drbd: Implemented two new connection states Ahead/Behind

In this connection mode, the ahead node no longer replicates
application IO. The behind's disk becomes out dated.

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

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 5c60d77d447c..60288fb3c4d7 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -948,6 +948,29 @@ allocate_barrier:
                                 ? queue_for_net_write
                                 : queue_for_net_read);
         }
+
+        if (remote && mdev->net_conf->on_congestion != OC_BLOCK) {
+                int congested = 0;
+
+                if (mdev->net_conf->cong_fill &&
+                    atomic_read(&mdev->ap_in_flight) >= mdev->net_conf->cong_fill) {
+                        dev_info(DEV, "Congestion-fill threshold reached\n");
+                        congested = 1;
+                }
+
+                if (mdev->act_log->used >= mdev->net_conf->cong_extents) {
+                        dev_info(DEV, "Congestion-extents threshold reached\n");
+                        congested = 1;
+                }
+
+                if (congested) {
+                        if (mdev->net_conf->on_congestion == OC_PULL_AHEAD)
+                                _drbd_set_state(_NS(mdev, conn, C_AHEAD), 0, NULL);
+                        else  /*mdev->net_conf->on_congestion == OC_DISCONNECT */
+                                _drbd_set_state(_NS(mdev, conn, C_DISCONNECTING), 0, NULL);
+                }
+        }
+
         spin_unlock_irq(&mdev->req_lock);
         kfree(b); /* if someone else has beaten us to it... */