code: synchronized void verifiedByClient(int namespaceId, Block block) {
      DataBlockScanner nsScanner = getNSScanner(namespaceId);
      if (nsScanner != null) {
        nsScanner.updateScanStatusUpdateOnly(block,
            DataBlockScanner.ScanType.REMOTE_READ, true);
      } else {
        LOG.warn("No namespace scanner found for namespaceId: " + nsScanner);
      }
    }
docs: /*
  A reader will try to indicate a block is verified and will add blocks to
  the DataBlockScannerSet before they are finished (due to concurrent
  readers).
  
  fixed so a read verification can't add the block