SUNRPC: Fix rpc_task_force_reencode

This patch fixes the bug that was reported in
  http://bugzilla.kernel.org/show_bug.cgi?id=14053

If we're in the case where we need to force a reencode and then resend of
the RPC request, due to xprt_transmit failing with a networking error, then
we _must_ retransmit the entire request.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

net/sunrpc/clnt.c

@@ -937,6 +937,7 @@ static inline void
 rpc_task_force_reencode(struct rpc_task *task)
 {
 	task->tk_rqstp->rq_snd_buf.len = 0;
+	task->tk_rqstp->rq_bytes_sent = 0;
 }
 
 static inline void