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drbd: don't send out P_BARRIER with stale information

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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>
This commit is contained in:
Lars Ellenberg 2012-08-20 11:05:23 +02:00 committed by Philipp Reisner
parent 08332d7325
commit 4eb9b3cba0
1 changed files with 25 additions and 24 deletions
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49
drivers/block/drbd/drbd_worker.c
View file

@ -1265,6 +1265,27 @@ int w_send_write_hint(struct drbd_work *w, int cancel)
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 @@ int w_send_out_of_sync(struct drbd_work *w, int cancel)
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 @@ int w_send_dblock(struct drbd_work *w, int cancel)
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 @@ int w_send_read_req(struct drbd_work *w, int cancel)
/* 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);