'Return model update from Storwize for migrated volume.
This method should rename the back-end volume name(id) on the
destination host back to its original name(id) on the source host.
:param ctxt: The context used to run the method update_migrated_volume
:param volume: The original volume that was migrated to this backend
:param new_volume: The migration volume object that was created on
this backend as part of the migration process
:param original_volume_status: The status of the original volume
:returns: model_update to update DB with any needed changes'

def update_migrated_volume(self, ctxt, volume, new_volume, original_volume_status):

    current_name = (CONF.volume_name_template % new_volume['id'])
    original_volume_name = (CONF.volume_name_template % volume['id'])
    try:
        self._helpers.rename_vdisk(current_name, original_volume_name)
        rep_type = self._get_volume_replicated_type(ctxt, new_volume)
        if rep_type:
            rel_info = self._helpers.get_relationship_info(current_name)
            aux_vol = (storwize_const.REPLICA_AUX_VOL_PREFIX + original_volume_name)
            self._aux_backend_helpers.rename_vdisk(rel_info['aux_vdisk_name'], aux_vol)
    except exception.VolumeBackendAPIException:
        LOG.error('Unable    to    rename    the    logical    volume    for    volume:    %s', volume['id'])
        return {'_name_id': (new_volume['_name_id'] or new_volume['id'])}
    model_update = {'_name_id': None}
    return model_update
