Merge branch 'master'; commit 'v2.6.38-rc7' into next

1 files changed, 24 insertions, 10 deletions

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 96549df836ee0..c431f5a579605 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -2359,6 +2359,15 @@ static struct rpc_xprt *xs_setup_bc_tcp(struct xprt_create *args)
 	struct svc_sock *bc_sock;
 	struct rpc_xprt *ret;
 
+	if (args->bc_xprt->xpt_bc_xprt) {
+		/*
+		 * This server connection already has a backchannel
+		 * export; we can't create a new one, as we wouldn't be
+		 * able to match replies based on xid any more.  So,
+		 * reuse the already-existing one:
+		 */
+		 return args->bc_xprt->xpt_bc_xprt;
+	}
 	xprt = xs_setup_xprt(args, xprt_tcp_slot_table_entries);
 	if (IS_ERR(xprt))
 		return xprt;
@@ -2375,16 +2384,6 @@ static struct rpc_xprt *xs_setup_bc_tcp(struct xprt_create *args)
 	xprt->reestablish_timeout = 0;
 	xprt->idle_timeout = 0;
 
-	/*
-	 * The backchannel uses the same socket connection as the
-	 * forechannel
-	 */
-	xprt->bc_xprt = args->bc_xprt;
-	bc_sock = container_of(args->bc_xprt, struct svc_sock, sk_xprt);
-	bc_sock->sk_bc_xprt = xprt;
-	transport->sock = bc_sock->sk_sock;
-	transport->inet = bc_sock->sk_sk;
-
 	xprt->ops = &bc_tcp_ops;
 
 	switch (addr->sa_family) {
@@ -2407,6 +2406,20 @@ static struct rpc_xprt *xs_setup_bc_tcp(struct xprt_create *args)
 			xprt->address_strings[RPC_DISPLAY_PROTO]);
 
 	/*
+	 * Once we've associated a backchannel xprt with a connection,
+	 * we want to keep it around as long as long as the connection
+	 * lasts, in case we need to start using it for a backchannel
+	 * again; this reference won't be dropped until bc_xprt is
+	 * destroyed.
+	 */
+	xprt_get(xprt);
+	args->bc_xprt->xpt_bc_xprt = xprt;
+	xprt->bc_xprt = args->bc_xprt;
+	bc_sock = container_of(args->bc_xprt, struct svc_sock, sk_xprt);
+	transport->sock = bc_sock->sk_sock;
+	transport->inet = bc_sock->sk_sk;
+
+	/*
 	 * Since we don't want connections for the backchannel, we set
 	 * the xprt status to connected
 	 */
@@ -2415,6 +2428,7 @@ static struct rpc_xprt *xs_setup_bc_tcp(struct xprt_create *args)
 
 	if (try_module_get(THIS_MODULE))
 		return xprt;
+	xprt_put(xprt);
 	ret = ERR_PTR(-EINVAL);
 out_err:
 	xprt_free(xprt);