Function spa_vdev_add

freebsd/contrib/openzfs/module/zfs/spa.c:6430–6578

* Add a device to a storage pool. */

 * Add a device to a storage pool.
 */
int
spa_vdev_add(spa_t *spa, nvlist_t *nvroot)
{
	uint64_t txg, ndraid = 0;
	int error;
	vdev_t *rvd = spa->spa_root_vdev;
	vdev_t *vd, *tvd;
	nvlist_t **spares, **l2cache;
	uint_t nspares, nl2cache;

	ASSERT(spa_writeable(spa));

	txg = spa_vdev_enter(spa);

	if ((error = spa_config_parse(spa, &vd, nvroot, NULL, 0,
	    VDEV_ALLOC_ADD)) != 0)
		return (spa_vdev_exit(spa, NULL, txg, error));

	spa->spa_pending_vdev = vd;	/* spa_vdev_exit() will clear this */

	if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES, &spares,
	    &nspares) != 0)
		nspares = 0;

	if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_L2CACHE, &l2cache,
	    &nl2cache) != 0)
		nl2cache = 0;

	if (vd->vdev_children == 0 && nspares == 0 && nl2cache == 0)
		return (spa_vdev_exit(spa, vd, txg, EINVAL));

	if (vd->vdev_children != 0 &&
	    (error = vdev_create(vd, txg, B_FALSE)) != 0) {
		return (spa_vdev_exit(spa, vd, txg, error));
	}

	/*
	 * The virtual dRAID spares must be added after vdev tree is created
	 * and the vdev guids are generated.  The guid of their assoicated
	 * dRAID is stored in the config and used when opening the spare.
	 */
	if ((error = vdev_draid_spare_create(nvroot, vd, &ndraid,
	    rvd->vdev_children)) == 0) {
		if (ndraid > 0 && nvlist_lookup_nvlist_array(nvroot,
		    ZPOOL_CONFIG_SPARES, &spares, &nspares) != 0)
			nspares = 0;
	} else {
		return (spa_vdev_exit(spa, vd, txg, error));
	}

	/*
	 * We must validate the spares and l2cache devices after checking the
	 * children.  Otherwise, vdev_inuse() will blindly overwrite the spare.
	 */
	if ((error = spa_validate_aux(spa, nvroot, txg, VDEV_ALLOC_ADD)) != 0)
		return (spa_vdev_exit(spa, vd, txg, error));

	/*