ext4: clear lockdep subtype for quota files on quota off

Quota files have special ranking of i_data_sem lock. We inform lockdep
about it when turning on quotas however when turning quotas off, we
don't clear the lockdep subclass from i_data_sem lock and thus when the
inode gets later reused for a normal file or directory, lockdep gets
confused and complains about possible deadlocks. Fix the problem by
resetting lockdep subclass of i_data_sem on quota off.

Cc: stable@vger.kernel.org
Fixes: daf647d2dd58cec59570d7698a45b98e580f2076
Reported-and-tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 5 insertions, 9 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 0b177da9ea82..8f05c72bc4ec 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -848,14 +848,9 @@ static inline void ext4_quota_off_umount(struct super_block *sb)
 {
         int type;
 
-        if (ext4_has_feature_quota(sb)) {
-                dquot_disable(sb, -1,
-                              DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
-        } else {
-                /* Use our quota_off function to clear inode flags etc. */
-                for (type = 0; type < EXT4_MAXQUOTAS; type++)
-                        ext4_quota_off(sb, type);
-        }
+        /* Use our quota_off function to clear inode flags etc. */
+        for (type = 0; type < EXT4_MAXQUOTAS; type++)
+                ext4_quota_off(sb, type);
 }
 #else
 static inline void ext4_quota_off_umount(struct super_block *sb)
@@ -5485,7 +5480,7 @@ static int ext4_quota_off(struct super_block *sb, int type)
                 goto out;
 
         err = dquot_quota_off(sb, type);
-        if (err)
+        if (err || ext4_has_feature_quota(sb))
                 goto out_put;
 
         inode_lock(inode);
@@ -5505,6 +5500,7 @@ static int ext4_quota_off(struct super_block *sb, int type)
 out_unlock:
         inode_unlock(inode);
 out_put:
+        lockdep_set_quota_inode(inode, I_DATA_SEM_NORMAL);
         iput(inode);
         return err;
 out: