Commit 371cdc07 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: introduce subpage metadata validation check 



For subpage metadata validation check, there are some differences:

- Read must finish in one bvec
  Since we're just reading one subpage range in one page, it should
  never be split into two bios nor two bvecs.

- How to grab the existing eb
  Instead of grabbing eb using page->private, we have to go search radix
  tree as we don't have any direct pointer at hand.

Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 4325cb22

fs/btrfs/disk-io.c

+57 −0
Original line number Diff line number Diff line
@@ -591,6 +591,59 @@ static int validate_extent_buffer(struct extent_buffer *eb) 
	return ret;

}



static int validate_subpage_buffer(struct page *page, u64 start, u64 end,

				   int mirror)

{

	struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb);

	struct extent_buffer *eb;

	bool reads_done;

	int ret = 0;



	/*

	 * We don't allow bio merge for subpage metadata read, so we should

	 * only get one eb for each endio hook.

	 */

	ASSERT(end == start + fs_info->nodesize - 1);

	ASSERT(PagePrivate(page));



	eb = find_extent_buffer(fs_info, start);

	/*

	 * When we are reading one tree block, eb must have been inserted into

	 * the radix tree. If not, something is wrong.

	 */

	ASSERT(eb);



	reads_done = atomic_dec_and_test(&eb->io_pages);

	/* Subpage read must finish in page read */

	ASSERT(reads_done);



	eb->read_mirror = mirror;

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

		ret = -EIO;

		goto err;

	}

	ret = validate_extent_buffer(eb);

	if (ret < 0)

		goto err;



	if (test_and_clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags))

		btree_readahead_hook(eb, ret);



	set_extent_buffer_uptodate(eb);



	free_extent_buffer(eb);

	return ret;

err:

	/*

	 * end_bio_extent_readpage decrements io_pages in case of error,

	 * make sure it has something to decrement.

	 */

	atomic_inc(&eb->io_pages);

	clear_extent_buffer_uptodate(eb);

	free_extent_buffer(eb);

	return ret;

}



int btrfs_validate_metadata_buffer(struct btrfs_io_bio *io_bio,

				   struct page *page, u64 start, u64 end,

				   int mirror)
@@ -600,6 +653,10 @@ int btrfs_validate_metadata_buffer(struct btrfs_io_bio *io_bio, 
	int reads_done;



	ASSERT(page->private);



	if (btrfs_sb(page->mapping->host->i_sb)->sectorsize < PAGE_SIZE)

		return validate_subpage_buffer(page, start, end, mirror);



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



	/*