NFSv4.1: Don't update sequence number if rpc_task is not sent

If we fail to contact the gss upcall program, then no message will
be sent to the server.  The client still updated the sequence number,
however, and this lead to NFS4ERR_SEQ_MISMATCH for the next several
RPC calls.
Signed-off-by: NBryan Schumaker <bjschuma@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -444,8 +444,8 @@ static int nfs41_sequence_done(struct rpc_task *task, struct nfs4_sequence_res *
 	if (res->sr_status == 1)
 		res->sr_status = NFS_OK;
 
-	/* -ERESTARTSYS can result in skipping nfs41_sequence_setup */
-	if (!res->sr_slot)
+	/* don't increment the sequence number if the task wasn't sent */
+	if (!RPC_WAS_SENT(task))
 		goto out;
 
 	/* Check the SEQUENCE operation status */

include/linux/sunrpc/sched.h

@@ -127,6 +127,7 @@ struct rpc_task_setup {
 #define RPC_TASK_KILLED		0x0100		/* task was killed */
 #define RPC_TASK_SOFT		0x0200		/* Use soft timeouts */
 #define RPC_TASK_SOFTCONN	0x0400		/* Fail if can't connect */
+#define RPC_TASK_SENT		0x0800		/* message was sent */
 
 #define RPC_IS_ASYNC(t)		((t)->tk_flags & RPC_TASK_ASYNC)
 #define RPC_IS_SWAPPER(t)	((t)->tk_flags & RPC_TASK_SWAPPER)
@@ -134,6 +135,7 @@ struct rpc_task_setup {
 #define RPC_ASSASSINATED(t)	((t)->tk_flags & RPC_TASK_KILLED)
 #define RPC_IS_SOFT(t)		((t)->tk_flags & RPC_TASK_SOFT)
 #define RPC_IS_SOFTCONN(t)	((t)->tk_flags & RPC_TASK_SOFTCONN)
+#define RPC_WAS_SENT(t)		((t)->tk_flags & RPC_TASK_SENT)
 
 #define RPC_TASK_RUNNING	0
 #define RPC_TASK_QUEUED		1

net/sunrpc/xprt.c

@@ -906,6 +906,7 @@ void xprt_transmit(struct rpc_task *task)
 	}
 
 	dprintk("RPC: %5u xmit complete\n", task->tk_pid);
+	task->tk_flags |= RPC_TASK_SENT;
 	spin_lock_bh(&xprt->transport_lock);
 
 	xprt->ops->set_retrans_timeout(task);