diff options
| author | Ian Kent | 2005-05-01 08:59:17 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2005-05-01 08:59:17 -0700 |
| commit | 3a9720ce73c9247e5262922d65e90444ea75eb50 (patch) | |
| tree | c70bba916168232f530c00858e7e8a0c5bd82b38 /fs | |
| parent | 4dcd00b18118d174c4b8d838c11f437f0af3c20c (diff) | |
[PATCH] autofs4: tree race fix
For tree mount maps, a call to chdir or chroot, to a directory above the
moint point directories at a certain time during the expire results in the
expire incorrectly thinking the tree is not busy. This patch adds a check
to see if the filesystem above the tree mount points is busy and also locks
the filesystem during the tree mount expire to prevent the race.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/autofs4/autofs_i.h | 14 | ||||
| -rw-r--r-- | fs/autofs4/expire.c | 16 | ||||
| -rw-r--r-- | fs/autofs4/inode.c | 1 |
3 files changed, 27 insertions, 4 deletions
diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h index 978987735252..c7b2b8890188 100644 --- a/fs/autofs4/autofs_i.h +++ b/fs/autofs4/autofs_i.h @@ -102,6 +102,7 @@ struct autofs_sb_info { int needs_reghost; struct super_block *sb; struct semaphore wq_sem; + spinlock_t fs_lock; struct autofs_wait_queue *queues; /* Wait queue pointer */ }; @@ -127,9 +128,18 @@ static inline int autofs4_oz_mode(struct autofs_sb_info *sbi) { static inline int autofs4_ispending(struct dentry *dentry) { struct autofs_info *inf = autofs4_dentry_ino(dentry); + int pending = 0; - return (dentry->d_flags & DCACHE_AUTOFS_PENDING) || - (inf != NULL && inf->flags & AUTOFS_INF_EXPIRING); + if (dentry->d_flags & DCACHE_AUTOFS_PENDING) + return 1; + + if (inf) { + spin_lock(&inf->sbi->fs_lock); + pending = inf->flags & AUTOFS_INF_EXPIRING; + spin_unlock(&inf->sbi->fs_lock); + } + + return pending; } static inline void autofs4_copy_atime(struct file *src, struct file *dst) diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c index 31540a6404d9..500425e24fba 100644 --- a/fs/autofs4/expire.c +++ b/fs/autofs4/expire.c @@ -99,6 +99,10 @@ static int autofs4_check_tree(struct vfsmount *mnt, if (!autofs4_can_expire(top, timeout, do_now)) return 0; + /* Is someone visiting anywhere in the tree ? */ + if (may_umount_tree(mnt)) + return 0; + spin_lock(&dcache_lock); repeat: next = this_parent->d_subdirs.next; @@ -270,10 +274,18 @@ static struct dentry *autofs4_expire(struct super_block *sb, /* Case 2: tree mount, expire iff entire tree is not busy */ if (!exp_leaves) { + /* Lock the tree as we must expire as a whole */ + spin_lock(&sbi->fs_lock); if (autofs4_check_tree(mnt, dentry, timeout, do_now)) { - expired = dentry; - break; + struct autofs_info *inf = autofs4_dentry_ino(dentry); + + /* Set this flag early to catch sys_chdir and the like */ + inf->flags |= AUTOFS_INF_EXPIRING; + spin_unlock(&sbi->fs_lock); + expired = dentry; + break; } + spin_unlock(&sbi->fs_lock); /* Case 3: direct mount, expire individual leaves */ } else { expired = autofs4_check_leaves(mnt, dentry, timeout, do_now); diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c index a52560746628..4bb14cc68040 100644 --- a/fs/autofs4/inode.c +++ b/fs/autofs4/inode.c @@ -206,6 +206,7 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent) sbi->version = 0; sbi->sub_version = 0; init_MUTEX(&sbi->wq_sem); + spin_lock_init(&sbi->fs_lock); sbi->queues = NULL; s->s_blocksize = 1024; s->s_blocksize_bits = 10; |