drbd: consolidate explicit drbd_md_sync into drbd_create_new_uuid

Every code path changing the current UUID needs to get it on stable
storage anyways. Flush it to disk right there, remove the now obsolte
explicit drbd_md_sync statements in the other code paths.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_main.c

@@ -1267,7 +1267,6 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
 			if (test_bit(NEW_CUR_UUID, &mdev->flags)) {
 				drbd_uuid_new_current(mdev);
 				clear_bit(NEW_CUR_UUID, &mdev->flags);
-				drbd_md_sync(mdev);
 			}
 			spin_lock_irq(&mdev->req_lock);
 			_drbd_set_state(_NS(mdev, susp_fen, 0), CS_VERBOSE, NULL);
@@ -3659,6 +3658,8 @@ void drbd_uuid_new_current(struct drbd_conf *mdev) __must_hold(local)
 
 	get_random_bytes(&val, sizeof(u64));
 	_drbd_uuid_set(mdev, UI_CURRENT, val);
+	/* get it to stable storage _now_ */
+	drbd_md_sync(mdev);
 }
 
 void drbd_uuid_set_bm(struct drbd_conf *mdev, u64 val) __must_hold(local)

drivers/block/drbd/drbd_nl.c

@@ -1953,7 +1953,6 @@ static int drbd_nl_resume_io(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp
 	if (test_bit(NEW_CUR_UUID, &mdev->flags)) {
 		drbd_uuid_new_current(mdev);
 		clear_bit(NEW_CUR_UUID, &mdev->flags);
-		drbd_md_sync(mdev);
 	}
 	drbd_suspend_io(mdev);
 	reply->ret_code = drbd_request_state(mdev, NS3(susp, 0, susp_nod, 0, susp_fen, 0));