Commit 31d89399 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by David Sterba
Browse files

btrfs: remove the extent_buffer lookup in btree block checksumming 



The checksumming of btree blocks always operates on the entire
extent_buffer, and because btree blocks are always allocated contiguously
on disk they are never split by btrfs_submit_bio.

Simplify the checksumming code by finding the extent_buffer in the
btrfs_bio private data instead of trying to search through the bio_vec.

Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent cd88a4fd

fs/btrfs/disk-io.c

+24 −96
Original line number Diff line number Diff line
@@ -254,12 +254,34 @@ int btrfs_read_extent_buffer(struct extent_buffer *eb, 
	return ret;

}



static int csum_one_extent_buffer(struct extent_buffer *eb)

/*

 * Checksum a dirty tree block before IO.

 */

blk_status_t btree_csum_one_bio(struct btrfs_bio *bbio)

{

	struct extent_buffer *eb = bbio->private;

	struct btrfs_fs_info *fs_info = eb->fs_info;

	u64 found_start = btrfs_header_bytenr(eb);

	u8 result[BTRFS_CSUM_SIZE];

	int ret;



	/* Btree blocks are always contiguous on disk. */

	if (WARN_ON_ONCE(bbio->file_offset != eb->start))

		return BLK_STS_IOERR;

	if (WARN_ON_ONCE(bbio->bio.bi_iter.bi_size != eb->len))

		return BLK_STS_IOERR;



	if (test_bit(EXTENT_BUFFER_NO_CHECK, &eb->bflags)) {

		WARN_ON_ONCE(found_start != 0);

		return BLK_STS_OK;

	}



	if (WARN_ON_ONCE(found_start != eb->start))

		return BLK_STS_IOERR;

	if (WARN_ON(!btrfs_page_test_uptodate(fs_info, eb->pages[0], eb->start,

					      eb->len)))

		return BLK_STS_IOERR;



	ASSERT(memcmp_extent_buffer(eb, fs_info->fs_devices->metadata_uuid,

				    offsetof(struct btrfs_header, fsid),

				    BTRFS_FSID_SIZE) == 0);
@@ -286,8 +308,7 @@ static int csum_one_extent_buffer(struct extent_buffer *eb) 
		goto error;

	}

	write_extent_buffer(eb, result, 0, fs_info->csum_size);



	return 0;

	return BLK_STS_OK;



error:

	btrfs_print_tree(eb, 0);
@@ -301,99 +322,6 @@ static int csum_one_extent_buffer(struct extent_buffer *eb) 
	 */

	WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG) ||

		btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID);

	return ret;

}



/* Checksum all dirty extent buffers in one bio_vec */

static int csum_dirty_subpage_buffers(struct btrfs_fs_info *fs_info,

				      struct bio_vec *bvec)

{

	struct page *page = bvec->bv_page;

	u64 bvec_start = page_offset(page) + bvec->bv_offset;

	u64 cur;

	int ret = 0;



	for (cur = bvec_start; cur < bvec_start + bvec->bv_len;

	     cur += fs_info->nodesize) {

		struct extent_buffer *eb;

		bool uptodate;



		eb = find_extent_buffer(fs_info, cur);

		uptodate = btrfs_subpage_test_uptodate(fs_info, page, cur,

						       fs_info->nodesize);



		/* A dirty eb shouldn't disappear from buffer_radix */

		if (WARN_ON(!eb))

			return -EUCLEAN;



		if (WARN_ON(cur != btrfs_header_bytenr(eb))) {

			free_extent_buffer(eb);

			return -EUCLEAN;

		}

		if (WARN_ON(!uptodate)) {

			free_extent_buffer(eb);

			return -EUCLEAN;

		}



		ret = csum_one_extent_buffer(eb);

		free_extent_buffer(eb);

		if (ret < 0)

			return ret;

	}

	return ret;

}



/*

 * Checksum a dirty tree block before IO.  This has extra checks to make sure

 * we only fill in the checksum field in the first page of a multi-page block.

 * For subpage extent buffers we need bvec to also read the offset in the page.

 */

static int csum_dirty_buffer(struct btrfs_fs_info *fs_info, struct bio_vec *bvec)

{

	struct page *page = bvec->bv_page;

	u64 start = page_offset(page);

	u64 found_start;

	struct extent_buffer *eb;



	if (fs_info->nodesize < PAGE_SIZE)

		return csum_dirty_subpage_buffers(fs_info, bvec);



	eb = (struct extent_buffer *)page->private;

	if (page != eb->pages[0])

		return 0;



	found_start = btrfs_header_bytenr(eb);



	if (test_bit(EXTENT_BUFFER_NO_CHECK, &eb->bflags)) {

		WARN_ON(found_start != 0);

		return 0;

	}



	/*

	 * Please do not consolidate these warnings into a single if.

	 * It is useful to know what went wrong.

	 */

	if (WARN_ON(found_start != start))

		return -EUCLEAN;

	if (WARN_ON(!PageUptodate(page)))

		return -EUCLEAN;



	return csum_one_extent_buffer(eb);

}



blk_status_t btree_csum_one_bio(struct btrfs_bio *bbio)

{

	struct btrfs_fs_info *fs_info = bbio->inode->root->fs_info;

	struct bvec_iter iter;

	struct bio_vec bv;

	int ret = 0;



	bio_for_each_segment(bv, &bbio->bio, iter) {

		ret = csum_dirty_buffer(fs_info, &bv);

		if (ret)

			break;

	}



	return errno_to_blk_status(ret);

}