Ignore calls to PowerFlex for host revocation when host is null (#6742)

This PR Fixes #6739 (for PowerFlex/ScaleIO only, Datera still needs to be addressed), which can occur if the last host the VM ran on is deleted from CloudStack. At the point the VM is deleted, cloudstack attempts to make a final call to revoke access to volumes, passing the last host the VM ran on. If this host is gone, we get an error and are unable to delete the VM.

It's possible that there may be a more holistic fix to this by identifying all of the places where revokeAccess() is called and checking for null host. It's possible other storage plugins don't even need host information to revoke access to volumes and may need this call to revoke. Therefore I'm only applying this fix to the ScaleIOPrimaryDataStoreDriver to skip revoking access when there is no host to revoke access for, and this should protect us as well when a new part of the code tries to use revokeAccess() in the future.

Signed-off-by: Marcus Sorensen <mls@apple.com>
Co-authored-by: Marcus Sorensen <mls@apple.com>

Author: mlsorensen

plugins/storage/volume/scaleio/src/main/java/org/apache/cloudstack/storage/datastore/driver/ScaleIOPrimaryDataStoreDriver.java

@@ -208,6 +208,11 @@ private boolean grantAccess(DataObject dataObject, EndPoint ep, DataStore dataSt
 
     @Override
     public void revokeAccess(DataObject dataObject, Host host, DataStore dataStore) {
+        if (host == null) {
+            LOGGER.info("Declining to revoke access to PowerFlex volume when a host is not provided");
+            return;
+        }
+
         try {
             if (DataObjectType.VOLUME.equals(dataObject.getType())) {
                 final VolumeVO volume = volumeDao.findById(dataObject.getId());