libceph: distinguish two phases of connect sequence

Currently a ceph connection enters a "CONNECTING" state when it
begins the process of (re-)connecting with its peer.  Once the two
ends have successfully exchanged their banner and addresses, an
additional NEGOTIATING bit is set in the ceph connection's state to
indicate the connection information exhange has begun.  The
CONNECTING bit/state continues to be set during this phase.

Rather than have the CONNECTING state continue while the NEGOTIATING
bit is set, interpret these two phases as distinct states.  In other
words, when NEGOTIATING is set, clear CONNECTING.  That way only
one of them will be active at a time.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>

net/ceph/messenger.c

@@ -1559,7 +1559,6 @@ static int process_connect(struct ceph_connection *con)
 			return -1;
 		}
 		clear_bit(NEGOTIATING, &con->state);
-		clear_bit(CONNECTING, &con->state);
 		set_bit(CONNECTED, &con->state);
 		con->peer_global_seq = le32_to_cpu(con->in_reply.global_seq);
 		con->connect_seq++;
@@ -2000,7 +1999,8 @@ static int try_write(struct ceph_connection *con)
 	}
 
 do_next:
-	if (!test_bit(CONNECTING, &con->state)) {
+	if (!test_bit(CONNECTING, &con->state) &&
+			!test_bit(NEGOTIATING, &con->state)) {
 		/* is anything else pending? */
 		if (!list_empty(&con->out_queue)) {
 			prepare_write_message(con);
@@ -2057,7 +2057,6 @@ static int try_read(struct ceph_connection *con)
 	}
 
 	if (test_bit(CONNECTING, &con->state)) {
-		if (!test_bit(NEGOTIATING, &con->state)) {
 		dout("try_read connecting\n");
 		ret = read_partial_banner(con);
 		if (ret <= 0)
@@ -2066,16 +2065,21 @@ static int try_read(struct ceph_connection *con)
 		if (ret < 0)
 			goto out;
 
+		clear_bit(CONNECTING, &con->state);
+		set_bit(NEGOTIATING, &con->state);
+
 		/* Banner is good, exchange connection info */
 		ret = prepare_write_connect(con);
 		if (ret < 0)
 			goto out;
 		prepare_read_connect(con);
-			set_bit(NEGOTIATING, &con->state);
 
 		/* Send connection info before awaiting response */
 		goto out;
 	}
+
+	if (test_bit(NEGOTIATING, &con->state)) {
+		dout("try_read negotiating\n");
 		ret = read_partial_connect(con);
 		if (ret <= 0)
 			goto out;
@@ -2197,12 +2201,12 @@ static void con_work(struct work_struct *work)
 	if (test_and_clear_bit(SOCK_CLOSED, &con->flags)) {
 		if (test_and_clear_bit(CONNECTED, &con->state))
 			con->error_msg = "socket closed";
-		else if (test_and_clear_bit(CONNECTING, &con->state)) {
-			clear_bit(NEGOTIATING, &con->state);
+		else if (test_and_clear_bit(NEGOTIATING, &con->state))
+			con->error_msg = "negotiation failed";
+		else if (test_and_clear_bit(CONNECTING, &con->state))
 			con->error_msg = "connection failed";
-		} else {
+		else
 			con->error_msg = "unrecognized con state";
-		}
 		goto fault;
 	}