dm log: remove struct dm_dirty_log_internal

Remove the 'dm_dirty_log_internal' structure.  The resulting cleanup
eliminates extra memory allocations.  Therefore exposing the internal
list_head to the external 'dm_dirty_log_type' structure is a worthwhile
compromise.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/include/linux/dm-dirty-log.h b/include/linux/dm-dirty-log.h
index 600c5fb..727602b 100644
--- a/include/linux/dm-dirty-log.h
+++ b/include/linux/dm-dirty-log.h
@@ -28,6 +28,9 @@
 	const char *name;
 	struct module *module;
 
+	/* For internal device-mapper use */
+	struct list_head list;
+
 	int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
 		   unsigned argc, char **argv);
 	void (*dtr)(struct dm_dirty_log *log);