is_vdev
is->is_vdev = vd;
rc = first->is_vdev->v_read(first->is_vdev, zio.io_bp,
rc = is->is_vdev->v_read(is->is_vdev, zio.io_bp,
vdev_t *is_vdev; /* top-level vdev */
is_vdev, cb);
is->is_vdev = vd;
first->is_vdev, first->is_target_offset,
is->is_vdev, is->is_target_offset,
vdev_t *is_vdev; /* top-level vdev */