NFLUSHINPROG
while (np->n_flag & NFLUSHINPROG) {
np->n_flag |= NFLUSHINPROG;
np->n_flag &= ~NFLUSHINPROG;
np->n_flag &= ~(NMODIFIED | NFLUSHINPROG);
np->n_flag &= (NMODIFIED | NFLUSHINPROG | NFLUSHWANT);
if (flag & NFLUSHINPROG)