Function vdev_propagate_state

freebsd/contrib/openzfs/module/zfs/vdev.c:4700–4755

* Propagate vdev state up from children to parent. */

 * Propagate vdev state up from children to parent.
 */
void
vdev_propagate_state(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;
	vdev_t *rvd = spa->spa_root_vdev;
	int degraded = 0, faulted = 0;
	int corrupted = 0;
	vdev_t *child;

	if (vd->vdev_children > 0) {
		for (int c = 0; c < vd->vdev_children; c++) {
			child = vd->vdev_child[c];

			/*
			 * Don't factor holes or indirect vdevs into the
			 * decision.
			 */
			if (!vdev_is_concrete(child))
				continue;

			if (!vdev_readable(child) ||
			    (!vdev_writeable(child) && spa_writeable(spa))) {
				/*
				 * Root special: if there is a top-level log
				 * device, treat the root vdev as if it were
				 * degraded.
				 */
				if (child->vdev_islog && vd == rvd)
					degraded++;
				else
					faulted++;
			} else if (child->vdev_state <= VDEV_STATE_DEGRADED) {
				degraded++;
			}

			if (child->vdev_stat.vs_aux == VDEV_AUX_CORRUPT_DATA)
				corrupted++;
		}

		vd->vdev_ops->vdev_op_state_change(vd, faulted, degraded);

		/*
		 * Root special: if there is a top-level vdev that cannot be
		 * opened due to corrupted metadata, then propagate the root
		 * vdev's aux state as 'corrupt' rather than 'insufficient
		 * replicas'.
		 */
		if (corrupted && vd == rvd &&
		    rvd->vdev_state == VDEV_STATE_CANT_OPEN)
			vdev_set_state(rvd, B_FALSE, VDEV_STATE_CANT_OPEN,
			    VDEV_AUX_CORRUPT_DATA);
	}

	if (vd->vdev_parent)
		vdev_propagate_state(vd->vdev_parent);
}

/*