===================================================================
@@ -96,6 +96,16 @@ struct dm_exception_store {
struct dm_dev *cow;
+ /*
+ * If the underlying exception store implementation is shared,
+ * it can set 'shared_uuid' to identify which 'dm_exception_store's
+ * share the same underlying implementation specific store.
+ *
+ * The user can use this ID to consolidate work/structures in
+ * the upper layers.
+ */
+ uint64_t shared_uuid;
+
/* Size of data blocks saved - must be a power of 2 */
chunk_t chunk_size;
chunk_t chunk_mask;
===================================================================
@@ -223,6 +223,7 @@ int dm_exception_store_create(const char
tmp_store->type = type;
tmp_store->ti = ti;
+ tmp_store->shared_uuid = 0;
/*
* COW-dev and chunk_size are common to all types of