kernfs-internal.h

  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 */