From 607f25e56ee0a31e451f6bd8a7109fa1f5dcbe29 Mon Sep 17 00:00:00 2001 From: Lars Ellenberg Date: Wed, 27 Mar 2013 14:08:45 +0100 Subject: [PATCH] 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 Signed-off-by: Lars Ellenberg Signed-off-by: Jens Axboe --- drivers/block/drbd/drbd_req.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c index beefe65..c24379f 100644 --- a/drivers/block/drbd/drbd_req.c +++ b/drivers/block/drbd/drbd_req.c @@ -865,8 +865,10 @@ static void maybe_pull_ahead(struct drbd_conf *mdev) bool congested = false; enum drbd_on_congestion on_congestion; + rcu_read_lock(); nc = rcu_dereference(tconn->net_conf); on_congestion = nc ? nc->on_congestion : OC_BLOCK; + rcu_read_unlock(); if (on_congestion == OC_BLOCK || tconn->agreed_pro_version < 96) return; @@ -960,14 +962,8 @@ static int drbd_process_write_request(struct drbd_request *req) struct drbd_conf *mdev = req->w.mdev; int remote, send_oos; - rcu_read_lock(); remote = drbd_should_do_remote(mdev->state); - if (remote) { - maybe_pull_ahead(mdev); - remote = drbd_should_do_remote(mdev->state); - } send_oos = drbd_should_send_out_of_sync(mdev->state); - rcu_read_unlock(); /* Need to replicate writes. Unless it is an empty flush, * which is better mapped to a DRBD P_BARRIER packet, @@ -1087,9 +1083,13 @@ static void drbd_send_and_submit(struct drbd_conf *mdev, struct drbd_request *re * but will re-aquire it before it returns here. * Needs to be before the check on drbd_suspended() */ complete_conflicting_writes(req); + /* no more giving up req_lock from now on! */ + + /* check for congestion, and potentially stop sending + * full data updates, but start sending "dirty bits" only. */ + maybe_pull_ahead(mdev); } - /* no more giving up req_lock from now on! */ if (drbd_suspended(mdev)) { /* push back and retry: */ -- 2.7.4