drbd: Call drbd_md_sync() explicitly after a state change on the connection

Without this, the meta-data gets updates after 5 seconds by the
md_sync_timer. Better to do it immeditaly after a state change.

If the asender detects a network failure, it may take a bit until
the worker processes the according after-conn-state-change work item.

  The worker might be blocked in sending something, i.e. it
  takes until it gets into its timeout. That is 6 seconds by
  default which is longer than the 5 seconds of the md_sync_timer.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_int.h

@@ -1116,6 +1116,7 @@ extern void drbd_free_bc(struct drbd_backing_dev *ldev);
 extern void drbd_mdev_cleanup(struct drbd_conf *mdev);
 void drbd_print_uuids(struct drbd_conf *mdev, const char *text);
 
+extern void conn_md_sync(struct drbd_tconn *tconn);
 extern void drbd_md_sync(struct drbd_conf *mdev);
 extern int  drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev);
 extern void drbd_uuid_set(struct drbd_conf *mdev, int idx, u64 val) __must_hold(local);

drivers/block/drbd/drbd_main.c

@@ -2820,6 +2820,22 @@ void drbd_free_sock(struct drbd_tconn *tconn)
 
 /* meta data management */
 
+void conn_md_sync(struct drbd_tconn *tconn)
+{
+	struct drbd_conf *mdev;
+	int vnr;
+
+	rcu_read_lock();
+	idr_for_each_entry(&tconn->volumes, mdev, vnr) {
+		kref_get(&mdev->kref);
+		rcu_read_unlock();
+		drbd_md_sync(mdev);
+		kref_put(&mdev->kref, &drbd_minor_destroy);
+		rcu_read_lock();
+	}
+	rcu_read_unlock();
+}
+
 struct meta_data_on_disk {
 	u64 la_size;           /* last agreed size. */
 	u64 uuid[UI_SIZE];   /* UUIDs. */

drivers/block/drbd/drbd_nl.c

@@ -363,22 +363,6 @@ int drbd_khelper(struct drbd_conf *mdev, char *cmd)
 	return ret;
 }
 
-static void conn_md_sync(struct drbd_tconn *tconn)
-{
-	struct drbd_conf *mdev;
-	int vnr;
-
-	rcu_read_lock();
-	idr_for_each_entry(&tconn->volumes, mdev, vnr) {
-		kref_get(&mdev->kref);
-		rcu_read_unlock();
-		drbd_md_sync(mdev);
-		kref_put(&mdev->kref, &drbd_minor_destroy);
-		rcu_read_lock();
-	}
-	rcu_read_unlock();
-}
-
 int conn_khelper(struct drbd_tconn *tconn, char *cmd)
 {
 	char *envp[] = { "HOME=/",

drivers/block/drbd/drbd_receiver.c

@@ -5390,6 +5390,7 @@ int drbd_asender(struct drbd_thread *thi)
 	if (0) {
 reconnect:
 		conn_request_state(tconn, NS(conn, C_NETWORK_FAILURE), CS_HARD);
+		conn_md_sync(tconn);
 	}
 	if (0) {
 disconnect:

drivers/block/drbd/drbd_state.c

@@ -1563,6 +1563,9 @@ static int w_after_conn_state_ch(struct drbd_work *w, int unused)
 		}
 	}
 	kref_put(&tconn->kref, &conn_destroy);
+
+	conn_md_sync(tconn);
+
 	return 0;
 }