nfs: Ensure that nfs_callback_start_svc sets the server rq_task...

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index 54de482..e3dd1cd 100644
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -244,6 +244,7 @@
 		cb_info->task = NULL;
 		return ret;
 	}
+	rqstp->rq_task = cb_info->task;
 	dprintk("nfs_callback_up: service started\n");
 	return 0;
 }