From f1ac5183d43459614ba5a356c2c7b50251fcd94f Mon Sep 17 00:00:00 2001
From: Matt Riedemann <mriedem.os@gmail.com>
Date: Tue, 5 Mar 2019 16:39:51 -0500
Subject: [PATCH] Temporarily mutate migration object in finish_revert_resize

As the comment in the code suggests, when calling migrate_instance_finish
in finish_revert_resize we need to temporarily set the migration
object dest_compute to the source_compute since we are moving port
bindings from the dest back to the source. However, this is not
really a temporary change to the object if something fails after
this because the @errors_out_migration decorator will persist the
change which could be confusing later if trying to debug this migration
from the API and the dest_compute and source_compute have the same value.

This fixes the issue by using the temporary_mutation utility.

Also, the obj_to_primitive dance in here is removed since it is not
necessary as migrate_instance_finish handles a Migration object.

Conflicts:
      nova/tests/unit/compute/test_compute_mgr.py

NOTE(mriedem): The conflict is due to not having change
I0851e2d54a1fdc82fe3291fb7e286e790f121e92 in Rocky.

Change-Id: I312d61383345ea0ac1ab0c277b4c468e6aa94656
Closes-Bug: #1818730
(cherry picked from commit 855b5546564f0ed96243623b67b1322e9b891c8b)
(cherry picked from commit bcb42a43a9f12d929ec7025f29bd2e3d482cd406)
---
 nova/compute/manager.py                     | 14 +++++++-------
 nova/tests/unit/compute/test_compute_mgr.py |  9 ++++++++-
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index 85427d62c5fb..89159b3ad3de 100644
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -4119,17 +4119,17 @@ class ComputeManager(manager.Manager):
 
             self.network_api.setup_networks_on_host(context, instance,
                                                     migration.source_compute)
-            migration_p = obj_base.obj_to_primitive(migration)
-            # NOTE(hanrong): we need to change migration_p['dest_compute'] to
+            # NOTE(hanrong): we need to change migration.dest_compute to
             # source host temporarily. "network_api.migrate_instance_finish"
             # will setup the network for the instance on the destination host.
             # For revert resize, the instance will back to the source host, the
             # setup of the network for instance should be on the source host.
-            # So set the migration_p['dest_compute'] to source host at here.
-            migration_p['dest_compute'] = migration.source_compute
-            self.network_api.migrate_instance_finish(context,
-                                                     instance,
-                                                     migration_p)
+            # So set the migration.dest_compute to source host at here.
+            with utils.temporary_mutation(
+                    migration, dest_compute=migration.source_compute):
+                self.network_api.migrate_instance_finish(context,
+                                                         instance,
+                                                         migration)
             network_info = self.network_api.get_instance_nw_info(context,
                                                                  instance)
 
diff --git a/nova/tests/unit/compute/test_compute_mgr.py b/nova/tests/unit/compute/test_compute_mgr.py
index 2b9364adae60..923747e3bf82 100644
--- a/nova/tests/unit/compute/test_compute_mgr.py
+++ b/nova/tests/unit/compute/test_compute_mgr.py
@@ -6631,9 +6631,10 @@ class ComputeManagerMigrationTestCase(test.NoDBTestCase):
             uuid=uuids.migration_uuid,
             instance_uuid=self.instance.uuid,
             new_instance_type_id=7,
-            dest_compute=None,
+            dest_compute='dest_compute',
             dest_node=None,
             dest_host=None,
+            source_compute='source_compute',
             status='migrating')
         self.migration.save = mock.MagicMock()
         self.useFixture(fixtures.SpawnIsSynchronousFixture())
@@ -6817,6 +6818,8 @@ class ComputeManagerMigrationTestCase(test.NoDBTestCase):
         self.nw_info = None
 
         def _migrate_instance_finish(context, instance, migration):
+            # The migration.dest_compute is temporarily set to source_compute.
+            self.assertEqual(migration.source_compute, migration.dest_compute)
             self.nw_info = 'nw_info'
 
         def _get_instance_nw_info(context, instance):
@@ -6863,6 +6866,10 @@ class ComputeManagerMigrationTestCase(test.NoDBTestCase):
                                               instance=self.instance)
             finish_revert_migration.assert_called_with(self.context,
                 self.instance, 'nw_info', mock.ANY, mock.ANY)
+            # Make sure the migration.dest_compute is not still set to the
+            # source_compute value.
+            self.assertNotEqual(self.migration.dest_compute,
+                                self.migration.source_compute)
 
         do_test()