FINUSE
old_inuse = tp->flag & FINUSE;
tp->flag |= FINUSE;
tp->flag = (tp->flag & ~FINUSE) | old_inuse;
if ((tp->flag & (FDELETE|FINUSE)) == FDELETE) {
if (tp->flag & FINUSE) {
} else if (!(tblp->flag & FINUSE)) {