code: public static long getDirPhysicalSize(List<FileStatus> lfs) {
      long totalSize = 0L;
      if (null == lfs) {
        return totalSize;
      }
      
      for (FileStatus fsStat : lfs) {
        totalSize += fsStat.getLen() * fsStat.getReplication();
      }
      return totalSize;
    }
docs: Get the total physical size in the directory
  @param lfs the Files under the directory
  @return