ceph: keep the session state until it is released

When reconnecting the session but if it is denied by the MDS due
to client was in blacklist or something else, kclient will receive
a session close reply, and we will never see the important log:

"ceph:  mds%d reconnect denied"

And with the confusing log:

"ceph:  handle_session mds0 close 0000000085804730 state ??? seq 0"

Let's keep the session state until its memories is released.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/mds_client.c

@@ -530,6 +530,7 @@ const char *ceph_session_state_name(int s)
 	case CEPH_MDS_SESSION_OPEN: return "open";
 	case CEPH_MDS_SESSION_HUNG: return "hung";
 	case CEPH_MDS_SESSION_CLOSING: return "closing";
+	case CEPH_MDS_SESSION_CLOSED: return "closed";
 	case CEPH_MDS_SESSION_RESTARTING: return "restarting";
 	case CEPH_MDS_SESSION_RECONNECTING: return "reconnecting";
 	case CEPH_MDS_SESSION_REJECTED: return "rejected";
@@ -674,7 +675,6 @@ static void __unregister_session(struct ceph_mds_client *mdsc,
 	dout("__unregister_session mds%d %p\n", s->s_mds, s);
 	BUG_ON(mdsc->sessions[s->s_mds] != s);
 	mdsc->sessions[s->s_mds] = NULL;
-	s->s_state = 0;
 	ceph_con_close(&s->s_con);
 	ceph_put_mds_session(s);
 	atomic_dec(&mdsc->num_sessions);
@@ -3166,6 +3166,7 @@ static void handle_session(struct ceph_mds_session *session,
 	case CEPH_SESSION_CLOSE:
 		if (session->s_state == CEPH_MDS_SESSION_RECONNECTING)
 			pr_info("mds%d reconnect denied\n", session->s_mds);
+		session->s_state = CEPH_MDS_SESSION_CLOSED;
 		cleanup_session_requests(mdsc, session);
 		remove_session_caps(session);
 		wake = 2; /* for good measure */

fs/ceph/mds_client.h

@@ -151,7 +151,8 @@ enum {
 	CEPH_MDS_SESSION_RESTARTING = 5,
 	CEPH_MDS_SESSION_RECONNECTING = 6,
 	CEPH_MDS_SESSION_CLOSING = 7,
-	CEPH_MDS_SESSION_REJECTED = 8,
+	CEPH_MDS_SESSION_CLOSED = 8,
+	CEPH_MDS_SESSION_REJECTED = 9,
 };
 
 struct ceph_mds_session {