Fix soft deleting vm fails after "nova resize" vm

Problem description:
When trying to soft-delete an instance that is just resized but the resize
action is not yet confirmed, the soft-delete call will first attempt to
confirm_resize the instance, then an error will occur since confirm_resize
method does not expect a SOFT_DELETING task_state currently.
https://github.com/openstack/nova/blob/8e052c7/nova/compute/manager.py#L3911

Fix steps:
1 Add SOFT_DELETING to the expected_task_state of confirm_resize method.
2 Since confirm_resize method sets instance.task_state to None, set
  instance.task_state to back to SOFT_DELETING after confirm_resize is
  executed, so the rest workflow should finish as normal situations.

Co-Authored-By: Chen <dstbtgagt@foxmail.com>

Change-Id: Ia4592adc93960625148ffa6e9f7d1cfa0c6046aa
Closes-Bug: #1712480

nova/compute/api.py

@@ -1895,6 +1895,18 @@ class API(base.Base):
 
             if instance.vm_state == vm_states.RESIZED:
                 self._confirm_resize_on_deleting(context, instance)
+                # NOTE(neha_alhat): After confirm resize vm_state will become
+                # 'active' and task_state will be set to 'None'. But for soft
+                # deleting a vm, the _do_soft_delete callback requires
+                # task_state in 'SOFT_DELETING' status. So, we need to set
+                # task_state as 'SOFT_DELETING' again for soft_delete case.
+                # After confirm resize and before saving the task_state to
+                # "SOFT_DELETING", during the short window, user can submit
+                # soft delete vm request again and system will accept and
+                # process it without any errors.
+                if delete_type == 'soft_delete':
+                    instance.task_state = instance_attrs['task_state']
+                    instance.save()
 
             is_local_delete = True
             try:

nova/compute/manager.py

@@ -3767,7 +3767,8 @@ class ComputeManager(manager.Manager):
 
             instance.vm_state = vm_state
             instance.task_state = None
-            instance.save(expected_task_state=[None, task_states.DELETING])
+            instance.save(expected_task_state=[None, task_states.DELETING,
+                                               task_states.SOFT_DELETING])
 
             self._notify_about_instance_usage(
                 context, instance, "resize.confirm.end",

nova/tests/unit/compute/test_compute_api.py

@@ -1037,6 +1037,13 @@ class _ComputeAPIUnitTestMixIn(object):
         mock_confirm = self.useFixture(
             fixtures.MockPatchObject(rpcapi, 'confirm_resize')).mock
 
+        def _reset_task_state(context, instance, migration, src_host,
+                              cast=False):
+            inst.update({'task_state': None})
+
+        # After confirm resize action, instance task_state is reset to None
+        mock_confirm.side_effect = _reset_task_state
+
         is_shelved = inst.vm_state in (vm_states.SHELVED,
                                        vm_states.SHELVED_OFFLOADED)
         if is_shelved:
@@ -1079,6 +1086,17 @@ class _ComputeAPIUnitTestMixIn(object):
                 expected_record_calls.append(
                     mock.call(self.context, inst,
                               instance_actions.CONFIRM_RESIZE))
+
+                # After confirm resize action, instance task_state
+                # is reset to None, so is the expected value. But
+                # for soft delete, task_state will be again reset
+                # back to soft-deleting in the code to avoid status
+                # checking failure.
+                updates['task_state'] = None
+                if delete_type == 'soft_delete':
+                    expected_save_calls.append(mock.call())
+                    updates['task_state'] = 'soft-deleting'
+
             if inst.host is not None:
                 mock_elevated.return_value = self.context
                 expected_elevated_calls.append(mock.call())
@@ -1222,6 +1240,9 @@ class _ComputeAPIUnitTestMixIn(object):
     def test_delete_soft_with_down_host(self):
         self._test_delete('soft_delete', host='down-host')
 
+    def test_delete_soft_in_resized(self):
+        self._test_delete('soft_delete', vm_state=vm_states.RESIZED)
+
     def test_delete_soft(self):
         self._test_delete('soft_delete')
 

nova/tests/unit/compute/test_compute_mgr.py

@@ -6551,6 +6551,9 @@ class ComputeManagerMigrationTestCase(test.NoDBTestCase):
                                                 self.migration,
                                                 self.instance.old_flavor,
                                                 self.migration.source_node)
+            mock_save.assert_called_with(expected_task_state=
+                                         [None, task_states.DELETING,
+                                         task_states.SOFT_DELETING])
 
         do_confirm_resize()