2 * inode.c - part of debugfs, a tiny little debug file system
4 * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
5 * Copyright (C) 2004 IBM Inc.
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License version
9 * 2 as published by the Free Software Foundation.
11 * debugfs is for people to use instead of /proc or /sys.
12 * See Documentation/DocBook/kernel-api for more details.
16 #include <linux/module.h>
18 #include <linux/mount.h>
19 #include <linux/pagemap.h>
20 #include <linux/init.h>
21 #include <linux/kobject.h>
22 #include <linux/namei.h>
23 #include <linux/debugfs.h>
24 #include <linux/fsnotify.h>
25 #include <linux/string.h>
26 #include <linux/seq_file.h>
27 #include <linux/parser.h>
28 #include <linux/magic.h>
29 #include <linux/slab.h>
31 #define DEBUGFS_DEFAULT_MODE 0700
33 static struct vfsmount
*debugfs_mount
;
34 static int debugfs_mount_count
;
35 static bool debugfs_registered
;
37 static struct inode
*debugfs_get_inode(struct super_block
*sb
, umode_t mode
, dev_t dev
,
38 void *data
, const struct file_operations
*fops
)
41 struct inode
*inode
= new_inode(sb
);
44 inode
->i_ino
= get_next_ino();
46 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
47 switch (mode
& S_IFMT
) {
49 init_special_inode(inode
, mode
, dev
);
52 inode
->i_fop
= fops
? fops
: &debugfs_file_operations
;
53 inode
->i_private
= data
;
56 inode
->i_op
= &debugfs_link_operations
;
57 inode
->i_private
= data
;
60 inode
->i_op
= &simple_dir_inode_operations
;
61 inode
->i_fop
= &simple_dir_operations
;
63 /* directory inodes start off with i_nlink == 2
73 static int debugfs_mknod(struct inode
*dir
, struct dentry
*dentry
,
74 umode_t mode
, dev_t dev
, void *data
,
75 const struct file_operations
*fops
)
83 inode
= debugfs_get_inode(dir
->i_sb
, mode
, dev
, data
, fops
);
85 d_instantiate(dentry
, inode
);
92 static int debugfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
96 mode
= (mode
& (S_IRWXUGO
| S_ISVTX
)) | S_IFDIR
;
97 res
= debugfs_mknod(dir
, dentry
, mode
, 0, NULL
, NULL
);
100 fsnotify_mkdir(dir
, dentry
);
105 static int debugfs_link(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
108 mode
= (mode
& S_IALLUGO
) | S_IFLNK
;
109 return debugfs_mknod(dir
, dentry
, mode
, 0, data
, NULL
);
112 static int debugfs_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
113 void *data
, const struct file_operations
*fops
)
117 mode
= (mode
& S_IALLUGO
) | S_IFREG
;
118 res
= debugfs_mknod(dir
, dentry
, mode
, 0, data
, fops
);
120 fsnotify_create(dir
, dentry
);
124 static inline int debugfs_positive(struct dentry
*dentry
)
126 return dentry
->d_inode
&& !d_unhashed(dentry
);
129 struct debugfs_mount_opts
{
142 static const match_table_t tokens
= {
145 {Opt_mode
, "mode=%o"},
149 struct debugfs_fs_info
{
150 struct debugfs_mount_opts mount_opts
;
153 static int debugfs_parse_options(char *data
, struct debugfs_mount_opts
*opts
)
155 substring_t args
[MAX_OPT_ARGS
];
162 opts
->mode
= DEBUGFS_DEFAULT_MODE
;
164 while ((p
= strsep(&data
, ",")) != NULL
) {
168 token
= match_token(p
, tokens
, args
);
171 if (match_int(&args
[0], &option
))
173 uid
= make_kuid(current_user_ns(), option
);
179 if (match_int(&args
[0], &option
))
181 gid
= make_kgid(current_user_ns(), option
);
187 if (match_octal(&args
[0], &option
))
189 opts
->mode
= option
& S_IALLUGO
;
192 * We might like to report bad mount options here;
193 * but traditionally debugfs has ignored all mount options
201 static int debugfs_apply_options(struct super_block
*sb
)
203 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
204 struct inode
*inode
= sb
->s_root
->d_inode
;
205 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
207 inode
->i_mode
&= ~S_IALLUGO
;
208 inode
->i_mode
|= opts
->mode
;
210 inode
->i_uid
= opts
->uid
;
211 inode
->i_gid
= opts
->gid
;
216 static int debugfs_remount(struct super_block
*sb
, int *flags
, char *data
)
219 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
221 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
225 debugfs_apply_options(sb
);
231 static int debugfs_show_options(struct seq_file
*m
, struct dentry
*root
)
233 struct debugfs_fs_info
*fsi
= root
->d_sb
->s_fs_info
;
234 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
236 if (!uid_eq(opts
->uid
, GLOBAL_ROOT_UID
))
237 seq_printf(m
, ",uid=%u",
238 from_kuid_munged(&init_user_ns
, opts
->uid
));
239 if (!gid_eq(opts
->gid
, GLOBAL_ROOT_GID
))
240 seq_printf(m
, ",gid=%u",
241 from_kgid_munged(&init_user_ns
, opts
->gid
));
242 if (opts
->mode
!= DEBUGFS_DEFAULT_MODE
)
243 seq_printf(m
, ",mode=%o", opts
->mode
);
248 static const struct super_operations debugfs_super_operations
= {
249 .statfs
= simple_statfs
,
250 .remount_fs
= debugfs_remount
,
251 .show_options
= debugfs_show_options
,
254 static int debug_fill_super(struct super_block
*sb
, void *data
, int silent
)
256 static struct tree_descr debug_files
[] = {{""}};
257 struct debugfs_fs_info
*fsi
;
260 save_mount_options(sb
, data
);
262 fsi
= kzalloc(sizeof(struct debugfs_fs_info
), GFP_KERNEL
);
269 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
273 err
= simple_fill_super(sb
, DEBUGFS_MAGIC
, debug_files
);
277 sb
->s_op
= &debugfs_super_operations
;
279 debugfs_apply_options(sb
);
285 sb
->s_fs_info
= NULL
;
289 static struct dentry
*debug_mount(struct file_system_type
*fs_type
,
290 int flags
, const char *dev_name
,
293 return mount_single(fs_type
, flags
, data
, debug_fill_super
);
296 static struct file_system_type debug_fs_type
= {
297 .owner
= THIS_MODULE
,
299 .mount
= debug_mount
,
300 .kill_sb
= kill_litter_super
,
303 static struct dentry
*__create_file(const char *name
, umode_t mode
,
304 struct dentry
*parent
, void *data
,
305 const struct file_operations
*fops
)
307 struct dentry
*dentry
= NULL
;
310 pr_debug("debugfs: creating file '%s'\n",name
);
312 error
= simple_pin_fs(&debug_fs_type
, &debugfs_mount
,
313 &debugfs_mount_count
);
317 /* If the parent is not specified, we create it in the root.
318 * We need the root dentry to do this, which is in the super
319 * block. A pointer to that is in the struct vfsmount that we
323 parent
= debugfs_mount
->mnt_root
;
325 mutex_lock(&parent
->d_inode
->i_mutex
);
326 dentry
= lookup_one_len(name
, parent
, strlen(name
));
327 if (!IS_ERR(dentry
)) {
328 switch (mode
& S_IFMT
) {
330 error
= debugfs_mkdir(parent
->d_inode
, dentry
, mode
);
334 error
= debugfs_link(parent
->d_inode
, dentry
, mode
,
338 error
= debugfs_create(parent
->d_inode
, dentry
, mode
,
344 error
= PTR_ERR(dentry
);
345 mutex_unlock(&parent
->d_inode
->i_mutex
);
349 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
356 * debugfs_create_file - create a file in the debugfs filesystem
357 * @name: a pointer to a string containing the name of the file to create.
358 * @mode: the permission that the file should have.
359 * @parent: a pointer to the parent dentry for this file. This should be a
360 * directory dentry if set. If this paramater is NULL, then the
361 * file will be created in the root of the debugfs filesystem.
362 * @data: a pointer to something that the caller will want to get to later
363 * on. The inode.i_private pointer will point to this value on
365 * @fops: a pointer to a struct file_operations that should be used for
368 * This is the basic "create a file" function for debugfs. It allows for a
369 * wide range of flexibility in creating a file, or a directory (if you want
370 * to create a directory, the debugfs_create_dir() function is
371 * recommended to be used instead.)
373 * This function will return a pointer to a dentry if it succeeds. This
374 * pointer must be passed to the debugfs_remove() function when the file is
375 * to be removed (no automatic cleanup happens if your module is unloaded,
376 * you are responsible here.) If an error occurs, %NULL will be returned.
378 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
381 struct dentry
*debugfs_create_file(const char *name
, umode_t mode
,
382 struct dentry
*parent
, void *data
,
383 const struct file_operations
*fops
)
385 switch (mode
& S_IFMT
) {
393 return __create_file(name
, mode
, parent
, data
, fops
);
395 EXPORT_SYMBOL_GPL(debugfs_create_file
);
398 * debugfs_create_dir - create a directory in the debugfs filesystem
399 * @name: a pointer to a string containing the name of the directory to
401 * @parent: a pointer to the parent dentry for this file. This should be a
402 * directory dentry if set. If this paramater is NULL, then the
403 * directory will be created in the root of the debugfs filesystem.
405 * This function creates a directory in debugfs with the given name.
407 * This function will return a pointer to a dentry if it succeeds. This
408 * pointer must be passed to the debugfs_remove() function when the file is
409 * to be removed (no automatic cleanup happens if your module is unloaded,
410 * you are responsible here.) If an error occurs, %NULL will be returned.
412 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
415 struct dentry
*debugfs_create_dir(const char *name
, struct dentry
*parent
)
417 return __create_file(name
, S_IFDIR
| S_IRWXU
| S_IRUGO
| S_IXUGO
,
420 EXPORT_SYMBOL_GPL(debugfs_create_dir
);
423 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
424 * @name: a pointer to a string containing the name of the symbolic link to
426 * @parent: a pointer to the parent dentry for this symbolic link. This
427 * should be a directory dentry if set. If this paramater is NULL,
428 * then the symbolic link will be created in the root of the debugfs
430 * @target: a pointer to a string containing the path to the target of the
433 * This function creates a symbolic link with the given name in debugfs that
434 * links to the given target path.
436 * This function will return a pointer to a dentry if it succeeds. This
437 * pointer must be passed to the debugfs_remove() function when the symbolic
438 * link is to be removed (no automatic cleanup happens if your module is
439 * unloaded, you are responsible here.) If an error occurs, %NULL will be
442 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
445 struct dentry
*debugfs_create_symlink(const char *name
, struct dentry
*parent
,
448 struct dentry
*result
;
451 link
= kstrdup(target
, GFP_KERNEL
);
455 result
= __create_file(name
, S_IFLNK
| S_IRWXUGO
, parent
, link
, NULL
);
460 EXPORT_SYMBOL_GPL(debugfs_create_symlink
);
462 static int __debugfs_remove(struct dentry
*dentry
, struct dentry
*parent
)
466 if (debugfs_positive(dentry
)) {
467 if (dentry
->d_inode
) {
469 switch (dentry
->d_inode
->i_mode
& S_IFMT
) {
471 ret
= simple_rmdir(parent
->d_inode
, dentry
);
474 kfree(dentry
->d_inode
->i_private
);
477 simple_unlink(parent
->d_inode
, dentry
);
489 * debugfs_remove - removes a file or directory from the debugfs filesystem
490 * @dentry: a pointer to a the dentry of the file or directory to be
493 * This function removes a file or directory in debugfs that was previously
494 * created with a call to another debugfs function (like
495 * debugfs_create_file() or variants thereof.)
497 * This function is required to be called in order for the file to be
498 * removed, no automatic cleanup of files will happen when a module is
499 * removed, you are responsible here.
501 void debugfs_remove(struct dentry
*dentry
)
503 struct dentry
*parent
;
506 if (IS_ERR_OR_NULL(dentry
))
509 parent
= dentry
->d_parent
;
510 if (!parent
|| !parent
->d_inode
)
513 mutex_lock(&parent
->d_inode
->i_mutex
);
514 ret
= __debugfs_remove(dentry
, parent
);
515 mutex_unlock(&parent
->d_inode
->i_mutex
);
517 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
519 EXPORT_SYMBOL_GPL(debugfs_remove
);
522 * debugfs_remove_recursive - recursively removes a directory
523 * @dentry: a pointer to a the dentry of the directory to be removed.
525 * This function recursively removes a directory tree in debugfs that
526 * was previously created with a call to another debugfs function
527 * (like debugfs_create_file() or variants thereof.)
529 * This function is required to be called in order for the file to be
530 * removed, no automatic cleanup of files will happen when a module is
531 * removed, you are responsible here.
533 void debugfs_remove_recursive(struct dentry
*dentry
)
535 struct dentry
*child
;
536 struct dentry
*parent
;
538 if (IS_ERR_OR_NULL(dentry
))
541 parent
= dentry
->d_parent
;
542 if (!parent
|| !parent
->d_inode
)
546 mutex_lock(&parent
->d_inode
->i_mutex
);
550 * When all dentries under "parent" has been removed,
551 * walk up the tree until we reach our starting point.
553 if (list_empty(&parent
->d_subdirs
)) {
554 mutex_unlock(&parent
->d_inode
->i_mutex
);
555 if (parent
== dentry
)
557 parent
= parent
->d_parent
;
558 mutex_lock(&parent
->d_inode
->i_mutex
);
560 child
= list_entry(parent
->d_subdirs
.next
, struct dentry
,
565 * If "child" isn't empty, walk down the tree and
566 * remove all its descendants first.
568 if (!list_empty(&child
->d_subdirs
)) {
569 mutex_unlock(&parent
->d_inode
->i_mutex
);
571 mutex_lock(&parent
->d_inode
->i_mutex
);
574 __debugfs_remove(child
, parent
);
575 if (parent
->d_subdirs
.next
== &child
->d_u
.d_child
) {
577 * Try the next sibling.
579 if (child
->d_u
.d_child
.next
!= &parent
->d_subdirs
) {
580 child
= list_entry(child
->d_u
.d_child
.next
,
587 * Avoid infinite loop if we fail to remove
590 mutex_unlock(&parent
->d_inode
->i_mutex
);
593 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
596 parent
= dentry
->d_parent
;
597 mutex_lock(&parent
->d_inode
->i_mutex
);
598 __debugfs_remove(dentry
, parent
);
599 mutex_unlock(&parent
->d_inode
->i_mutex
);
600 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
602 EXPORT_SYMBOL_GPL(debugfs_remove_recursive
);
605 * debugfs_rename - rename a file/directory in the debugfs filesystem
606 * @old_dir: a pointer to the parent dentry for the renamed object. This
607 * should be a directory dentry.
608 * @old_dentry: dentry of an object to be renamed.
609 * @new_dir: a pointer to the parent dentry where the object should be
610 * moved. This should be a directory dentry.
611 * @new_name: a pointer to a string containing the target name.
613 * This function renames a file/directory in debugfs. The target must not
614 * exist for rename to succeed.
616 * This function will return a pointer to old_dentry (which is updated to
617 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
620 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
623 struct dentry
*debugfs_rename(struct dentry
*old_dir
, struct dentry
*old_dentry
,
624 struct dentry
*new_dir
, const char *new_name
)
627 struct dentry
*dentry
= NULL
, *trap
;
628 const char *old_name
;
630 trap
= lock_rename(new_dir
, old_dir
);
631 /* Source or destination directories don't exist? */
632 if (!old_dir
->d_inode
|| !new_dir
->d_inode
)
634 /* Source does not exist, cyclic rename, or mountpoint? */
635 if (!old_dentry
->d_inode
|| old_dentry
== trap
||
636 d_mountpoint(old_dentry
))
638 dentry
= lookup_one_len(new_name
, new_dir
, strlen(new_name
));
639 /* Lookup failed, cyclic rename or target exists? */
640 if (IS_ERR(dentry
) || dentry
== trap
|| dentry
->d_inode
)
643 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
645 error
= simple_rename(old_dir
->d_inode
, old_dentry
, new_dir
->d_inode
,
648 fsnotify_oldname_free(old_name
);
651 d_move(old_dentry
, dentry
);
652 fsnotify_move(old_dir
->d_inode
, new_dir
->d_inode
, old_name
,
653 S_ISDIR(old_dentry
->d_inode
->i_mode
),
655 fsnotify_oldname_free(old_name
);
656 unlock_rename(new_dir
, old_dir
);
660 if (dentry
&& !IS_ERR(dentry
))
662 unlock_rename(new_dir
, old_dir
);
665 EXPORT_SYMBOL_GPL(debugfs_rename
);
668 * debugfs_initialized - Tells whether debugfs has been registered
670 bool debugfs_initialized(void)
672 return debugfs_registered
;
674 EXPORT_SYMBOL_GPL(debugfs_initialized
);
677 static struct kobject
*debug_kobj
;
679 static int __init
debugfs_init(void)
683 debug_kobj
= kobject_create_and_add("debug", kernel_kobj
);
687 retval
= register_filesystem(&debug_fs_type
);
689 kobject_put(debug_kobj
);
691 debugfs_registered
= true;
695 core_initcall(debugfs_init
);