code: void setQuota(String src, long nsQuota, long dsQuota)
                  throws FileNotFoundException, QuotaExceededException {
      writeLock();
      try {
        INodeDirectory dir = unprotectedSetQuota(src, nsQuota, dsQuota);
        if (dir != null) {
          fsImage.getEditLog().logSetQuota(src, dir.getNsQuota(),
                                           dir.getDsQuota());
        }
      } finally {
        writeUnlock();
      }
    }
docs: See {@link ClientProtocol#setQuota(String, long, long)} for the
  contract.
  @see #unprotectedSetQuota(String, long, long)