Commit e2eb0248 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by David Sterba
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btrfs: cleanup the main loop in btrfs_lookup_bio_sums 



Introduce a bio_offset variable for the current offset into the bio
instead of recalculating it over and over.   Remove the now only used
once search_len and sector_offset variables, and reduce the scope for
count and cur_disk_bytenr.

Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 65886d2b

fs/btrfs/file-item.c

+9 −24
Original line number Diff line number Diff line
@@ -350,10 +350,9 @@ blk_status_t btrfs_lookup_bio_sums(struct btrfs_bio *bbio) 
	const u32 csum_size = fs_info->csum_size;

	u32 orig_len = bio->bi_iter.bi_size;

	u64 orig_disk_bytenr = bio->bi_iter.bi_sector << SECTOR_SHIFT;

	u64 cur_disk_bytenr;

	const unsigned int nblocks = orig_len >> fs_info->sectorsize_bits;

	int count = 0;

	blk_status_t ret = BLK_STS_OK;

	u32 bio_offset = 0;



	if ((inode->flags & BTRFS_INODE_NODATASUM) ||

	    test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state))
@@ -404,28 +403,14 @@ blk_status_t btrfs_lookup_bio_sums(struct btrfs_bio *bbio) 
		path->skip_locking = 1;

	}



	for (cur_disk_bytenr = orig_disk_bytenr;

	     cur_disk_bytenr < orig_disk_bytenr + orig_len;

	     cur_disk_bytenr += (count * sectorsize)) {

		u64 search_len = orig_disk_bytenr + orig_len - cur_disk_bytenr;

		unsigned int sector_offset;

		u8 *csum_dst;



		/*

		 * Although both cur_disk_bytenr and orig_disk_bytenr is u64,

		 * we're calculating the offset to the bio start.

		 *

		 * Bio size is limited to UINT_MAX, thus unsigned int is large

		 * enough to contain the raw result, not to mention the right

		 * shifted result.

		 */

		ASSERT(cur_disk_bytenr - orig_disk_bytenr < UINT_MAX);

		sector_offset = (cur_disk_bytenr - orig_disk_bytenr) >>

				fs_info->sectorsize_bits;

		csum_dst = bbio->csum + sector_offset * csum_size;

	while (bio_offset < orig_len) {

		int count;

		u64 cur_disk_bytenr = orig_disk_bytenr + bio_offset;

		u8 *csum_dst = bbio->csum +

			(bio_offset >> fs_info->sectorsize_bits) * csum_size;



		count = search_csum_tree(fs_info, path, cur_disk_bytenr,

					 search_len, csum_dst);

					 orig_len - bio_offset, csum_dst);

		if (count < 0) {

			ret = errno_to_blk_status(count);

			if (bbio->csum != bbio->csum_inline)
@@ -450,8 +435,7 @@ blk_status_t btrfs_lookup_bio_sums(struct btrfs_bio *bbio) 


			if (inode->root->root_key.objectid ==

			    BTRFS_DATA_RELOC_TREE_OBJECTID) {

				u64 file_offset = bbio->file_offset +

					cur_disk_bytenr - orig_disk_bytenr;

				u64 file_offset = bbio->file_offset + bio_offset;



				set_extent_bits(&inode->io_tree, file_offset,

						file_offset + sectorsize - 1,
@@ -462,6 +446,7 @@ blk_status_t btrfs_lookup_bio_sums(struct btrfs_bio *bbio) 
				cur_disk_bytenr, cur_disk_bytenr + sectorsize);

			}

		}

		bio_offset += count * sectorsize;

	}



	btrfs_free_path(path);