ZIL_MIN_BLKSZ
wsz = P2ROUNDUP_TYPED(lwb->lwb_nused, ZIL_MIN_BLKSZ, uint64_t);
NULL, ZIL_MIN_BLKSZ, &slog);
size = P2ROUNDUP_TYPED(zilc.zc_nused, ZIL_MIN_BLKSZ,
size = P2ROUNDUP_TYPED(nused, ZIL_MIN_BLKSZ, uint64_t);