drbd: fix drbd epoch write count for ahead/behind mode
The sanity check when receiving P_BARRIER_ACK does expect all write requests with a given req->epoch to have been either all replicated, or all not replicated. Because req->epoch was assigned before calling maybe_pull_ahead(), this expectation was not met, leading to an off-by-one in the sanity check, and further to a "Protocol Error". Fix: move the call to maybe_pull_ahead() a few lines up, and assign req->epoch only after that. Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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@ -865,8 +865,10 @@ static void maybe_pull_ahead(struct drbd_conf *mdev)
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bool congested = false;
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enum drbd_on_congestion on_congestion;
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rcu_read_lock();
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nc = rcu_dereference(tconn->net_conf);
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on_congestion = nc ? nc->on_congestion : OC_BLOCK;
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rcu_read_unlock();
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if (on_congestion == OC_BLOCK ||
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tconn->agreed_pro_version < 96)
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return;
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@ -960,14 +962,8 @@ static int drbd_process_write_request(struct drbd_request *req)
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struct drbd_conf *mdev = req->w.mdev;
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int remote, send_oos;
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rcu_read_lock();
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remote = drbd_should_do_remote(mdev->state);
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if (remote) {
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maybe_pull_ahead(mdev);
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remote = drbd_should_do_remote(mdev->state);
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}
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send_oos = drbd_should_send_out_of_sync(mdev->state);
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rcu_read_unlock();
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/* Need to replicate writes. Unless it is an empty flush,
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* which is better mapped to a DRBD P_BARRIER packet,
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@ -1087,9 +1083,13 @@ static void drbd_send_and_submit(struct drbd_conf *mdev, struct drbd_request *re
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* but will re-aquire it before it returns here.
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* Needs to be before the check on drbd_suspended() */
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complete_conflicting_writes(req);
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/* no more giving up req_lock from now on! */
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/* check for congestion, and potentially stop sending
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* full data updates, but start sending "dirty bits" only. */
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maybe_pull_ahead(mdev);
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}
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/* no more giving up req_lock from now on! */
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if (drbd_suspended(mdev)) {
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/* push back and retry: */
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