docs: def _get_all_volumes_paths(conn):
      '''
      Extract the path and backing stores path of all volumes.
  
      :param conn: libvirt connection to use
      '''
      volumes = [vol for l in [obj.listAllVolumes() for obj in conn.listAllStoragePools()] for vol in l]
      return {vol.path(): [path.text for path in ElementTree.fromstring(vol.XMLDesc()).findall('.//backingStore/path')]
              for vol in volumes if _is_valid_volume(vol)}