hpfs_prefetch_sectors
hpfs_prefetch_sectors(s, secno, 4 + ahead);
hpfs_prefetch_sectors(s, secno, ahead);
void hpfs_prefetch_sectors(struct super_block *, unsigned, int);
hpfs_prefetch_sectors(s, to_prefetch, 4 + 4 * (to_prefetch + 4 == next_prefetch));