1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * fs/kernfs/kernfs-internal.h - kernfs internal header file
4 *
5 * Copyright (c) 2001-3 Patrick Mochel
6 * Copyright (c) 2007 SUSE Linux Products GmbH
7 * Copyright (c) 2007, 2013 Tejun Heo <teheo@suse.de>
8 */
9
10#ifndef __KERNFS_INTERNAL_H
11#define __KERNFS_INTERNAL_H
12
13#include <linux/lockdep.h>
14#include <linux/fs.h>
15#include <linux/mutex.h>
16#include <linux/rwsem.h>
17#include <linux/xattr.h>
18
19#include <linux/kernfs.h>
20#include <linux/fs_context.h>
21
22struct kernfs_iattrs {
23 kuid_t ia_uid;
24 kgid_t ia_gid;
25 struct timespec64 ia_atime;
26 struct timespec64 ia_mtime;
27 struct timespec64 ia_ctime;
28
29 struct simple_xattrs xattrs;
30 atomic_t nr_user_xattrs;
31 atomic_t user_xattr_size;
32};
33
34struct kernfs_root {
35 /* published fields */
36 struct kernfs_node *kn;
37 unsigned int flags; /* KERNFS_ROOT_* flags */
38
39 /* private fields, do not use outside kernfs proper */
40 struct idr ino_idr;
41 spinlock_t kernfs_idr_lock; /* root->ino_idr */
42 u32 last_id_lowbits;
43 u32 id_highbits;
44 struct kernfs_syscall_ops *syscall_ops;
45
46 /* list of kernfs_super_info of this root, protected by kernfs_rwsem */
47 struct list_head supers;
48
49 wait_queue_head_t deactivate_waitq;
50 struct rw_semaphore kernfs_rwsem;
51 struct rw_semaphore kernfs_iattr_rwsem;
52 struct rw_semaphore kernfs_supers_rwsem;
53
54 /* kn->parent and kn->name */
55 rwlock_t kernfs_rename_lock;
56
57 struct rcu_head rcu;
58};
59
60/* +1 to avoid triggering overflow warning when negating it */
61#define KN_DEACTIVATED_BIAS (INT_MIN + 1)
62
63/* KERNFS_TYPE_MASK and types are defined in include/linux/kernfs.h */
64
65/**
66 * kernfs_root - find out the kernfs_root a kernfs_node belongs to
67 * @kn: kernfs_node of interest
68 *
69 * Return: the kernfs_root @kn belongs to.
70 */
71static inline struct kernfs_root *kernfs_root(const struct kernfs_node *kn)
72{
73 const struct kernfs_node *knp;
74 /* if parent exists, it's always a dir; otherwise, @sd is a dir */
75 guard(rcu)();
76 knp = rcu_dereference(kn->__parent);
77 if (knp)
78 kn = knp;
79 return kn->dir.root;
80}
81
82/*
83 * mount.c
84 */
85struct kernfs_super_info {
86 struct super_block *sb;
87
88 /*
89 * The root associated with this super_block. Each super_block is
90 * identified by the root and ns it's associated with.
91 */
92 struct kernfs_root *root;
93
94 /*
95 * Each sb is associated with one namespace tag, currently the
96 * network namespace of the task which mounted this kernfs
97 * instance. If multiple tags become necessary, make the following
98 * an array and compare kernfs_node tag against every entry.
99 */
100 const void *ns;
101
102 /* anchored at kernfs_root->supers, protected by kernfs_rwsem */
103 struct list_head node;
104};
105#define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info))
106
107static inline bool kernfs_root_is_locked(const struct kernfs_node *kn)
108{
109 return lockdep_is_held(&kernfs_root(kn)->kernfs_rwsem);
110}
111
112static inline bool kernfs_rename_is_locked(const struct kernfs_node *kn)
113{
114 return lockdep_is_held(&kernfs_root(kn)->kernfs_rename_lock);
115}
116
117static inline const char *kernfs_rcu_name(const struct kernfs_node *kn)
118{
119 return rcu_dereference_check(kn->name, kernfs_root_is_locked(kn));
120}
121
122static inline struct kernfs_node *kernfs_parent(const struct kernfs_node *kn)
123{
124 /*
125 * The kernfs_node::__parent remains valid within a RCU section. The kn
126 * can be reparented (and renamed) which changes the entry. This can be
127 * avoided by locking kernfs_root::kernfs_rwsem or
128 * kernfs_root::kernfs_rename_lock.
129 * Both locks can be used to obtain a reference on __parent. Once the
130 * reference count reaches 0 then the node is about to be freed
131 * and can not be renamed (or become a different parent) anymore.
132 */
133 return rcu_dereference_check(kn->__parent,
134 kernfs_root_is_locked(kn) ||
135 kernfs_rename_is_locked(kn) ||
136 !atomic_read(&kn->count));
137}
138
139static inline struct kernfs_node *kernfs_dentry_node(struct dentry *dentry)
140{
141 if (d_really_is_negative(dentry))
142 return NULL;
143 return d_inode(dentry)->i_private;
144}
145
146static inline void kernfs_set_rev(struct kernfs_node *parent,
147 struct dentry *dentry)
148{
149 dentry->d_time = parent->dir.rev;
150}
151
152static inline void kernfs_inc_rev(struct kernfs_node *parent)
153{
154 parent->dir.rev++;
155}
156
157static inline bool kernfs_dir_changed(struct kernfs_node *parent,
158 struct dentry *dentry)
159{
160 if (parent->dir.rev != dentry->d_time)
161 return true;
162 return false;
163}
164
165extern const struct super_operations kernfs_sops;
166extern struct kmem_cache *kernfs_node_cache, *kernfs_iattrs_cache;
167
168/*
169 * inode.c
170 */
171extern const struct xattr_handler * const kernfs_xattr_handlers[];
172void kernfs_evict_inode(struct inode *inode);
173int kernfs_iop_permission(struct mnt_idmap *idmap,
174 struct inode *inode, int mask);
175int kernfs_iop_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
176 struct iattr *iattr);
177int kernfs_iop_getattr(struct mnt_idmap *idmap,
178 const struct path *path, struct kstat *stat,
179 u32 request_mask, unsigned int query_flags);
180ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size);
181int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
182
183/*
184 * dir.c
185 */
186extern const struct dentry_operations kernfs_dops;
187extern const struct file_operations kernfs_dir_fops;
188extern const struct inode_operations kernfs_dir_iops;
189
190struct kernfs_node *kernfs_get_active(struct kernfs_node *kn);
191void kernfs_put_active(struct kernfs_node *kn);
192int kernfs_add_one(struct kernfs_node *kn);
193struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
194 const char *name, umode_t mode,
195 kuid_t uid, kgid_t gid,
196 unsigned flags);
197
198/*
199 * file.c
200 */
201extern const struct file_operations kernfs_file_fops;
202
203bool kernfs_should_drain_open_files(struct kernfs_node *kn);
204void kernfs_drain_open_files(struct kernfs_node *kn);
205
206/*
207 * symlink.c
208 */
209extern const struct inode_operations kernfs_symlink_iops;
210
211/*
212 * kernfs locks
213 */
214extern struct kernfs_global_locks *kernfs_locks;
215#endif /* __KERNFS_INTERNAL_H */
216