MIN_PBL_SHIFT
rdev->stats.pbl.cur += roundup(size, 1 << MIN_PBL_SHIFT);
rdev->stats.pbl.cur -= roundup(size, 1 << MIN_PBL_SHIFT);
rdev->pbl_pool = gen_pool_create(MIN_PBL_SHIFT, -1);
if (pbl_chunk <= 1024 << MIN_PBL_SHIFT) {