code: private NameWithINode getParityFile(Codec codec, String src)
        throws IOException {
      String parity;
      if (codec.isDirRaid) {
        String parent = getParentPath(src);      
        parity = codec.parityDirectory + parent;
      } else {
        parity = codec.parityDirectory + src;
      }
      byte[][] components = INodeDirectory.getPathComponents(parity);
      INode parityInode = namesystem.dir.getINode(components);
      if (parityInode == null)
        return null;
      return new NameWithINode(parity, parityInode);
    }
docs: Get path for the parity file. Returns null if it does not exists
  @param codec the codec of the parity file.
  @return the toUri path of the parity file