Avoid live migrate overwriting the other task_state

As commit 4082c83 says,
one ordinary task is running, so that task_state is set. The
live_migrate task is accepted at API, and will change task_state to
MIGRATING. However the first task may continue to update task_state or
set it to None as it finishes.

This patch avoids it by updating task_state in compute.api.live_migrate
level with expected_task_state=None.

Add test case for compute.api.live_migrate.

Fixes bug 1049533

Change-Id: Ida8cef4797de421a7e356c9f5e882fe926535639

nova/compute/api.py

@@ -1941,6 +1941,10 @@ def live_migrate(self, context, instance, block_migration,
         LOG.debug(_("Going to try to live migrate instance to %s"),
                   host, instance=instance)
 
+        instance = self.update(context, instance,
+                               task_state=task_states.MIGRATING,
+                               expected_task_state=None)
+
         self.scheduler_rpcapi.live_migration(context, block_migration,
                 disk_over_commit, instance, host)
 

nova/scheduler/driver.py

@@ -203,19 +203,10 @@ def schedule_live_migration(self, context, instance, dest,
         migrate_data = self.compute_rpcapi.check_can_live_migrate_destination(
                 context, instance, dest, block_migration, disk_over_commit)
 
-        # Change instance_state
-        values = {"task_state": task_states.MIGRATING}
-
-        # update instance state and notify
-        (old_ref, new_instance_ref) = db.instance_update_and_get_original(
-                context, instance['uuid'], values)
-        notifications.send_update(context, old_ref, new_instance_ref,
-                service="scheduler")
-
         # Perform migration
         src = instance['host']
         self.compute_rpcapi.live_migration(context, host=src,
-                instance=new_instance_ref, dest=dest,
+                instance=instance, dest=dest,
                 block_migration=block_migration,
                 migrate_data=migrate_data)
 

nova/tests/api/openstack/compute/contrib/test_admin_actions.py

@@ -139,6 +139,13 @@ def test_migrate_live_enabled(self):
             }
         })
         req.content_type = 'application/json'
+
+        def fake_update(inst, context, instance,
+                        task_state, expected_task_state):
+            return None
+
+        self.stubs.Set(compute.API, 'update', fake_update)
+
         res = req.get_response(app)
         self.assertEqual(res.status_int, 202)
 

nova/tests/compute/test_compute.py

@@ -80,6 +80,10 @@ def run_instance(self, ctxt, request_spec, admin_password,
             filter_properties):
         pass
 
+    def live_migration(self, ctxt, block_migration, disk_over_commit,
+            instance, dest):
+        pass
+
 
 class BaseTestCase(test.TestCase):
 
@@ -4449,6 +4453,19 @@ def group_get(*args, **kwargs):
 
         self.security_group_api.trigger_rules_refresh(self.context, [1, 2])
 
+    def test_live_migrate(self):
+        instance, instance_uuid = self._run_instance()
+
+        self.compute_api.live_migrate(self.context, instance,
+                                      block_migration=True,
+                                      disk_over_commit=True,
+                                      host='fake_dest_host')
+
+        instance = db.instance_get_by_uuid(self.context, instance_uuid)
+        self.assertEqual(instance['task_state'], task_states.MIGRATING)
+
+        db.instance_destroy(self.context, instance['uuid'])
+
 
 def fake_rpc_method(context, topic, msg, do_cast=True):
     pass

nova/tests/scheduler/test_scheduler.py

@@ -311,10 +311,8 @@ def test_live_migration_basic(self):
         self.mox.StubOutWithMock(self.driver, '_live_migration_common_check')
         self.mox.StubOutWithMock(self.driver.compute_rpcapi,
                                  'check_can_live_migrate_destination')
-        self.mox.StubOutWithMock(db, 'instance_update_and_get_original')
         self.mox.StubOutWithMock(self.driver.compute_rpcapi,
                                  'live_migration')
-        self.mox.StubOutWithMock(notifications, 'send_update')
 
         dest = 'fake_host2'
         block_migration = False
@@ -330,11 +328,6 @@ def test_live_migration_basic(self):
         self.driver.compute_rpcapi.check_can_live_migrate_destination(
                self.context, instance, dest, block_migration,
                disk_over_commit).AndReturn({})
-        db.instance_update_and_get_original(self.context, instance_uuid,
-                {"task_state": task_states.MIGRATING}).AndReturn(
-                        (instance, instance))
-        notifications.send_update(self.context, instance, instance,
-                                  service="scheduler")
         self.driver.compute_rpcapi.live_migration(self.context,
                 host=instance['host'], instance=instance, dest=dest,
                 block_migration=block_migration, migrate_data={})
@@ -353,7 +346,6 @@ def test_live_migration_all_checks_pass(self):
         self.mox.StubOutWithMock(db, 'instance_get_all_by_host')
         self.mox.StubOutWithMock(rpc, 'call')
         self.mox.StubOutWithMock(rpc, 'cast')
-        self.mox.StubOutWithMock(db, 'instance_update_and_get_original')
         self.mox.StubOutWithMock(self.driver.compute_rpcapi,
                                  'live_migration')
 
@@ -398,10 +390,6 @@ def test_live_migration_all_checks_pass(self):
                     "version": compute_rpcapi.ComputeAPI.BASE_RPC_API_VERSION},
                  None).AndReturn({})
 
-        db.instance_update_and_get_original(self.context, instance_uuid,
-                {"task_state": task_states.MIGRATING}).AndReturn(
-                        (instance, instance))
-
         self.driver.compute_rpcapi.live_migration(self.context,
                 host=instance['host'], instance=instance, dest=dest,
                 block_migration=block_migration, migrate_data={})