[PATCH 4.9 087/175] SUNRPC: xprt_load_transport() needs to support the netid "rdma6"

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Trond Myklebust <trond.myklebust@hammerspace.com>

[ Upstream commit d5aa6b22e2258f05317313ecc02efbb988ed6d38 ]

According to RFC5666, the correct netid for an IPv6 addressed RDMA
transport is "rdma6", which we've supported as a mount option since
Linux-4.7. The problem is when we try to load the module "xprtrdma6",
that will fail, since there is no modulealias of that name.

Fixes: 181342c5ebe8 ("xprtrdma: Add rdma6 option to support NFS/RDMA IPv6")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/sunrpc/xprt.h     |  1 +
 net/sunrpc/xprt.c               | 65 +++++++++++++++++++++++++--------
 net/sunrpc/xprtrdma/module.c    |  1 +
 net/sunrpc/xprtrdma/transport.c |  1 +
 net/sunrpc/xprtsock.c           |  4 ++
 5 files changed, 56 insertions(+), 16 deletions(-)

diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index a5da60b24d83e..15bab51a3aef1 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -310,6 +310,7 @@ struct xprt_class {
 	struct rpc_xprt *	(*setup)(struct xprt_create *);
 	struct module		*owner;
 	char			name[32];
+	const char *		netid[];
 };
 
 /*
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 1a8df242d26a1..9491fc81d50ad 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -143,31 +143,64 @@ out:
 }
 EXPORT_SYMBOL_GPL(xprt_unregister_transport);
 
+static void
+xprt_class_release(const struct xprt_class *t)
+{
+	module_put(t->owner);
+}
+
+static const struct xprt_class *
+xprt_class_find_by_netid_locked(const char *netid)
+{
+	const struct xprt_class *t;
+	unsigned int i;
+
+	list_for_each_entry(t, &xprt_list, list) {
+		for (i = 0; t->netid[i][0] != '\0'; i++) {
+			if (strcmp(t->netid[i], netid) != 0)
+				continue;
+			if (!try_module_get(t->owner))
+				continue;
+			return t;
+		}
+	}
+	return NULL;
+}
+
+static const struct xprt_class *
+xprt_class_find_by_netid(const char *netid)
+{
+	const struct xprt_class *t;
+
+	spin_lock(&xprt_list_lock);
+	t = xprt_class_find_by_netid_locked(netid);
+	if (!t) {
+		spin_unlock(&xprt_list_lock);
+		request_module("rpc%s", netid);
+		spin_lock(&xprt_list_lock);
+		t = xprt_class_find_by_netid_locked(netid);
+	}
+	spin_unlock(&xprt_list_lock);
+	return t;
+}
+
 /**
  * xprt_load_transport - load a transport implementation
- * @transport_name: transport to load
+ * @netid: transport to load
  *
  * Returns:
  * 0:		transport successfully loaded
  * -ENOENT:	transport module not available
  */
-int xprt_load_transport(const char *transport_name)
+int xprt_load_transport(const char *netid)
 {
-	struct xprt_class *t;
-	int result;
+	const struct xprt_class *t;
 
-	result = 0;
-	spin_lock(&xprt_list_lock);
-	list_for_each_entry(t, &xprt_list, list) {
-		if (strcmp(t->name, transport_name) == 0) {
-			spin_unlock(&xprt_list_lock);
-			goto out;
-		}
-	}
-	spin_unlock(&xprt_list_lock);
-	result = request_module("xprt%s", transport_name);
-out:
-	return result;
+	t = xprt_class_find_by_netid(netid);
+	if (!t)
+		return -ENOENT;
+	xprt_class_release(t);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(xprt_load_transport);
 
diff --git a/net/sunrpc/xprtrdma/module.c b/net/sunrpc/xprtrdma/module.c
index 560712bd9fa2c..dd227de31a589 100644
--- a/net/sunrpc/xprtrdma/module.c
+++ b/net/sunrpc/xprtrdma/module.c
@@ -19,6 +19,7 @@ MODULE_DESCRIPTION("RPC/RDMA Transport");
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_ALIAS("svcrdma");
 MODULE_ALIAS("xprtrdma");
+MODULE_ALIAS("rpcrdma6");
 
 static void __exit rpc_rdma_cleanup(void)
 {
diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index fa324fe739466..3ea3bb64b6d5c 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -777,6 +777,7 @@ static struct xprt_class xprt_rdma = {
 	.owner			= THIS_MODULE,
 	.ident			= XPRT_TRANSPORT_RDMA,
 	.setup			= xprt_setup_rdma,
+	.netid			= { "rdma", "rdma6", "" },
 };
 
 void xprt_rdma_cleanup(void)
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index f3f05148922a1..bf20ea2606389 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -3147,6 +3147,7 @@ static struct xprt_class	xs_local_transport = {
 	.owner		= THIS_MODULE,
 	.ident		= XPRT_TRANSPORT_LOCAL,
 	.setup		= xs_setup_local,
+	.netid		= { "" },
 };
 
 static struct xprt_class	xs_udp_transport = {
@@ -3155,6 +3156,7 @@ static struct xprt_class	xs_udp_transport = {
 	.owner		= THIS_MODULE,
 	.ident		= XPRT_TRANSPORT_UDP,
 	.setup		= xs_setup_udp,
+	.netid		= { "udp", "udp6", "" },
 };
 
 static struct xprt_class	xs_tcp_transport = {
@@ -3163,6 +3165,7 @@ static struct xprt_class	xs_tcp_transport = {
 	.owner		= THIS_MODULE,
 	.ident		= XPRT_TRANSPORT_TCP,
 	.setup		= xs_setup_tcp,
+	.netid		= { "tcp", "tcp6", "" },
 };
 
 static struct xprt_class	xs_bc_tcp_transport = {
@@ -3171,6 +3174,7 @@ static struct xprt_class	xs_bc_tcp_transport = {
 	.owner		= THIS_MODULE,
 	.ident		= XPRT_TRANSPORT_BC_TCP,
 	.setup		= xs_setup_bc_tcp,
+	.netid		= { "" },
 };
 
 /**
-- 
2.27.0