Function vdev_config_dirty

freebsd/contrib/openzfs/module/zfs/vdev.c:4568–4640

* Mark a top-level vdev's config as dirty, placing it on the dirty list * so that it will be written out next time the vdev configuration is synced. * If the root vdev is specified (vdev_top == NULL), dirty all top-level vdevs. */

 * If the root vdev is specified (vdev_top == NULL), dirty all top-level vdevs.
 */
void
vdev_config_dirty(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;
	vdev_t *rvd = spa->spa_root_vdev;
	int c;

	ASSERT(spa_writeable(spa));

	/*
	 * If this is an aux vdev (as with l2cache and spare devices), then we
	 * update the vdev config manually and set the sync flag.
	 */
	if (vd->vdev_aux != NULL) {
		spa_aux_vdev_t *sav = vd->vdev_aux;
		nvlist_t **aux;
		uint_t naux;

		for (c = 0; c < sav->sav_count; c++) {
			if (sav->sav_vdevs[c] == vd)
				break;
		}

		if (c == sav->sav_count) {
			/*
			 * We're being removed.  There's nothing more to do.
			 */
			ASSERT(sav->sav_sync == B_TRUE);
			return;
		}

		sav->sav_sync = B_TRUE;

		if (nvlist_lookup_nvlist_array(sav->sav_config,
		    ZPOOL_CONFIG_L2CACHE, &aux, &naux) != 0) {
			VERIFY(nvlist_lookup_nvlist_array(sav->sav_config,
			    ZPOOL_CONFIG_SPARES, &aux, &naux) == 0);
		}

		ASSERT(c < naux);

		/*
		 * Setting the nvlist in the middle if the array is a little
		 * sketchy, but it will work.
		 */
		nvlist_free(aux[c]);
		aux[c] = vdev_config_generate(spa, vd, B_TRUE, 0);

		return;
	}

	/*
	 * The dirty list is protected by the SCL_CONFIG lock.  The caller
	 * must either hold SCL_CONFIG as writer, or must be the sync thread
	 * (which holds SCL_CONFIG as reader).  There's only one sync thread,
	 * so this is sufficient to ensure mutual exclusion.
	 */
	ASSERT(spa_config_held(spa, SCL_CONFIG, RW_WRITER) ||