+ if (spa_version(spa) >= SPA_VERSION_FEATURES) {
+ boolean_t missing_feat_read = B_FALSE;
+ nvlist_t *unsup_feat, *enabled_feat;
+
+ if (spa_dir_prop(spa, DMU_POOL_FEATURES_FOR_READ,
+ &spa->spa_feat_for_read_obj) != 0) {
+ return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+ }
+
+ if (spa_dir_prop(spa, DMU_POOL_FEATURES_FOR_WRITE,
+ &spa->spa_feat_for_write_obj) != 0) {
+ return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+ }
+
+ if (spa_dir_prop(spa, DMU_POOL_FEATURE_DESCRIPTIONS,
+ &spa->spa_feat_desc_obj) != 0) {
+ return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+ }
+
+ enabled_feat = fnvlist_alloc();
+ unsup_feat = fnvlist_alloc();
+
+ if (!feature_is_supported(spa->spa_meta_objset,
+ spa->spa_feat_for_read_obj, spa->spa_feat_desc_obj,
+ unsup_feat, enabled_feat))
+ missing_feat_read = B_TRUE;
+
+ if (spa_writeable(spa) || state == SPA_LOAD_TRYIMPORT) {
+ if (!feature_is_supported(spa->spa_meta_objset,
+ spa->spa_feat_for_write_obj, spa->spa_feat_desc_obj,
+ unsup_feat, enabled_feat)) {
+ missing_feat_write = B_TRUE;
+ }
+ }
+
+ fnvlist_add_nvlist(spa->spa_load_info,
+ ZPOOL_CONFIG_ENABLED_FEAT, enabled_feat);
+
+ if (!nvlist_empty(unsup_feat)) {
+ fnvlist_add_nvlist(spa->spa_load_info,
+ ZPOOL_CONFIG_UNSUP_FEAT, unsup_feat);
+ }
+
+ fnvlist_free(enabled_feat);
+ fnvlist_free(unsup_feat);
+
+ if (!missing_feat_read) {
+ fnvlist_add_boolean(spa->spa_load_info,
+ ZPOOL_CONFIG_CAN_RDONLY);
+ }
+
+ /*
+ * If the state is SPA_LOAD_TRYIMPORT, our objective is
+ * twofold: to determine whether the pool is available for
+ * import in read-write mode and (if it is not) whether the
+ * pool is available for import in read-only mode. If the pool
+ * is available for import in read-write mode, it is displayed
+ * as available in userland; if it is not available for import
+ * in read-only mode, it is displayed as unavailable in
+ * userland. If the pool is available for import in read-only
+ * mode but not read-write mode, it is displayed as unavailable
+ * in userland with a special note that the pool is actually
+ * available for open in read-only mode.
+ *
+ * As a result, if the state is SPA_LOAD_TRYIMPORT and we are
+ * missing a feature for write, we must first determine whether
+ * the pool can be opened read-only before returning to
+ * userland in order to know whether to display the
+ * abovementioned note.
+ */
+ if (missing_feat_read || (missing_feat_write &&
+ spa_writeable(spa))) {
+ return (spa_vdev_err(rvd, VDEV_AUX_UNSUP_FEAT,
+ ENOTSUP));
+ }
+ }
+
+ spa->spa_is_initializing = B_TRUE;
+ error = dsl_pool_open(spa->spa_dsl_pool);
+ spa->spa_is_initializing = B_FALSE;
+ if (error != 0)
+ return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+