sb_oldfscompat_write
void sb_oldfscompat_write(struct fs *, struct fs *);
sb_oldfscompat_write(sblk.b_un.b_fs, sblocksave); \
sb_oldfscompat_write(sblock, sblocksave);
sb_oldfscompat_write(sblock, sblock);
sb_oldfscompat_write(sblk.b_un.b_fs, sblocksave);