ns: add to_<type>_ns() to respective headers

Every namespace type has a container_of(ns, <ns_type>, ns) static inline
function that is currently not exposed in the header. So we have a bunch
of places that open-code it via container_of(). Move it to the headers
so we can use it directly.

Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

include/linux/cgroup.h

@@ -794,6 +794,11 @@ extern struct cgroup_namespace init_cgroup_ns;
 
 #ifdef CONFIG_CGROUPS
 
+static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct cgroup_namespace, ns);
+}
+
 void free_cgroup_ns(struct cgroup_namespace *ns);
 
 struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,

include/linux/ipc_namespace.h

@@ -129,6 +129,11 @@ static inline int mq_init_ns(struct ipc_namespace *ns) { return 0; }
 #endif
 
 #if defined(CONFIG_IPC_NS)
+static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct ipc_namespace, ns);
+}
+
 extern struct ipc_namespace *copy_ipcs(unsigned long flags,
 	struct user_namespace *user_ns, struct ipc_namespace *ns);
 

include/linux/pid_namespace.h

@@ -54,6 +54,11 @@ extern struct pid_namespace init_pid_ns;
 #define PIDNS_ADDING (1U << 31)
 
 #ifdef CONFIG_PID_NS
+static inline struct pid_namespace *to_pid_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct pid_namespace, ns);
+}
+
 static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns)
 {
 	if (ns != &init_pid_ns)

include/linux/time_namespace.h

@@ -33,6 +33,10 @@ struct time_namespace {
 extern struct time_namespace init_time_ns;
 
 #ifdef CONFIG_TIME_NS
+static inline struct time_namespace *to_time_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct time_namespace, ns);
+}
 void __init time_ns_init(void);
 extern int vdso_join_timens(struct task_struct *task,
 			    struct time_namespace *ns);

include/linux/user_namespace.h

@@ -168,6 +168,11 @@ static inline void set_userns_rlimit_max(struct user_namespace *ns,
 
 #ifdef CONFIG_USER_NS
 
+static inline struct user_namespace *to_user_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct user_namespace, ns);
+}
+
 static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
 {
 	if (ns)

include/linux/utsname.h

@@ -30,6 +30,11 @@ struct uts_namespace {
 extern struct uts_namespace init_uts_ns;
 
 #ifdef CONFIG_UTS_NS
+static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct uts_namespace, ns);
+}
+
 static inline void get_uts_ns(struct uts_namespace *ns)
 {
 	refcount_inc(&ns->ns.count);

include/net/net_namespace.h

@@ -262,6 +262,11 @@ void ipx_unregister_sysctl(void);
 #ifdef CONFIG_NET_NS
 void __put_net(struct net *net);
 
+static inline struct net *to_net_ns(struct ns_common *ns)
+{
+	return container_of(ns, struct net, ns);
+}
+
 /* Try using get_net_track() instead */
 static inline struct net *get_net(struct net *net)
 {

ipc/namespace.c

@@ -209,11 +209,6 @@ void put_ipc_ns(struct ipc_namespace *ns)
 	}
 }
 
-static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
-{
-	return container_of(ns, struct ipc_namespace, ns);
-}
-
 static struct ns_common *ipcns_get(struct task_struct *task)
 {
 	struct ipc_namespace *ns = NULL;

kernel/cgroup/namespace.c

@@ -89,11 +89,6 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
 	return new_ns;
 }
 
-static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
-{
-	return container_of(ns, struct cgroup_namespace, ns);
-}
-
 static int cgroupns_install(struct nsset *nsset, struct ns_common *ns)
 {
 	struct nsproxy *nsproxy = nsset->nsproxy;

kernel/pid_namespace.c

@@ -345,11 +345,6 @@ int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
 	return 0;
 }
 
-static inline struct pid_namespace *to_pid_ns(struct ns_common *ns)
-{
-	return container_of(ns, struct pid_namespace, ns);
-}
-
 static struct ns_common *pidns_get(struct task_struct *task)
 {
 	struct pid_namespace *ns;

kernel/time/namespace.c

@@ -261,11 +261,6 @@ void free_time_ns(struct time_namespace *ns)
 	kfree_rcu(ns, ns.ns_rcu);
 }
 
-static struct time_namespace *to_time_ns(struct ns_common *ns)
-{
-	return container_of(ns, struct time_namespace, ns);
-}
-
 static struct ns_common *timens_get(struct task_struct *task)
 {
 	struct time_namespace *ns = NULL;

kernel/user_namespace.c

@@ -1325,11 +1325,6 @@ bool current_in_userns(const struct user_namespace *target_ns)
 }
 EXPORT_SYMBOL(current_in_userns);
 
-static inline struct user_namespace *to_user_ns(struct ns_common *ns)
-{
-	return container_of(ns, struct user_namespace, ns);
-}
-
 static struct ns_common *userns_get(struct task_struct *task)
 {
 	struct user_namespace *user_ns;

kernel/utsname.c

@@ -103,11 +103,6 @@ void free_uts_ns(struct uts_namespace *ns)
 	kfree_rcu(ns, ns.ns_rcu);
 }
 
-static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
-{
-	return container_of(ns, struct uts_namespace, ns);
-}
-
 static struct ns_common *utsns_get(struct task_struct *task)
 {
 	struct uts_namespace *ns = NULL;

net/core/net_namespace.c

@@ -1541,11 +1541,6 @@ static struct ns_common *netns_get(struct task_struct *task)
 	return net ? &net->ns : NULL;
 }
 
-static inline struct net *to_net_ns(struct ns_common *ns)
-{
-	return container_of(ns, struct net, ns);
-}
-
 static void netns_put(struct ns_common *ns)
 {
 	put_net(to_net_ns(ns));