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