SUNRPC: Add srcaddr as a file in sysfs

I don't support changing it right now, but it could be useful
information for clients with multiple network cards.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/sysfs.c

@@ -100,6 +100,28 @@ static ssize_t rpc_sysfs_xprt_dstaddr_show(struct kobject *kobj,
 	return ret + 1;
 }
 
+static ssize_t rpc_sysfs_xprt_srcaddr_show(struct kobject *kobj,
+					   struct kobj_attribute *attr,
+					   char *buf)
+{
+	struct rpc_xprt *xprt = rpc_sysfs_xprt_kobj_get_xprt(kobj);
+	struct sockaddr_storage saddr;
+	struct sock_xprt *sock;
+	ssize_t ret = -1;
+
+	if (!xprt)
+		return 0;
+
+	sock = container_of(xprt, struct sock_xprt, xprt);
+	if (kernel_getsockname(sock->sock, (struct sockaddr *)&saddr) < 0)
+		goto out;
+
+	ret = sprintf(buf, "%pISc\n", &saddr);
+out:
+	xprt_put(xprt);
+	return ret + 1;
+}
+
 static ssize_t rpc_sysfs_xprt_info_show(struct kobject *kobj,
 					struct kobj_attribute *attr,
 					char *buf)
@@ -376,6 +398,9 @@ static const void *rpc_sysfs_xprt_namespace(struct kobject *kobj)
 static struct kobj_attribute rpc_sysfs_xprt_dstaddr = __ATTR(dstaddr,
 	0644, rpc_sysfs_xprt_dstaddr_show, rpc_sysfs_xprt_dstaddr_store);
 
+static struct kobj_attribute rpc_sysfs_xprt_srcaddr = __ATTR(srcaddr,
+	0644, rpc_sysfs_xprt_srcaddr_show, NULL);
+
 static struct kobj_attribute rpc_sysfs_xprt_info = __ATTR(xprt_info,
 	0444, rpc_sysfs_xprt_info_show, NULL);
 
@@ -384,6 +409,7 @@ static struct kobj_attribute rpc_sysfs_xprt_change_state = __ATTR(xprt_state,
 
 static struct attribute *rpc_sysfs_xprt_attrs[] = {
 	&rpc_sysfs_xprt_dstaddr.attr,
+	&rpc_sysfs_xprt_srcaddr.attr,
 	&rpc_sysfs_xprt_info.attr,
 	&rpc_sysfs_xprt_change_state.attr,
 	NULL,