HFS_SECTOR_SIZE
size = sb_min_blocksize(sb, HFS_SECTOR_SIZE);
if (!size || (size & (HFS_SECTOR_SIZE - 1))) {
size -= HFS_SECTOR_SIZE;
memcpy(HFS_SB(sb)->alt_mdb, HFS_SB(sb)->mdb, HFS_SECTOR_SIZE);
#define HFSPLUS_SECTOR_SIZE HFS_SECTOR_SIZE