Commit 0ae653fb authored by Johannes Thumshirn's avatar Johannes Thumshirn Committed by David Sterba
Browse files

btrfs: reduce chunk_map lookups in btrfs_map_block() 



Currently we're calling btrfs_num_copies() before btrfs_get_chunk_map() in
btrfs_map_block(). But btrfs_num_copies() itself does a chunk map lookup
to be able to calculate the number of copies.

So split out the code getting the number of copies from btrfs_num_copies()
into a helper called btrfs_chunk_map_num_copies() and directly call it
from btrfs_map_block() and btrfs_num_copies().

This saves us one rbtree lookup per btrfs_map_block() invocation.

Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 6d752cac

fs/btrfs/volumes.c

+27 −22
Original line number Diff line number Diff line
@@ -5781,11 +5781,31 @@ void btrfs_mapping_tree_free(struct btrfs_fs_info *fs_info) 
	write_unlock(&fs_info->mapping_tree_lock);

}



static int btrfs_chunk_map_num_copies(const struct btrfs_chunk_map *map)

{

	enum btrfs_raid_types index = btrfs_bg_flags_to_raid_index(map->type);



	if (map->type & BTRFS_BLOCK_GROUP_RAID5)

		return 2;



	/*

	 * There could be two corrupted data stripes, we need to loop retry in

	 * order to rebuild the correct data.

	 *

	 * Fail a stripe at a time on every retry except the stripe under

	 * reconstruction.

	 */

	if (map->type & BTRFS_BLOCK_GROUP_RAID6)

		return map->num_stripes;



	/* Non-RAID56, use their ncopies from btrfs_raid_array. */

	return btrfs_raid_array[index].ncopies;

}



int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len)

{

	struct btrfs_chunk_map *map;

	enum btrfs_raid_types index;

	int ret = 1;

	int ret;



	map = btrfs_get_chunk_map(fs_info, logical, len);

	if (IS_ERR(map))
@@ -5797,22 +5817,7 @@ int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len) 
		 */

		return 1;



	index = btrfs_bg_flags_to_raid_index(map->type);



	/* Non-RAID56, use their ncopies from btrfs_raid_array. */

	if (!(map->type & BTRFS_BLOCK_GROUP_RAID56_MASK))

		ret = btrfs_raid_array[index].ncopies;

	else if (map->type & BTRFS_BLOCK_GROUP_RAID5)

		ret = 2;

	else if (map->type & BTRFS_BLOCK_GROUP_RAID6)

		/*

		 * There could be two corrupted data stripes, we need

		 * to loop retry in order to rebuild the correct data.

		 *

		 * Fail a stripe at a time on every retry except the

		 * stripe under reconstruction.

		 */

		ret = map->num_stripes;

	ret = btrfs_chunk_map_num_copies(map);

	btrfs_free_chunk_map(map);

	return ret;

}
@@ -6462,14 +6467,14 @@ int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op, 
	io_geom.stripe_index = 0;

	io_geom.op = op;



	num_copies = btrfs_num_copies(fs_info, logical, fs_info->sectorsize);

	if (io_geom.mirror_num > num_copies)

		return -EINVAL;



	map = btrfs_get_chunk_map(fs_info, logical, *length);

	if (IS_ERR(map))

		return PTR_ERR(map);



	num_copies = btrfs_chunk_map_num_copies(map);

	if (io_geom.mirror_num > num_copies)

		return -EINVAL;



	map_offset = logical - map->start;

	io_geom.raid56_full_stripe_start = (u64)-1;

	max_len = btrfs_max_io_len(map, map_offset, &io_geom);