sunrpc: replace svc_serv->sv_bc_xprt by boolean flag

svc_serv-> sv_bc_xprt is netns-unsafe and cannot be used as pointer.
To prevent its misuse in future it is replaced by new boolean flag.
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfs/callback.c

@@ -206,11 +206,13 @@ static int nfs_callback_up_net(int minorversion, struct svc_serv *serv,
 		goto err_bind;
 	}
 
-	ret = -EPROTONOSUPPORT;
+	ret = 0;
 	if (!IS_ENABLED(CONFIG_NFS_V4_1) || minorversion == 0)
 		ret = nfs4_callback_up_net(serv, net);
-	else if (xprt->ops->bc_up)
-		ret = xprt->ops->bc_up(serv, net);
+	else if (xprt->ops->bc_setup)
+		serv->sv_bc_enabled = true;
+	else
+		ret = -EPROTONOSUPPORT;
 
 	if (ret < 0) {
 		printk(KERN_ERR "NFS: callback service start failed\n");

include/linux/sunrpc/bc_xprt.h

@@ -47,11 +47,9 @@ void xprt_free_bc_rqst(struct rpc_rqst *req);
 /*
  * Determine if a shared backchannel is in use
  */
-static inline int svc_is_backchannel(const struct svc_rqst *rqstp)
+static inline bool svc_is_backchannel(const struct svc_rqst *rqstp)
 {
-	if (rqstp->rq_server->sv_bc_xprt)
-		return 1;
-	return 0;
+	return rqstp->rq_server->sv_bc_enabled;
 }
 #else /* CONFIG_SUNRPC_BACKCHANNEL */
 static inline int xprt_setup_backchannel(struct rpc_xprt *xprt,
@@ -60,9 +58,9 @@ static inline int xprt_setup_backchannel(struct rpc_xprt *xprt,
 	return 0;
 }
 
-static inline int svc_is_backchannel(const struct svc_rqst *rqstp)
+static inline bool svc_is_backchannel(const struct svc_rqst *rqstp)
 {
-	return 0;
+	return false;
 }
 
 static inline void xprt_free_bc_request(struct rpc_rqst *req)

include/linux/sunrpc/svc.h

@@ -109,7 +109,7 @@ struct svc_serv {
 	spinlock_t		sv_cb_lock;	/* protects the svc_cb_list */
 	wait_queue_head_t	sv_cb_waitq;	/* sleep here if there are no
 						 * entries in the svc_cb_list */
-	struct svc_xprt		*sv_bc_xprt;	/* callback on fore channel */
+	bool			sv_bc_enabled;	/* service uses backchannel */
 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
 };
 

net/sunrpc/svcsock.c

@@ -1623,8 +1623,6 @@ static struct svc_xprt *svc_bc_create_socket(struct svc_serv *serv,
 	svc_xprt_init(net, &svc_tcp_bc_class, xprt, serv);
 	set_bit(XPT_CONG_CTRL, &svsk->sk_xprt.xpt_flags);
 
-	serv->sv_bc_xprt = xprt;
-
 	return xprt;
 }
 

net/sunrpc/xprtrdma/svc_rdma_transport.c

@@ -136,7 +136,6 @@ static struct svc_xprt *svc_rdma_bc_create(struct svc_serv *serv,
 
 	svc_xprt_init(net, &svc_rdma_bc_class, xprt, serv);
 	set_bit(XPT_CONG_CTRL, &xprt->xpt_flags);
-	serv->sv_bc_xprt = xprt;
 
 	dprintk("svcrdma: %s(%p)\n", __func__, xprt);
 	return xprt;