code: public static String getUfsBlockPath(UfsManager.UfsClient ufsInfo, long blockId) {
      return PathUtils.concatPath(ufsInfo.getUfsMountPointUri(),
          PathUtils.temporaryFileName(MAGIC_NUMBER, ".alluxio_ufs_blocks"), blockId);
    }
docs: For a given block ID, derives the corresponding UFS file of this block if it falls back to
  be stored in UFS.
  
  @param ufsInfo the UFS information for the mount point backing this file
  @param blockId block ID
  @return the UFS path of a block