btrfs: use btrfs_finish_ordered_extent to complete buffered writes

Use the btrfs_finish_ordered_extent helper to complete compressed writes
using the bbio->ordered pointer instead of requiring an rbtree lookup
in the otherwise equivalent btrfs_mark_ordered_io_finished called from
btrfs_writepage_endio_finish_ordered.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -557,8 +557,7 @@ static void end_bio_extent_writepage(struct btrfs_bio *bbio)
 		"incomplete page write with offset %u and length %u",
 				   bvec->bv_offset, bvec->bv_len);
 
-		btrfs_writepage_endio_finish_ordered(BTRFS_I(inode), page, start,
-						     start + len - 1, !error);
+		btrfs_finish_ordered_extent(bbio->ordered, page, start, len, !error);
 		if (error) {
 			btrfs_page_clear_uptodate(fs_info, page, start, len);
 			mapping_set_error(page->mapping, error);