Merge "Add ability to failback for replication V2.1"

cinder/volume/api.py

@@ -1593,9 +1593,10 @@ class API(base.Base):
         ctxt = context.get_admin_context()
         svc_host = volume_utils.extract_host(host, 'backend')
 
-        service = objects.Service.get_by_host_and_topic(
+        service = objects.Service.get_by_args(
             ctxt, svc_host, CONF.volume_topic)
-        expected = {'replication_status': fields.ReplicationStatus.ENABLED}
+        expected = {'replication_status': [fields.ReplicationStatus.ENABLED,
+                    fields.ReplicationStatus.FAILED_OVER]}
         result = service.conditional_update(
             {'replication_status': fields.ReplicationStatus.FAILING_OVER},
             expected)

cinder/volume/manager.py

@@ -3296,11 +3296,19 @@ class VolumeManager(manager.SchedulerDependentManager):
                  secondary_backend_id})
             return None
 
-        service.replication_status = fields.ReplicationStatus.FAILED_OVER
-        service.active_backend_id = active_backend_id
-        service.disabled = True
-        service.disabled_reason = "failed-over"
-        service.save()
+        if secondary_backend_id == "default":
+            service.replication_status = fields.ReplicationStatus.ENABLED
+            service.active_backend_id = ""
+            service.disabled = False
+            service.disabled_reason = ""
+            service.save()
+
+        else:
+            service.replication_status = fields.ReplicationStatus.FAILED_OVER
+            service.active_backend_id = active_backend_id
+            service.disabled = True
+            service.disabled_reason = "failed-over"
+            service.save()
 
         for update in volume_update_list:
             # Response must include an id key: {volume_id: <cinder-uuid>}