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9p: Add fscache support to 9p

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This patch adds a persistent, read-only caching facility for
9p clients using the FS-Cache caching backend.

When the fscache facility is enabled, each inode is associated
with a corresponding vcookie which is an index into the FS-Cache
indexing tree. The FS-Cache indexing tree is indexed at 3 levels:
- session object associated with each mount.
- inode/vcookie
- actual data (pages)

A cache tag is chosen randomly for each session. These tags can
be read off /sys/fs/9p/caches and can be passed as a mount-time
parameter to re-attach to the specified caching session.

Signed-off-by: Abhishek Kulkarni <adkulkar@umail.iu.edu>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
This commit is contained in:
Abhishek Kulkarni
2009-09-23 13:00:27 -05:00
committed by Eric Van Hensbergen
parent 637d020a02
commit 60e78d2c99
12 changed files with 1009 additions and 42 deletions
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57
fs/9p/vfs_inode.c
View File

@@ -40,6 +40,7 @@
#include "v9fs.h"
#include "v9fs_vfs.h"
#include "fid.h"
#include "cache.h"
static const struct inode_operations v9fs_dir_inode_operations;
static const struct inode_operations v9fs_dir_inode_operations_ext;
@@ -197,6 +198,39 @@ v9fs_blank_wstat(struct p9_wstat *wstat)
wstat->extension = NULL;
}
#ifdef CONFIG_9P_FSCACHE
/**
* v9fs_alloc_inode - helper function to allocate an inode
* This callback is executed before setting up the inode so that we
* can associate a vcookie with each inode.
*
*/
struct inode *v9fs_alloc_inode(struct super_block *sb)
{
struct v9fs_cookie *vcookie;
vcookie = (struct v9fs_cookie *)kmem_cache_alloc(vcookie_cache,
GFP_KERNEL);
if (!vcookie)
return NULL;
vcookie->fscache = NULL;
vcookie->qid = NULL;
spin_lock_init(&vcookie->lock);
return &vcookie->inode;
}
/**
* v9fs_destroy_inode - destroy an inode
*
*/
void v9fs_destroy_inode(struct inode *inode)
{
kmem_cache_free(vcookie_cache, v9fs_inode2cookie(inode));
}
#endif
/**
* v9fs_get_inode - helper function to setup an inode
* @sb: superblock
@@ -326,6 +360,21 @@ error:
}
*/
/**
* v9fs_clear_inode - release an inode
* @inode: inode to release
*
*/
void v9fs_clear_inode(struct inode *inode)
{
filemap_fdatawrite(inode->i_mapping);
#ifdef CONFIG_9P_FSCACHE
v9fs_cache_inode_put_cookie(inode);
#endif
}
/**
* v9fs_inode_from_fid - populate an inode by issuing a attribute request
* @v9ses: session information
@@ -356,8 +405,14 @@ v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
v9fs_stat2inode(st, ret, sb);
ret->i_ino = v9fs_qid2ino(&st->qid);
#ifdef CONFIG_9P_FSCACHE
v9fs_vcookie_set_qid(ret, &st->qid);
v9fs_cache_inode_get_cookie(ret);
#endif
p9stat_free(st);
kfree(st);
return ret;
error:
@@ -751,7 +806,7 @@ v9fs_vfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
P9_DPRINTK(P9_DEBUG_VFS, "dentry: %p\n", dentry);
err = -EPERM;
v9ses = v9fs_inode2v9ses(dentry->d_inode);
if (v9ses->cache == CACHE_LOOSE)
if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
return simple_getattr(mnt, dentry, stat);
fid = v9fs_fid_lookup(dentry);