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
)
39 struct inode
*inode
= new_inode(sb
);
41 inode
->i_ino
= get_next_ino();
42 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
47 static inline int debugfs_positive(struct dentry
*dentry
)
49 return d_really_is_positive(dentry
) && !d_unhashed(dentry
);
52 struct debugfs_mount_opts
{
65 static const match_table_t tokens
= {
68 {Opt_mode
, "mode=%o"},
72 struct debugfs_fs_info
{
73 struct debugfs_mount_opts mount_opts
;
76 static int debugfs_parse_options(char *data
, struct debugfs_mount_opts
*opts
)
78 substring_t args
[MAX_OPT_ARGS
];
85 opts
->mode
= DEBUGFS_DEFAULT_MODE
;
87 while ((p
= strsep(&data
, ",")) != NULL
) {
91 token
= match_token(p
, tokens
, args
);
94 if (match_int(&args
[0], &option
))
96 uid
= make_kuid(current_user_ns(), option
);
102 if (match_int(&args
[0], &option
))
104 gid
= make_kgid(current_user_ns(), option
);
110 if (match_octal(&args
[0], &option
))
112 opts
->mode
= option
& S_IALLUGO
;
115 * We might like to report bad mount options here;
116 * but traditionally debugfs has ignored all mount options
124 static int debugfs_apply_options(struct super_block
*sb
)
126 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
127 struct inode
*inode
= d_inode(sb
->s_root
);
128 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
130 inode
->i_mode
&= ~S_IALLUGO
;
131 inode
->i_mode
|= opts
->mode
;
133 inode
->i_uid
= opts
->uid
;
134 inode
->i_gid
= opts
->gid
;
139 static int debugfs_remount(struct super_block
*sb
, int *flags
, char *data
)
142 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
145 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
149 debugfs_apply_options(sb
);
155 static int debugfs_show_options(struct seq_file
*m
, struct dentry
*root
)
157 struct debugfs_fs_info
*fsi
= root
->d_sb
->s_fs_info
;
158 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
160 if (!uid_eq(opts
->uid
, GLOBAL_ROOT_UID
))
161 seq_printf(m
, ",uid=%u",
162 from_kuid_munged(&init_user_ns
, opts
->uid
));
163 if (!gid_eq(opts
->gid
, GLOBAL_ROOT_GID
))
164 seq_printf(m
, ",gid=%u",
165 from_kgid_munged(&init_user_ns
, opts
->gid
));
166 if (opts
->mode
!= DEBUGFS_DEFAULT_MODE
)
167 seq_printf(m
, ",mode=%o", opts
->mode
);
172 static void debugfs_evict_inode(struct inode
*inode
)
174 truncate_inode_pages_final(&inode
->i_data
);
176 if (S_ISLNK(inode
->i_mode
))
177 kfree(inode
->i_private
);
180 static const struct super_operations debugfs_super_operations
= {
181 .statfs
= simple_statfs
,
182 .remount_fs
= debugfs_remount
,
183 .show_options
= debugfs_show_options
,
184 .evict_inode
= debugfs_evict_inode
,
187 static struct vfsmount
*debugfs_automount(struct path
*path
)
189 struct vfsmount
*(*f
)(void *);
190 f
= (struct vfsmount
*(*)(void *))path
->dentry
->d_fsdata
;
191 return f(d_inode(path
->dentry
)->i_private
);
194 static const struct dentry_operations debugfs_dops
= {
195 .d_delete
= always_delete_dentry
,
196 .d_automount
= debugfs_automount
,
199 static int debug_fill_super(struct super_block
*sb
, void *data
, int silent
)
201 static struct tree_descr debug_files
[] = {{""}};
202 struct debugfs_fs_info
*fsi
;
205 save_mount_options(sb
, data
);
207 fsi
= kzalloc(sizeof(struct debugfs_fs_info
), GFP_KERNEL
);
214 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
218 err
= simple_fill_super(sb
, DEBUGFS_MAGIC
, debug_files
);
222 sb
->s_op
= &debugfs_super_operations
;
223 sb
->s_d_op
= &debugfs_dops
;
225 debugfs_apply_options(sb
);
231 sb
->s_fs_info
= NULL
;
235 static struct dentry
*debug_mount(struct file_system_type
*fs_type
,
236 int flags
, const char *dev_name
,
239 return mount_single(fs_type
, flags
, data
, debug_fill_super
);
242 static struct file_system_type debug_fs_type
= {
243 .owner
= THIS_MODULE
,
245 .mount
= debug_mount
,
246 .kill_sb
= kill_litter_super
,
248 MODULE_ALIAS_FS("debugfs");
250 static struct dentry
*start_creating(const char *name
, struct dentry
*parent
)
252 struct dentry
*dentry
;
255 pr_debug("debugfs: creating file '%s'\n",name
);
260 error
= simple_pin_fs(&debug_fs_type
, &debugfs_mount
,
261 &debugfs_mount_count
);
263 return ERR_PTR(error
);
265 /* If the parent is not specified, we create it in the root.
266 * We need the root dentry to do this, which is in the super
267 * block. A pointer to that is in the struct vfsmount that we
271 parent
= debugfs_mount
->mnt_root
;
273 mutex_lock(&d_inode(parent
)->i_mutex
);
274 dentry
= lookup_one_len(name
, parent
, strlen(name
));
275 if (!IS_ERR(dentry
) && d_really_is_positive(dentry
)) {
277 dentry
= ERR_PTR(-EEXIST
);
280 mutex_unlock(&d_inode(parent
)->i_mutex
);
284 static struct dentry
*failed_creating(struct dentry
*dentry
)
286 mutex_unlock(&d_inode(dentry
->d_parent
)->i_mutex
);
288 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
292 static struct dentry
*end_creating(struct dentry
*dentry
)
294 mutex_unlock(&d_inode(dentry
->d_parent
)->i_mutex
);
299 * debugfs_create_file - create a file in the debugfs filesystem
300 * @name: a pointer to a string containing the name of the file to create.
301 * @mode: the permission that the file should have.
302 * @parent: a pointer to the parent dentry for this file. This should be a
303 * directory dentry if set. If this parameter is NULL, then the
304 * file will be created in the root of the debugfs filesystem.
305 * @data: a pointer to something that the caller will want to get to later
306 * on. The inode.i_private pointer will point to this value on
308 * @fops: a pointer to a struct file_operations that should be used for
311 * This is the basic "create a file" function for debugfs. It allows for a
312 * wide range of flexibility in creating a file, or a directory (if you want
313 * to create a directory, the debugfs_create_dir() function is
314 * recommended to be used instead.)
316 * This function will return a pointer to a dentry if it succeeds. This
317 * pointer must be passed to the debugfs_remove() function when the file is
318 * to be removed (no automatic cleanup happens if your module is unloaded,
319 * you are responsible here.) If an error occurs, %NULL will be returned.
321 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
324 struct dentry
*debugfs_create_file(const char *name
, umode_t mode
,
325 struct dentry
*parent
, void *data
,
326 const struct file_operations
*fops
)
328 struct dentry
*dentry
;
331 if (!(mode
& S_IFMT
))
333 BUG_ON(!S_ISREG(mode
));
334 dentry
= start_creating(name
, parent
);
339 inode
= debugfs_get_inode(dentry
->d_sb
);
340 if (unlikely(!inode
))
341 return failed_creating(dentry
);
343 inode
->i_mode
= mode
;
344 inode
->i_fop
= fops
? fops
: &debugfs_file_operations
;
345 inode
->i_private
= data
;
346 d_instantiate(dentry
, inode
);
347 fsnotify_create(d_inode(dentry
->d_parent
), dentry
);
348 return end_creating(dentry
);
350 EXPORT_SYMBOL_GPL(debugfs_create_file
);
353 * debugfs_create_file_size - create a file in the debugfs filesystem
354 * @name: a pointer to a string containing the name of the file to create.
355 * @mode: the permission that the file should have.
356 * @parent: a pointer to the parent dentry for this file. This should be a
357 * directory dentry if set. If this parameter is NULL, then the
358 * file will be created in the root of the debugfs filesystem.
359 * @data: a pointer to something that the caller will want to get to later
360 * on. The inode.i_private pointer will point to this value on
362 * @fops: a pointer to a struct file_operations that should be used for
364 * @file_size: initial file size
366 * This is the basic "create a file" function for debugfs. It allows for a
367 * wide range of flexibility in creating a file, or a directory (if you want
368 * to create a directory, the debugfs_create_dir() function is
369 * recommended to be used instead.)
371 * This function will return a pointer to a dentry if it succeeds. This
372 * pointer must be passed to the debugfs_remove() function when the file is
373 * to be removed (no automatic cleanup happens if your module is unloaded,
374 * you are responsible here.) If an error occurs, %NULL will be returned.
376 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
379 struct dentry
*debugfs_create_file_size(const char *name
, umode_t mode
,
380 struct dentry
*parent
, void *data
,
381 const struct file_operations
*fops
,
384 struct dentry
*de
= debugfs_create_file(name
, mode
, parent
, data
, fops
);
387 d_inode(de
)->i_size
= file_size
;
390 EXPORT_SYMBOL_GPL(debugfs_create_file_size
);
393 * debugfs_create_dir - create a directory in the debugfs filesystem
394 * @name: a pointer to a string containing the name of the directory to
396 * @parent: a pointer to the parent dentry for this file. This should be a
397 * directory dentry if set. If this parameter is NULL, then the
398 * directory will be created in the root of the debugfs filesystem.
400 * This function creates a directory in debugfs with the given name.
402 * This function will return a pointer to a dentry if it succeeds. This
403 * pointer must be passed to the debugfs_remove() function when the file is
404 * to be removed (no automatic cleanup happens if your module is unloaded,
405 * you are responsible here.) If an error occurs, %NULL will be returned.
407 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
410 struct dentry
*debugfs_create_dir(const char *name
, struct dentry
*parent
)
412 struct dentry
*dentry
= start_creating(name
, parent
);
418 inode
= debugfs_get_inode(dentry
->d_sb
);
419 if (unlikely(!inode
))
420 return failed_creating(dentry
);
422 inode
->i_mode
= S_IFDIR
| S_IRWXU
| S_IRUGO
| S_IXUGO
;
423 inode
->i_op
= &simple_dir_inode_operations
;
424 inode
->i_fop
= &simple_dir_operations
;
426 /* directory inodes start off with i_nlink == 2 (for "." entry) */
428 d_instantiate(dentry
, inode
);
429 inc_nlink(d_inode(dentry
->d_parent
));
430 fsnotify_mkdir(d_inode(dentry
->d_parent
), dentry
);
431 return end_creating(dentry
);
433 EXPORT_SYMBOL_GPL(debugfs_create_dir
);
436 * debugfs_create_automount - create automount point in the debugfs filesystem
437 * @name: a pointer to a string containing the name of the file to create.
438 * @parent: a pointer to the parent dentry for this file. This should be a
439 * directory dentry if set. If this parameter is NULL, then the
440 * file will be created in the root of the debugfs filesystem.
441 * @f: function to be called when pathname resolution steps on that one.
442 * @data: opaque argument to pass to f().
444 * @f should return what ->d_automount() would.
446 struct dentry
*debugfs_create_automount(const char *name
,
447 struct dentry
*parent
,
448 struct vfsmount
*(*f
)(void *),
451 struct dentry
*dentry
= start_creating(name
, parent
);
457 inode
= debugfs_get_inode(dentry
->d_sb
);
458 if (unlikely(!inode
))
459 return failed_creating(dentry
);
461 inode
->i_mode
= S_IFDIR
| S_IRWXU
| S_IRUGO
| S_IXUGO
;
462 inode
->i_flags
|= S_AUTOMOUNT
;
463 inode
->i_private
= data
;
464 dentry
->d_fsdata
= (void *)f
;
465 d_instantiate(dentry
, inode
);
466 return end_creating(dentry
);
468 EXPORT_SYMBOL(debugfs_create_automount
);
471 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
472 * @name: a pointer to a string containing the name of the symbolic link to
474 * @parent: a pointer to the parent dentry for this symbolic link. This
475 * should be a directory dentry if set. If this parameter is NULL,
476 * then the symbolic link will be created in the root of the debugfs
478 * @target: a pointer to a string containing the path to the target of the
481 * This function creates a symbolic link with the given name in debugfs that
482 * links to the given target path.
484 * This function will return a pointer to a dentry if it succeeds. This
485 * pointer must be passed to the debugfs_remove() function when the symbolic
486 * link is to be removed (no automatic cleanup happens if your module is
487 * unloaded, you are responsible here.) If an error occurs, %NULL will be
490 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
493 struct dentry
*debugfs_create_symlink(const char *name
, struct dentry
*parent
,
496 struct dentry
*dentry
;
498 char *link
= kstrdup(target
, GFP_KERNEL
);
502 dentry
= start_creating(name
, parent
);
503 if (IS_ERR(dentry
)) {
508 inode
= debugfs_get_inode(dentry
->d_sb
);
509 if (unlikely(!inode
)) {
511 return failed_creating(dentry
);
513 inode
->i_mode
= S_IFLNK
| S_IRWXUGO
;
514 inode
->i_op
= &debugfs_link_operations
;
515 inode
->i_private
= link
;
516 d_instantiate(dentry
, inode
);
517 return end_creating(dentry
);
519 EXPORT_SYMBOL_GPL(debugfs_create_symlink
);
521 static int __debugfs_remove(struct dentry
*dentry
, struct dentry
*parent
)
525 if (debugfs_positive(dentry
)) {
527 if (d_is_dir(dentry
))
528 ret
= simple_rmdir(d_inode(parent
), dentry
);
530 simple_unlink(d_inode(parent
), dentry
);
539 * debugfs_remove - removes a file or directory from the debugfs filesystem
540 * @dentry: a pointer to a the dentry of the file or directory to be
543 * This function removes a file or directory in debugfs that was previously
544 * created with a call to another debugfs function (like
545 * debugfs_create_file() or variants thereof.)
547 * This function is required to be called in order for the file to be
548 * removed, no automatic cleanup of files will happen when a module is
549 * removed, you are responsible here.
551 void debugfs_remove(struct dentry
*dentry
)
553 struct dentry
*parent
;
556 if (IS_ERR_OR_NULL(dentry
))
559 parent
= dentry
->d_parent
;
560 if (!parent
|| d_really_is_negative(parent
))
563 mutex_lock(&d_inode(parent
)->i_mutex
);
564 ret
= __debugfs_remove(dentry
, parent
);
565 mutex_unlock(&d_inode(parent
)->i_mutex
);
567 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
569 EXPORT_SYMBOL_GPL(debugfs_remove
);
572 * debugfs_remove_recursive - recursively removes a directory
573 * @dentry: a pointer to a the dentry of the directory to be removed.
575 * This function recursively removes a directory tree in debugfs that
576 * was previously created with a call to another debugfs function
577 * (like debugfs_create_file() or variants thereof.)
579 * This function is required to be called in order for the file to be
580 * removed, no automatic cleanup of files will happen when a module is
581 * removed, you are responsible here.
583 void debugfs_remove_recursive(struct dentry
*dentry
)
585 struct dentry
*child
, *parent
;
587 if (IS_ERR_OR_NULL(dentry
))
590 parent
= dentry
->d_parent
;
591 if (!parent
|| d_really_is_negative(parent
))
596 mutex_lock(&d_inode(parent
)->i_mutex
);
599 * The parent->d_subdirs is protected by the d_lock. Outside that
600 * lock, the child can be unlinked and set to be freed which can
601 * use the d_u.d_child as the rcu head and corrupt this list.
603 spin_lock(&parent
->d_lock
);
604 list_for_each_entry(child
, &parent
->d_subdirs
, d_child
) {
605 if (!debugfs_positive(child
))
608 /* perhaps simple_empty(child) makes more sense */
609 if (!list_empty(&child
->d_subdirs
)) {
610 spin_unlock(&parent
->d_lock
);
611 mutex_unlock(&d_inode(parent
)->i_mutex
);
616 spin_unlock(&parent
->d_lock
);
618 if (!__debugfs_remove(child
, parent
))
619 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
622 * The parent->d_lock protects agaist child from unlinking
623 * from d_subdirs. When releasing the parent->d_lock we can
624 * no longer trust that the next pointer is valid.
625 * Restart the loop. We'll skip this one with the
626 * debugfs_positive() check.
630 spin_unlock(&parent
->d_lock
);
632 mutex_unlock(&d_inode(parent
)->i_mutex
);
634 parent
= parent
->d_parent
;
635 mutex_lock(&d_inode(parent
)->i_mutex
);
641 if (!__debugfs_remove(child
, parent
))
642 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
643 mutex_unlock(&d_inode(parent
)->i_mutex
);
645 EXPORT_SYMBOL_GPL(debugfs_remove_recursive
);
648 * debugfs_rename - rename a file/directory in the debugfs filesystem
649 * @old_dir: a pointer to the parent dentry for the renamed object. This
650 * should be a directory dentry.
651 * @old_dentry: dentry of an object to be renamed.
652 * @new_dir: a pointer to the parent dentry where the object should be
653 * moved. This should be a directory dentry.
654 * @new_name: a pointer to a string containing the target name.
656 * This function renames a file/directory in debugfs. The target must not
657 * exist for rename to succeed.
659 * This function will return a pointer to old_dentry (which is updated to
660 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
663 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
666 struct dentry
*debugfs_rename(struct dentry
*old_dir
, struct dentry
*old_dentry
,
667 struct dentry
*new_dir
, const char *new_name
)
670 struct dentry
*dentry
= NULL
, *trap
;
671 const char *old_name
;
673 trap
= lock_rename(new_dir
, old_dir
);
674 /* Source or destination directories don't exist? */
675 if (d_really_is_negative(old_dir
) || d_really_is_negative(new_dir
))
677 /* Source does not exist, cyclic rename, or mountpoint? */
678 if (d_really_is_negative(old_dentry
) || old_dentry
== trap
||
679 d_mountpoint(old_dentry
))
681 dentry
= lookup_one_len(new_name
, new_dir
, strlen(new_name
));
682 /* Lookup failed, cyclic rename or target exists? */
683 if (IS_ERR(dentry
) || dentry
== trap
|| d_really_is_positive(dentry
))
686 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
688 error
= simple_rename(d_inode(old_dir
), old_dentry
, d_inode(new_dir
),
691 fsnotify_oldname_free(old_name
);
694 d_move(old_dentry
, dentry
);
695 fsnotify_move(d_inode(old_dir
), d_inode(new_dir
), old_name
,
696 d_is_dir(old_dentry
),
698 fsnotify_oldname_free(old_name
);
699 unlock_rename(new_dir
, old_dir
);
703 if (dentry
&& !IS_ERR(dentry
))
705 unlock_rename(new_dir
, old_dir
);
708 EXPORT_SYMBOL_GPL(debugfs_rename
);
711 * debugfs_initialized - Tells whether debugfs has been registered
713 bool debugfs_initialized(void)
715 return debugfs_registered
;
717 EXPORT_SYMBOL_GPL(debugfs_initialized
);
720 static struct kobject
*debug_kobj
;
722 static int __init
debugfs_init(void)
726 debug_kobj
= kobject_create_and_add("debug", kernel_kobj
);
730 retval
= register_filesystem(&debug_fs_type
);
732 kobject_put(debug_kobj
);
734 debugfs_registered
= true;
738 core_initcall(debugfs_init
);