drbd: fix disconnect/reconnect loop, if ping-timeout == ping-int

If there is no replication traffic within the idle timeout
(ping-int seconds), DRBD will send a P_PING,
and adjust the timeout to ping-timeout.

If there is no P_PING_ACK received within this ping-timeout,
DRBD finally drops the connection, and tries to re-establish it.

To decide which timeout was active, we compared the current timeout
with the ping-timeout, and dropped the connection, if that was the case.

By default, ping-int is 10 seconds, ping-timeout is 500 ms.

Unfortunately, if you configure ping-timeout to be the same as ping-int,
expiry of the idle-timeout had been mistaken for a missing ping ack,
and caused an immediate reconnection attempt.

Fix:
Allow both timeouts to be equal, use a local variable
to store which timeout is active.

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

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index fd26666..0b17d42 100644 (file)
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -4554,6 +4554,7 @@ int drbd_asender(struct drbd_thread *thi)
        int received = 0;
        int expect   = sizeof(struct p_header80);
        int empty;
+       int ping_timeout_active = 0;
 
        sprintf(current->comm, "drbd%d_asender", mdev_to_minor(mdev));
 
@@ -4566,6 +4567,7 @@ int drbd_asender(struct drbd_thread *thi)
                        ERR_IF(!drbd_send_ping(mdev)) goto reconnect;
                        mdev->meta.socket->sk->sk_rcvtimeo =
                                mdev->net_conf->ping_timeo*HZ/10;
+                       ping_timeout_active = 1;
                }
 
                /* conditionally cork;
@@ -4620,8 +4622,7 @@ int drbd_asender(struct drbd_thread *thi)
                        dev_err(DEV, "meta connection shut down by peer.\n");
                        goto reconnect;
                } else if (rv == -EAGAIN) {
-                       if (mdev->meta.socket->sk->sk_rcvtimeo ==
-                           mdev->net_conf->ping_timeo*HZ/10) {
+                       if (ping_timeout_active) {
                                dev_err(DEV, "PingAck did not arrive in time.\n");
                                goto reconnect;
                        }
@@ -4660,6 +4661,11 @@ int drbd_asender(struct drbd_thread *thi)
                        if (!cmd->process(mdev, h))
                                goto reconnect;
 
+                       /* the idle_timeout (ping-int)
+                        * has been restored in got_PingAck() */
+                       if (cmd == get_asender_cmd(P_PING_ACK))
+                               ping_timeout_active = 0;
+
                        buf      = h;
                        received = 0;
                        expect   = sizeof(struct p_header80);