vp = *vpp;
vp->v_type = lowervp->v_type;
if (vp->v_type == VCHR || vp->v_type == VBLK)
addalias(vp, lowervp->v_un.vu_spec.vu_specinfo);
else
vp->v_un = lowervp->v_un;
lockinit(&xp->null_lock, PINOD, "nullnode", 0, LK_CANRECURSE);
xp->null_vnode = vp;
vp->v_data = xp;