unsigned version[CACHE_POLICY_VERSION_SIZE];
/*
+ * For use by an alias dm_cache_policy_type to point to the
+ * real dm_cache_policy_type.
+ */
+ struct dm_cache_policy_type *real;
+
+ /*
* Policies may store a hint for each each cache block.
* Currently the size of this hint must be 0 or 4 bytes but we
* expect to relax this in future.