UDF_ROUNDDOWN
rel_block = phys - (UDF_ROUNDDOWN(phys, layout.blockingnr) + wrtrack_skew);
UDF_ROUNDDOWN(location, blockingnr) + wrtrack_skew;
last_lba - UDF_ROUNDDOWN(
last_lba = UDF_ROUNDDOWN(last_lba, align_blockingnr);
UDF_ROUNDDOWN(layout.meta_part_size_lba, layout.meta_blockingnr);
uint64_t max_len = UDF_ROUNDDOWN(UDF_EXT_MAXLEN, sector_size);