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a534c8d15b
During fid lookup we need to make sure that the dentry->d_parent doesn't change so that we can safely walk the parent dentries. To ensure that we need to prevent cross directory rename during fid_lookup. Add a per superblock rename_sem rw_semaphore to prevent parallel fid lookup and rename. 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>
139 lines
4.5 KiB
C
139 lines
4.5 KiB
C
/*
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* V9FS definitions.
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*
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* Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
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* Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to:
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* Free Software Foundation
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* 51 Franklin Street, Fifth Floor
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* Boston, MA 02111-1301 USA
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*
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*/
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#include <linux/backing-dev.h>
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/**
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* enum p9_session_flags - option flags for each 9P session
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* @V9FS_PROTO_2000U: whether or not to use 9P2000.u extensions
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* @V9FS_PROTO_2000L: whether or not to use 9P2000.l extensions
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* @V9FS_ACCESS_SINGLE: only the mounting user can access the hierarchy
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* @V9FS_ACCESS_USER: a new attach will be issued for every user (default)
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* @V9FS_ACCESS_ANY: use a single attach for all users
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* @V9FS_ACCESS_MASK: bit mask of different ACCESS options
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*
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* Session flags reflect options selected by users at mount time
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*/
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enum p9_session_flags {
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V9FS_PROTO_2000U = 0x01,
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V9FS_PROTO_2000L = 0x02,
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V9FS_ACCESS_SINGLE = 0x04,
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V9FS_ACCESS_USER = 0x08,
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V9FS_ACCESS_ANY = 0x0C,
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V9FS_ACCESS_MASK = 0x0C,
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};
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/* possible values of ->cache */
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/**
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* enum p9_cache_modes - user specified cache preferences
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* @CACHE_NONE: do not cache data, dentries, or directory contents (default)
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* @CACHE_LOOSE: cache data, dentries, and directory contents w/no consistency
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*
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* eventually support loose, tight, time, session, default always none
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*/
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enum p9_cache_modes {
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CACHE_NONE,
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CACHE_LOOSE,
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CACHE_FSCACHE,
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};
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/**
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* struct v9fs_session_info - per-instance session information
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* @flags: session options of type &p9_session_flags
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* @nodev: set to 1 to disable device mapping
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* @debug: debug level
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* @afid: authentication handle
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* @cache: cache mode of type &p9_cache_modes
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* @cachetag: the tag of the cache associated with this session
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* @fscache: session cookie associated with FS-Cache
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* @options: copy of options string given by user
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* @uname: string user name to mount hierarchy as
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* @aname: mount specifier for remote hierarchy
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* @maxdata: maximum data to be sent/recvd per protocol message
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* @dfltuid: default numeric userid to mount hierarchy as
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* @dfltgid: default numeric groupid to mount hierarchy as
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* @uid: if %V9FS_ACCESS_SINGLE, the numeric uid which mounted the hierarchy
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* @clnt: reference to 9P network client instantiated for this session
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* @slist: reference to list of registered 9p sessions
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*
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* This structure holds state for each session instance established during
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* a sys_mount() .
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*
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* Bugs: there seems to be a lot of state which could be condensed and/or
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* removed.
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*/
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struct v9fs_session_info {
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/* options */
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unsigned char flags;
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unsigned char nodev;
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unsigned short debug;
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unsigned int afid;
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unsigned int cache;
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#ifdef CONFIG_9P_FSCACHE
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char *cachetag;
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struct fscache_cookie *fscache;
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#endif
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char *uname; /* user name to mount as */
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char *aname; /* name of remote hierarchy being mounted */
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unsigned int maxdata; /* max data for client interface */
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unsigned int dfltuid; /* default uid/muid for legacy support */
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unsigned int dfltgid; /* default gid for legacy support */
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u32 uid; /* if ACCESS_SINGLE, the uid that has access */
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struct p9_client *clnt; /* 9p client */
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struct list_head slist; /* list of sessions registered with v9fs */
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struct backing_dev_info bdi;
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struct rw_semaphore rename_sem;
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};
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struct p9_fid *v9fs_session_init(struct v9fs_session_info *, const char *,
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char *);
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void v9fs_session_close(struct v9fs_session_info *v9ses);
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void v9fs_session_cancel(struct v9fs_session_info *v9ses);
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void v9fs_session_begin_cancel(struct v9fs_session_info *v9ses);
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#define V9FS_MAGIC 0x01021997
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/* other default globals */
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#define V9FS_PORT 564
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#define V9FS_DEFUSER "nobody"
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#define V9FS_DEFANAME ""
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#define V9FS_DEFUID (-2)
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#define V9FS_DEFGID (-2)
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static inline struct v9fs_session_info *v9fs_inode2v9ses(struct inode *inode)
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{
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return (inode->i_sb->s_fs_info);
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}
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static inline int v9fs_proto_dotu(struct v9fs_session_info *v9ses)
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{
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return v9ses->flags & V9FS_PROTO_2000U;
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}
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static inline int v9fs_proto_dotl(struct v9fs_session_info *v9ses)
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{
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return v9ses->flags & V9FS_PROTO_2000L;
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}
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