btrfs: factor out do_free_extent_accounting helper

__btrfs_free_extent() does all of the hard work of updating the extent
ref items, and then at the end if we dropped the extent completely it
does the cleanup accounting work.  We're going to only want to do that
work for metadata with extent tree v2, so extract this bit into its own
helper.
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/extent-tree.c

@@ -2853,6 +2853,35 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans)
 	return 0;
 }
 
+static int do_free_extent_accounting(struct btrfs_trans_handle *trans,
+				     u64 bytenr, u64 num_bytes, bool is_data)
+{
+	int ret;
+
+	if (is_data) {
+		struct btrfs_root *csum_root;
+
+		csum_root = btrfs_csum_root(trans->fs_info, bytenr);
+		ret = btrfs_del_csums(trans, csum_root, bytenr, num_bytes);
+		if (ret) {
+			btrfs_abort_transaction(trans, ret);
+			return ret;
+		}
+	}
+
+	ret = add_to_free_space_tree(trans, bytenr, num_bytes);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		return ret;
+	}
+
+	ret = btrfs_update_block_group(trans, bytenr, num_bytes, false);
+	if (ret)
+		btrfs_abort_transaction(trans, ret);
+
+	return ret;
+}
+
 /*
  * Drop one or more refs of @node.
  *
@@ -3178,28 +3207,7 @@ static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
 		}
 		btrfs_release_path(path);
 
-		if (is_data) {
-			struct btrfs_root *csum_root;
-			csum_root = btrfs_csum_root(info, bytenr);
-			ret = btrfs_del_csums(trans, csum_root, bytenr,
-					      num_bytes);
-			if (ret) {
-				btrfs_abort_transaction(trans, ret);
-				goto out;
-			}
-		}
-
-		ret = add_to_free_space_tree(trans, bytenr, num_bytes);
-		if (ret) {
-			btrfs_abort_transaction(trans, ret);
-			goto out;
-		}
-
-		ret = btrfs_update_block_group(trans, bytenr, num_bytes, false);
-		if (ret) {
-			btrfs_abort_transaction(trans, ret);
-			goto out;
-		}
+		ret = do_free_extent_accounting(trans, bytenr, num_bytes, is_data);
 	}
 	btrfs_release_path(path);