drbd: Work on the Ahead -> SyncSource transition

The test if rs_pending_cnt == 0 was too weak. Using Test for
unacked_cnt == 0 instead. Moved that into the worker.

Since unacked_cnt gets already increased when an P_RS_DATA_REQ
comes in.

Also using a timer to make Ahead -> SyncSource -> Ahead cycles
slower...

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

1 files changed, 3 insertions, 5 deletions

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 7991183749e3..18cb8b609fe4 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -4392,11 +4392,9 @@ static int got_BarrierAck(struct drbd_conf *mdev, struct p_header80 *h)
 
         if (mdev->state.conn == C_AHEAD &&
             atomic_read(&mdev->ap_in_flight) == 0 &&
-            atomic_read(&mdev->rs_pending_cnt) == 0 &&
-            list_empty(&mdev->start_resync_work.list)) {
-                    struct drbd_work *w = &mdev->start_resync_work;
-                    w->cb = w_start_resync;
-                    drbd_queue_work(&mdev->data.work, w);
+            !test_and_set_bit(AHEAD_TO_SYNC_SOURCE, &mdev->current_epoch->flags)) {
+                mdev->start_resync_timer.expires = jiffies + HZ;
+                add_timer(&mdev->start_resync_timer);
         }
 
         return true;