-extern void metaslab_class_add(metaslab_class_t *mc, metaslab_group_t *mg);
-extern void metaslab_class_remove(metaslab_class_t *mc, metaslab_group_t *mg);
+extern int metaslab_class_validate(metaslab_class_t *mc);
+
+extern void metaslab_class_space_update(metaslab_class_t *mc,
+ int64_t alloc_delta, int64_t defer_delta,
+ int64_t space_delta, int64_t dspace_delta);
+extern uint64_t metaslab_class_get_alloc(metaslab_class_t *mc);
+extern uint64_t metaslab_class_get_space(metaslab_class_t *mc);
+extern uint64_t metaslab_class_get_dspace(metaslab_class_t *mc);
+extern uint64_t metaslab_class_get_deferred(metaslab_class_t *mc);