From 3a9720ce73c9247e5262922d65e90444ea75eb50 Mon Sep 17 00:00:00 2001
From: Ian Kent <raven@themaw.net>
Date: Sun, 1 May 2005 08:59:17 -0700
Subject: [PATCH] [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>
---
fs/autofs4/autofs_i.h | 14 ++++++++++++--
fs/autofs4/expire.c | 16 ++++++++++++++--
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;
--
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