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