libceph: define and use an explicit CONNECTED state

There is no state explicitly defined when a ceph connection is fully
operational.  So define one.

It's set when the connection sequence completes successfully, and is
cleared when the connection gets closed.

Be a little more careful when examining the old state when a socket
disconnect event is reported.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>

include/linux/ceph/messenger.h

@@ -120,6 +120,7 @@ struct ceph_msg_pos {
  */
 #define CONNECTING	1
 #define NEGOTIATING	2
+#define CONNECTED	5
 #define STANDBY		8  /* no outgoing messages, socket closed.  we keep
 			    * the ceph_connection around to maintain shared
 			    * state with the peer. */

net/ceph/messenger.c

@@ -463,6 +463,7 @@ void ceph_con_close(struct ceph_connection *con)
 	     ceph_pr_addr(&con->peer_addr.in_addr));
 	clear_bit(NEGOTIATING, &con->state);
 	clear_bit(CONNECTING, &con->state);
+	clear_bit(CONNECTED, &con->state);
 	clear_bit(STANDBY, &con->state);  /* avoid connect_seq bump */
 	set_bit(CLOSED, &con->state);
 
@@ -1564,6 +1565,7 @@ static int process_connect(struct ceph_connection *con)
 		}
 		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++;
 		con->peer_features = server_feat;
@@ -2114,6 +2116,7 @@ static int try_read(struct ceph_connection *con)
 			prepare_read_ack(con);
 			break;
 		case CEPH_MSGR_TAG_CLOSE:
+			clear_bit(CONNECTED, &con->state);
 			set_bit(CLOSED, &con->state);   /* fixme */
 			goto out;
 		default:
@@ -2190,11 +2193,13 @@ static void con_work(struct work_struct *work)
 	mutex_lock(&con->mutex);
 restart:
 	if (test_and_clear_bit(SOCK_CLOSED, &con->flags)) {
-		if (test_and_clear_bit(CONNECTING, &con->state)) {
+		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);
 			con->error_msg = "connection failed";
 		} else {
-			con->error_msg = "socket closed";
+			con->error_msg = "unrecognized con state";
 		}
 		goto fault;
 	}