- Limit volume size at mount time to 2TiB on architectures where
  unsigned long is 32-bits (fs/ntfs/super.c::parse_ntfs_boot_sector()).
  This is the most we can do without overflowing the 32-bit limit of
  the block device size imposed on us by sb_bread() and sb_getblk()
  for the time being.
- Limit file/directory size at open() time to 16TiB on architectures
  where unsigned long is 32-bits (fs/ntfs/file.c::ntfs_file_open() and
  fs/ntfs/dir.c::ntfs_dir_open()). This is the most we can do without
  overflowing the page cache page index.