FIFOOPEN
oldfnp->fn_flag &= ~FIFOOPEN;
VTOF(vp2)->fn_flag &= ~FIFOOPEN;
while (fnp->fn_flag & FIFOOPEN) {
fnp->fn_flag |= FIFOOPEN;
fnp->fn_flag &= ~FIFOOPEN;
VTOF(vp2)->fn_flag |= FIFOOPEN;