dm snapshot: rename struct exception_store

Rename struct exception_store to dm_exception_store.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-snap.h b/drivers/md/dm-snap.h
index 6e4beaf..9281236 100644
--- a/drivers/md/dm-snap.h
+++ b/drivers/md/dm-snap.h
@@ -61,7 +61,7 @@
 	spinlock_t pe_lock;
 
 	/* The on disk metadata handler */
-	struct exception_store store;
+	struct dm_exception_store store;
 
 	struct dm_kcopyd_client *kcopyd_client;