code: public static long getFileLengthFromBlockSize(long blockSize,
        int bytesPerChecksum, int checksumSize) {
      long numChunks; 
      if (blockSize % bytesPerChecksum == 0) {    
        numChunks = blockSize / bytesPerChecksum; 
      } else {    
        numChunks = blockSize / bytesPerChecksum + 1; 
      }   
      return blockSize + numChunks * checksumSize 
          + BlockInlineChecksumReader.getHeaderSize();  
    }
docs: get file length for the block size.
  
  @param blockSize
  @param bytesPerChecksum
  @param checksumSize
  @return