procfs_allocvp
int procfs_allocvp (struct mount *, struct vnode **, long, pfstype);
return (procfs_allocvp(mp, vpp, 0, Proot));
error = procfs_allocvp(dvp->v_mount, vpp, 0, Pcurproc);
error = procfs_allocvp(dvp->v_mount, vpp, pid, Pproc);
error = procfs_allocvp(dvp->v_mount, vpp, pfs->pfs_pid,