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[PATCH] autofs4: tree race fix

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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>
This commit is contained in:
Ian Kent
2005-05-01 08:59:17 -07:00
committed by Linus Torvalds
parent 4dcd00b181
commit 3a9720ce73
3 changed files with 27 additions and 4 deletions
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16
fs/autofs4/expire.c
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@@ -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);