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>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/dquot.c b/fs/dquot.c
index 3a995841de90..8819d281500c 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -1421,7 +1421,7 @@ int vfs_quota_off(struct super_block *sb, int type)
                         /* If quota was reenabled in the meantime, we have
                          * nothing to do */
                         if (!sb_has_quota_enabled(sb, cnt)) {
-                                mutex_lock(&toputinode[cnt]->i_mutex);
+                                mutex_lock_nested(&toputinode[cnt]->i_mutex, I_MUTEX_QUOTA);
                                 toputinode[cnt]->i_flags &= ~(S_IMMUTABLE |
                                   S_NOATIME | S_NOQUOTA);
                                 truncate_inode_pages(&toputinode[cnt]->i_data, 0);