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5a7e0a8cf5
linux/fs/9p/v9fs.h
Aneesh Kumar K.V 5a7e0a8cf5 fs/9p: Fix race in initializing writeback fid 
When two process open the same file we can end up with both of them
allocating the writeback_fid. Add a new mutex which can be used
for synchronizing v9fs_inode member values.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
2011-03-22 15:43:35 -05:00

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/*
* V9FS definitions.
*
* Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
* Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
*
* 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 FS_9P_V9FS_H
#define FS_9P_V9FS_H
#include <linux/backing-dev.h>
/**
* enum p9_session_flags - option flags for each 9P session
* @V9FS_PROTO_2000U: whether or not to use 9P2000.u extensions
* @V9FS_PROTO_2000L: whether or not to use 9P2000.l extensions
* @V9FS_ACCESS_SINGLE: only the mounting user can access the hierarchy
* @V9FS_ACCESS_USER: a new attach will be issued for every user (default)
* @V9FS_ACCESS_CLIENT: Just like user, but access check is performed on client.
* @V9FS_ACCESS_ANY: use a single attach for all users
* @V9FS_ACCESS_MASK: bit mask of different ACCESS options
* @V9FS_POSIX_ACL: POSIX ACLs are enforced
*
* Session flags reflect options selected by users at mount time
*/
#define V9FS_ACCESS_ANY (V9FS_ACCESS_SINGLE | \
V9FS_ACCESS_USER | \
V9FS_ACCESS_CLIENT)
#define V9FS_ACCESS_MASK V9FS_ACCESS_ANY
#define V9FS_ACL_MASK V9FS_POSIX_ACL
enum p9_session_flags {
V9FS_PROTO_2000U = 0x01,
V9FS_PROTO_2000L = 0x02,
V9FS_ACCESS_SINGLE = 0x04,
V9FS_ACCESS_USER = 0x08,
V9FS_ACCESS_CLIENT = 0x10,
V9FS_POSIX_ACL = 0x20
};
/* possible values of ->cache */
/**
* enum p9_cache_modes - user specified cache preferences
* @CACHE_NONE: do not cache data, dentries, or directory contents (default)
* @CACHE_LOOSE: cache data, dentries, and directory contents w/no consistency
*
* eventually support loose, tight, time, session, default always none
*/
enum p9_cache_modes {
CACHE_NONE,
CACHE_LOOSE,
CACHE_FSCACHE,
};
/**
* struct v9fs_session_info - per-instance session information
* @flags: session options of type &p9_session_flags
* @nodev: set to 1 to disable device mapping
* @debug: debug level
* @afid: authentication handle
* @cache: cache mode of type &p9_cache_modes
* @cachetag: the tag of the cache associated with this session
* @fscache: session cookie associated with FS-Cache
* @options: copy of options string given by user
* @uname: string user name to mount hierarchy as
* @aname: mount specifier for remote hierarchy
* @maxdata: maximum data to be sent/recvd per protocol message
* @dfltuid: default numeric userid to mount hierarchy as
* @dfltgid: default numeric groupid to mount hierarchy as
* @uid: if %V9FS_ACCESS_SINGLE, the numeric uid which mounted the hierarchy
* @clnt: reference to 9P network client instantiated for this session
* @slist: reference to list of registered 9p sessions
*
* This structure holds state for each session instance established during
* a sys_mount() .
*
* Bugs: there seems to be a lot of state which could be condensed and/or
* removed.
*/
struct v9fs_session_info {
/* options */
unsigned char flags;
unsigned char nodev;
unsigned short debug;
unsigned int afid;
unsigned int cache;
#ifdef CONFIG_9P_FSCACHE
char *cachetag;
struct fscache_cookie *fscache;
#endif
char *uname; /* user name to mount as */
char *aname; /* name of remote hierarchy being mounted */
unsigned int maxdata; /* max data for client interface */
unsigned int dfltuid; /* default uid/muid for legacy support */
unsigned int dfltgid; /* default gid for legacy support */
u32 uid; /* if ACCESS_SINGLE, the uid that has access */
struct p9_client *clnt; /* 9p client */
struct list_head slist; /* list of sessions registered with v9fs */
struct backing_dev_info bdi;
struct rw_semaphore rename_sem;
struct p9_fid *root_fid; /* Used for file system sync */
};
/* cache_validity flags */
#define V9FS_INO_INVALID_ATTR 0x01
struct v9fs_inode {
#ifdef CONFIG_9P_FSCACHE
spinlock_t fscache_lock;
struct fscache_cookie *fscache;
struct p9_qid *fscache_key;
#endif
unsigned int cache_validity;
struct p9_fid *writeback_fid;
struct mutex v_mutex;
struct inode vfs_inode;
};
static inline struct v9fs_inode *V9FS_I(const struct inode *inode)
{
return container_of(inode, struct v9fs_inode, vfs_inode);
}
struct p9_fid *v9fs_session_init(struct v9fs_session_info *, const char *,
char *);
extern void v9fs_session_close(struct v9fs_session_info *v9ses);
extern void v9fs_session_cancel(struct v9fs_session_info *v9ses);
extern void v9fs_session_begin_cancel(struct v9fs_session_info *v9ses);
extern struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nameidata);
extern int v9fs_vfs_unlink(struct inode *i, struct dentry *d);
extern int v9fs_vfs_rmdir(struct inode *i, struct dentry *d);
extern int v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry);
extern void v9fs_vfs_put_link(struct dentry *dentry, struct nameidata *nd,
void *p);
extern struct inode *v9fs_inode_from_fid(struct v9fs_session_info *v9ses,
struct p9_fid *fid,
struct super_block *sb);
extern const struct inode_operations v9fs_dir_inode_operations_dotl;
extern const struct inode_operations v9fs_file_inode_operations_dotl;
extern const struct inode_operations v9fs_symlink_inode_operations_dotl;
extern struct inode *v9fs_inode_from_fid_dotl(struct v9fs_session_info *v9ses,
struct p9_fid *fid,
struct super_block *sb);
/* other default globals */
#define V9FS_PORT 564
#define V9FS_DEFUSER "nobody"
#define V9FS_DEFANAME ""
#define V9FS_DEFUID (-2)
#define V9FS_DEFGID (-2)
static inline struct v9fs_session_info *v9fs_inode2v9ses(struct inode *inode)
{
return (inode->i_sb->s_fs_info);
}
static inline int v9fs_proto_dotu(struct v9fs_session_info *v9ses)
{
return v9ses->flags & V9FS_PROTO_2000U;
}
static inline int v9fs_proto_dotl(struct v9fs_session_info *v9ses)
{
return v9ses->flags & V9FS_PROTO_2000L;
}
/**
* v9fs_get_inode_from_fid - Helper routine to populate an inode by
* issuing a attribute request
* @v9ses: session information
* @fid: fid to issue attribute request for
* @sb: superblock on which to create inode
*
*/
static inline struct inode *
v9fs_get_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
struct super_block *sb)
{
if (v9fs_proto_dotl(v9ses))
return v9fs_inode_from_fid_dotl(v9ses, fid, sb);
else
return v9fs_inode_from_fid(v9ses, fid, sb);
}
#endif
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