IMNT_UNMOUNT
mp->mnt_iflag |= IMNT_UNMOUNT;
mp->mnt_iflag &= ~IMNT_UNMOUNT;
(IMNT_UNMOUNT | IMNT_WANTRDONLY))) {
vp->v_mount->mnt_iflag & (IMNT_UNMOUNT | IMNT_WANTRDONLY))
if (ap->a_vp->v_mount->mnt_iflag & IMNT_UNMOUNT) {