drbd: Reduce the time an empty resync takes usually

This mitigates changes introduced with commit:
http://git.drbd.org/?p=drbd-8.3.git;a=commit;h=4b6803a3276652da3737

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

3 files changed, 12 insertions, 3 deletions

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 844206c31851..2d5cebbbf253 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -800,6 +800,7 @@ enum {
         RESIZE_PENDING,         /* Size change detected locally, waiting for the response from
                                  * the peer, if it changed there as well. */
         CONN_DRY_RUN,           /* Expect disconnect after resync handshake. */
+        GOT_PING_ACK,           /* set when we receive a ping_ack packet, misc wait gets woken */
 };
 
 struct drbd_bitmap; /* opaque for drbd_conf */
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index d803e6c257e2..ed9f1de24a71 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -4074,6 +4074,8 @@ static int got_PingAck(struct drbd_conf *mdev, struct p_header *h)
 {
         /* restore idle timeout */
         mdev->meta.socket->sk->sk_rcvtimeo = mdev->net_conf->ping_int*HZ;
+        if (!test_and_set_bit(GOT_PING_ACK, &mdev->flags))
+                wake_up(&mdev->misc_wait);
 
         return TRUE;
 }
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index d97a811ad0d2..4672f2f37b51 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -1289,6 +1289,14 @@ int drbd_alter_sa(struct drbd_conf *mdev, int na)
         return retcode;
 }
 
+static void ping_peer(struct drbd_conf *mdev)
+{
+        clear_bit(GOT_PING_ACK, &mdev->flags);
+        request_ping(mdev);
+        wait_event(mdev->misc_wait,
+                   test_bit(GOT_PING_ACK, &mdev->flags) || mdev->state.conn < C_CONNECTED);
+}
+
 /**
  * drbd_start_resync() - Start the resync process
  * @mdev:       DRBD device.
@@ -1383,9 +1391,7 @@ void drbd_start_resync(struct drbd_conf *mdev, enum drbd_conns side)
 
                 if (mdev->rs_total == 0) {
                         /* Peer still reachable? Beware of failing before-resync-target handlers! */
-                        request_ping(mdev);
-                        __set_current_state(TASK_INTERRUPTIBLE);
-                        schedule_timeout(mdev->net_conf->ping_timeo*HZ/9); /* 9 instead 10 */
+                        ping_peer(mdev);
                         drbd_resync_finished(mdev);
                         return;
                 }