PowerMax Driver - Fix for create snapshot

Payload response change from REST means that the
Device Label no longer exists in the format expected and
causes an IndexError exception. This is the case in PowerMaxOS
5978.711 and later.

Closes-Bug: #1939139

Change-Id: If465bc719cea2d4e85b37527f3f7ac916b5de638
(cherry picked from commit 672a0e9798)

cinder/tests/unit/volume/drivers/dell_emc/powermax/powermax_data.py

@@ -1467,6 +1467,7 @@ class PowerMaxData(object):
 
     snap_device_label = ('%(dev)s:%(label)s' % {'dev': device_id,
                                                 'label': managed_snap_id})
+
     priv_snap_response = {
         'deviceName': snap_device_label, 'snapshotLnks': [],
         'snapshotSrcs': [
@@ -1478,6 +1479,9 @@ class PowerMaxData(object):
              'snapshotName': test_snapshot_snap_name,
              'state': 'Established'}]}
 
+    priv_snap_response_no_label = deepcopy(priv_snap_response)
+    priv_snap_response_no_label.update({'deviceName': device_id})
+
     volume_metadata = {
         'DeviceID': device_id, 'ArrayID': array, 'ArrayModel': array_model}
 

cinder/tests/unit/volume/drivers/dell_emc/powermax/test_powermax_common.py

@@ -3852,6 +3852,22 @@ class PowerMaxCommonTest(test.TestCase):
             array, device_id, snap_name)
         self.assertEqual(ref_metadata, act_metadata)
 
+    @mock.patch.object(
+        rest.PowerMaxRest, 'get_volume_snap_info',
+        return_value=(tpd.PowerMaxData.priv_snap_response_no_label))
+    def test_get_snapshot_metadata_no_label(self, mck_snap):
+        array = self.data.array
+        device_id = self.data.device_id
+        snap_name = self.data.test_snapshot_snap_name
+        ref_metadata = {'SnapshotLabel': snap_name,
+                        'SourceDeviceID': device_id,
+                        'SnapIdList': six.text_type(self.data.snap_id),
+                        'is_snap_id': True}
+
+        act_metadata = self.common.get_snapshot_metadata(
+            array, device_id, snap_name)
+        self.assertEqual(ref_metadata, act_metadata)
+
     def test_update_metadata(self):
         model_update = {'provider_location': six.text_type(
             self.data.provider_location)}

cinder/volume/drivers/dell_emc/powermax/common.py

@@ -6847,14 +6847,17 @@ class PowerMaxCommon(object):
                 snap_id_list.append(snapshot_src.get(
                     'snap_id') if self.rest.is_snap_id else snapshot_src.get(
                         'generation'))
-        device_label = device_name.split(':')[1]
+        try:
+            device_label = device_name.split(':')[1] if device_name else None
+        except IndexError:
+            device_label = None
         metadata = {'SnapshotLabel': snap_name,
                     'SourceDeviceID': device_id,
-                    'SourceDeviceLabel': device_label,
                     'SnapIdList': ', '.join(
                         six.text_type(v) for v in snap_id_list),
                     'is_snap_id': self.rest.is_snap_id}
-
+        if device_label:
+            metadata['SourceDeviceLabel'] = device_label
         return metadata
 
     def _check_and_add_tags_to_storage_array(

releasenotes/notes/bug-1939139-02ab552420813e70.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    PowerMax driver `bug #1939139
+    <https://bugs.launchpad.net/cinder/+bug/1939139>`_: Fix
+    on create snapshot operation that exists when using PowerMax OS
+    5978.711 and later.