NFSv4.1: Clear the old state by our client id before establishing a new lease

If the call to exchange-id returns with the EXCHGID4_FLAG_CONFIRMED_R flag
set, then that means our lease was established by a previous mount instance.
Ensure that we detect this situation, and that we clear the state held by
that mount.

Reported-by: Jorge Mora <Jorge.Mora@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 732526e..627f37c 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6897,9 +6897,13 @@
 
 	if (status == 0) {
 		clp->cl_clientid = res.clientid;
-		clp->cl_exchange_flags = (res.flags & ~EXCHGID4_FLAG_CONFIRMED_R);
-		if (!(res.flags & EXCHGID4_FLAG_CONFIRMED_R))
+		clp->cl_exchange_flags = res.flags;
+		/* Client ID is not confirmed */
+		if (!(res.flags & EXCHGID4_FLAG_CONFIRMED_R)) {
+			clear_bit(NFS4_SESSION_ESTABLISHED,
+					&clp->cl_session->session_state);
 			clp->cl_seqid = res.seqid;
+		}
 
 		kfree(clp->cl_serverowner);
 		clp->cl_serverowner = res.server_owner;
@@ -7231,6 +7235,9 @@
 		struct nfs41_create_session_res *res)
 {
 	nfs4_copy_sessionid(&session->sess_id, &res->sessionid);
+	/* Mark client id and session as being confirmed */
+	session->clp->cl_exchange_flags |= EXCHGID4_FLAG_CONFIRMED_R;
+	set_bit(NFS4_SESSION_ESTABLISHED, &session->session_state);
 	session->flags = res->flags;
 	memcpy(&session->fc_attrs, &res->fc_attrs, sizeof(session->fc_attrs));
 	if (res->flags & SESSION4_BACK_CHAN)
@@ -7326,8 +7333,8 @@
 	dprintk("--> nfs4_proc_destroy_session\n");
 
 	/* session is still being setup */
-	if (session->clp->cl_cons_state != NFS_CS_READY)
-		return status;
+	if (!test_and_clear_bit(NFS4_SESSION_ESTABLISHED, &session->session_state))
+		return 0;
 
 	status = rpc_call_sync(session->clp->cl_rpcclient, &msg, RPC_TASK_TIMEOUT);
 	trace_nfs4_destroy_session(session->clp, status);