Fix r2_hbo_grub_memmove ext2 crash
grub_disk_cache_unlock (unsigned long dev_id, unsigned long disk_id,
			grub_disk_addr_t sector)
{
  struct grub_disk_cache *cache;
  unsigned index;

  index = grub_disk_cache_get_index (dev_id, disk_id, sector);
  cache = grub_disk_cache_table + index;

  if (cache->dev_id == dev_id && cache->disk_id == disk_id
      && cache->sector == sector)
    cache->lock = 0;
}

grub_disk_cache_unlock (unsigned long dev_id, unsigned long disk_id,
			grub_disk_addr_t sector)
{
  struct grub_disk_cache *cache;
  unsigned index;

  index = grub_disk_cache_get_index (dev_id, disk_id, sector);
  cache = grub_disk_cache_table + index;

  if (cache->dev_id == dev_id && cache->disk_id == disk_id
      && cache->sector == sector)
    cache->lock = 0;
}
