drbd: Fixes to the new delay_probes code

* Only send delay_probes with protocol 93 or newer
* drbd_send_delay_probes() is called only from worker context,
  no atomic_t needed for delay_seq

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_int.h

@@ -552,7 +552,7 @@ struct p_delay_probe {
 
 struct delay_probe {
 	struct list_head list;
-	int seq_num;
+	unsigned int seq_num;
 	struct timeval time;
 };
 
@@ -1048,9 +1048,9 @@ struct drbd_conf {
 	char congestion_reason;  /* Why we where congested... */
 	struct list_head delay_probes; /* protected by peer_seq_lock */
 	int data_delay;   /* Delay of packets on the data-sock behind meta-sock */
-	atomic_t delay_seq; /* To generate sequence numbers of delay probes */
+	unsigned int delay_seq; /* To generate sequence numbers of delay probes */
 	struct timeval dps_time; /* delay-probes-start-time */
-	int dp_volume_last;  /* send_cnt of last delay probe */
+	unsigned int dp_volume_last;  /* send_cnt of last delay probe */
 	int c_sync_rate; /* current resync rate after delay_probe magic */
 };
 

drivers/block/drbd/drbd_main.c

@@ -2199,7 +2199,7 @@ static int drbd_send_delay_probe(struct drbd_conf *mdev, struct drbd_socket *ds)
 		do_gettimeofday(&now);
 		offset = now.tv_usec - mdev->dps_time.tv_usec +
 			 (now.tv_sec - mdev->dps_time.tv_sec) * 1000000;
-		dp.seq_num  = cpu_to_be32(atomic_read(&mdev->delay_seq));
+		dp.seq_num  = cpu_to_be32(mdev->delay_seq);
 		dp.offset   = cpu_to_be32(offset);
 
 		ok = _drbd_send_cmd(mdev, ds->socket, P_DELAY_PROBE,
@@ -2213,7 +2213,8 @@ static int drbd_send_delay_probe(struct drbd_conf *mdev, struct drbd_socket *ds)
 static int drbd_send_delay_probes(struct drbd_conf *mdev)
 {
 	int ok;
-	atomic_inc(&mdev->delay_seq);
+
+	mdev->delay_seq++;
 	do_gettimeofday(&mdev->dps_time);
 	ok = drbd_send_delay_probe(mdev, &mdev->meta);
 	ok = ok && drbd_send_delay_probe(mdev, &mdev->data);
@@ -2355,7 +2356,7 @@ static int _drbd_send_zc_bio(struct drbd_conf *mdev, struct bio *bio)
 
 static void consider_delay_probes(struct drbd_conf *mdev)
 {
-	if (mdev->state.conn != C_SYNC_SOURCE)
+	if (mdev->state.conn != C_SYNC_SOURCE || mdev->agreed_pro_version < 93)
 		return;
 
 	if (mdev->dp_volume_last + mdev->sync_conf.dp_volume * 2 < mdev->send_cnt)
@@ -2677,7 +2678,6 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
 	atomic_set(&mdev->net_cnt, 0);
 	atomic_set(&mdev->packet_seq, 0);
 	atomic_set(&mdev->pp_in_use, 0);
-	atomic_set(&mdev->delay_seq, 0);
 
 	mutex_init(&mdev->md_io_mutex);
 	mutex_init(&mdev->data.mutex);

drivers/block/drbd/drbd_proc.c

@@ -86,8 +86,7 @@ static void drbd_syncer_progress(struct drbd_conf *mdev, struct seq_file *seq)
 			   mdev->data_delay / 1000,
 			   (mdev->data_delay % 1000) / 100);
 	else if (mdev->state.conn == C_SYNC_SOURCE)
-		seq_printf(seq, " delay_probe: %d\n\t",
-			   atomic_read(&mdev->delay_seq));
+		seq_printf(seq, " delay_probe: %u\n\t", mdev->delay_seq);
 
 	/* see drivers/md/md.c
 	 * We do not want to overflow, so the order of operands and