code: protected void initDataSetAndScanner(Configuration conf,
        AbstractList<File> dataDirs, int numOfNameSpaces) throws IOException {
      initFsDataSet(conf, dataDirs, numOfNameSpaces);
      initDataBlockScanner(conf); 
      initDirectoryScanner(conf);
    }
docs: Initialize dataset and block scanner
  
  @param conf  Configuration
  @param dataDirs data directories
  @param numOfNameSpaces number of name spaces
  @throws IOException