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>
30 #include <linux/srcu.h>
34 #define DEBUGFS_DEFAULT_MODE 0700
36 DEFINE_SRCU(debugfs_srcu
);
38 static struct vfsmount
*debugfs_mount
;
39 static int debugfs_mount_count
;
40 static bool debugfs_registered
;
42 static struct inode
*debugfs_get_inode(struct super_block
*sb
)
44 struct inode
*inode
= new_inode(sb
);
46 inode
->i_ino
= get_next_ino();
47 inode
->i_atime
= inode
->i_mtime
=
48 inode
->i_ctime
= current_time(inode
);
53 struct debugfs_mount_opts
{
66 static const match_table_t tokens
= {
69 {Opt_mode
, "mode=%o"},
73 struct debugfs_fs_info
{
74 struct debugfs_mount_opts mount_opts
;
77 static int debugfs_parse_options(char *data
, struct debugfs_mount_opts
*opts
)
79 substring_t args
[MAX_OPT_ARGS
];
86 opts
->mode
= DEBUGFS_DEFAULT_MODE
;
88 while ((p
= strsep(&data
, ",")) != NULL
) {
92 token
= match_token(p
, tokens
, args
);
95 if (match_int(&args
[0], &option
))
97 uid
= make_kuid(current_user_ns(), option
);
103 if (match_int(&args
[0], &option
))
105 gid
= make_kgid(current_user_ns(), option
);
111 if (match_octal(&args
[0], &option
))
113 opts
->mode
= option
& S_IALLUGO
;
116 * We might like to report bad mount options here;
117 * but traditionally debugfs has ignored all mount options
125 static int debugfs_apply_options(struct super_block
*sb
)
127 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
128 struct inode
*inode
= d_inode(sb
->s_root
);
129 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
131 inode
->i_mode
&= ~S_IALLUGO
;
132 inode
->i_mode
|= opts
->mode
;
134 inode
->i_uid
= opts
->uid
;
135 inode
->i_gid
= opts
->gid
;
140 static int debugfs_remount(struct super_block
*sb
, int *flags
, char *data
)
143 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
146 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
150 debugfs_apply_options(sb
);
156 static int debugfs_show_options(struct seq_file
*m
, struct dentry
*root
)
158 struct debugfs_fs_info
*fsi
= root
->d_sb
->s_fs_info
;
159 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
161 if (!uid_eq(opts
->uid
, GLOBAL_ROOT_UID
))
162 seq_printf(m
, ",uid=%u",
163 from_kuid_munged(&init_user_ns
, opts
->uid
));
164 if (!gid_eq(opts
->gid
, GLOBAL_ROOT_GID
))
165 seq_printf(m
, ",gid=%u",
166 from_kgid_munged(&init_user_ns
, opts
->gid
));
167 if (opts
->mode
!= DEBUGFS_DEFAULT_MODE
)
168 seq_printf(m
, ",mode=%o", opts
->mode
);
173 static void debugfs_evict_inode(struct inode
*inode
)
175 truncate_inode_pages_final(&inode
->i_data
);
177 if (S_ISLNK(inode
->i_mode
))
178 kfree(inode
->i_link
);
181 static const struct super_operations debugfs_super_operations
= {
182 .statfs
= simple_statfs
,
183 .remount_fs
= debugfs_remount
,
184 .show_options
= debugfs_show_options
,
185 .evict_inode
= debugfs_evict_inode
,
188 static struct vfsmount
*debugfs_automount(struct path
*path
)
190 debugfs_automount_t f
;
191 f
= (debugfs_automount_t
)path
->dentry
->d_fsdata
;
192 return f(path
->dentry
, d_inode(path
->dentry
)->i_private
);
195 static const struct dentry_operations debugfs_dops
= {
196 .d_delete
= always_delete_dentry
,
197 .d_automount
= debugfs_automount
,
200 static int debug_fill_super(struct super_block
*sb
, void *data
, int silent
)
202 static struct tree_descr debug_files
[] = {{""}};
203 struct debugfs_fs_info
*fsi
;
206 save_mount_options(sb
, data
);
208 fsi
= kzalloc(sizeof(struct debugfs_fs_info
), GFP_KERNEL
);
215 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
219 err
= simple_fill_super(sb
, DEBUGFS_MAGIC
, debug_files
);
223 sb
->s_op
= &debugfs_super_operations
;
224 sb
->s_d_op
= &debugfs_dops
;
226 debugfs_apply_options(sb
);
232 sb
->s_fs_info
= NULL
;
236 static struct dentry
*debug_mount(struct file_system_type
*fs_type
,
237 int flags
, const char *dev_name
,
240 return mount_single(fs_type
, flags
, data
, debug_fill_super
);
243 static struct file_system_type debug_fs_type
= {
244 .owner
= THIS_MODULE
,
246 .mount
= debug_mount
,
247 .kill_sb
= kill_litter_super
,
249 MODULE_ALIAS_FS("debugfs");
252 * debugfs_lookup() - look up an existing debugfs file
253 * @name: a pointer to a string containing the name of the file to look up.
254 * @parent: a pointer to the parent dentry of the file.
256 * This function will return a pointer to a dentry if it succeeds. If the file
257 * doesn't exist or an error occurs, %NULL will be returned. The returned
258 * dentry must be passed to dput() when it is no longer needed.
260 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
263 struct dentry
*debugfs_lookup(const char *name
, struct dentry
*parent
)
265 struct dentry
*dentry
;
271 parent
= debugfs_mount
->mnt_root
;
273 inode_lock(d_inode(parent
));
274 dentry
= lookup_one_len(name
, parent
, strlen(name
));
275 inode_unlock(d_inode(parent
));
279 if (!d_really_is_positive(dentry
)) {
285 EXPORT_SYMBOL_GPL(debugfs_lookup
);
287 static struct dentry
*start_creating(const char *name
, struct dentry
*parent
)
289 struct dentry
*dentry
;
292 pr_debug("debugfs: creating file '%s'\n",name
);
297 error
= simple_pin_fs(&debug_fs_type
, &debugfs_mount
,
298 &debugfs_mount_count
);
300 return ERR_PTR(error
);
302 /* If the parent is not specified, we create it in the root.
303 * We need the root dentry to do this, which is in the super
304 * block. A pointer to that is in the struct vfsmount that we
308 parent
= debugfs_mount
->mnt_root
;
310 inode_lock(d_inode(parent
));
311 dentry
= lookup_one_len(name
, parent
, strlen(name
));
312 if (!IS_ERR(dentry
) && d_really_is_positive(dentry
)) {
314 dentry
= ERR_PTR(-EEXIST
);
317 if (IS_ERR(dentry
)) {
318 inode_unlock(d_inode(parent
));
319 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
325 static struct dentry
*failed_creating(struct dentry
*dentry
)
327 inode_unlock(d_inode(dentry
->d_parent
));
329 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
333 static struct dentry
*end_creating(struct dentry
*dentry
)
335 inode_unlock(d_inode(dentry
->d_parent
));
339 static struct dentry
*__debugfs_create_file(const char *name
, umode_t mode
,
340 struct dentry
*parent
, void *data
,
341 const struct file_operations
*proxy_fops
,
342 const struct file_operations
*real_fops
)
344 struct dentry
*dentry
;
347 if (!(mode
& S_IFMT
))
349 BUG_ON(!S_ISREG(mode
));
350 dentry
= start_creating(name
, parent
);
355 inode
= debugfs_get_inode(dentry
->d_sb
);
356 if (unlikely(!inode
))
357 return failed_creating(dentry
);
359 inode
->i_mode
= mode
;
360 inode
->i_private
= data
;
362 inode
->i_fop
= proxy_fops
;
363 dentry
->d_fsdata
= (void *)real_fops
;
365 d_instantiate(dentry
, inode
);
366 fsnotify_create(d_inode(dentry
->d_parent
), dentry
);
367 return end_creating(dentry
);
371 * debugfs_create_file - create a file in the debugfs filesystem
372 * @name: a pointer to a string containing the name of the file to create.
373 * @mode: the permission that the file should have.
374 * @parent: a pointer to the parent dentry for this file. This should be a
375 * directory dentry if set. If this parameter is NULL, then the
376 * file will be created in the root of the debugfs filesystem.
377 * @data: a pointer to something that the caller will want to get to later
378 * on. The inode.i_private pointer will point to this value on
380 * @fops: a pointer to a struct file_operations that should be used for
383 * This is the basic "create a file" function for debugfs. It allows for a
384 * wide range of flexibility in creating a file, or a directory (if you want
385 * to create a directory, the debugfs_create_dir() function is
386 * recommended to be used instead.)
388 * This function will return a pointer to a dentry if it succeeds. This
389 * pointer must be passed to the debugfs_remove() function when the file is
390 * to be removed (no automatic cleanup happens if your module is unloaded,
391 * you are responsible here.) If an error occurs, %NULL will be returned.
393 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
396 struct dentry
*debugfs_create_file(const char *name
, umode_t mode
,
397 struct dentry
*parent
, void *data
,
398 const struct file_operations
*fops
)
401 return __debugfs_create_file(name
, mode
, parent
, data
,
402 fops
? &debugfs_full_proxy_file_operations
:
403 &debugfs_noop_file_operations
,
406 EXPORT_SYMBOL_GPL(debugfs_create_file
);
409 * debugfs_create_file_unsafe - create a file in the debugfs filesystem
410 * @name: a pointer to a string containing the name of the file to create.
411 * @mode: the permission that the file should have.
412 * @parent: a pointer to the parent dentry for this file. This should be a
413 * directory dentry if set. If this parameter is NULL, then the
414 * file will be created in the root of the debugfs filesystem.
415 * @data: a pointer to something that the caller will want to get to later
416 * on. The inode.i_private pointer will point to this value on
418 * @fops: a pointer to a struct file_operations that should be used for
421 * debugfs_create_file_unsafe() is completely analogous to
422 * debugfs_create_file(), the only difference being that the fops
423 * handed it will not get protected against file removals by the
426 * It is your responsibility to protect your struct file_operation
427 * methods against file removals by means of debugfs_use_file_start()
428 * and debugfs_use_file_finish(). ->open() is still protected by
431 * Any struct file_operations defined by means of
432 * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
433 * thus, may be used here.
435 struct dentry
*debugfs_create_file_unsafe(const char *name
, umode_t mode
,
436 struct dentry
*parent
, void *data
,
437 const struct file_operations
*fops
)
440 return __debugfs_create_file(name
, mode
, parent
, data
,
441 fops
? &debugfs_open_proxy_file_operations
:
442 &debugfs_noop_file_operations
,
445 EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe
);
448 * debugfs_create_file_size - create a file in the debugfs filesystem
449 * @name: a pointer to a string containing the name of the file to create.
450 * @mode: the permission that the file should have.
451 * @parent: a pointer to the parent dentry for this file. This should be a
452 * directory dentry if set. If this parameter is NULL, then the
453 * file will be created in the root of the debugfs filesystem.
454 * @data: a pointer to something that the caller will want to get to later
455 * on. The inode.i_private pointer will point to this value on
457 * @fops: a pointer to a struct file_operations that should be used for
459 * @file_size: initial file size
461 * This is the basic "create a file" function for debugfs. It allows for a
462 * wide range of flexibility in creating a file, or a directory (if you want
463 * to create a directory, the debugfs_create_dir() function is
464 * recommended to be used instead.)
466 * This function will return a pointer to a dentry if it succeeds. This
467 * pointer must be passed to the debugfs_remove() function when the file is
468 * to be removed (no automatic cleanup happens if your module is unloaded,
469 * you are responsible here.) If an error occurs, %NULL will be returned.
471 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
474 struct dentry
*debugfs_create_file_size(const char *name
, umode_t mode
,
475 struct dentry
*parent
, void *data
,
476 const struct file_operations
*fops
,
479 struct dentry
*de
= debugfs_create_file(name
, mode
, parent
, data
, fops
);
482 d_inode(de
)->i_size
= file_size
;
485 EXPORT_SYMBOL_GPL(debugfs_create_file_size
);
488 * debugfs_create_dir - create a directory in the debugfs filesystem
489 * @name: a pointer to a string containing the name of the directory to
491 * @parent: a pointer to the parent dentry for this file. This should be a
492 * directory dentry if set. If this parameter is NULL, then the
493 * directory will be created in the root of the debugfs filesystem.
495 * This function creates a directory in debugfs with the given name.
497 * This function will return a pointer to a dentry if it succeeds. This
498 * pointer must be passed to the debugfs_remove() function when the file is
499 * to be removed (no automatic cleanup happens if your module is unloaded,
500 * you are responsible here.) If an error occurs, %NULL will be returned.
502 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
505 struct dentry
*debugfs_create_dir(const char *name
, struct dentry
*parent
)
507 struct dentry
*dentry
= start_creating(name
, parent
);
513 inode
= debugfs_get_inode(dentry
->d_sb
);
514 if (unlikely(!inode
))
515 return failed_creating(dentry
);
517 inode
->i_mode
= S_IFDIR
| S_IRWXU
| S_IRUGO
| S_IXUGO
;
518 inode
->i_op
= &simple_dir_inode_operations
;
519 inode
->i_fop
= &simple_dir_operations
;
521 /* directory inodes start off with i_nlink == 2 (for "." entry) */
523 d_instantiate(dentry
, inode
);
524 inc_nlink(d_inode(dentry
->d_parent
));
525 fsnotify_mkdir(d_inode(dentry
->d_parent
), dentry
);
526 return end_creating(dentry
);
528 EXPORT_SYMBOL_GPL(debugfs_create_dir
);
531 * debugfs_create_automount - create automount point in the debugfs filesystem
532 * @name: a pointer to a string containing the name of the file to create.
533 * @parent: a pointer to the parent dentry for this file. This should be a
534 * directory dentry if set. If this parameter is NULL, then the
535 * file will be created in the root of the debugfs filesystem.
536 * @f: function to be called when pathname resolution steps on that one.
537 * @data: opaque argument to pass to f().
539 * @f should return what ->d_automount() would.
541 struct dentry
*debugfs_create_automount(const char *name
,
542 struct dentry
*parent
,
543 debugfs_automount_t f
,
546 struct dentry
*dentry
= start_creating(name
, parent
);
552 inode
= debugfs_get_inode(dentry
->d_sb
);
553 if (unlikely(!inode
))
554 return failed_creating(dentry
);
556 make_empty_dir_inode(inode
);
557 inode
->i_flags
|= S_AUTOMOUNT
;
558 inode
->i_private
= data
;
559 dentry
->d_fsdata
= (void *)f
;
560 /* directory inodes start off with i_nlink == 2 (for "." entry) */
562 d_instantiate(dentry
, inode
);
563 inc_nlink(d_inode(dentry
->d_parent
));
564 fsnotify_mkdir(d_inode(dentry
->d_parent
), dentry
);
565 return end_creating(dentry
);
567 EXPORT_SYMBOL(debugfs_create_automount
);
570 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
571 * @name: a pointer to a string containing the name of the symbolic link to
573 * @parent: a pointer to the parent dentry for this symbolic link. This
574 * should be a directory dentry if set. If this parameter is NULL,
575 * then the symbolic link will be created in the root of the debugfs
577 * @target: a pointer to a string containing the path to the target of the
580 * This function creates a symbolic link with the given name in debugfs that
581 * links to the given target path.
583 * This function will return a pointer to a dentry if it succeeds. This
584 * pointer must be passed to the debugfs_remove() function when the symbolic
585 * link is to be removed (no automatic cleanup happens if your module is
586 * unloaded, you are responsible here.) If an error occurs, %NULL will be
589 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
592 struct dentry
*debugfs_create_symlink(const char *name
, struct dentry
*parent
,
595 struct dentry
*dentry
;
597 char *link
= kstrdup(target
, GFP_KERNEL
);
601 dentry
= start_creating(name
, parent
);
602 if (IS_ERR(dentry
)) {
607 inode
= debugfs_get_inode(dentry
->d_sb
);
608 if (unlikely(!inode
)) {
610 return failed_creating(dentry
);
612 inode
->i_mode
= S_IFLNK
| S_IRWXUGO
;
613 inode
->i_op
= &simple_symlink_inode_operations
;
614 inode
->i_link
= link
;
615 d_instantiate(dentry
, inode
);
616 return end_creating(dentry
);
618 EXPORT_SYMBOL_GPL(debugfs_create_symlink
);
620 static int __debugfs_remove(struct dentry
*dentry
, struct dentry
*parent
)
624 if (simple_positive(dentry
)) {
626 if (d_is_dir(dentry
))
627 ret
= simple_rmdir(d_inode(parent
), dentry
);
629 simple_unlink(d_inode(parent
), dentry
);
638 * debugfs_remove - removes a file or directory from the debugfs filesystem
639 * @dentry: a pointer to a the dentry of the file or directory to be
640 * removed. If this parameter is NULL or an error value, nothing
643 * This function removes a file or directory in debugfs that was previously
644 * created with a call to another debugfs function (like
645 * debugfs_create_file() or variants thereof.)
647 * This function is required to be called in order for the file to be
648 * removed, no automatic cleanup of files will happen when a module is
649 * removed, you are responsible here.
651 void debugfs_remove(struct dentry
*dentry
)
653 struct dentry
*parent
;
656 if (IS_ERR_OR_NULL(dentry
))
659 parent
= dentry
->d_parent
;
660 inode_lock(d_inode(parent
));
661 ret
= __debugfs_remove(dentry
, parent
);
662 inode_unlock(d_inode(parent
));
664 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
666 synchronize_srcu(&debugfs_srcu
);
668 EXPORT_SYMBOL_GPL(debugfs_remove
);
671 * debugfs_remove_recursive - recursively removes a directory
672 * @dentry: a pointer to a the dentry of the directory to be removed. If this
673 * parameter is NULL or an error value, nothing will be done.
675 * This function recursively removes a directory tree in debugfs that
676 * was previously created with a call to another debugfs function
677 * (like debugfs_create_file() or variants thereof.)
679 * This function is required to be called in order for the file to be
680 * removed, no automatic cleanup of files will happen when a module is
681 * removed, you are responsible here.
683 void debugfs_remove_recursive(struct dentry
*dentry
)
685 struct dentry
*child
, *parent
;
687 if (IS_ERR_OR_NULL(dentry
))
692 inode_lock(d_inode(parent
));
695 * The parent->d_subdirs is protected by the d_lock. Outside that
696 * lock, the child can be unlinked and set to be freed which can
697 * use the d_u.d_child as the rcu head and corrupt this list.
699 spin_lock(&parent
->d_lock
);
700 list_for_each_entry(child
, &parent
->d_subdirs
, d_child
) {
701 if (!simple_positive(child
))
704 /* perhaps simple_empty(child) makes more sense */
705 if (!list_empty(&child
->d_subdirs
)) {
706 spin_unlock(&parent
->d_lock
);
707 inode_unlock(d_inode(parent
));
712 spin_unlock(&parent
->d_lock
);
714 if (!__debugfs_remove(child
, parent
))
715 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
718 * The parent->d_lock protects agaist child from unlinking
719 * from d_subdirs. When releasing the parent->d_lock we can
720 * no longer trust that the next pointer is valid.
721 * Restart the loop. We'll skip this one with the
722 * simple_positive() check.
726 spin_unlock(&parent
->d_lock
);
728 inode_unlock(d_inode(parent
));
730 parent
= parent
->d_parent
;
731 inode_lock(d_inode(parent
));
737 if (!__debugfs_remove(child
, parent
))
738 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
739 inode_unlock(d_inode(parent
));
741 synchronize_srcu(&debugfs_srcu
);
743 EXPORT_SYMBOL_GPL(debugfs_remove_recursive
);
746 * debugfs_rename - rename a file/directory in the debugfs filesystem
747 * @old_dir: a pointer to the parent dentry for the renamed object. This
748 * should be a directory dentry.
749 * @old_dentry: dentry of an object to be renamed.
750 * @new_dir: a pointer to the parent dentry where the object should be
751 * moved. This should be a directory dentry.
752 * @new_name: a pointer to a string containing the target name.
754 * This function renames a file/directory in debugfs. The target must not
755 * exist for rename to succeed.
757 * This function will return a pointer to old_dentry (which is updated to
758 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
761 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
764 struct dentry
*debugfs_rename(struct dentry
*old_dir
, struct dentry
*old_dentry
,
765 struct dentry
*new_dir
, const char *new_name
)
768 struct dentry
*dentry
= NULL
, *trap
;
769 const char *old_name
;
771 trap
= lock_rename(new_dir
, old_dir
);
772 /* Source or destination directories don't exist? */
773 if (d_really_is_negative(old_dir
) || d_really_is_negative(new_dir
))
775 /* Source does not exist, cyclic rename, or mountpoint? */
776 if (d_really_is_negative(old_dentry
) || old_dentry
== trap
||
777 d_mountpoint(old_dentry
))
779 dentry
= lookup_one_len(new_name
, new_dir
, strlen(new_name
));
780 /* Lookup failed, cyclic rename or target exists? */
781 if (IS_ERR(dentry
) || dentry
== trap
|| d_really_is_positive(dentry
))
784 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
786 error
= simple_rename(d_inode(old_dir
), old_dentry
, d_inode(new_dir
),
789 fsnotify_oldname_free(old_name
);
792 d_move(old_dentry
, dentry
);
793 fsnotify_move(d_inode(old_dir
), d_inode(new_dir
), old_name
,
794 d_is_dir(old_dentry
),
796 fsnotify_oldname_free(old_name
);
797 unlock_rename(new_dir
, old_dir
);
801 if (dentry
&& !IS_ERR(dentry
))
803 unlock_rename(new_dir
, old_dir
);
806 EXPORT_SYMBOL_GPL(debugfs_rename
);
809 * debugfs_initialized - Tells whether debugfs has been registered
811 bool debugfs_initialized(void)
813 return debugfs_registered
;
815 EXPORT_SYMBOL_GPL(debugfs_initialized
);
817 static int __init
debugfs_init(void)
821 retval
= sysfs_create_mount_point(kernel_kobj
, "debug");
825 retval
= register_filesystem(&debug_fs_type
);
827 sysfs_remove_mount_point(kernel_kobj
, "debug");
829 debugfs_registered
= true;
833 core_initcall(debugfs_init
);