SUNRPC: Add a /sys/kernel/debug/fail_sunrpc/ directory

This directory will contain a set of administrative controls for
enabling error injection for kernel RPC consumers.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/debugfs.c

@@ -8,7 +8,9 @@
 #include <linux/debugfs.h>
 #include <linux/sunrpc/sched.h>
 #include <linux/sunrpc/clnt.h>
+
 #include "netns.h"
+#include "fail.h"
 
 static struct dentry *topdir;
 static struct dentry *rpc_clnt_dir;
@@ -297,6 +299,22 @@ static const struct file_operations fault_disconnect_fops = {
 	.release	= fault_release,
 };
 
+struct fail_sunrpc_attr fail_sunrpc = {
+	.attr			= FAULT_ATTR_INITIALIZER,
+};
+
+#if IS_ENABLED(CONFIG_FAULT_INJECTION_DEBUG_FS)
+static void fail_sunrpc_init(void)
+{
+	fault_create_debugfs_attr("fail_sunrpc", NULL,
+				  &fail_sunrpc.attr);
+}
+#else
+static inline void fail_sunrpc_init(void)
+{
+}
+#endif
+
 void __exit
 sunrpc_debugfs_exit(void)
 {
@@ -321,4 +339,6 @@ sunrpc_debugfs_init(void)
 
 	debugfs_create_file("disconnect", S_IFREG | 0400, rpc_fault_dir, NULL,
 			    &fault_disconnect_fops);
+
+	fail_sunrpc_init();
 }

net/sunrpc/fail.h

@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2021, Oracle. All rights reserved.
+ */
+
+#ifndef _NET_SUNRPC_FAIL_H_
+#define _NET_SUNRPC_FAIL_H_
+
+#include <linux/fault-inject.h>
+
+struct fail_sunrpc_attr {
+	struct fault_attr	attr;
+};
+
+extern struct fail_sunrpc_attr fail_sunrpc;
+
+#endif /* _NET_SUNRPC_FAIL_H_ */