Function spa_sync_config_object

freebsd/contrib/openzfs/module/zfs/spa.c:8444–8553

}

static void
spa_sync_config_object(spa_t *spa, dmu_tx_t *tx)
{
	nvlist_t *config;

	/*
	 * If the pool is being imported from a pre-per-vdev-ZAP version of ZFS,
	 * its config may not be dirty but we still need to build per-vdev ZAPs.
	 * Similarly, if the pool is being assembled (e.g. after a split), we
	 * need to rebuild the AVZ although the config may not be dirty.
	 */
	if (list_is_empty(&spa->spa_config_dirty_list) &&
	    spa->spa_avz_action == AVZ_ACTION_NONE)
		return;

	spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);

	ASSERT(spa->spa_avz_action == AVZ_ACTION_NONE ||
	    spa->spa_avz_action == AVZ_ACTION_INITIALIZE ||
	    spa->spa_all_vdev_zaps != 0);

	if (spa->spa_avz_action == AVZ_ACTION_REBUILD) {
		/* Make and build the new AVZ */
		uint64_t new_avz = zap_create(spa->spa_meta_objset,
		    DMU_OTN_ZAP_METADATA, DMU_OT_NONE, 0, tx);
		spa_avz_build(spa->spa_root_vdev, new_avz, tx);

		/* Diff old AVZ with new one */
		zap_cursor_t zc;
		zap_attribute_t za;

		for (zap_cursor_init(&zc, spa->spa_meta_objset,
		    spa->spa_all_vdev_zaps);
		    zap_cursor_retrieve(&zc, &za) == 0;
		    zap_cursor_advance(&zc)) {
			uint64_t vdzap = za.za_first_integer;
			if (zap_lookup_int(spa->spa_meta_objset, new_avz,
			    vdzap) == ENOENT) {
				/*
				 * ZAP is listed in old AVZ but not in new one;
				 * destroy it
				 */
				VERIFY0(zap_destroy(spa->spa_meta_objset, vdzap,
				    tx));
			}
		}

		zap_cursor_fini(&zc);

		/* Destroy the old AVZ */
		VERIFY0(zap_destroy(spa->spa_meta_objset,
		    spa->spa_all_vdev_zaps, tx));

		/* Replace the old AVZ in the dir obj with the new one */
		VERIFY0(zap_update(spa->spa_meta_objset,
		    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_VDEV_ZAP_MAP,
		    sizeof (new_avz), 1, &new_avz, tx));