vdev_space_update
vdev_space_update(dev->l2ad_vdev, -asize, 0, 0);
vdev_space_update(dev->l2ad_vdev, -bytes_dropped, 0, 0);
vdev_space_update(dev->l2ad_vdev, -asize, 0, 0);
vdev_space_update(dev->l2ad_vdev, asize, 0, 0);
vdev_space_update(vd, 0, 0, adddev->l2ad_end - adddev->l2ad_hand);
vdev_space_update(vd, asize, 0, 0);
vdev_space_update(dev->l2ad_vdev, asize, 0, 0);
vdev_space_update(dev->l2ad_vdev, asize, 0, 0);
vdev_space_update(dev->l2ad_vdev, asize, 0, 0);
vdev_space_update(vd, alloc_delta, defer_delta, space_delta);
extern void vdev_space_update(vdev_t *vd,