nstree: move nstree types into separate header

/* SPDX-License-Identifier: GPL-2.0 */

/* Copyright (c) 2025 Christian Brauner <brauner@kernel.org> */

#ifndef _LINUX_NSTREE_TYPES_H

#define _LINUX_NSTREE_TYPES_H

#include <linux/rbtree.h>

#include <linux/list.h>

/**

 * struct ns_tree_root - Root of a namespace tree

 * @ns_rb: Red-black tree root for efficient lookups

 * @ns_list_head: List head for sequential iteration

 *

 * Each namespace tree maintains both an rbtree (for O(log n) lookups)

 * and a list (for efficient sequential iteration). The list is kept in

 * the same sorted order as the rbtree.

 */

struct ns_tree_root {

	struct rb_root ns_rb;

	struct list_head ns_list_head;

};

/**

 * struct ns_tree_node - Node in a namespace tree

 * @ns_node: Red-black tree node

 * @ns_list_entry: List entry for sequential iteration

 *

 * Represents a namespace's position in a tree. Each namespace has

 * multiple tree nodes for different trees (unified, per-type, owner).

 */

struct ns_tree_node {

	struct rb_node ns_node;

	struct list_head ns_list_entry;

};

#endif /* _LINUX_NSTREE_TYPES_H */

#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>