Btrfs: fix return value of setflags ioctl

setflags ioctl should return error when any checks fail.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/ioctl.c

@@ -247,9 +247,11 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
 	btrfs_end_transaction(trans, root);
 
 	mnt_drop_write(file->f_path.mnt);
+
+	ret = 0;
  out_unlock:
 	mutex_unlock(&inode->i_mutex);
-	return 0;
+	return ret;
 }
 
 static int btrfs_ioctl_getversion(struct file *file, int __user *arg)