libceph: handle discarding acked and requeued messages separately

Make it easier to follow and remove dependency on msgr1 specific
CEPH_MSGR_TAG_SEQ.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

net/ceph/messenger.c

@@ -760,6 +760,56 @@ static u32 get_global_seq(struct ceph_messenger *msgr, u32 gt)
 	return ret;
 }
 
+/*
+ * Discard messages that have been acked by the server.
+ */
+static void ceph_con_discard_sent(struct ceph_connection *con, u64 ack_seq)
+{
+	struct ceph_msg *msg;
+	u64 seq;
+
+	dout("%s con %p ack_seq %llu\n", __func__, con, ack_seq);
+	while (!list_empty(&con->out_sent)) {
+		msg = list_first_entry(&con->out_sent, struct ceph_msg,
+				       list_head);
+		WARN_ON(msg->needs_out_seq);
+		seq = le64_to_cpu(msg->hdr.seq);
+		if (seq > ack_seq)
+			break;
+
+		dout("%s con %p discarding msg %p seq %llu\n", __func__, con,
+		     msg, seq);
+		ceph_msg_remove(msg);
+	}
+}
+
+/*
+ * Discard messages that have been requeued in con_fault(), up to
+ * reconnect_seq.  This avoids gratuitously resending messages that
+ * the server had received and handled prior to reconnect.
+ */
+static void ceph_con_discard_requeued(struct ceph_connection *con,
+				      u64 reconnect_seq)
+{
+	struct ceph_msg *msg;
+	u64 seq;
+
+	dout("%s con %p reconnect_seq %llu\n", __func__, con, reconnect_seq);
+	while (!list_empty(&con->out_queue)) {
+		msg = list_first_entry(&con->out_queue, struct ceph_msg,
+				       list_head);
+		if (msg->needs_out_seq)
+			break;
+		seq = le64_to_cpu(msg->hdr.seq);
+		if (seq > reconnect_seq)
+			break;
+
+		dout("%s con %p discarding msg %p seq %llu\n", __func__, con,
+		     msg, seq);
+		ceph_msg_remove(msg);
+	}
+}
+
 static void con_out_kvec_reset(struct ceph_connection *con)
 {
 	BUG_ON(con->out_skip);
@@ -2259,28 +2309,12 @@ static int read_partial_ack(struct ceph_connection *con)
  */
 static void process_ack(struct ceph_connection *con)
 {
-	struct ceph_msg *m;
 	u64 ack = le64_to_cpu(con->in_temp_ack);
-	u64 seq;
-	bool reconnect = (con->in_tag == CEPH_MSGR_TAG_SEQ);
-	struct list_head *list = reconnect ? &con->out_queue : &con->out_sent;
 
-	/*
-	 * In the reconnect case, con_fault() has requeued messages
-	 * in out_sent. We should cleanup old messages according to
-	 * the reconnect seq.
-	 */
-	while (!list_empty(list)) {
-		m = list_first_entry(list, struct ceph_msg, list_head);
-		if (reconnect && m->needs_out_seq)
-			break;
-		seq = le64_to_cpu(m->hdr.seq);
-		if (seq > ack)
-			break;
-		dout("got ack for seq %llu type %d at %p\n", seq,
-		     le16_to_cpu(m->hdr.type), m);
-		ceph_msg_remove(m);
-	}
+	if (con->in_tag == CEPH_MSGR_TAG_ACK)
+		ceph_con_discard_sent(con, ack);
+	else
+		ceph_con_discard_requeued(con, ack);
 
 	prepare_read_tag(con);
 }