code: @Override
      public long getTotalSpace() {
          checkClosed();
  
          if (fatType == FatType.FAT32) {
              return bs.getNrTotalSectors() * bs.getBytesPerSector();
          }
  
          return -1;
      }
docs: The total size of this file system.
  
  @return if -1 this feature is unsupported