2 files changed, 136 insertions, 40 deletions

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index f29f107be9b8..fa010ea3a4bf 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -720,6 +720,13 @@ struct drbd_connection {
 	struct drbd_thread worker;
 	struct drbd_thread asender;
 
+	/* cached pointers,
+	 * so we can look up the oldest pending requests more quickly.
+	 * protected by resource->req_lock */
+	struct drbd_request *req_next; /* DRBD 9: todo.req_next */
+	struct drbd_request *req_ack_pending;
+	struct drbd_request *req_not_net_done;
+
 	/* sender side */
 	struct drbd_work_queue sender_work;
 
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 23cd909dc7f1..3f6a6ed2fd03 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -345,12 +345,91 @@ static int drbd_req_put_completion_ref(struct drbd_request *req, struct bio_and_
 	return 1;
 }
 
+static void set_if_null_req_next(struct drbd_peer_device *peer_device, struct drbd_request *req)
+{
+	struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
+	if (!connection)
+		return;
+	if (connection->req_next == NULL)
+		connection->req_next = req;
+}
+
+static void advance_conn_req_next(struct drbd_peer_device *peer_device, struct drbd_request *req)
+{
+	struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
+	if (!connection)
+		return;
+	if (connection->req_next != req)
+		return;
+	list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) {
+		const unsigned s = req->rq_state;
+		if (s & RQ_NET_QUEUED)
+			break;
+	}
+	if (&req->tl_requests == &connection->transfer_log)
+		req = NULL;
+	connection->req_next = req;
+}
+
+static void set_if_null_req_ack_pending(struct drbd_peer_device *peer_device, struct drbd_request *req)
+{
+	struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
+	if (!connection)
+		return;
+	if (connection->req_ack_pending == NULL)
+		connection->req_ack_pending = req;
+}
+
+static void advance_conn_req_ack_pending(struct drbd_peer_device *peer_device, struct drbd_request *req)
+{
+	struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
+	if (!connection)
+		return;
+	if (connection->req_ack_pending != req)
+		return;
+	list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) {
+		const unsigned s = req->rq_state;
+		if ((s & RQ_NET_SENT) && (s & RQ_NET_PENDING))
+			break;
+	}
+	if (&req->tl_requests == &connection->transfer_log)
+		req = NULL;
+	connection->req_ack_pending = req;
+}
+
+static void set_if_null_req_not_net_done(struct drbd_peer_device *peer_device, struct drbd_request *req)
+{
+	struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
+	if (!connection)
+		return;
+	if (connection->req_not_net_done == NULL)
+		connection->req_not_net_done = req;
+}
+
+static void advance_conn_req_not_net_done(struct drbd_peer_device *peer_device, struct drbd_request *req)
+{
+	struct drbd_connection *connection = peer_device ? peer_device->connection : NULL;
+	if (!connection)
+		return;
+	if (connection->req_not_net_done != req)
+		return;
+	list_for_each_entry_continue(req, &connection->transfer_log, tl_requests) {
+		const unsigned s = req->rq_state;
+		if ((s & RQ_NET_SENT) && !(s & RQ_NET_DONE))
+			break;
+	}
+	if (&req->tl_requests == &connection->transfer_log)
+		req = NULL;
+	connection->req_not_net_done = req;
+}
+
 /* I'd like this to be the only place that manipulates
  * req->completion_ref and req->kref. */
 static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m,
 		int clear, int set)
 {
 	struct drbd_device *device = req->device;
+	struct drbd_peer_device *peer_device = first_peer_device(device);
 	unsigned s = req->rq_state;
 	int c_put = 0;
 	int k_put = 0;
@@ -379,6 +458,7 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m,
 
 	if (!(s & RQ_NET_QUEUED) && (set & RQ_NET_QUEUED)) {
 		atomic_inc(&req->completion_ref);
+		set_if_null_req_next(peer_device, req);
 	}
 
 	if (!(s & RQ_EXP_BARR_ACK) && (set & RQ_EXP_BARR_ACK))
@@ -386,8 +466,12 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m,
 
 	if (!(s & RQ_NET_SENT) && (set & RQ_NET_SENT)) {
 		/* potentially already completed in the asender thread */
-		if (!(s & RQ_NET_DONE))
+		if (!(s & RQ_NET_DONE)) {
 			atomic_add(req->i.size >> 9, &device->ap_in_flight);
+			set_if_null_req_not_net_done(peer_device, req);
+		}
+		if (s & RQ_NET_PENDING)
+			set_if_null_req_ack_pending(peer_device, req);
 	}
 
 	if (!(s & RQ_COMPLETION_SUSP) && (set & RQ_COMPLETION_SUSP))
@@ -418,10 +502,13 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m,
 		dec_ap_pending(device);
 		++c_put;
 		req->acked_jif = jiffies;
+		advance_conn_req_ack_pending(peer_device, req);
 	}
 
-	if ((s & RQ_NET_QUEUED) && (clear & RQ_NET_QUEUED))
+	if ((s & RQ_NET_QUEUED) && (clear & RQ_NET_QUEUED)) {
 		++c_put;
+		advance_conn_req_next(peer_device, req);
+	}
 
 	if (!(s & RQ_NET_DONE) && (set & RQ_NET_DONE)) {
 		if (s & RQ_NET_SENT)
@@ -429,6 +516,13 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m,
 		if (s & RQ_EXP_BARR_ACK)
 			++k_put;
 		req->net_done_jif = jiffies;
+
+		/* in ahead/behind mode, or just in case,
+		 * before we finally destroy this request,
+		 * the caching pointers must not reference it anymore */
+		advance_conn_req_next(peer_device, req);
+		advance_conn_req_ack_pending(peer_device, req);
+		advance_conn_req_not_net_done(peer_device, req);
 	}
 
 	/* potentially complete and destroy */
@@ -1423,36 +1517,13 @@ int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct
 	return limit;
 }
 
-static void find_oldest_requests(
-		struct drbd_connection *connection,
-		struct drbd_device *device,
-		struct drbd_request **oldest_req_waiting_for_peer,
-		struct drbd_request **oldest_req_waiting_for_disk)
-{
-	struct drbd_request *r;
-	*oldest_req_waiting_for_peer = NULL;
-	*oldest_req_waiting_for_disk = NULL;
-	list_for_each_entry(r, &connection->transfer_log, tl_requests) {
-		const unsigned s = r->rq_state;
-		if (!*oldest_req_waiting_for_peer
-		&& ((s & RQ_NET_MASK) && !(s & RQ_NET_DONE)))
-			*oldest_req_waiting_for_peer = r;
-
-		if (!*oldest_req_waiting_for_disk
-		&& (s & RQ_LOCAL_PENDING) && r->device == device)
-			*oldest_req_waiting_for_disk = r;
-
-		if (*oldest_req_waiting_for_peer && *oldest_req_waiting_for_disk)
-			break;
-	}
-}
-
 void request_timer_fn(unsigned long data)
 {
 	struct drbd_device *device = (struct drbd_device *) data;
 	struct drbd_connection *connection = first_peer_device(device)->connection;
-	struct drbd_request *req_disk, *req_peer; /* oldest request */
+	struct drbd_request *req_read, *req_write, *req_peer; /* oldest request */
 	struct net_conf *nc;
+	unsigned long oldest_submit_jif;
 	unsigned long ent = 0, dt = 0, et, nt; /* effective timeout = ko_count * timeout */
 	unsigned long now;
 
@@ -1473,14 +1544,31 @@ void request_timer_fn(unsigned long data)
 		return; /* Recurring timer stopped */
 
 	now = jiffies;
+	nt = now + et;
 
 	spin_lock_irq(&device->resource->req_lock);
-	find_oldest_requests(connection, device, &req_peer, &req_disk);
-	if (req_peer == NULL && req_disk == NULL) {
-		spin_unlock_irq(&device->resource->req_lock);
-		mod_timer(&device->request_timer, now + et);
-		return;
-	}
+	req_read = list_first_entry_or_null(&device->pending_completion[0], struct drbd_request, req_pending_local);
+	req_write = list_first_entry_or_null(&device->pending_completion[1], struct drbd_request, req_pending_local);
+	req_peer = connection->req_not_net_done;
+	/* maybe the oldest request waiting for the peer is in fact still
+	 * blocking in tcp sendmsg */
+	if (!req_peer && connection->req_next && connection->req_next->pre_send_jif)
+		req_peer = connection->req_next;
+
+	/* evaluate the oldest peer request only in one timer! */
+	if (req_peer && req_peer->device != device)
+		req_peer = NULL;
+
+	/* do we have something to evaluate? */
+	if (req_peer == NULL && req_write == NULL && req_read == NULL)
+		goto out;
+
+	oldest_submit_jif =
+		(req_write && req_read)
+		? ( time_before(req_write->pre_submit_jif, req_read->pre_submit_jif)
+		  ? req_write->pre_submit_jif : req_read->pre_submit_jif )
+		: req_write ? req_write->pre_submit_jif
+		: req_read ? req_read->pre_submit_jif : now;
 
 	/* The request is considered timed out, if
 	 * - we have some effective timeout from the configuration,
@@ -1499,13 +1587,13 @@ void request_timer_fn(unsigned long data)
 	 * to expire twice (worst case) to become effective. Good enough.
 	 */
 	if (ent && req_peer &&
-		 time_after(now, req_peer->start_jif + ent) &&
+		 time_after(now, req_peer->pre_send_jif + ent) &&
 		!time_in_range(now, connection->last_reconnect_jif, connection->last_reconnect_jif + ent)) {
 		drbd_warn(device, "Remote failed to finish a request within ko-count * timeout\n");
 		_drbd_set_state(_NS(device, conn, C_TIMEOUT), CS_VERBOSE | CS_HARD, NULL);
 	}
-	if (dt && req_disk &&
-		 time_after(now, req_disk->start_jif + dt) &&
+	if (dt && oldest_submit_jif != now &&
+		 time_after(now, oldest_submit_jif + dt) &&
 		!time_in_range(now, device->last_reattach_jif, device->last_reattach_jif + dt)) {
 		drbd_warn(device, "Local backing device failed to meet the disk-timeout\n");
 		__drbd_chk_io_error(device, DRBD_FORCE_DETACH);
@@ -1513,11 +1601,12 @@ void request_timer_fn(unsigned long data)
 
 	/* Reschedule timer for the nearest not already expired timeout.
 	 * Fallback to now + min(effective network timeout, disk timeout). */
-	ent = (ent && req_peer && time_before(now, req_peer->start_jif + ent))
-		? req_peer->start_jif + ent : now + et;
-	dt = (dt && req_disk && time_before(now, req_disk->start_jif + dt))
-		? req_disk->start_jif + dt : now + et;
+	ent = (ent && req_peer && time_before(now, req_peer->pre_send_jif + ent))
+		? req_peer->pre_send_jif + ent : now + et;
+	dt = (dt && oldest_submit_jif != now && time_before(now, oldest_submit_jif + dt))
+		? oldest_submit_jif + dt : now + et;
 	nt = time_before(ent, dt) ? ent : dt;
+out:
 	spin_unlock_irq(&connection->resource->req_lock);
 	mod_timer(&device->request_timer, nt);
 }