drbd: don't send out P_BARRIER with stale information
We must only send P_BARRIER for epochs we actually sent P_DATA in.
If we (re-)establish a connection, we reinitialized the
send.current_epoch_nr, but forgot to reset send.current_epoch_writes.
This could result in a spurious P_BARRIER with stale epoch information,
and a disconnect/reconnect cycle once the then "unexpected"
P_BARRIER_ACK is received:
BAD! BarrierAck #28823 received, expected #28829!
Introduce re_init_if_first_write() and maybe_send_barrier() helpers,
and call them appropriately for read/write/set-out-of-sync requests.
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_worker.c b/drivers/block/drbd/drbd_worker.c
index 1c9c6fd..c674f17 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -1265,6 +1265,27 @@
return drbd_send_command(mdev, sock, P_UNPLUG_REMOTE, 0, NULL, 0);
}
+static void re_init_if_first_write(struct drbd_tconn *tconn, unsigned int epoch)
+{
+ if (!tconn->send.seen_any_write_yet) {
+ tconn->send.seen_any_write_yet = true;
+ tconn->send.current_epoch_nr = epoch;
+ tconn->send.current_epoch_writes = 0;
+ }
+}
+
+static void maybe_send_barrier(struct drbd_tconn *tconn, unsigned int epoch)
+{
+ /* re-init if first write on this connection */
+ if (!tconn->send.seen_any_write_yet)
+ return;
+ if (tconn->send.current_epoch_nr != epoch) {
+ if (tconn->send.current_epoch_writes)
+ drbd_send_barrier(tconn);
+ tconn->send.current_epoch_nr = epoch;
+ }
+}
+
int w_send_out_of_sync(struct drbd_work *w, int cancel)
{
struct drbd_request *req = container_of(w, struct drbd_request, w);
@@ -1277,19 +1298,11 @@
return 0;
}
- if (!tconn->send.seen_any_write_yet) {
- tconn->send.seen_any_write_yet = true;
- tconn->send.current_epoch_nr = req->epoch;
- }
- if (tconn->send.current_epoch_nr != req->epoch) {
- if (tconn->send.current_epoch_writes)
- drbd_send_barrier(tconn);
- tconn->send.current_epoch_nr = req->epoch;
- }
/* this time, no tconn->send.current_epoch_writes++;
* If it was sent, it was the closing barrier for the last
* replicated epoch, before we went into AHEAD mode.
* No more barriers will be sent, until we leave AHEAD mode again. */
+ maybe_send_barrier(tconn, req->epoch);
err = drbd_send_out_of_sync(mdev, req);
req_mod(req, OOS_HANDED_TO_NETWORK);
@@ -1315,15 +1328,8 @@
return 0;
}
- if (!tconn->send.seen_any_write_yet) {
- tconn->send.seen_any_write_yet = true;
- tconn->send.current_epoch_nr = req->epoch;
- }
- if (tconn->send.current_epoch_nr != req->epoch) {
- if (tconn->send.current_epoch_writes)
- drbd_send_barrier(tconn);
- tconn->send.current_epoch_nr = req->epoch;
- }
+ re_init_if_first_write(tconn, req->epoch);
+ maybe_send_barrier(tconn, req->epoch);
tconn->send.current_epoch_writes++;
err = drbd_send_dblock(mdev, req);
@@ -1352,12 +1358,7 @@
/* Even read requests may close a write epoch,
* if there was any yet. */
- if (tconn->send.seen_any_write_yet &&
- tconn->send.current_epoch_nr != req->epoch) {
- if (tconn->send.current_epoch_writes)
- drbd_send_barrier(tconn);
- tconn->send.current_epoch_nr = req->epoch;
- }
+ maybe_send_barrier(tconn, req->epoch);
err = drbd_send_drequest(mdev, P_DATA_REQUEST, req->i.sector, req->i.size,
(unsigned long)req);