fsinit
void fsinit(time_t);
fsinit(utime);
int (*fsinit)(void);
.fsinit = boot2_ufs_init,
if (boot2_ufs_api.fsinit() == 0) {
} else if (boot2_hammer2_api.fsinit() == 0) {
return fsapi->fsinit();
.fsinit = boot2_hammer_init,
.fsinit = boot2_hammer2_init,