'All metadata is backed up but we selectively restore.
Returns a dictionary of the form:
{<type tag>: (<restore function>, <fields list>)}
Empty field list indicates that all backed up fields should be
restored.'

def _v2_restore_factory(self):

    return {self.TYPE_TAG_VOL_BASE_META: (self._restore_vol_base_meta, ['display_name', 'display_description', 'encryption_key_id']), self.TYPE_TAG_VOL_META: (self._restore_vol_meta, []), self.TYPE_TAG_VOL_GLANCE_META: (self._restore_vol_glance_meta, [])}
