NetApp ONTAP: Fix JSON serialization error on EMS logs

The NetApp cDOT Driver is now fixed to periodically generate EMS
logging messages. The issue was occurring due to incompatible
python 3 code when gathering volume names.

Change-Id: I5ded00b0d743bfb1a9da33d602b9264630979f19
Closes-bug: #1833115

cinder/volume/drivers/netapp/dataontap/block_cmode.py

@@ -432,7 +432,9 @@ class NetAppBlockStorageCmodeLibrary(block_base.NetAppBlockStorageLibrary,
 
     def _get_backing_flexvol_names(self):
         """Returns a list of backing flexvol names."""
-        return self.ssc_library.get_ssc().keys()
+
+        ssc = self.ssc_library.get_ssc()
+        return list(ssc.keys())
 
     def create_group(self, group):
         """Driver entry point for creating a generic volume group.

cinder/volume/drivers/netapp/dataontap/nfs_cmode.py

@@ -687,7 +687,9 @@ class NetAppCmodeNfsDriver(nfs_base.NetAppNfsDriver,
 
     def _get_backing_flexvol_names(self):
         """Returns a list of backing flexvol names."""
-        return self.ssc_library.get_ssc().keys()
+
+        ssc = self.ssc_library.get_ssc()
+        return list(ssc.keys())
 
     def _get_flexvol_names_from_hosts(self, hosts):
         """Returns a set of flexvol names."""

cinder/volume/drivers/netapp/dataontap/utils/capabilities.py

@@ -99,8 +99,9 @@ class CapabilitiesLibrary(object):
 
     def get_ssc_flexvol_names(self):
         """Get the names of the FlexVols in the Storage Service Catalog."""
+
         ssc = self.get_ssc()
-        return ssc.keys()
+        return list(ssc.keys())
 
     def get_ssc_for_flexvol(self, flexvol_name):
         """Get map of Storage Service Catalog entries for a single flexvol."""

releasenotes/notes/bug-1833115-fix-netapp-ontap-python3-failures-dd869e602f9539e1.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Fix python 3 incompatibility issues preventing NetApp cDOT driver from
+    generating EMS logging messages (Bug #1833115).