Add functional test for bug 1937375

Related-Bug: #1937375
Change-Id: I332d4f33ea6b9506cc24ac12e5c0994f208a3107

Author: lyarwood

nova/tests/functional/regressions/test_bug_1937375.py

@@ -0,0 +1,95 @@
+# Copyright 2020, Red Hat, Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import mock
+import time
+
+from nova import context
+from nova import objects
+from nova.tests.functional import integrated_helpers
+
+
+class TestDuplicateVolAttachRace(integrated_helpers._IntegratedTestBase):
+    """Regression test for bug #1937375
+
+    A regression test to assert the behaviour of bug #1937375 where calls
+    to reserve_block_device_name can race and create duplicate bdm records.
+
+    As we can't recreate the race with pure API driven requests in our
+    functional tests this instead makes duplicate calls to
+    reserve_block_device_name during an attach to mimic the behaviour.
+    """
+
+    microversion = 'latest'
+
+    # TODO(lyarwood): Copied from test_bug_1675570.py, move both into
+    # _IntegratedTestBase.
+    def _wait_for_volume_attach(self, server_id, volume_id):
+        timeout = 0.0
+        server = self.api.get_server(server_id)
+        attached_vols = [vol['id'] for vol in
+                         server['os-extended-volumes:volumes_attached']]
+
+        while volume_id not in attached_vols and timeout < 10.0:
+            time.sleep(.1)
+            timeout += .1
+            server = self.api.get_server(server_id)
+            attached_vols = [vol['id'] for vol in
+                             server['os-extended-volumes:volumes_attached']]
+
+        if volume_id not in attached_vols:
+            self.fail('Timed out waiting for volume %s to be attached to '
+                      'server %s. Currently attached volumes: %s' %
+                      (volume_id, server_id, attached_vols))
+
+    def test_duplicate_volume_attach_race(self):
+
+        ctxt = context.get_admin_context()
+        volume_id = self.cinder.IMAGE_BACKED_VOL
+        server_id = self._create_server(networks='none')['id']
+        original_reserve_name = self.compute.manager.reserve_block_device_name
+
+        def wrap_reserve_block_device_name(*args, **kwargs):
+            # We can't cause a race with duplicate API requests as functional
+            # tests are single threaded and the first would always complete
+            # before the second was serviced. Instead we can wrap
+            # reserve_block_device_name on the compute manager and call it
+            # twice to mimic two callers racing each other after the checks on
+            # the api.
+            original_bdm = original_reserve_name(*args, **kwargs)
+            original_reserve_name(*args, **kwargs)
+            return original_bdm
+
+        with mock.patch.object(
+            self.compute.manager,
+            'reserve_block_device_name',
+            wrap_reserve_block_device_name
+        ):
+            self.api.post_server_volume(
+                server_id, {'volumeAttachment': {'volumeId': volume_id}})
+
+        # Wait for a volume to be attached
+        self._wait_for_volume_attach(server_id, volume_id)
+
+        # Fetch all bdms for the instance to assert what we have
+        bdms = objects.BlockDeviceMappingList.get_by_instance_uuid(
+            ctxt, server_id)
+
+        # FIXME(lyarwood): This is bug #1937375, we now have 3 bdms for the
+        # instance, the original root disk and two duplicate volume bdms for
+        # the same volume attachment.
+        self.assertEqual(3, len(bdms))
+        self.assertEqual(volume_id, bdms[2].volume_id)
+        self.assertEqual(volume_id, bdms[1].volume_id)
+        self.assertEqual('local', bdms[0].destination_type)