HFSPLUS_SECTOR_SHIFT
wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
loff_t start = (loff_t)sector << HFSPLUS_SECTOR_SHIFT;
sector &= ~((io_size >> HFSPLUS_SECTOR_SHIFT) - 1);