btrfs: handle btrfs_update_reloc_root failure in insert_dirty_subvol

btrfs_update_reloc_root will will return errors in the future, so handle
the error properly in insert_dirty_subvol.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/relocation.c

@@ -1571,6 +1571,7 @@ static int insert_dirty_subvol(struct btrfs_trans_handle *trans,
 {
 	struct btrfs_root *reloc_root = root->reloc_root;
 	struct btrfs_root_item *reloc_root_item;
+	int ret;
 
 	/* @root must be a subvolume tree root with a valid reloc tree */
 	ASSERT(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
@@ -1581,7 +1582,9 @@ static int insert_dirty_subvol(struct btrfs_trans_handle *trans,
 		sizeof(reloc_root_item->drop_progress));
 	btrfs_set_root_drop_level(reloc_root_item, 0);
 	btrfs_set_root_refs(reloc_root_item, 0);
-	btrfs_update_reloc_root(trans, root);
+	ret = btrfs_update_reloc_root(trans, root);
+	if (ret)
+		return ret;
 
 	if (list_empty(&root->reloc_dirty_list)) {
 		btrfs_grab_root(root);