NFSv4: Fix NFSv4 trunking discovery

If walking the list in nfs4[01]_walk_client_list fails, then the most
likely explanation is that the server dropped the clientid before we
actually managed to confirm it. As long as our nfs_client is the very
last one in the list to be tested, the caller can be assured that this
is the case when the final return value is NFS4ERR_STALE_CLIENTID.

Reported-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: stable@vger.kernel.org [>=3.7]
Tested-by: Ben Greear <greearb@candelatech.com>
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 9448c57..f72561ca 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -136,16 +136,11 @@
 	clp->cl_confirm = clid.confirm;
 
 	status = nfs40_walk_client_list(clp, result, cred);
-	switch (status) {
-	case -NFS4ERR_STALE_CLIENTID:
-		set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
-	case 0:
+	if (status == 0) {
 		/* Sustain the lease, even if it's empty.  If the clientid4
 		 * goes stale it's of no use for trunking discovery. */
 		nfs4_schedule_state_renewal(*result);
-		break;
 	}
-
 out:
 	return status;
 }
@@ -1863,6 +1858,7 @@
 	case -ETIMEDOUT:
 	case -EAGAIN:
 		ssleep(1);
+	case -NFS4ERR_STALE_CLIENTID:
 		dprintk("NFS: %s after status %d, retrying\n",
 			__func__, status);
 		goto again;