drbd: Improve readability of IO resuming after freeze due to no data access

The previous way of doing the state change was also okay since the
state change on the susp flag gets propagated from the mdev
to the tconn.

Fortunately all this goes away in drbd-9.0

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

drivers/block/drbd/drbd_state.c

@@ -1187,21 +1187,25 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
 	   state change. This function might sleep */
 
 	if (ns.susp_nod) {
+		struct drbd_tconn *tconn = mdev->tconn;
 		enum drbd_req_event what = NOTHING;
 
-		if (os.conn < C_CONNECTED && conn_lowest_conn(mdev->tconn) >= C_CONNECTED)
+		spin_lock_irq(&tconn->req_lock);
+		if (os.conn < C_CONNECTED && conn_lowest_conn(tconn) >= C_CONNECTED)
 			what = RESEND;
 
 		if ((os.disk == D_ATTACHING || os.disk == D_NEGOTIATING) &&
-		    conn_lowest_disk(mdev->tconn) > D_NEGOTIATING)
+		    conn_lowest_disk(tconn) > D_NEGOTIATING)
 			what = RESTART_FROZEN_DISK_IO;
 
-		if (what != NOTHING) {
-			spin_lock_irq(&mdev->tconn->req_lock);
-			_tl_restart(mdev->tconn, what);
-			_drbd_set_state(_NS(mdev, susp_nod, 0), CS_VERBOSE, NULL);
-			spin_unlock_irq(&mdev->tconn->req_lock);
+		if (tconn->susp_nod && what != NOTHING) {
+			_tl_restart(tconn, what);
+			_conn_request_state(tconn,
+					    (union drbd_state) { { .susp_nod = 1 } },
+					    (union drbd_state) { { .susp_nod = 0 } },
+					    CS_VERBOSE);
 		}
+		spin_unlock_irq(&tconn->req_lock);
 	}
 
 	if (ns.susp_fen) {