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authorJan Kara <jack@suse.cz>2007-05-16 22:11:19 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-17 05:23:05 -0700
commit7925409e202a41176b729671eab6e610a54153cd (patch)
tree7b97858fa33169a1616cc6f1e05b66117e97c1b3 /fs/quota.c
parentbb49b32fece7910fbb02a6934bca4495596f6c8c (diff)
circular locking dependency found in QUOTA OFF
i_mutex on quota files is special. Unlike i_mutexes for other inodes it is acquired under dqonoff_mutex. Tell lockdep about this lock ranking. Also comment and code in quota_sync_sb() seem to be bogus (as i_mutex for quota file can be acquired under dqonoff_mutex). Move truncate_inode_pages() call under dqonoff_mutex and save some problems with races... Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/quota.c')
-rw-r--r--fs/quota.c23
1 files changed, 7 insertions, 16 deletions
diff --git a/fs/quota.c b/fs/quota.c
index e9d88fd0eca..9f237d6182c 100644
--- a/fs/quota.c
+++ b/fs/quota.c
@@ -157,7 +157,6 @@ static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t
static void quota_sync_sb(struct super_block *sb, int type)
{
int cnt;
- struct inode *discard[MAXQUOTAS];
sb->s_qcop->quota_sync(sb, type);
/* This is not very clever (and fast) but currently I don't know about
@@ -167,29 +166,21 @@ static void quota_sync_sb(struct super_block *sb, int type)
sb->s_op->sync_fs(sb, 1);
sync_blockdev(sb->s_bdev);
- /* Now when everything is written we can discard the pagecache so
- * that userspace sees the changes. We need i_mutex and so we could
- * not do it inside dqonoff_mutex. Moreover we need to be carefull
- * about races with quotaoff() (that is the reason why we have own
- * reference to inode). */
+ /*
+ * Now when everything is written we can discard the pagecache so
+ * that userspace sees the changes.
+ */
mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
- discard[cnt] = NULL;
if (type != -1 && cnt != type)
continue;
if (!sb_has_quota_enabled(sb, cnt))
continue;
- discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]);
+ mutex_lock_nested(&sb_dqopt(sb)->files[cnt]->i_mutex, I_MUTEX_QUOTA);
+ truncate_inode_pages(&sb_dqopt(sb)->files[cnt]->i_data, 0);
+ mutex_unlock(&sb_dqopt(sb)->files[cnt]->i_mutex);
}
mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
- for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
- if (discard[cnt]) {
- mutex_lock(&discard[cnt]->i_mutex);
- truncate_inode_pages(&discard[cnt]->i_data, 0);
- mutex_unlock(&discard[cnt]->i_mutex);
- iput(discard[cnt]);
- }
- }
}
void sync_dquots(struct super_block *sb, int type)