sysctl: Add a root pointer to ctl_table_set

Add a ctl_table_root pointer to ctl_table set so it is easy to
go from a ctl_table_set to a ctl_table_root.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>

fs/proc/proc_sysctl.c

@@ -45,6 +45,7 @@ static struct ctl_table_header root_table_header = {
 static struct ctl_table_root sysctl_table_root = {
 	.root_list = LIST_HEAD_INIT(sysctl_table_root.root_list),
 	.default_set.list = LIST_HEAD_INIT(root_table_header.ctl_entry),
+	.default_set.root = &sysctl_table_root,
 };
 
 static DEFINE_SPINLOCK(sysctl_lock);
@@ -1348,9 +1349,11 @@ void unregister_sysctl_table(struct ctl_table_header * header)
 EXPORT_SYMBOL(unregister_sysctl_table);
 
 void setup_sysctl_set(struct ctl_table_set *p,
+	struct ctl_table_root *root,
 	int (*is_seen)(struct ctl_table_set *))
 {
 	INIT_LIST_HEAD(&p->list);
+	p->root = root;
 	p->is_seen = is_seen;
 }
 

include/linux/sysctl.h

@@ -1047,6 +1047,7 @@ struct ctl_table_header
 
 struct ctl_table_set {
 	struct list_head list;
+	struct ctl_table_root *root;
 	int (*is_seen)(struct ctl_table_set *);
 };
 
@@ -1069,6 +1070,7 @@ struct ctl_path {
 void proc_sys_poll_notify(struct ctl_table_poll *poll);
 
 extern void setup_sysctl_set(struct ctl_table_set *p,
+	struct ctl_table_root *root,
 	int (*is_seen)(struct ctl_table_set *));
 extern void retire_sysctl_set(struct ctl_table_set *set);
 
@@ -1103,6 +1105,7 @@ static inline void unregister_sysctl_table(struct ctl_table_header * table)
 }
 
 static inline void setup_sysctl_set(struct ctl_table_set *p,
+	struct ctl_table_root *root,
 	int (*is_seen)(struct ctl_table_set *))
 {
 }

net/sysctl_net.c

@@ -74,8 +74,7 @@ static struct ctl_table_root net_sysctl_ro_root = {
 
 static int __net_init sysctl_net_init(struct net *net)
 {
-	setup_sysctl_set(&net->sysctls,
-			 is_seen);
+	setup_sysctl_set(&net->sysctls, &net_sysctl_root, is_seen);
 	return 0;
 }
 
@@ -95,7 +94,7 @@ static __init int net_sysctl_init(void)
 	ret = register_pernet_subsys(&sysctl_pernet_ops);
 	if (ret)
 		goto out;
-	setup_sysctl_set(&net_sysctl_ro_root.default_set, NULL);
+	setup_sysctl_set(&net_sysctl_ro_root.default_set, &net_sysctl_ro_root, NULL);
 	register_sysctl_root(&net_sysctl_ro_root);
 	register_sysctl_root(&net_sysctl_root);
 out: