'Increase the size of the root vmdk if necessary.'

def _extend_if_required(self, dc_info, image_info, instance, root_vmdk_path):

    if ((instance.flavor.root_gb * units.Gi) > image_info.file_size):
        size_in_kb = (instance.flavor.root_gb * units.Mi)
        self._extend_virtual_disk(instance, size_in_kb, root_vmdk_path, dc_info.ref)
