
netfs: Fix missing wakeup after issuing writes After dividing up a proposed write into subrequests, netfslib sets NETFS_RREQ_ALL_QUEUED to indicate to the collector that it can move on to the final cleanup once it has emptied the subrequest queues. Now, whilst the collector will normally end up running at least once after this bit is set just because it takes a while to process all the write subrequests before the collector runs out of subrequests, there exists the possibility that the issuing thread will be forced to sleep and the collector thread will clean up all the subrequests before ALL_QUEUED gets set. In such a case, the collector thread will not get triggered again and will never clear NETFS_RREQ_IN_PROGRESS thus leaving a request uncompleted and causing a potential futute hang. Fix this by scheduling the write collector if all the subrequest queues are empty (and thus no writes pending issuance). Note that we'd do this ideally before queuing the subrequest, but in the case of buffered writeback, at least, we can't find out that we've run out of folios until after we've called writeback_iter() and it has returned NULL - at which point we might not actually have any subrequests still under construction. Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/3317784.1727880350@warthog.procyon.org.uk cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-02 07:45:50 -07:00
netfs_end_issue_write(wreq);
netfs: Revert "netfs: Switch debug logging to pr_debug()" Revert commit 163eae0fb0d4c610c59a8de38040f8e12f89fd43 to get back the original operation of the debugging macros. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20240608151352.22860-2-ukleinek@kernel.org Link: https://lore.kernel.org/r/1410685.1721333252@warthog.procyon.org.uk cc: Uwe Kleine-König <ukleinek@kernel.org> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-18 13:07:32 -07:00
_leave(" = %d", error);
netfs: New writeback implementation The current netfslib writeback implementation creates writeback requests of contiguous folio data and then separately tiles subrequests over the space twice, once for the server and once for the cache. This creates a few issues: (1) Every time there's a discontiguity or a change between writing to only one destination or writing to both, it must create a new request. This makes it harder to do vectored writes. (2) The folios don't have the writeback mark removed until the end of the request - and a request could be hundreds of megabytes. (3) In future, I want to support a larger cache granularity, which will require aggregation of some folios that contain unmodified data (which only need to go to the cache) and some which contain modifications (which need to be uploaded and stored to the cache) - but, currently, these are treated as discontiguous. There's also a move to get everyone to use writeback_iter() to extract writable folios from the pagecache. That said, currently writeback_iter() has some issues that make it less than ideal: (1) there's no way to cancel the iteration, even if you find a "temporary" error that means the current folio and all subsequent folios are going to fail; (2) there's no way to filter the folios being written back - something that will impact Ceph with it's ordered snap system; (3) and if you get a folio you can't immediately deal with (say you need to flush the preceding writes), you are left with a folio hanging in the locked state for the duration, when really we should unlock it and relock it later. In this new implementation, I use writeback_iter() to pump folios, progressively creating two parallel, but separate streams and cleaning up the finished folios as the subrequests complete. Either or both streams can contain gaps, and the subrequests in each stream can be of variable size, don't need to align with each other and don't need to align with the folios. Indeed, subrequests can cross folio boundaries, may cover several folios or a folio may be spanned by multiple folios, e.g.: +---+---+-----+-----+---+----------+ Folios: | | | | | | | +---+---+-----+-----+---+----------+ +------+------+ +----+----+ Upload: | | |.....| | | +------+------+ +----+----+ +------+------+------+------+------+ Cache: | | | | | | +------+------+------+------+------+ The progressive subrequest construction permits the algorithm to be preparing both the next upload to the server and the next write to the cache whilst the previous ones are already in progress. Throttling can be applied to control the rate of production of subrequests - and, in any case, we probably want to write them to the server in ascending order, particularly if the file will be extended. Content crypto can also be prepared at the same time as the subrequests and run asynchronously, with the prepped requests being stalled until the crypto catches up with them. This might also be useful for transport crypto, but that happens at a lower layer, so probably would be harder to pull off. The algorithm is split into three parts: (1) The issuer. This walks through the data, packaging it up, encrypting it and creating subrequests. The part of this that generates subrequests only deals with file positions and spans and so is usable for DIO/unbuffered writes as well as buffered writes. (2) The collector. This asynchronously collects completed subrequests, unlocks folios, frees crypto buffers and performs any retries. This runs in a work queue so that the issuer can return to the caller for writeback (so that the VM can have its kswapd thread back) or async writes. (3) The retryer. This pauses the issuer, waits for all outstanding subrequests to complete and then goes through the failed subrequests to reissue them. This may involve reprepping them (with cifs, the credits must be renegotiated, and a subrequest may need splitting), and doing RMW for content crypto if there's a conflicting change on the server. [!] Note that some of the functions are prefixed with "new_" to avoid clashes with existing functions. These will be renamed in a later patch that cuts over to the new algorithm. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: Eric Van Hensbergen <ericvh@kernel.org> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org
2024-03-18 09:52:05 -07:00
return error;
}
Copy Permalink