disk_read_sectors
if (disk_read_sectors(strat, lp, bp, LABELSECTOR, 1) != 0) {
disk_read_sectors(strat, lp, bp, secperunit - 1, 1) == 0)
error = disk_read_sectors(a->strat, a->lp, a->bp, sector, count);
int disk_read_sectors(void (*)(struct buf *), const struct disklabel *,