code: static public MetaDataInputStream getMetaDataInputStream(
        FSDatasetInterface dataset, int namespace, Block b) throws IOException {
      File checksumFile = getMetaFile(dataset, namespace, b);
      return new MetaDataInputStream(new FileInputStream(checksumFile),
                                                      checksumFile.length());
    }
docs: Returns metaData of block b as an input stream (and its length)
  @param namespaceId - parent namespace id
  @param b - the block
  @return the metadata input stream;
  @throws IOException