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linux/fs/xfs/xfs_aops.c
Vivek Goyal 3f666c56c6 dax: Pass dax_dev instead of bdev to dax_writeback_mapping_range()
As of now dax_writeback_mapping_range() takes "struct block_device" as a
parameter and dax_dev is searched from bdev name. This also involves taking
a fresh reference on dax_dev and putting that reference at the end of
function.

We are developing a new filesystem virtio-fs and using dax to access host
page cache directly. But there is no block device. IOW, we want to make
use of dax but want to get rid of this assumption that there is always
a block device associated with dax_dev.

So pass in "struct dax_device" as parameter instead of bdev.

ext2/ext4/xfs are current users and they already have a reference on
dax_device. So there is no need to take reference and drop reference to
dax_device on each call of this function.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Link: https://lore.kernel.org/r/20200103183307.GB13350@redhat.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2020-01-03 11:13:12 -08:00

668 lines
18 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2005 Silicon Graphics, Inc.
* Copyright (c) 2016-2018 Christoph Hellwig.
* All Rights Reserved.
*/
#include "xfs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_iomap.h"
#include "xfs_trace.h"
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_reflink.h"
struct xfs_writepage_ctx {
struct iomap_writepage_ctx ctx;
unsigned int data_seq;
unsigned int cow_seq;
};
static inline struct xfs_writepage_ctx *
XFS_WPC(struct iomap_writepage_ctx *ctx)
{
return container_of(ctx, struct xfs_writepage_ctx, ctx);
}
/*
* Fast and loose check if this write could update the on-disk inode size.
*/
static inline bool xfs_ioend_is_append(struct iomap_ioend *ioend)
{
return ioend->io_offset + ioend->io_size >
XFS_I(ioend->io_inode)->i_d.di_size;
}
STATIC int
xfs_setfilesize_trans_alloc(
struct iomap_ioend *ioend)
{
struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount;
struct xfs_trans *tp;
int error;
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);
if (error)
return error;
ioend->io_private = tp;
/*
* We may pass freeze protection with a transaction. So tell lockdep
* we released it.
*/
__sb_writers_release(ioend->io_inode->i_sb, SB_FREEZE_FS);
/*
* We hand off the transaction to the completion thread now, so
* clear the flag here.
*/
current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
return 0;
}
/*
* Update on-disk file size now that data has been written to disk.
*/
STATIC int
__xfs_setfilesize(
struct xfs_inode *ip,
struct xfs_trans *tp,
xfs_off_t offset,
size_t size)
{
xfs_fsize_t isize;
xfs_ilock(ip, XFS_ILOCK_EXCL);
isize = xfs_new_eof(ip, offset + size);
if (!isize) {
xfs_iunlock(ip, XFS_ILOCK_EXCL);
xfs_trans_cancel(tp);
return 0;
}
trace_xfs_setfilesize(ip, offset, size);
ip->i_d.di_size = isize;
xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
return xfs_trans_commit(tp);
}
int
xfs_setfilesize(
struct xfs_inode *ip,
xfs_off_t offset,
size_t size)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_trans *tp;
int error;
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);
if (error)
return error;
return __xfs_setfilesize(ip, tp, offset, size);
}
STATIC int
xfs_setfilesize_ioend(
struct iomap_ioend *ioend,
int error)
{
struct xfs_inode *ip = XFS_I(ioend->io_inode);
struct xfs_trans *tp = ioend->io_private;
/*
* The transaction may have been allocated in the I/O submission thread,
* thus we need to mark ourselves as being in a transaction manually.
* Similarly for freeze protection.
*/
current_set_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
__sb_writers_acquired(VFS_I(ip)->i_sb, SB_FREEZE_FS);
/* we abort the update if there was an IO error */
if (error) {
xfs_trans_cancel(tp);
return error;
}
return __xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size);
}
/*
* IO write completion.
*/
STATIC void
xfs_end_ioend(
struct iomap_ioend *ioend)
{
struct xfs_inode *ip = XFS_I(ioend->io_inode);
xfs_off_t offset = ioend->io_offset;
size_t size = ioend->io_size;
unsigned int nofs_flag;
int error;
/*
* We can allocate memory here while doing writeback on behalf of
* memory reclaim. To avoid memory allocation deadlocks set the
* task-wide nofs context for the following operations.
*/
nofs_flag = memalloc_nofs_save();
/*
* Just clean up the in-memory strutures if the fs has been shut down.
*/
if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
error = -EIO;
goto done;
}
/*
* Clean up any COW blocks on an I/O error.
*/
error = blk_status_to_errno(ioend->io_bio->bi_status);
if (unlikely(error)) {
if (ioend->io_flags & IOMAP_F_SHARED)
xfs_reflink_cancel_cow_range(ip, offset, size, true);
goto done;
}
/*
* Success: commit the COW or unwritten blocks if needed.
*/
if (ioend->io_flags & IOMAP_F_SHARED)
error = xfs_reflink_end_cow(ip, offset, size);
else if (ioend->io_type == IOMAP_UNWRITTEN)
error = xfs_iomap_write_unwritten(ip, offset, size, false);
else
ASSERT(!xfs_ioend_is_append(ioend) || ioend->io_private);
done:
if (ioend->io_private)
error = xfs_setfilesize_ioend(ioend, error);
iomap_finish_ioends(ioend, error);
memalloc_nofs_restore(nofs_flag);
}
/*
* If the to be merged ioend has a preallocated transaction for file
* size updates we need to ensure the ioend it is merged into also
* has one. If it already has one we can simply cancel the transaction
* as it is guaranteed to be clean.
*/
static void
xfs_ioend_merge_private(
struct iomap_ioend *ioend,
struct iomap_ioend *next)
{
if (!ioend->io_private) {
ioend->io_private = next->io_private;
next->io_private = NULL;
} else {
xfs_setfilesize_ioend(next, -ECANCELED);
}
}
/* Finish all pending io completions. */
void
xfs_end_io(
struct work_struct *work)
{
struct xfs_inode *ip =
container_of(work, struct xfs_inode, i_ioend_work);
struct iomap_ioend *ioend;
struct list_head tmp;
unsigned long flags;
spin_lock_irqsave(&ip->i_ioend_lock, flags);
list_replace_init(&ip->i_ioend_list, &tmp);
spin_unlock_irqrestore(&ip->i_ioend_lock, flags);
iomap_sort_ioends(&tmp);
while ((ioend = list_first_entry_or_null(&tmp, struct iomap_ioend,
io_list))) {
list_del_init(&ioend->io_list);
iomap_ioend_try_merge(ioend, &tmp, xfs_ioend_merge_private);
xfs_end_ioend(ioend);
}
}
static inline bool xfs_ioend_needs_workqueue(struct iomap_ioend *ioend)
{
return ioend->io_private ||
ioend->io_type == IOMAP_UNWRITTEN ||
(ioend->io_flags & IOMAP_F_SHARED);
}
STATIC void
xfs_end_bio(
struct bio *bio)
{
struct iomap_ioend *ioend = bio->bi_private;
struct xfs_inode *ip = XFS_I(ioend->io_inode);
unsigned long flags;
ASSERT(xfs_ioend_needs_workqueue(ioend));
spin_lock_irqsave(&ip->i_ioend_lock, flags);
if (list_empty(&ip->i_ioend_list))
WARN_ON_ONCE(!queue_work(ip->i_mount->m_unwritten_workqueue,
&ip->i_ioend_work));
list_add_tail(&ioend->io_list, &ip->i_ioend_list);
spin_unlock_irqrestore(&ip->i_ioend_lock, flags);
}
/*
* Fast revalidation of the cached writeback mapping. Return true if the current
* mapping is valid, false otherwise.
*/
static bool
xfs_imap_valid(
struct iomap_writepage_ctx *wpc,
struct xfs_inode *ip,
loff_t offset)
{
if (offset < wpc->iomap.offset ||
offset >= wpc->iomap.offset + wpc->iomap.length)
return false;
/*
* If this is a COW mapping, it is sufficient to check that the mapping
* covers the offset. Be careful to check this first because the caller
* can revalidate a COW mapping without updating the data seqno.
*/
if (wpc->iomap.flags & IOMAP_F_SHARED)
return true;
/*
* This is not a COW mapping. Check the sequence number of the data fork
* because concurrent changes could have invalidated the extent. Check
* the COW fork because concurrent changes since the last time we
* checked (and found nothing at this offset) could have added
* overlapping blocks.
*/
if (XFS_WPC(wpc)->data_seq != READ_ONCE(ip->i_df.if_seq))
return false;
if (xfs_inode_has_cow_data(ip) &&
XFS_WPC(wpc)->cow_seq != READ_ONCE(ip->i_cowfp->if_seq))
return false;
return true;
}
/*
* Pass in a dellalloc extent and convert it to real extents, return the real
* extent that maps offset_fsb in wpc->iomap.
*
* The current page is held locked so nothing could have removed the block
* backing offset_fsb, although it could have moved from the COW to the data
* fork by another thread.
*/
static int
xfs_convert_blocks(
struct iomap_writepage_ctx *wpc,
struct xfs_inode *ip,
int whichfork,
loff_t offset)
{
int error;
unsigned *seq;
if (whichfork == XFS_COW_FORK)
seq = &XFS_WPC(wpc)->cow_seq;
else
seq = &XFS_WPC(wpc)->data_seq;
/*
* Attempt to allocate whatever delalloc extent currently backs offset
* and put the result into wpc->iomap. Allocate in a loop because it
* may take several attempts to allocate real blocks for a contiguous
* delalloc extent if free space is sufficiently fragmented.
*/
do {
error = xfs_bmapi_convert_delalloc(ip, whichfork, offset,
&wpc->iomap, seq);
if (error)
return error;
} while (wpc->iomap.offset + wpc->iomap.length <= offset);
return 0;
}
static int
xfs_map_blocks(
struct iomap_writepage_ctx *wpc,
struct inode *inode,
loff_t offset)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
ssize_t count = i_blocksize(inode);
xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
xfs_fileoff_t cow_fsb = NULLFILEOFF;
int whichfork = XFS_DATA_FORK;
struct xfs_bmbt_irec imap;
struct xfs_iext_cursor icur;
int retries = 0;
int error = 0;
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
/*
* COW fork blocks can overlap data fork blocks even if the blocks
* aren't shared. COW I/O always takes precedent, so we must always
* check for overlap on reflink inodes unless the mapping is already a
* COW one, or the COW fork hasn't changed from the last time we looked
* at it.
*
* It's safe to check the COW fork if_seq here without the ILOCK because
* we've indirectly protected against concurrent updates: writeback has
* the page locked, which prevents concurrent invalidations by reflink
* and directio and prevents concurrent buffered writes to the same
* page. Changes to if_seq always happen under i_lock, which protects
* against concurrent updates and provides a memory barrier on the way
* out that ensures that we always see the current value.
*/
if (xfs_imap_valid(wpc, ip, offset))
return 0;
/*
* If we don't have a valid map, now it's time to get a new one for this
* offset. This will convert delayed allocations (including COW ones)
* into real extents. If we return without a valid map, it means we
* landed in a hole and we skip the block.
*/
retry:
xfs_ilock(ip, XFS_ILOCK_SHARED);
ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
(ip->i_df.if_flags & XFS_IFEXTENTS));
/*
* Check if this is offset is covered by a COW extents, and if yes use
* it directly instead of looking up anything in the data fork.
*/
if (xfs_inode_has_cow_data(ip) &&
xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &imap))
cow_fsb = imap.br_startoff;
if (cow_fsb != NULLFILEOFF && cow_fsb <= offset_fsb) {
XFS_WPC(wpc)->cow_seq = READ_ONCE(ip->i_cowfp->if_seq);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
whichfork = XFS_COW_FORK;
goto allocate_blocks;
}
/*
* No COW extent overlap. Revalidate now that we may have updated
* ->cow_seq. If the data mapping is still valid, we're done.
*/
if (xfs_imap_valid(wpc, ip, offset)) {
xfs_iunlock(ip, XFS_ILOCK_SHARED);
return 0;
}
/*
* If we don't have a valid map, now it's time to get a new one for this
* offset. This will convert delayed allocations (including COW ones)
* into real extents.
*/
if (!xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap))
imap.br_startoff = end_fsb; /* fake a hole past EOF */
XFS_WPC(wpc)->data_seq = READ_ONCE(ip->i_df.if_seq);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
/* landed in a hole or beyond EOF? */
if (imap.br_startoff > offset_fsb) {
imap.br_blockcount = imap.br_startoff - offset_fsb;
imap.br_startoff = offset_fsb;
imap.br_startblock = HOLESTARTBLOCK;
imap.br_state = XFS_EXT_NORM;
}
/*
* Truncate to the next COW extent if there is one. This is the only
* opportunity to do this because we can skip COW fork lookups for the
* subsequent blocks in the mapping; however, the requirement to treat
* the COW range separately remains.
*/
if (cow_fsb != NULLFILEOFF &&
cow_fsb < imap.br_startoff + imap.br_blockcount)
imap.br_blockcount = cow_fsb - imap.br_startoff;
/* got a delalloc extent? */
if (imap.br_startblock != HOLESTARTBLOCK &&
isnullstartblock(imap.br_startblock))
goto allocate_blocks;
xfs_bmbt_to_iomap(ip, &wpc->iomap, &imap, 0);
trace_xfs_map_blocks_found(ip, offset, count, whichfork, &imap);
return 0;
allocate_blocks:
error = xfs_convert_blocks(wpc, ip, whichfork, offset);
if (error) {
/*
* If we failed to find the extent in the COW fork we might have
* raced with a COW to data fork conversion or truncate.
* Restart the lookup to catch the extent in the data fork for
* the former case, but prevent additional retries to avoid
* looping forever for the latter case.
*/
if (error == -EAGAIN && whichfork == XFS_COW_FORK && !retries++)
goto retry;
ASSERT(error != -EAGAIN);
return error;
}
/*
* Due to merging the return real extent might be larger than the
* original delalloc one. Trim the return extent to the next COW
* boundary again to force a re-lookup.
*/
if (whichfork != XFS_COW_FORK && cow_fsb != NULLFILEOFF) {
loff_t cow_offset = XFS_FSB_TO_B(mp, cow_fsb);
if (cow_offset < wpc->iomap.offset + wpc->iomap.length)
wpc->iomap.length = cow_offset - wpc->iomap.offset;
}
ASSERT(wpc->iomap.offset <= offset);
ASSERT(wpc->iomap.offset + wpc->iomap.length > offset);
trace_xfs_map_blocks_alloc(ip, offset, count, whichfork, &imap);
return 0;
}
static int
xfs_prepare_ioend(
struct iomap_ioend *ioend,
int status)
{
unsigned int nofs_flag;
/*
* We can allocate memory here while doing writeback on behalf of
* memory reclaim. To avoid memory allocation deadlocks set the
* task-wide nofs context for the following operations.
*/
nofs_flag = memalloc_nofs_save();
/* Convert CoW extents to regular */
if (!status && (ioend->io_flags & IOMAP_F_SHARED)) {
status = xfs_reflink_convert_cow(XFS_I(ioend->io_inode),
ioend->io_offset, ioend->io_size);
}
/* Reserve log space if we might write beyond the on-disk inode size. */
if (!status &&
((ioend->io_flags & IOMAP_F_SHARED) ||
ioend->io_type != IOMAP_UNWRITTEN) &&
xfs_ioend_is_append(ioend) &&
!ioend->io_private)
status = xfs_setfilesize_trans_alloc(ioend);
memalloc_nofs_restore(nofs_flag);
if (xfs_ioend_needs_workqueue(ioend))
ioend->io_bio->bi_end_io = xfs_end_bio;
return status;
}
/*
* If the page has delalloc blocks on it, we need to punch them out before we
* invalidate the page. If we don't, we leave a stale delalloc mapping on the
* inode that can trip up a later direct I/O read operation on the same region.
*
* We prevent this by truncating away the delalloc regions on the page. Because
* they are delalloc, we can do this without needing a transaction. Indeed - if
* we get ENOSPC errors, we have to be able to do this truncation without a
* transaction as there is no space left for block reservation (typically why we
* see a ENOSPC in writeback).
*/
static void
xfs_discard_page(
struct page *page)
{
struct inode *inode = page->mapping->host;
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
loff_t offset = page_offset(page);
xfs_fileoff_t start_fsb = XFS_B_TO_FSBT(mp, offset);
int error;
if (XFS_FORCED_SHUTDOWN(mp))
goto out_invalidate;
xfs_alert(mp,
"page discard on page "PTR_FMT", inode 0x%llx, offset %llu.",
page, ip->i_ino, offset);
error = xfs_bmap_punch_delalloc_range(ip, start_fsb,
PAGE_SIZE / i_blocksize(inode));
if (error && !XFS_FORCED_SHUTDOWN(mp))
xfs_alert(mp, "page discard unable to remove delalloc mapping.");
out_invalidate:
iomap_invalidatepage(page, 0, PAGE_SIZE);
}
static const struct iomap_writeback_ops xfs_writeback_ops = {
.map_blocks = xfs_map_blocks,
.prepare_ioend = xfs_prepare_ioend,
.discard_page = xfs_discard_page,
};
STATIC int
xfs_vm_writepage(
struct page *page,
struct writeback_control *wbc)
{
struct xfs_writepage_ctx wpc = { };
return iomap_writepage(page, wbc, &wpc.ctx, &xfs_writeback_ops);
}
STATIC int
xfs_vm_writepages(
struct address_space *mapping,
struct writeback_control *wbc)
{
struct xfs_writepage_ctx wpc = { };
xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
return iomap_writepages(mapping, wbc, &wpc.ctx, &xfs_writeback_ops);
}
STATIC int
xfs_dax_writepages(
struct address_space *mapping,
struct writeback_control *wbc)
{
struct xfs_inode *ip = XFS_I(mapping->host);
xfs_iflags_clear(ip, XFS_ITRUNCATED);
return dax_writeback_mapping_range(mapping,
xfs_inode_buftarg(ip)->bt_daxdev, wbc);
}
STATIC sector_t
xfs_vm_bmap(
struct address_space *mapping,
sector_t block)
{
struct xfs_inode *ip = XFS_I(mapping->host);
trace_xfs_vm_bmap(ip);
/*
* The swap code (ab-)uses ->bmap to get a block mapping and then
* bypasses the file system for actual I/O. We really can't allow
* that on reflinks inodes, so we have to skip out here. And yes,
* 0 is the magic code for a bmap error.
*
* Since we don't pass back blockdev info, we can't return bmap
* information for rt files either.
*/
if (xfs_is_cow_inode(ip) || XFS_IS_REALTIME_INODE(ip))
return 0;
return iomap_bmap(mapping, block, &xfs_read_iomap_ops);
}
STATIC int
xfs_vm_readpage(
struct file *unused,
struct page *page)
{
return iomap_readpage(page, &xfs_read_iomap_ops);
}
STATIC int
xfs_vm_readpages(
struct file *unused,
struct address_space *mapping,
struct list_head *pages,
unsigned nr_pages)
{
return iomap_readpages(mapping, pages, nr_pages, &xfs_read_iomap_ops);
}
static int
xfs_iomap_swapfile_activate(
struct swap_info_struct *sis,
struct file *swap_file,
sector_t *span)
{
sis->bdev = xfs_inode_buftarg(XFS_I(file_inode(swap_file)))->bt_bdev;
return iomap_swapfile_activate(sis, swap_file, span,
&xfs_read_iomap_ops);
}
const struct address_space_operations xfs_address_space_operations = {
.readpage = xfs_vm_readpage,
.readpages = xfs_vm_readpages,
.writepage = xfs_vm_writepage,
.writepages = xfs_vm_writepages,
.set_page_dirty = iomap_set_page_dirty,
.releasepage = iomap_releasepage,
.invalidatepage = iomap_invalidatepage,
.bmap = xfs_vm_bmap,
.direct_IO = noop_direct_IO,
.migratepage = iomap_migrate_page,
.is_partially_uptodate = iomap_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
.swap_activate = xfs_iomap_swapfile_activate,
};
const struct address_space_operations xfs_dax_aops = {
.writepages = xfs_dax_writepages,
.direct_IO = noop_direct_IO,
.set_page_dirty = noop_set_page_dirty,
.invalidatepage = noop_invalidatepage,
.swap_activate = xfs_iomap_swapfile_activate,
};