btrfs: use test_and_set_bit() in btrfs_delayed_delete_inode_ref()

Instead of testing and setting the BTRFS_DELAYED_NODE_DEL_IREF bit in the
delayed node's flags, use test_and_set_bit() which makes the code shorter
without compromising readability and getting rid of the label and goto.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Daniel Vacek <neelx@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: fdmanana

fs/btrfs/delayed-inode.c

@@ -2008,13 +2008,10 @@ int btrfs_delayed_delete_inode_ref(struct btrfs_inode *inode)
 	 *   It is very rare.
 	 */
 	mutex_lock(&delayed_node->mutex);
-	if (test_bit(BTRFS_DELAYED_NODE_DEL_IREF, &delayed_node->flags))
-		goto release_node;
-
-	set_bit(BTRFS_DELAYED_NODE_DEL_IREF, &delayed_node->flags);
-	delayed_node->count++;
-	atomic_inc(&fs_info->delayed_root->items);
-release_node:
+	if (!test_and_set_bit(BTRFS_DELAYED_NODE_DEL_IREF, &delayed_node->flags)) {
+		delayed_node->count++;
+		atomic_inc(&fs_info->delayed_root->items);
+	}
 	mutex_unlock(&delayed_node->mutex);
 	btrfs_release_delayed_node(delayed_node, &delayed_node_tracker);
 	return 0;