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authorLars Ellenberg <lars.ellenberg@linbit.com>2013-03-27 14:08:45 +0100
committerJens Axboe <axboe@kernel.dk>2013-03-28 10:10:25 -0600
commit607f25e56ee0a31e451f6bd8a7109fa1f5dcbe29 (patch)
tree712acc8e7f7c7eac67ce8f9ed36535914f0ebc9b /drivers/block/drbd/drbd_req.c
parentef57f9e6bb9278720c8a5278728f252ab85d7ac6 (diff)
downloadvexpress-lsk-607f25e56ee0a31e451f6bd8a7109fa1f5dcbe29.tar.gz
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>
Diffstat (limited to 'drivers/block/drbd/drbd_req.c')
-rw-r--r--drivers/block/drbd/drbd_req.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index beefe65764f..c24379ffd4e 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: */