libvirt: Always disconnect volumes after libvirtError exceptions

Building on Ib440f4f2e484312af5f393722363846f6c95b760 we should always
attempt to disconnect volumes from the host when exceptions are thrown
while attempting to attach a volume to a domain. This was previously
done for generic exceptions but not for libvirtError exceptions.

Closes-Bug: #1826523
Change-Id: If21230869826c992e7d0398434b9a4b255940213
(cherry picked from commit 091a910)
(cherry picked from commit 048d5b7)

Author: lyarwood

nova/tests/unit/virt/libvirt/test_driver.py

@@ -7759,11 +7759,13 @@ def test_attach_volume_with_libvirt_bug_breadcrumb(self, mock_get_info):
             mock.patch.object(drvr._host, 'get_guest'),
             mock.patch('nova.virt.libvirt.driver.LOG'),
             mock.patch.object(drvr, '_connect_volume'),
+            mock.patch.object(drvr, '_disconnect_volume'),
             mock.patch.object(drvr, '_get_volume_config'),
             mock.patch.object(drvr, '_check_discard_for_attach_volume'),
             mock.patch.object(drvr, '_build_device_metadata'),
         ) as (mock_get_guest, mock_log, mock_connect_volume,
-              mock_get_volume_config, mock_check_discard, mock_build_metadata):
+              mock_disconnect_volume, mock_get_volume_config,
+              mock_check_discard, mock_build_metadata):
 
             mock_conf = mock.MagicMock()
             mock_guest = mock.MagicMock()
@@ -7777,6 +7779,7 @@ def test_attach_volume_with_libvirt_bug_breadcrumb(self, mock_get_info):
                 self.context, connection_info, instance, "/dev/vdb",
                 disk_bus=bdm['disk_bus'], device_type=bdm['device_type'])
             mock_log.warning.assert_called_once()
+            mock_disconnect_volume.assert_called_once()
 
     @mock.patch('nova.virt.libvirt.blockinfo.get_info_from_bdm')
     def test_attach_volume_with_libvirt_exception(self, mock_get_info):
@@ -7798,11 +7801,13 @@ def test_attach_volume_with_libvirt_exception(self, mock_get_info):
             mock.patch.object(drvr._host, 'get_guest'),
             mock.patch('nova.virt.libvirt.driver.LOG'),
             mock.patch.object(drvr, '_connect_volume'),
+            mock.patch.object(drvr, '_disconnect_volume'),
             mock.patch.object(drvr, '_get_volume_config'),
             mock.patch.object(drvr, '_check_discard_for_attach_volume'),
             mock.patch.object(drvr, '_build_device_metadata'),
         ) as (mock_get_guest, mock_log, mock_connect_volume,
-              mock_get_volume_config, mock_check_discard, mock_build_metadata):
+              mock_disconnect_volume, mock_get_volume_config,
+              mock_check_discard, mock_build_metadata):
 
             mock_conf = mock.MagicMock()
             mock_guest = mock.MagicMock()
@@ -7817,6 +7822,7 @@ def test_attach_volume_with_libvirt_exception(self, mock_get_info):
                 disk_bus=bdm['disk_bus'], device_type=bdm['device_type'])
             mock_log.exception.assert_called_once_with(u'Failed to attach '
                 'volume at mountpoint: %s', '/dev/vdb', instance=instance)
+            mock_disconnect_volume.assert_called_once()
 
     @mock.patch('nova.utils.get_image_from_system_metadata')
     @mock.patch('nova.virt.libvirt.blockinfo.get_info_from_bdm')

nova/virt/libvirt/driver.py

@@ -1477,6 +1477,8 @@ def attach_volume(self, context, connection_info, instance, mountpoint,
                 else:
                     LOG.exception(_('Failed to attach volume at mountpoint: '
                                     '%s'), mountpoint, instance=instance)
+                self._disconnect_volume(context, connection_info, instance,
+                                        encryption=encryption)
         except Exception:
             LOG.exception(_('Failed to attach volume at mountpoint: %s'),
                           mountpoint, instance=instance)