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Commit b874d231 authored by Philipp Reisner's avatar Philipp Reisner Committed by Jens Axboe
Browse files

drbd: Fix an connection drop issue after enabling allow-two-primaries 



Since drbd-8.4.0 it is possible to change the allow-two-primaries
network option while the connection is established.

The sequence code used to partially order packets from the
data socket with packets from the meta-data socket, still assued
that the allow-two-primaries option is constant while the
connection is established.

I.e.
On a node that has the RESOLVE_CONFLICTS bits set, after enabling
allow-two-primaries, when receiving the next data packet it timed out
while waiting for the necessary packets on the data socket to arrive
(wait_for_and_update_peer_seq() function).

Fixed that by always tracking the sequence number, but only waiting
for it if allow-two-primaries is set.

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 69babf05

drivers/block/drbd/drbd_receiver.c

+16 −23
Original line number Diff line number Diff line
@@ -1890,29 +1890,11 @@ static u32 seq_max(u32 a, u32 b) 
	return seq_greater(a, b) ? a : b;

}



static bool need_peer_seq(struct drbd_conf *mdev)

{

	struct drbd_tconn *tconn = mdev->tconn;

	int tp;



	/*

	 * We only need to keep track of the last packet_seq number of our peer

	 * if we are in dual-primary mode and we have the resolve-conflicts flag set; see

	 * handle_write_conflicts().

	 */



	rcu_read_lock();

	tp = rcu_dereference(mdev->tconn->net_conf)->two_primaries;

	rcu_read_unlock();



	return tp && test_bit(RESOLVE_CONFLICTS, &tconn->flags);

}



static void update_peer_seq(struct drbd_conf *mdev, unsigned int peer_seq)

{

	unsigned int newest_peer_seq;



	if (need_peer_seq(mdev)) {

	if (test_bit(RESOLVE_CONFLICTS, &mdev->tconn->flags)) {

		spin_lock(&mdev->peer_seq_lock);

		newest_peer_seq = seq_max(mdev->peer_seq, peer_seq);

		mdev->peer_seq = newest_peer_seq;
@@ -1972,22 +1954,31 @@ static int wait_for_and_update_peer_seq(struct drbd_conf *mdev, const u32 peer_s 
{

	DEFINE_WAIT(wait);

	long timeout;

	int ret;

	int ret = 0, tp;



	if (!need_peer_seq(mdev))

	if (!test_bit(RESOLVE_CONFLICTS, &mdev->tconn->flags))

		return 0;



	spin_lock(&mdev->peer_seq_lock);

	for (;;) {

		if (!seq_greater(peer_seq - 1, mdev->peer_seq)) {

			mdev->peer_seq = seq_max(mdev->peer_seq, peer_seq);

			ret = 0;

			break;

		}



		if (signal_pending(current)) {

			ret = -ERESTARTSYS;

			break;

		}



		rcu_read_lock();

		tp = rcu_dereference(mdev->tconn->net_conf)->two_primaries;

		rcu_read_unlock();



		if (!tp)

			break;



		/* Only need to wait if two_primaries is enabled */

		prepare_to_wait(&mdev->seq_wait, &wait, TASK_INTERRUPTIBLE);

		spin_unlock(&mdev->peer_seq_lock);

		rcu_read_lock();
@@ -2228,8 +2219,10 @@ static int receive_Data(struct drbd_tconn *tconn, struct packet_info *pi) 
			}

			goto out_interrupted;

		}

	} else

	} else {

		update_peer_seq(mdev, peer_seq);

		spin_lock_irq(&mdev->tconn->req_lock);

	}

	list_add(&peer_req->w.list, &mdev->active_ee);

	spin_unlock_irq(&mdev->tconn->req_lock);