calcsb
if (bflag || preen || calcsb(realdev, fsreadfd, &proto, lp) == 0)
int calcsb(char *, int, struct m_ext2fs *, struct disklabel *);
calcsb(realdev, fsreadfd, &proto, lp, SBLOCK_UFS1) == 0)
calcsb(realdev, fsreadfd, &proto, lp, SBLOCK_UFS2);
int calcsb(char *, int, struct fs *, struct disklabel *, uint32_t);