nstree_types.h

 1/* SPDX-License-Identifier: GPL-2.0 */
 2/* Copyright (c) 2025 Christian Brauner <brauner@kernel.org> */
 3#ifndef _LINUX_NSTREE_TYPES_H
 4#define _LINUX_NSTREE_TYPES_H
 5
 6#include <linux/rbtree.h>
 7#include <linux/list.h>
 8
 9/**
10 * struct ns_tree_root - Root of a namespace tree
11 * @ns_rb: Red-black tree root for efficient lookups
12 * @ns_list_head: List head for sequential iteration
13 *
14 * Each namespace tree maintains both an rbtree (for O(log n) lookups)
15 * and a list (for efficient sequential iteration). The list is kept in
16 * the same sorted order as the rbtree.
17 */
18struct ns_tree_root {
19	struct rb_root ns_rb;
20	struct list_head ns_list_head;
21};
22
23/**
24 * struct ns_tree_node - Node in a namespace tree
25 * @ns_node: Red-black tree node
26 * @ns_list_entry: List entry for sequential iteration
27 *
28 * Represents a namespace's position in a tree. Each namespace has
29 * multiple tree nodes for different trees (unified, per-type, owner).
30 */
31struct ns_tree_node {
32	struct rb_node ns_node;
33	struct list_head ns_list_entry;
34};
35
36/**
37 * struct ns_tree - Namespace tree nodes and active reference count
38 * @ns_id: Unique namespace identifier
39 * @__ns_ref_active: Active reference count (do not use directly)
40 * @ns_unified_node: Node in the global namespace tree
41 * @ns_tree_node: Node in the per-type namespace tree
42 * @ns_owner_node: Node in the owner namespace's tree of owned namespaces
43 * @ns_owner_root: Root of the tree of namespaces owned by this namespace
44 *                 (only used when this namespace is an owner)
45 */
46struct ns_tree {
47	u64 ns_id;
48	atomic_t __ns_ref_active;
49	struct ns_tree_node ns_unified_node;
50	struct ns_tree_node ns_tree_node;
51	struct ns_tree_node ns_owner_node;
52	struct ns_tree_root ns_owner_root;
53};
54
55#endif /* _LINUX_NSTREE_TYPES_H */