ext4: make sure quota gets properly shutdown on error

When we hit an error when enabling quotas and setting inode flags, we do
not properly shutdown quota subsystem despite returning error from
Q_QUOTAON quotactl. This can lead to some odd situations like kernel
using quota file while it is still writeable for userspace. Make sure we
properly cleanup the quota subsystem in case of error.
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20211007155336.12493-2-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/super.c

@@ -6749,10 +6749,7 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id,
 
 	lockdep_set_quota_inode(path->dentry->d_inode, I_DATA_SEM_QUOTA);
 	err = dquot_quota_on(sb, type, format_id, path);
-	if (err) {
-		lockdep_set_quota_inode(path->dentry->d_inode,
-					     I_DATA_SEM_NORMAL);
-	} else {
+	if (!err) {
 		struct inode *inode = d_inode(path->dentry);
 		handle_t *handle;
 
@@ -6772,7 +6769,12 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id,
 		ext4_journal_stop(handle);
 	unlock_inode:
 		inode_unlock(inode);
+		if (err)
+			dquot_quota_off(sb, type);
 	}
+	if (err)
+		lockdep_set_quota_inode(path->dentry->d_inode,
+					     I_DATA_SEM_NORMAL);
 	return err;
 }