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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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176
fs/9p/cache.h Normal file
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/*
* V9FS cache definitions.
*
* Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to:
* Free Software Foundation
* 51 Franklin Street, Fifth Floor
* Boston, MA 02111-1301 USA
*
*/
#ifndef _9P_CACHE_H
#ifdef CONFIG_9P_FSCACHE
#include <linux/fscache.h>
#include <linux/spinlock.h>
extern struct kmem_cache *vcookie_cache;
struct v9fs_cookie {
spinlock_t lock;
struct inode inode;
struct fscache_cookie *fscache;
struct p9_qid *qid;
};
static inline struct v9fs_cookie *v9fs_inode2cookie(const struct inode *inode)
{
return container_of(inode, struct v9fs_cookie, inode);
}
extern struct fscache_netfs v9fs_cache_netfs;
extern const struct fscache_cookie_def v9fs_cache_session_index_def;
extern const struct fscache_cookie_def v9fs_cache_inode_index_def;
extern void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses);
extern void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses);
extern void v9fs_cache_inode_get_cookie(struct inode *inode);
extern void v9fs_cache_inode_put_cookie(struct inode *inode);
extern void v9fs_cache_inode_flush_cookie(struct inode *inode);
extern void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp);
extern void v9fs_cache_inode_reset_cookie(struct inode *inode);
extern int __v9fs_cache_register(void);
extern void __v9fs_cache_unregister(void);
extern int __v9fs_fscache_release_page(struct page *page, gfp_t gfp);
extern void __v9fs_fscache_invalidate_page(struct page *page);
extern int __v9fs_readpage_from_fscache(struct inode *inode,
struct page *page);
extern int __v9fs_readpages_from_fscache(struct inode *inode,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages);
extern void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page);
/**
* v9fs_cache_register - Register v9fs file system with the cache
*/
static inline int v9fs_cache_register(void)
{
return __v9fs_cache_register();
}
/**
* v9fs_cache_unregister - Unregister v9fs from the cache
*/
static inline void v9fs_cache_unregister(void)
{
__v9fs_cache_unregister();
}
static inline int v9fs_fscache_release_page(struct page *page,
gfp_t gfp)
{
return __v9fs_fscache_release_page(page, gfp);
}
static inline void v9fs_fscache_invalidate_page(struct page *page)
{
__v9fs_fscache_invalidate_page(page);
}
static inline int v9fs_readpage_from_fscache(struct inode *inode,
struct page *page)
{
return __v9fs_readpage_from_fscache(inode, page);
}
static inline int v9fs_readpages_from_fscache(struct inode *inode,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages)
{
return __v9fs_readpages_from_fscache(inode, mapping, pages,
nr_pages);
}
static inline void v9fs_readpage_to_fscache(struct inode *inode,
struct page *page)
{
if (PageFsCache(page))
__v9fs_readpage_to_fscache(inode, page);
}
static inline void v9fs_uncache_page(struct inode *inode, struct page *page)
{
struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
fscache_uncache_page(vcookie->fscache, page);
BUG_ON(PageFsCache(page));
}
static inline void v9fs_vcookie_set_qid(struct inode *inode,
struct p9_qid *qid)
{
struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);
spin_lock(&vcookie->lock);
vcookie->qid = qid;
spin_unlock(&vcookie->lock);
}
#else /* CONFIG_9P_FSCACHE */
static inline int v9fs_cache_register(void)
{
return 1;
}
static inline void v9fs_cache_unregister(void) {}
static inline int v9fs_fscache_release_page(struct page *page,
gfp_t gfp) {
return 1;
}
static inline void v9fs_fscache_invalidate_page(struct page *page) {}
static inline int v9fs_readpage_from_fscache(struct inode *inode,
struct page *page)
{
return -ENOBUFS;
}
static inline int v9fs_readpages_from_fscache(struct inode *inode,
struct address_space *mapping,
struct list_head *pages,
unsigned *nr_pages)
{
return -ENOBUFS;
}
static inline void v9fs_readpage_to_fscache(struct inode *inode,
struct page *page)
{}
static inline void v9fs_uncache_page(struct inode *inode, struct page *page)
{}
static inline void v9fs_vcookie_set_qid(struct inode *inode,
struct p9_qid *qid)
{}
#endif /* CONFIG_9P_FSCACHE */
#endif /* _9P_CACHE_H */