dm log: split suspend

There are now two phases to a suspend in device-mapper -
presuspend and postsuspend.  This patch removes the
single 'suspend' in the logging API and replaces it with
'presuspend' and 'postsuspend' functions to align it
better with core device-mapper.

A subsequent patch will make use of 'presuspend'.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-log.h b/drivers/md/dm-log.h
index 86a301c..3fae87e 100644
--- a/drivers/md/dm-log.h
+++ b/drivers/md/dm-log.h
@@ -32,7 +32,8 @@
 	 * There are times when we don't want the log to touch
 	 * the disk.
 	 */
-	int (*suspend)(struct dirty_log *log);
+	int (*presuspend)(struct dirty_log *log);
+	int (*postsuspend)(struct dirty_log *log);
 	int (*resume)(struct dirty_log *log);
 
 	/*