[PATCH 2/4] nfs: remove sv_bc_enabled using in svc_is_backchannel()

[Vasily Averin <vvs@virtuozzo.com>]

serv->sv_bc_xprt cannot be used as pointer,
serv is global structure, but sv_bc_xprt is assigned per-netnamespace

The only user of this field is svc_is_backchannel() where it is used
not as pointer but as mark of backchannel-compatible servers. 

Convert netns-unsafe xprt pointer to simple boolean mark,
Hope it helps to prevent misuse of sv_bc_xpr in future. 

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
---
 include/linux/sunrpc/bc_xprt.h           | 10 ++++------
 include/linux/sunrpc/svc.h               |  2 +-
 net/sunrpc/svcsock.c                     |  2 +-
 net/sunrpc/xprtrdma/svc_rdma_transport.c |  2 +-
 4 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/include/linux/sunrpc/bc_xprt.h b/include/linux/sunrpc/bc_xprt.h
index 28721cf73ec3..4e8c773d02be 100644
--- a/include/linux/sunrpc/bc_xprt.h
+++ b/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)
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 73e130a840ce..bf21609160c1 100644
--- a/include/linux/sunrpc/svc.h
+++ b/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;	/* server uses backchannel */
 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
 };
 
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 986f3ed7d1a2..5a6b3ba555c7 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -1623,7 +1623,7 @@ 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;
+	serv->sv_bc_enabled = true;
 
 	return xprt;
 }
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 2f7ec8912f49..88694048d5c0 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -136,7 +136,7 @@ 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;
+	serv->sv_bc_enabled = true;
 
 	dprintk("svcrdma: %s(%p)\n", __func__, xprt);
 	return xprt;
-- 
2.17.1