Fix SMB volume detachment issue

A recent change introduced a regression which prevents SMB volumes
from being detached. By passing the volume tag to os-win when
detaching a disk, os-win then ignores the disk path and attempts
to retrieve the attachment using the tag.

Virtual images don't get tagged, for which reason detaches will fail
siliently.

For now, we'll just skip passing the tag when detaching such disks.

Change-Id: Ie0500c29bfbbd63761b732872f1dda92720dbe21
Closes-Bug: #1710616

compute_hyperv/nova/volumeops.py

@@ -410,10 +410,13 @@ class BaseVolumeDriver(object):
         # on this tag.
         if not self._is_block_dev:
             disk_path = self.get_disk_resource_path(connection_info)
+            # In this case, we're not tagging the disks, so we want os-win
+            # to use the disk path to identify the attachment.
+            serial = None
         else:
             disk_path = None
+            serial = connection_info['serial']
 
-        serial = connection_info['serial']
         LOG.debug("Detaching disk from instance: %(instance_name)s. "
                   "Disk path: %(disk_path)s. Disk serial tag: %(serial)s.",
                   dict(disk_path=disk_path,

compute_hyperv/tests/unit/test_volumeops.py

@@ -624,9 +624,11 @@ class BaseVolumeDriverTestCase(test_base.HyperVBaseTestCase):
                                             mock.sentinel.instance_name)
 
         if is_block_dev:
+            exp_serial = connection_info['serial']
             exp_disk_res_path = None
             self.assertFalse(mock_get_disk_resource_path.called)
         else:
+            exp_serial = None
             exp_disk_res_path = mock_get_disk_resource_path.return_value
             mock_get_disk_resource_path.assert_called_once_with(
                 connection_info)
@@ -635,7 +637,7 @@ class BaseVolumeDriverTestCase(test_base.HyperVBaseTestCase):
             mock.sentinel.instance_name,
             exp_disk_res_path,
             is_physical=is_block_dev,
-            serial=connection_info['serial'])
+            serial=exp_serial)
 
     def test_get_disk_ctrl_and_slot_ide(self):
         ctrl, slot = self._base_vol_driver._get_disk_ctrl_and_slot(