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Commit 60e78d2c authored by Abhishek Kulkarni's avatar Abhishek Kulkarni Committed by Eric Van Hensbergen
Browse files

9p: Add fscache support to 9p 



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: default avatarAbhishek Kulkarni <adkulkar@umail.iu.edu>
Signed-off-by: default avatarEric Van Hensbergen <ericvh@gmail.com>
parent 637d020a

fs/9p/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -8,3 +8,12 @@ config 9P_FS 
	  See <http://v9fs.sf.net> for more information.



	  If unsure, say N.



config 9P_FSCACHE

	bool "Enable 9P client caching support (EXPERIMENTAL)"

	depends on EXPERIMENTAL

	depends on 9P_FS=m && FSCACHE || 9P_FS=y && FSCACHE=y

	help

	  Choose Y here to enable persistent, read-only local

	  caching support for 9p clients using FS-Cache

fs/9p/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -8,5 +8,6 @@ obj-$(CONFIG_9P_FS) := 9p.o 
	vfs_dir.o \

	vfs_dentry.o \

	v9fs.o \

	fid.o \

	fid.o



9p-$(CONFIG_9P_FSCACHE) += cache.o

fs/9p/cache.c

0 → 100644
+474 −0
Original line number Diff line number Diff line 
/*

 * 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

 *

 */



#include <linux/jiffies.h>

#include <linux/file.h>

#include <linux/stat.h>

#include <linux/sched.h>

#include <linux/fs.h>

#include <net/9p/9p.h>



#include "v9fs.h"

#include "cache.h"



#define CACHETAG_LEN  11



struct kmem_cache *vcookie_cache;



struct fscache_netfs v9fs_cache_netfs = {

	.name 		= "9p",

	.version 	= 0,

};



static void init_once(void *foo)

{

	struct v9fs_cookie *vcookie = (struct v9fs_cookie *) foo;

	vcookie->fscache = NULL;

	vcookie->qid = NULL;

	inode_init_once(&vcookie->inode);

}



/**

 * v9fs_init_vcookiecache - initialize a cache for vcookies to maintain

 *			    vcookie to inode mapping

 *

 * Returns 0 on success.

 */



static int v9fs_init_vcookiecache(void)

{

	vcookie_cache = kmem_cache_create("vcookie_cache",

					  sizeof(struct v9fs_cookie),

					  0, (SLAB_RECLAIM_ACCOUNT|

					      SLAB_MEM_SPREAD),

					  init_once);

	if (!vcookie_cache)

		return -ENOMEM;



	return 0;

}



/**

 * v9fs_destroy_vcookiecache - destroy the cache of vcookies

 *

 */



static void v9fs_destroy_vcookiecache(void)

{

	kmem_cache_destroy(vcookie_cache);

}



int __v9fs_cache_register(void)

{

	int ret;

	ret = v9fs_init_vcookiecache();

	if (ret < 0)

		return ret;



	return fscache_register_netfs(&v9fs_cache_netfs);

}



void __v9fs_cache_unregister(void)

{

	v9fs_destroy_vcookiecache();

	fscache_unregister_netfs(&v9fs_cache_netfs);

}



/**

 * v9fs_random_cachetag - Generate a random tag to be associated

 *			  with a new cache session.

 *

 * The value of jiffies is used for a fairly randomly cache tag.

 */



static

int v9fs_random_cachetag(struct v9fs_session_info *v9ses)

{

	v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);

	if (!v9ses->cachetag)

		return -ENOMEM;



	return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);

}



static uint16_t v9fs_cache_session_get_key(const void *cookie_netfs_data,

					   void *buffer, uint16_t bufmax)

{

	struct v9fs_session_info *v9ses;

	uint16_t klen = 0;



	v9ses = (struct v9fs_session_info *)cookie_netfs_data;

	P9_DPRINTK(P9_DEBUG_FSC, "session %p buf %p size %u", v9ses,

		   buffer, bufmax);



	if (v9ses->cachetag)

		klen = strlen(v9ses->cachetag);



	if (klen > bufmax)

		return 0;



	memcpy(buffer, v9ses->cachetag, klen);

	P9_DPRINTK(P9_DEBUG_FSC, "cache session tag %s", v9ses->cachetag);

	return klen;

}



const struct fscache_cookie_def v9fs_cache_session_index_def = {

	.name 		= "9P.session",

	.type 		= FSCACHE_COOKIE_TYPE_INDEX,

	.get_key 	= v9fs_cache_session_get_key,

};



void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)

{

	/* If no cache session tag was specified, we generate a random one. */

	if (!v9ses->cachetag)

		v9fs_random_cachetag(v9ses);



	v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,

						&v9fs_cache_session_index_def,

						v9ses);

	P9_DPRINTK(P9_DEBUG_FSC, "session %p get cookie %p", v9ses,

		   v9ses->fscache);

}



void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)

{

	P9_DPRINTK(P9_DEBUG_FSC, "session %p put cookie %p", v9ses,

		   v9ses->fscache);

	fscache_relinquish_cookie(v9ses->fscache, 0);

	v9ses->fscache = NULL;

}





static uint16_t v9fs_cache_inode_get_key(const void *cookie_netfs_data,

					 void *buffer, uint16_t bufmax)

{

	const struct v9fs_cookie *vcookie = cookie_netfs_data;

	memcpy(buffer, &vcookie->qid->path, sizeof(vcookie->qid->path));



	P9_DPRINTK(P9_DEBUG_FSC, "inode %p get key %llu", &vcookie->inode,

		   vcookie->qid->path);

	return sizeof(vcookie->qid->path);

}



static void v9fs_cache_inode_get_attr(const void *cookie_netfs_data,

				      uint64_t *size)

{

	const struct v9fs_cookie *vcookie = cookie_netfs_data;

	*size = i_size_read(&vcookie->inode);



	P9_DPRINTK(P9_DEBUG_FSC, "inode %p get attr %llu", &vcookie->inode,

		   *size);

}



static uint16_t v9fs_cache_inode_get_aux(const void *cookie_netfs_data,

					 void *buffer, uint16_t buflen)

{

	const struct v9fs_cookie *vcookie = cookie_netfs_data;

	memcpy(buffer, &vcookie->qid->version, sizeof(vcookie->qid->version));



	P9_DPRINTK(P9_DEBUG_FSC, "inode %p get aux %u", &vcookie->inode,

		   vcookie->qid->version);

	return sizeof(vcookie->qid->version);

}



static enum

fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,

					    const void *buffer,

					    uint16_t buflen)

{

	const struct v9fs_cookie *vcookie = cookie_netfs_data;



	if (buflen != sizeof(vcookie->qid->version))

		return FSCACHE_CHECKAUX_OBSOLETE;



	if (memcmp(buffer, &vcookie->qid->version,

		   sizeof(vcookie->qid->version)))

		return FSCACHE_CHECKAUX_OBSOLETE;



	return FSCACHE_CHECKAUX_OKAY;

}



static void v9fs_cache_inode_now_uncached(void *cookie_netfs_data)

{

	struct v9fs_cookie *vcookie = cookie_netfs_data;

	struct pagevec pvec;

	pgoff_t first;

	int loop, nr_pages;



	pagevec_init(&pvec, 0);

	first = 0;



	for (;;) {

		nr_pages = pagevec_lookup(&pvec, vcookie->inode.i_mapping,

					  first,

					  PAGEVEC_SIZE - pagevec_count(&pvec));

		if (!nr_pages)

			break;



		for (loop = 0; loop < nr_pages; loop++)

			ClearPageFsCache(pvec.pages[loop]);



		first = pvec.pages[nr_pages - 1]->index + 1;



		pvec.nr = nr_pages;

		pagevec_release(&pvec);

		cond_resched();

	}

}



const struct fscache_cookie_def v9fs_cache_inode_index_def = {

	.name		= "9p.inode",

	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,

	.get_key	= v9fs_cache_inode_get_key,

	.get_attr	= v9fs_cache_inode_get_attr,

	.get_aux	= v9fs_cache_inode_get_aux,

	.check_aux	= v9fs_cache_inode_check_aux,

	.now_uncached	= v9fs_cache_inode_now_uncached,

};



void v9fs_cache_inode_get_cookie(struct inode *inode)

{

	struct v9fs_cookie *vcookie;

	struct v9fs_session_info *v9ses;



	if (!S_ISREG(inode->i_mode))

		return;



	vcookie = v9fs_inode2cookie(inode);

	if (vcookie->fscache)

		return;



	v9ses = v9fs_inode2v9ses(inode);

	vcookie->fscache = fscache_acquire_cookie(v9ses->fscache,

						  &v9fs_cache_inode_index_def,

						  vcookie);



	P9_DPRINTK(P9_DEBUG_FSC, "inode %p get cookie %p", inode,

		   vcookie->fscache);

}



void v9fs_cache_inode_put_cookie(struct inode *inode)

{

	struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);



	if (!vcookie->fscache)

		return;

	P9_DPRINTK(P9_DEBUG_FSC, "inode %p put cookie %p", inode,

		   vcookie->fscache);



	fscache_relinquish_cookie(vcookie->fscache, 0);

	vcookie->fscache = NULL;

}



void v9fs_cache_inode_flush_cookie(struct inode *inode)

{

	struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);



	if (!vcookie->fscache)

		return;

	P9_DPRINTK(P9_DEBUG_FSC, "inode %p flush cookie %p", inode,

		   vcookie->fscache);



	fscache_relinquish_cookie(vcookie->fscache, 1);

	vcookie->fscache = NULL;

}



void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)

{

	struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);

	struct p9_fid *fid;



	if (!vcookie->fscache)

		return;



	spin_lock(&vcookie->lock);

	fid = filp->private_data;

	if ((filp->f_flags & O_ACCMODE) != O_RDONLY)

		v9fs_cache_inode_flush_cookie(inode);

	else

		v9fs_cache_inode_get_cookie(inode);



	spin_unlock(&vcookie->lock);

}



void v9fs_cache_inode_reset_cookie(struct inode *inode)

{

	struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);

	struct v9fs_session_info *v9ses;

	struct fscache_cookie *old;



	if (!vcookie->fscache)

		return;



	old = vcookie->fscache;



	spin_lock(&vcookie->lock);

	fscache_relinquish_cookie(vcookie->fscache, 1);



	v9ses = v9fs_inode2v9ses(inode);

	vcookie->fscache = fscache_acquire_cookie(v9ses->fscache,

						  &v9fs_cache_inode_index_def,

						  vcookie);



	P9_DPRINTK(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p",

		   inode, old, vcookie->fscache);



	spin_unlock(&vcookie->lock);

}



int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)

{

	struct inode *inode = page->mapping->host;

	struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);



	BUG_ON(!vcookie->fscache);



	if (PageFsCache(page)) {

		if (fscache_check_page_write(vcookie->fscache, page)) {

			if (!(gfp & __GFP_WAIT))

				return 0;

			fscache_wait_on_page_write(vcookie->fscache, page);

		}



		fscache_uncache_page(vcookie->fscache, page);

		ClearPageFsCache(page);

	}



	return 1;

}



void __v9fs_fscache_invalidate_page(struct page *page)

{

	struct inode *inode = page->mapping->host;

	struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);



	BUG_ON(!vcookie->fscache);



	if (PageFsCache(page)) {

		fscache_wait_on_page_write(vcookie->fscache, page);

		BUG_ON(!PageLocked(page));

		fscache_uncache_page(vcookie->fscache, page);

		ClearPageFsCache(page);

	}

}



static void v9fs_vfs_readpage_complete(struct page *page, void *data,

				       int error)

{

	if (!error)

		SetPageUptodate(page);



	unlock_page(page);

}



/**

 * __v9fs_readpage_from_fscache - read a page from cache

 *

 * Returns 0 if the pages are in cache and a BIO is submitted,

 * 1 if the pages are not in cache and -error otherwise.

 */



int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)

{

	int ret;

	const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);



	P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);

	if (!vcookie->fscache)

		return -ENOBUFS;



	ret = fscache_read_or_alloc_page(vcookie->fscache,

					 page,

					 v9fs_vfs_readpage_complete,

					 NULL,

					 GFP_KERNEL);

	switch (ret) {

	case -ENOBUFS:

	case -ENODATA:

		P9_DPRINTK(P9_DEBUG_FSC, "page/inode not in cache %d", ret);

		return 1;

	case 0:

		P9_DPRINTK(P9_DEBUG_FSC, "BIO submitted");

		return ret;

	default:

		P9_DPRINTK(P9_DEBUG_FSC, "ret %d", ret);

		return ret;

	}

}



/**

 * __v9fs_readpages_from_fscache - read multiple pages from cache

 *

 * Returns 0 if the pages are in cache and a BIO is submitted,

 * 1 if the pages are not in cache and -error otherwise.

 */



int __v9fs_readpages_from_fscache(struct inode *inode,

				  struct address_space *mapping,

				  struct list_head *pages,

				  unsigned *nr_pages)

{

	int ret;

	const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);



	P9_DPRINTK(P9_DEBUG_FSC, "inode %p pages %u", inode, *nr_pages);

	if (!vcookie->fscache)

		return -ENOBUFS;



	ret = fscache_read_or_alloc_pages(vcookie->fscache,

					  mapping, pages, nr_pages,

					  v9fs_vfs_readpage_complete,

					  NULL,

					  mapping_gfp_mask(mapping));

	switch (ret) {

	case -ENOBUFS:

	case -ENODATA:

		P9_DPRINTK(P9_DEBUG_FSC, "pages/inodes not in cache %d", ret);

		return 1;

	case 0:

		BUG_ON(!list_empty(pages));

		BUG_ON(*nr_pages != 0);

		P9_DPRINTK(P9_DEBUG_FSC, "BIO submitted");

		return ret;

	default:

		P9_DPRINTK(P9_DEBUG_FSC, "ret %d", ret);

		return ret;

	}

}



/**

 * __v9fs_readpage_to_fscache - write a page to the cache

 *

 */



void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)

{

	int ret;

	const struct v9fs_cookie *vcookie = v9fs_inode2cookie(inode);



	P9_DPRINTK(P9_DEBUG_FSC, "inode %p page %p", inode, page);

	ret = fscache_write_page(vcookie->fscache, page, GFP_KERNEL);

	P9_DPRINTK(P9_DEBUG_FSC, "ret =  %d", ret);

	if (ret != 0)

		v9fs_uncache_page(inode, page);

}

fs/9p/cache.h

0 → 100644
+176 −0
Original line number Diff line number Diff line 
/*

 * 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 */

fs/9p/v9fs.c

+175 −21
Original line number Diff line number Diff line
@@ -34,6 +34,10 @@ 
#include <net/9p/transport.h>

#include "v9fs.h"

#include "v9fs_vfs.h"

#include "cache.h"



static DEFINE_SPINLOCK(v9fs_sessionlist_lock);

static LIST_HEAD(v9fs_sessionlist);



/*

 * Option Parsing (code inspired by NFS code)
@@ -44,11 +48,11 @@ enum { 
	/* Options that take integer arguments */

	Opt_debug, Opt_dfltuid, Opt_dfltgid, Opt_afid,

	/* String options */

	Opt_uname, Opt_remotename, Opt_trans,

	Opt_uname, Opt_remotename, Opt_trans, Opt_cache, Opt_cachetag,

	/* Options that take no arguments */

	Opt_nodevmap,

	/* Cache options */

	Opt_cache_loose,

	Opt_cache_loose, Opt_fscache,

	/* Access options */

	Opt_access,

	/* Error token */
@@ -63,8 +67,10 @@ static const match_table_t tokens = { 
	{Opt_uname, "uname=%s"},

	{Opt_remotename, "aname=%s"},

	{Opt_nodevmap, "nodevmap"},

	{Opt_cache_loose, "cache=loose"},

	{Opt_cache, "cache=%s"},

	{Opt_cache_loose, "loose"},

	{Opt_fscache, "fscache"},

	{Opt_cachetag, "cachetag=%s"},

	{Opt_access, "access=%s"},

	{Opt_err, NULL}

};
@@ -89,16 +95,16 @@ static int v9fs_parse_options(struct v9fs_session_info *v9ses, char *opts) 
	v9ses->afid = ~0;

	v9ses->debug = 0;

	v9ses->cache = 0;

#ifdef CONFIG_9P_FSCACHE

	v9ses->cachetag = NULL;

#endif



	if (!opts)

		return 0;



	options = kstrdup(opts, GFP_KERNEL);

	if (!options) {

		P9_DPRINTK(P9_DEBUG_ERROR,

			   "failed to allocate copy of option string\n");

		return -ENOMEM;

	}

	if (!options)

		goto fail_option_alloc;



	while ((p = strsep(&options, ",")) != NULL) {

		int token;
@@ -143,16 +149,33 @@ static int v9fs_parse_options(struct v9fs_session_info *v9ses, char *opts) 
		case Opt_cache_loose:

			v9ses->cache = CACHE_LOOSE;

			break;

		case Opt_fscache:

			v9ses->cache = CACHE_FSCACHE;

			break;

		case Opt_cachetag:

#ifdef CONFIG_9P_FSCACHE

			v9ses->cachetag = match_strdup(&args[0]);

#endif

			break;

		case Opt_cache:

			s = match_strdup(&args[0]);

			if (!s)

				goto fail_option_alloc;



			if (strcmp(s, "loose") == 0)

				v9ses->cache = CACHE_LOOSE;

			else if (strcmp(s, "fscache") == 0)

				v9ses->cache = CACHE_FSCACHE;

			else

				v9ses->cache = CACHE_NONE;

			kfree(s);

			break;



		case Opt_access:

			s = match_strdup(&args[0]);

			if (!s) {

				P9_DPRINTK(P9_DEBUG_ERROR,

					   "failed to allocate copy"

					   " of option argument\n");

				ret = -ENOMEM;

				break;

			}

			if (!s)

				goto fail_option_alloc;



			v9ses->flags &= ~V9FS_ACCESS_MASK;

			if (strcmp(s, "user") == 0)

				v9ses->flags |= V9FS_ACCESS_USER;
@@ -173,6 +196,11 @@ static int v9fs_parse_options(struct v9fs_session_info *v9ses, char *opts) 
	}

	kfree(options);

	return ret;



fail_option_alloc:

	P9_DPRINTK(P9_DEBUG_ERROR,

		   "failed to allocate copy of option argument\n");

	return -ENOMEM;

}



/**
@@ -200,6 +228,10 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses, 
		return ERR_PTR(-ENOMEM);

	}



	spin_lock(&v9fs_sessionlist_lock);

	list_add(&v9ses->slist, &v9fs_sessionlist);

	spin_unlock(&v9fs_sessionlist_lock);



	v9ses->flags = V9FS_EXTENDED | V9FS_ACCESS_USER;

	strcpy(v9ses->uname, V9FS_DEFUSER);

	strcpy(v9ses->aname, V9FS_DEFANAME);
@@ -249,6 +281,11 @@ struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses, 
	else

		fid->uid = ~0;



#ifdef CONFIG_9P_FSCACHE

	/* register the session for caching */

	v9fs_cache_session_get_cookie(v9ses);

#endif



	return fid;



error:
@@ -268,8 +305,18 @@ void v9fs_session_close(struct v9fs_session_info *v9ses) 
		v9ses->clnt = NULL;

	}



#ifdef CONFIG_9P_FSCACHE

	if (v9ses->fscache) {

		v9fs_cache_session_put_cookie(v9ses);

		kfree(v9ses->cachetag);

	}

#endif

	__putname(v9ses->uname);

	__putname(v9ses->aname);



	spin_lock(&v9fs_sessionlist_lock);

	list_del(&v9ses->slist);

	spin_unlock(&v9fs_sessionlist_lock);

}



/**
@@ -286,25 +333,132 @@ void v9fs_session_cancel(struct v9fs_session_info *v9ses) { 


extern int v9fs_error_init(void);



static struct kobject *v9fs_kobj;



#ifdef CONFIG_9P_FSCACHE

/**

 * caches_show - list caches associated with a session

 *

 * Returns the size of buffer written.

 */



static ssize_t caches_show(struct kobject *kobj,

			   struct kobj_attribute *attr,

			   char *buf)

{

	ssize_t n = 0, count = 0, limit = PAGE_SIZE;

	struct v9fs_session_info *v9ses;



	spin_lock(&v9fs_sessionlist_lock);

	list_for_each_entry(v9ses, &v9fs_sessionlist, slist) {

		if (v9ses->cachetag) {

			n = snprintf(buf, limit, "%s\n", v9ses->cachetag);

			if (n < 0) {

				count = n;

				break;

			}



			count += n;

			limit -= n;

		}

	}



	spin_unlock(&v9fs_sessionlist_lock);

	return count;

}



static struct kobj_attribute v9fs_attr_cache = __ATTR_RO(caches);

#endif /* CONFIG_9P_FSCACHE */



static struct attribute *v9fs_attrs[] = {

#ifdef CONFIG_9P_FSCACHE

	&v9fs_attr_cache.attr,

#endif

	NULL,

};



static struct attribute_group v9fs_attr_group = {

	.attrs = v9fs_attrs,

};



/**

 * v9fs_init - Initialize module

 * v9fs_sysfs_init - Initialize the v9fs sysfs interface

 *

 */



static int v9fs_sysfs_init(void)

{

	v9fs_kobj = kobject_create_and_add("9p", fs_kobj);

	if (!v9fs_kobj)

		return -ENOMEM;



	if (sysfs_create_group(v9fs_kobj, &v9fs_attr_group)) {

		kobject_put(v9fs_kobj);

		return -ENOMEM;

	}



	return 0;

}



/**

 * v9fs_sysfs_cleanup - Unregister the v9fs sysfs interface

 *

 */



static void v9fs_sysfs_cleanup(void)

{

	sysfs_remove_group(v9fs_kobj, &v9fs_attr_group);

	kobject_put(v9fs_kobj);

}



/**

 * init_v9fs - Initialize module

 *

 */



static int __init init_v9fs(void)

{

	int err;

	printk(KERN_INFO "Installing v9fs 9p2000 file system support\n");

	/* TODO: Setup list of registered trasnport modules */

	return register_filesystem(&v9fs_fs_type);

	err = register_filesystem(&v9fs_fs_type);

	if (err < 0) {

		printk(KERN_ERR "Failed to register filesystem\n");

		return err;

	}



	err = v9fs_cache_register();

	if (err < 0) {

		printk(KERN_ERR "Failed to register v9fs for caching\n");

		goto out_fs_unreg;

	}



	err = v9fs_sysfs_init();

	if (err < 0) {

		printk(KERN_ERR "Failed to register with sysfs\n");

		goto out_sysfs_cleanup;

	}



	return 0;



out_sysfs_cleanup:

	v9fs_sysfs_cleanup();



out_fs_unreg:

	unregister_filesystem(&v9fs_fs_type);



	return err;

}



/**

 * v9fs_init - shutdown module

 * exit_v9fs - shutdown module

 *

 */



static void __exit exit_v9fs(void)

{

	v9fs_sysfs_cleanup();

	v9fs_cache_unregister();

	unregister_filesystem(&v9fs_fs_type);

}