+static void maybe_pull_ahead(struct drbd_conf *mdev)
+{
+ int congested = 0;
+
+ /* If I don't even have good local storage, we can not reasonably try
+ * to pull ahead of the peer. We also need the local reference to make
+ * sure mdev->act_log is there.
+ * Note: caller has to make sure that net_conf is there.
+ */
+ if (!get_ldev_if_state(mdev, D_UP_TO_DATE))
+ return;
+
+ 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) {
+ queue_barrier(mdev); /* last barrier, after mirrored writes */
+
+ 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);
+ }
+ put_ldev(mdev);
+}
+