code: public boolean reportChecksumFailure(Path f, 
                                         FSDataInputStream in, long inPos, 
                                         FSDataInputStream sums, long sumsPos) {
      return getDFS().reportChecksumFailure(f, in, inPos, sums, sumsPos);
    }
docs: We need to find the blocks that didn't match.  Likely only one
  is corrupt but we will report both to the namenode.  In the future,
  we can consider figuring out exactly which block is corrupt.