Commit 61ce908a authored by Filipe Manana's avatar Filipe Manana Committed by David Sterba
Browse files

btrfs: send: avoid unnecessary path allocations when finding extent clone 



When looking for an extent clone, at find_extent_clone(), we start by
allocating a path and then check for cases where we can't have clones
and exit immediately in those cases. It's a waste of time to allocate
the path before those cases, so reorder the logic so that we check for
those cases before allocating the path.

Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 1a1a2851

fs/btrfs/send.c

+16 −21
Original line number Diff line number Diff line
@@ -1365,40 +1365,35 @@ static int find_extent_clone(struct send_ctx *sctx, 
	int compressed;

	u32 i;



	tmp_path = alloc_path_for_send();

	if (!tmp_path)

		return -ENOMEM;



	/* We only use this path under the commit sem */

	tmp_path->need_commit_sem = 0;



	if (data_offset >= ino_size) {

		/*

		 * There may be extents that lie behind the file's size.

		 * I at least had this in combination with snapshotting while

		 * writing large files.

		 */

		ret = 0;

		goto out;

		return 0;

	}



	fi = btrfs_item_ptr(eb, path->slots[0],

			struct btrfs_file_extent_item);

	fi = btrfs_item_ptr(eb, path->slots[0], struct btrfs_file_extent_item);

	extent_type = btrfs_file_extent_type(eb, fi);

	if (extent_type == BTRFS_FILE_EXTENT_INLINE) {

		ret = -ENOENT;

		goto out;

	}

	compressed = btrfs_file_extent_compression(eb, fi);

	if (extent_type == BTRFS_FILE_EXTENT_INLINE)

		return -ENOENT;



	num_bytes = btrfs_file_extent_num_bytes(eb, fi);

	disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);

	if (disk_byte == 0) {

		ret = -ENOENT;

		goto out;

	}

	if (disk_byte == 0)

		return -ENOENT;



	compressed = btrfs_file_extent_compression(eb, fi);

	num_bytes = btrfs_file_extent_num_bytes(eb, fi);

	logical = disk_byte + btrfs_file_extent_offset(eb, fi);



	tmp_path = alloc_path_for_send();

	if (!tmp_path)

		return -ENOMEM;



	/* We only use this path under the commit sem */

	tmp_path->need_commit_sem = 0;



	down_read(&fs_info->commit_root_sem);

	ret = extent_from_logical(fs_info, disk_byte, tmp_path,

				  &found_key, &flags);