staging/lustre/ptlrpc: hold rq_lock when modify rq_flags

In after_reply(), take the rq_lock for changing the rq_resend.

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-on: http://review.whamcloud.com/11957
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5633
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Johann Lombardi <johann.lombardi@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/ptlrpc/client.c

@@ -1247,7 +1247,9 @@ static int after_reply(struct ptlrpc_request *req)
 		time_t	now = get_seconds();
 
 		DEBUG_REQ(D_RPCTRACE, req, "Resending request on EINPROGRESS");
+		spin_lock(&req->rq_lock);
 		req->rq_resend = 1;
+		spin_unlock(&req->rq_lock);
 		req->rq_nr_resend++;
 
 		/* allocate new xid to avoid reply reconstruction */