code: private void writeControlFile(FileSystem fs, Path outputPath, 
          Path checksumFile, String name) throws IOException {
        SequenceFile.Writer write = null;
        try {
          Path parentDir = new Path(rtc.input, "filelists");
          if (!fs.exists(parentDir)) {
            fs.mkdirs(parentDir);
          }
          Path controlFile = new Path(parentDir, name);
          write = SequenceFile.createWriter(fs, fs.getConf(), controlFile,
              Text.class, Text.class, CompressionType.NONE);
          write.append(new Text(outputPath.toString()), 
              new Text(checksumFile.toString()));
        } finally {
          if (write != null)
            write.close();
          write = null;
        }
      }
docs: This is used for verification
  Each mapper writes one control file
  control file only contains the base directory written by this mapper
  and the checksum file path so that we could create a Read mapper which
  scanned the files under the base directory and verify the checksum of
  files with the information given in the checksum file.
  @param fs
  @param outputPath base directory of mapper
  @param checksumFile location of checksum file
  @param name name of control file
  @throws IOException