1 files changed, 96 insertions, 0 deletions
diff --git a/include/linux/nstree.h b/include/linux/nstree.h
new file mode 100644
index 000000000000..175e4625bfa6
--- /dev/null
+++ b/include/linux/nstree.h
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2025 Christian Brauner <brauner@kernel.org> */
+#ifndef _LINUX_NSTREE_H
+#define _LINUX_NSTREE_H
+
+#include <linux/ns/nstree_types.h>
+#include <linux/nsproxy.h>
+#include <linux/rbtree.h>
+#include <linux/seqlock.h>
+#include <linux/rculist.h>
+#include <linux/cookie.h>
+#include <uapi/linux/nsfs.h>
+
+struct ns_common;
+
+extern struct ns_tree_root cgroup_ns_tree;
+extern struct ns_tree_root ipc_ns_tree;
+extern struct ns_tree_root mnt_ns_tree;
+extern struct ns_tree_root net_ns_tree;
+extern struct ns_tree_root pid_ns_tree;
+extern struct ns_tree_root time_ns_tree;
+extern struct ns_tree_root user_ns_tree;
+extern struct ns_tree_root uts_ns_tree;
+
+void ns_tree_node_init(struct ns_tree_node *node);
+void ns_tree_root_init(struct ns_tree_root *root);
+bool ns_tree_node_empty(const struct ns_tree_node *node);
+struct rb_node *ns_tree_node_add(struct ns_tree_node *node,
+				  struct ns_tree_root *root,
+				  int (*cmp)(struct rb_node *, const struct rb_node *));
+void ns_tree_node_del(struct ns_tree_node *node, struct ns_tree_root *root);
+
+#define to_ns_tree(__ns)					\
+	_Generic((__ns),					\
+		struct cgroup_namespace *: &(cgroup_ns_tree),	\
+		struct ipc_namespace *:    &(ipc_ns_tree),	\
+		struct net *:              &(net_ns_tree),	\
+		struct pid_namespace *:    &(pid_ns_tree),	\
+		struct mnt_namespace *:    &(mnt_ns_tree),	\
+		struct time_namespace *:   &(time_ns_tree),	\
+		struct user_namespace *:   &(user_ns_tree),	\
+		struct uts_namespace *:    &(uts_ns_tree))
+
+#define ns_tree_gen_id(__ns)                 \
+	__ns_tree_gen_id(to_ns_common(__ns), \
+			 (((__ns) == ns_init_ns(__ns)) ? ns_init_id(__ns) : 0))
+
+u64 __ns_tree_gen_id(struct ns_common *ns, u64 id);
+void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree_root *ns_tree);
+void __ns_tree_remove(struct ns_common *ns, struct ns_tree_root *ns_tree);
+struct ns_common *ns_tree_lookup_rcu(u64 ns_id, int ns_type);
+struct ns_common *__ns_tree_adjoined_rcu(struct ns_common *ns,
+					 struct ns_tree_root *ns_tree,
+					 bool previous);
+
+static inline void __ns_tree_add(struct ns_common *ns, struct ns_tree_root *ns_tree, u64 id)
+{
+	__ns_tree_gen_id(ns, id);
+	__ns_tree_add_raw(ns, ns_tree);
+}
+
+/**
+ * ns_tree_add_raw - Add a namespace to a namespace
+ * @ns: Namespace to add
+ *
+ * This function adds a namespace to the appropriate namespace tree
+ * without assigning a id.
+ */
+#define ns_tree_add_raw(__ns) __ns_tree_add_raw(to_ns_common(__ns), to_ns_tree(__ns))
+
+/**
+ * ns_tree_add - Add a namespace to a namespace tree
+ * @ns: Namespace to add
+ *
+ * This function assigns a new id to the namespace and adds it to the
+ * appropriate namespace tree and list.
+ */
+#define ns_tree_add(__ns)                                   \
+	__ns_tree_add(to_ns_common(__ns), to_ns_tree(__ns), \
+		      (((__ns) == ns_init_ns(__ns)) ? ns_init_id(__ns) : 0))
+
+/**
+ * ns_tree_remove - Remove a namespace from a namespace tree
+ * @ns: Namespace to remove
+ *
+ * This function removes a namespace from the appropriate namespace
+ * tree and list.
+ */
+#define ns_tree_remove(__ns)  __ns_tree_remove(to_ns_common(__ns), to_ns_tree(__ns))
+
+#define ns_tree_adjoined_rcu(__ns, __previous) \
+	__ns_tree_adjoined_rcu(to_ns_common(__ns), to_ns_tree(__ns), __previous)
+
+#define ns_tree_active(__ns) (!RB_EMPTY_NODE(&to_ns_common(__ns)->ns_tree_node.ns_node))
+
+#endif /* _LINUX_NSTREE_H */