THIN_METADATA_BLOCK_SIZE
disk_super->metadata_block_size = cpu_to_le32(THIN_METADATA_BLOCK_SIZE);
pmd->bm = dm_block_manager_create(pmd->bdev, THIN_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
sector_div(metadata_dev_size, THIN_METADATA_BLOCK_SIZE);