[PATCH_V4 1/9] SUNRPC new transport for the NFSv4.1 shared back channel

[andros@netapp.com]

From: Andy Adamson <andros@netapp.com>

Create a new transport for the shared back channel.l Move the current sock
create and destroy routines into the new transport ops.

Reference the back channel transport across message processing (recv/send).

Signed-off-by: Andy Adamson <andros@netapp.com>
---
 include/linux/sunrpc/svcsock.h |    1 +
 net/sunrpc/svc.c               |   18 +++---
 net/sunrpc/svcsock.c           |  122 +++++++++++++++++++++++++++++++++-------
 3 files changed, 112 insertions(+), 29 deletions(-)

diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h
index 1b353a7..3a45a80 100644
--- a/include/linux/sunrpc/svcsock.h
+++ b/include/linux/sunrpc/svcsock.h
@@ -45,6 +45,7 @@ int		svc_sock_names(struct svc_serv *serv, char *buf,
 int		svc_addsock(struct svc_serv *serv, const int fd,
 					char *name_return, const size_t len);
 void		svc_init_xprt_sock(void);
+void		svc_init_bc_xprt_sock(void);
 void		svc_cleanup_xprt_sock(void);
 struct svc_xprt *svc_sock_create(struct svc_serv *serv, int prot);
 void		svc_sock_destroy(struct svc_xprt *);
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 6359c42..3520cb3 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -488,10 +488,6 @@ svc_destroy(struct svc_serv *serv)
 	if (svc_serv_is_pooled(serv))
 		svc_pool_map_put();
 
-#if defined(CONFIG_NFS_V4_1)
-	svc_sock_destroy(serv->bc_xprt);
-#endif /* CONFIG_NFS_V4_1 */
-
 	svc_unregister(serv);
 	kfree(serv->sv_pools);
 	kfree(serv);
@@ -1264,7 +1260,7 @@ bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req,
 {
 	struct kvec	*argv = &rqstp->rq_arg.head[0];
 	struct kvec	*resv = &rqstp->rq_res.head[0];
-	int 		error;
+	int		ret;
 
 	/* Build the svc_rqst used by the common processing routine */
 	rqstp->rq_xprt = serv->bc_xprt;
@@ -1292,12 +1288,16 @@ bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req,
 	svc_getu32(argv);	/* XID */
 	svc_getnl(argv);	/* CALLDIR */
 
-	error = svc_process_common(rqstp, argv, resv);
-	if (error <= 0)
-		return error;
+	/* Hold a reference to the back channel socket across the call */
+	svc_xprt_get(serv->bc_xprt);
+	ret = svc_process_common(rqstp, argv, resv);
+	if (ret <= 0)
+		return ret;
 
 	memcpy(&req->rq_snd_buf, &rqstp->rq_res, sizeof(req->rq_snd_buf));
-	return bc_send(req);
+	ret = bc_send(req);
+	svc_xprt_put(serv->bc_xprt);
+	return ret;
 }
 EXPORT_SYMBOL(bc_svc_process);
 #endif /* CONFIG_NFS_V4_1 */
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 07919e1..5875551 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -66,6 +66,13 @@ static void		svc_sock_free(struct svc_xprt *);
 static struct svc_xprt *svc_create_socket(struct svc_serv *, int,
 					  struct net *, struct sockaddr *,
 					  int, int);
+#if defined(CONFIG_NFS_V4_1)
+static struct svc_xprt *svc_bc_create_socket(struct svc_serv *, int,
+					     struct net *, struct sockaddr *,
+					     int, int);
+static void svc_bc_sock_free(struct svc_xprt *xprt);
+#endif /* CONFIG_NFS_V4_1 */
+
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 static struct lock_class_key svc_key[2];
 static struct lock_class_key svc_slock_key[2];
@@ -1184,6 +1191,79 @@ static struct svc_xprt *svc_tcp_create(struct svc_serv *serv,
 	return svc_create_socket(serv, IPPROTO_TCP, net, sa, salen, flags);
 }
 
+#if defined(CONFIG_NFS_V4_1)
+static struct svc_xprt *svc_bc_create_socket(struct svc_serv *, int,
+					     struct net *, struct sockaddr *,
+					     int, int);
+static void svc_bc_sock_free(struct svc_xprt *xprt);
+
+static struct svc_xprt *svc_bc_tcp_create(struct svc_serv *serv,
+				       struct net *net,
+				       struct sockaddr *sa, int salen,
+				       int flags)
+{
+	return svc_bc_create_socket(serv, IPPROTO_TCP, net, sa, salen, flags);
+}
+
+static void svc_bc_tcp_sock_detach(struct svc_xprt *xprt)
+{
+}
+
+/* These bc ops are never called. The shared fore channel is used instead */
+static int svc_bc_tcp_recvfrom(struct svc_rqst *rqstp)
+{
+	return 0;
+}
+
+static int svc_bc_tcp_sendto(struct svc_rqst *rqstp)
+{
+	return 0;
+}
+
+static void svc_bc_tcp_prep_reply_hdr(struct svc_rqst *rqstp)
+{
+}
+
+static void svc_bc_release_skb(struct svc_rqst *rqstp)
+{
+}
+
+static int svc_bc_tcp_has_wspace(struct svc_xprt *xprt)
+{
+	return 0;
+}
+
+static struct svc_xprt *svc_bc_tcp_accept(struct svc_xprt *xprt)
+{
+	return NULL;
+}
+
+static struct svc_xprt_ops svc_tcp_bc_ops = {
+	.xpo_create = svc_bc_tcp_create,
+	.xpo_recvfrom = svc_bc_tcp_recvfrom,
+	.xpo_sendto = svc_bc_tcp_sendto,
+	.xpo_release_rqst = svc_bc_release_skb,
+	.xpo_detach = svc_bc_tcp_sock_detach,
+	.xpo_free = svc_bc_sock_free,
+	.xpo_prep_reply_hdr = svc_bc_tcp_prep_reply_hdr,
+	.xpo_has_wspace = svc_bc_tcp_has_wspace,
+	.xpo_accept = svc_bc_tcp_accept,
+};
+
+static struct svc_xprt_class svc_tcp_bc_class = {
+	.xcl_name = "tcp-bc",
+	.xcl_owner = THIS_MODULE,
+	.xcl_ops = &svc_tcp_bc_ops,
+	.xcl_max_payload = RPCSVC_MAXPAYLOAD_TCP,
+};
+
+void svc_init_bc_xprt_sock(void)
+{
+	svc_reg_xprt_class(&svc_tcp_bc_class);
+}
+EXPORT_SYMBOL_GPL(svc_init_bc_xprt_sock);
+#endif /* CONFIG_NFS_V4_1 */
+
 static struct svc_xprt_ops svc_tcp_ops = {
 	.xpo_create = svc_tcp_create,
 	.xpo_recvfrom = svc_tcp_recvfrom,
@@ -1509,41 +1589,43 @@ static void svc_sock_free(struct svc_xprt *xprt)
 	kfree(svsk);
 }
 
+#if defined(CONFIG_NFS_V4_1)
 /*
- * Create a svc_xprt.
- *
- * For internal use only (e.g. nfsv4.1 backchannel).
- * Callers should typically use the xpo_create() method.
+ * Create a back channel svc_xprt which shares the fore channel socket.
  */
-struct svc_xprt *svc_sock_create(struct svc_serv *serv, int prot)
+static struct svc_xprt *svc_bc_create_socket(struct svc_serv *serv,
+					     int protocol,
+					     struct net *net,
+					     struct sockaddr *sin, int len,
+					     int flags)
 {
 	struct svc_sock *svsk;
-	struct svc_xprt *xprt = NULL;
+	struct svc_xprt *xprt;
+
+	if (protocol != IPPROTO_TCP) {
+		printk(KERN_WARNING "svc: only and TCP sockets"
+			" supported on shared back channel\n");
+		return ERR_PTR(-EINVAL);
+	}
 
-	dprintk("svc: %s\n", __func__);
 	svsk = kzalloc(sizeof(*svsk), GFP_KERNEL);
 	if (!svsk)
-		goto out;
+		return ERR_PTR(-ENOMEM);
 
 	xprt = &svsk->sk_xprt;
-	if (prot == IPPROTO_TCP)
-		svc_xprt_init(&svc_tcp_class, xprt, serv);
-	else if (prot == IPPROTO_UDP)
-		svc_xprt_init(&svc_udp_class, xprt, serv);
-	else
-		BUG();
-out:
-	dprintk("svc: %s return %p\n", __func__, xprt);
+	svc_xprt_init(&svc_tcp_bc_class, xprt, serv);
+
+	serv->bc_xprt = xprt;
+
 	return xprt;
 }
-EXPORT_SYMBOL_GPL(svc_sock_create);
 
 /*
- * Destroy a svc_sock.
+ * Free a back channel svc_sock.
  */
-void svc_sock_destroy(struct svc_xprt *xprt)
+static void svc_bc_sock_free(struct svc_xprt *xprt)
 {
 	if (xprt)
 		kfree(container_of(xprt, struct svc_sock, sk_xprt));
 }
-EXPORT_SYMBOL_GPL(svc_sock_destroy);
+#endif /* CONFIG_NFS_V4_1 */
-- 
1.6.6