1
linux/fs/nfs/fscache.c

331 lines
8.6 KiB
C
Raw Normal View History

/* NFS filesystem cache interface
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/in6.h>
#include <linux/seq_file.h>
#include "internal.h"
#include "fscache.h"
#define NFSDBG_FACILITY NFSDBG_FSCACHE
NFS: Define and create superblock-level objects Define and create superblock-level cache index objects (as managed by nfs_server structs). Each superblock object is created in a server level index object and is itself an index into which inode-level objects are inserted. Ideally there would be one superblock-level object per server, and the former would be folded into the latter; however, since the "nosharecache" option exists this isn't possible. The superblock object key is a sequence consisting of: (1) Certain superblock s_flags. (2) Various connection parameters that serve to distinguish superblocks for sget(). (3) The volume FSID. (4) The security flavour. (5) The uniquifier length. (6) The uniquifier text. This is normally an empty string, unless the fsc=xyz mount option was used to explicitly specify a uniquifier. The key blob is of variable length, depending on the length of (6). The superblock object is given no coherency data to carry in the auxiliary data permitted by the cache. It is assumed that the superblock is always coherent. This patch also adds uniquification handling such that two otherwise identical superblocks, at least one of which is marked "nosharecache", won't end up trying to share the on-disk cache. It will be possible to manually provide a uniquifier through a mount option with a later patch to avoid the error otherwise produced. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 08:42:42 -07:00
static struct rb_root nfs_fscache_keys = RB_ROOT;
static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
/*
* Get the per-client index cookie for an NFS client if the appropriate mount
* flag was set
* - We always try and get an index cookie for the client, but get filehandle
* cookies on a per-superblock basis, depending on the mount flags
*/
void nfs_fscache_get_client_cookie(struct nfs_client *clp)
{
/* create a cache index for looking up filehandles */
clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
&nfs_fscache_server_index_def,
clp);
dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
clp, clp->fscache);
}
/*
* Dispose of a per-client cookie
*/
void nfs_fscache_release_client_cookie(struct nfs_client *clp)
{
dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
clp, clp->fscache);
fscache_relinquish_cookie(clp->fscache, 0);
clp->fscache = NULL;
}
NFS: Define and create superblock-level objects Define and create superblock-level cache index objects (as managed by nfs_server structs). Each superblock object is created in a server level index object and is itself an index into which inode-level objects are inserted. Ideally there would be one superblock-level object per server, and the former would be folded into the latter; however, since the "nosharecache" option exists this isn't possible. The superblock object key is a sequence consisting of: (1) Certain superblock s_flags. (2) Various connection parameters that serve to distinguish superblocks for sget(). (3) The volume FSID. (4) The security flavour. (5) The uniquifier length. (6) The uniquifier text. This is normally an empty string, unless the fsc=xyz mount option was used to explicitly specify a uniquifier. The key blob is of variable length, depending on the length of (6). The superblock object is given no coherency data to carry in the auxiliary data permitted by the cache. It is assumed that the superblock is always coherent. This patch also adds uniquification handling such that two otherwise identical superblocks, at least one of which is marked "nosharecache", won't end up trying to share the on-disk cache. It will be possible to manually provide a uniquifier through a mount option with a later patch to avoid the error otherwise produced. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
2009-04-03 08:42:42 -07:00
/*
* Get the cache cookie for an NFS superblock. We have to handle
* uniquification here because the cache doesn't do it for us.
*/
void nfs_fscache_get_super_cookie(struct super_block *sb,
struct nfs_parsed_mount_data *data)
{
struct nfs_fscache_key *key, *xkey;
struct nfs_server *nfss = NFS_SB(sb);
struct rb_node **p, *parent;
const char *uniq = data->fscache_uniq ?: "";
int diff, ulen;
ulen = strlen(uniq);
key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
if (!key)
return;
key->nfs_client = nfss->nfs_client;
key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
key->key.nfs_server.flags = nfss->flags;
key->key.nfs_server.rsize = nfss->rsize;
key->key.nfs_server.wsize = nfss->wsize;
key->key.nfs_server.acregmin = nfss->acregmin;
key->key.nfs_server.acregmax = nfss->acregmax;
key->key.nfs_server.acdirmin = nfss->acdirmin;
key->key.nfs_server.acdirmax = nfss->acdirmax;
key->key.nfs_server.fsid = nfss->fsid;
key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
key->key.uniq_len = ulen;
memcpy(key->key.uniquifier, uniq, ulen);
spin_lock(&nfs_fscache_keys_lock);
p = &nfs_fscache_keys.rb_node;
parent = NULL;
while (*p) {
parent = *p;
xkey = rb_entry(parent, struct nfs_fscache_key, node);
if (key->nfs_client < xkey->nfs_client)
goto go_left;
if (key->nfs_client > xkey->nfs_client)
goto go_right;
diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
if (diff < 0)
goto go_left;
if (diff > 0)
goto go_right;
if (key->key.uniq_len == 0)
goto non_unique;
diff = memcmp(key->key.uniquifier,
xkey->key.uniquifier,
key->key.uniq_len);
if (diff < 0)
goto go_left;
if (diff > 0)
goto go_right;
goto non_unique;
go_left:
p = &(*p)->rb_left;
continue;
go_right:
p = &(*p)->rb_right;
}
rb_link_node(&key->node, parent, p);
rb_insert_color(&key->node, &nfs_fscache_keys);
spin_unlock(&nfs_fscache_keys_lock);
nfss->fscache_key = key;
/* create a cache index for looking up filehandles */
nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
&nfs_fscache_super_index_def,
nfss);
dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
nfss, nfss->fscache);
return;
non_unique:
spin_unlock(&nfs_fscache_keys_lock);
kfree(key);
nfss->fscache_key = NULL;
nfss->fscache = NULL;
printk(KERN_WARNING "NFS:"
" Cache request denied due to non-unique superblock keys\n");
}
/*
* release a per-superblock cookie
*/
void nfs_fscache_release_super_cookie(struct super_block *sb)
{
struct nfs_server *nfss = NFS_SB(sb);
dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
nfss, nfss->fscache);
fscache_relinquish_cookie(nfss->fscache, 0);
nfss->fscache = NULL;
if (nfss->fscache_key) {
spin_lock(&nfs_fscache_keys_lock);
rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
spin_unlock(&nfs_fscache_keys_lock);
kfree(nfss->fscache_key);
nfss->fscache_key = NULL;
}
}
/*
* Initialise the per-inode cache cookie pointer for an NFS inode.
*/
void nfs_fscache_init_inode_cookie(struct inode *inode)
{
NFS_I(inode)->fscache = NULL;
if (S_ISREG(inode->i_mode))
set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
}
/*
* Get the per-inode cache cookie for an NFS inode.
*/
static void nfs_fscache_enable_inode_cookie(struct inode *inode)
{
struct super_block *sb = inode->i_sb;
struct nfs_inode *nfsi = NFS_I(inode);
if (nfsi->fscache || !NFS_FSCACHE(inode))
return;
if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
nfsi->fscache = fscache_acquire_cookie(
NFS_SB(sb)->fscache,
&nfs_fscache_inode_object_def,
nfsi);
dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
sb, nfsi, nfsi->fscache);
}
}
/*
* Release a per-inode cookie.
*/
void nfs_fscache_release_inode_cookie(struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
nfsi, nfsi->fscache);
fscache_relinquish_cookie(nfsi->fscache, 0);
nfsi->fscache = NULL;
}
/*
* Retire a per-inode cookie, destroying the data attached to it.
*/
void nfs_fscache_zap_inode_cookie(struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
nfsi, nfsi->fscache);
fscache_relinquish_cookie(nfsi->fscache, 1);
nfsi->fscache = NULL;
}
/*
* Turn off the cache with regard to a per-inode cookie if opened for writing,
* invalidating all the pages in the page cache relating to the associated
* inode to clear the per-page caching.
*/
static void nfs_fscache_disable_inode_cookie(struct inode *inode)
{
clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
if (NFS_I(inode)->fscache) {
dfprintk(FSCACHE,
"NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));
/* Need to invalidate any mapped pages that were read in before
* turning off the cache.
*/
if (inode->i_mapping && inode->i_mapping->nrpages)
invalidate_inode_pages2(inode->i_mapping);
nfs_fscache_zap_inode_cookie(inode);
}
}
/*
* wait_on_bit() sleep function for uninterruptible waiting
*/
static int nfs_fscache_wait_bit(void *flags)
{
schedule();
return 0;
}
/*
* Lock against someone else trying to also acquire or relinquish a cookie
*/
static inline void nfs_fscache_inode_lock(struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
}
/*
* Unlock cookie management lock
*/
static inline void nfs_fscache_inode_unlock(struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
smp_mb__before_clear_bit();
clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
smp_mb__after_clear_bit();
wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
}
/*
* Decide if we should enable or disable local caching for this inode.
* - For now, with NFS, only regular files that are open read-only will be able
* to use the cache.
* - May be invoked multiple times in parallel by parallel nfs_open() functions.
*/
void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
{
if (NFS_FSCACHE(inode)) {
nfs_fscache_inode_lock(inode);
if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
nfs_fscache_disable_inode_cookie(inode);
else
nfs_fscache_enable_inode_cookie(inode);
nfs_fscache_inode_unlock(inode);
}
}
/*
* Replace a per-inode cookie due to revalidation detecting a file having
* changed on the server.
*/
void nfs_fscache_reset_inode_cookie(struct inode *inode)
{
struct nfs_inode *nfsi = NFS_I(inode);
struct nfs_server *nfss = NFS_SERVER(inode);
struct fscache_cookie *old = nfsi->fscache;
nfs_fscache_inode_lock(inode);
if (nfsi->fscache) {
/* retire the current fscache cache and get a new one */
fscache_relinquish_cookie(nfsi->fscache, 1);
nfsi->fscache = fscache_acquire_cookie(
nfss->nfs_client->fscache,
&nfs_fscache_inode_object_def,
nfsi);
dfprintk(FSCACHE,
"NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
nfss, nfsi, old, nfsi->fscache);
}
nfs_fscache_inode_unlock(inode);
}