Patch name: dm-exception-store-add-shared_uuid.patch
This patch adds the shared_uuid to the dm_exception_store structure.
Exception store implementations can set this to a unique non-zero
value if they wish to express that the back-end is optimized for
sharing.
Signed-off-by: Jonathan Brassow <jbrassow@xxxxxxxxxx>
Index: linux-2.6/drivers/md/dm-exception-store.h
===================================================================
--- linux-2.6.orig/drivers/md/dm-exception-store.h
+++ linux-2.6/drivers/md/dm-exception-store.h
@@ -97,6 +97,16 @@ 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;
Index: linux-2.6/drivers/md/dm-exception-store.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-exception-store.c
+++ linux-2.6/drivers/md/dm-exception-store.c
@@ -218,6 +218,7 @@ 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
--
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