vdev_remove_child
vdev_remove_child(vd, tvd);
vdev_remove_child(newrootvd, newvd);
vdev_remove_child(pvd, vd);
extern void vdev_remove_child(vdev_t *pvd, vdev_t *cvd);
vdev_remove_child(pvd, cvd);
vdev_remove_child(mvd, cvd);
vdev_remove_child(pvd, mvd);
vdev_remove_child(pvd, vd);
vdev_remove_child(vd->vdev_parent, vd);
vdev_remove_child(ivd, vd);