1 // SPDX-License-Identifier: GPL-2.0
3 * inode.c - part of debugfs, a tiny little debug file system
5 * Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com>
6 * Copyright (C) 2004 IBM Inc.
7 * Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org>
9 * debugfs is for people to use instead of /proc or /sys.
10 * See ./Documentation/core-api/kernel-api.rst for more details.
13 #define pr_fmt(fmt) "debugfs: " fmt
15 #include <linux/module.h>
17 #include <linux/mount.h>
18 #include <linux/pagemap.h>
19 #include <linux/init.h>
20 #include <linux/kobject.h>
21 #include <linux/namei.h>
22 #include <linux/debugfs.h>
23 #include <linux/fsnotify.h>
24 #include <linux/string.h>
25 #include <linux/seq_file.h>
26 #include <linux/parser.h>
27 #include <linux/magic.h>
28 #include <linux/slab.h>
29 #include <linux/security.h>
33 #define DEBUGFS_DEFAULT_MODE 0700
35 static struct vfsmount
*debugfs_mount
;
36 static int debugfs_mount_count
;
37 static bool debugfs_registered
;
40 * Don't allow access attributes to be changed whilst the kernel is locked down
41 * so that we can use the file mode as part of a heuristic to determine whether
42 * to lock down individual files.
44 static int debugfs_setattr(struct dentry
*dentry
, struct iattr
*ia
)
46 int ret
= security_locked_down(LOCKDOWN_DEBUGFS
);
48 if (ret
&& (ia
->ia_valid
& (ATTR_MODE
| ATTR_UID
| ATTR_GID
)))
50 return simple_setattr(dentry
, ia
);
53 static const struct inode_operations debugfs_file_inode_operations
= {
54 .setattr
= debugfs_setattr
,
56 static const struct inode_operations debugfs_dir_inode_operations
= {
57 .lookup
= simple_lookup
,
58 .setattr
= debugfs_setattr
,
60 static const struct inode_operations debugfs_symlink_inode_operations
= {
61 .get_link
= simple_get_link
,
62 .setattr
= debugfs_setattr
,
65 static struct inode
*debugfs_get_inode(struct super_block
*sb
)
67 struct inode
*inode
= new_inode(sb
);
69 inode
->i_ino
= get_next_ino();
70 inode
->i_atime
= inode
->i_mtime
=
71 inode
->i_ctime
= current_time(inode
);
76 struct debugfs_mount_opts
{
89 static const match_table_t tokens
= {
92 {Opt_mode
, "mode=%o"},
96 struct debugfs_fs_info
{
97 struct debugfs_mount_opts mount_opts
;
100 static int debugfs_parse_options(char *data
, struct debugfs_mount_opts
*opts
)
102 substring_t args
[MAX_OPT_ARGS
];
109 opts
->mode
= DEBUGFS_DEFAULT_MODE
;
111 while ((p
= strsep(&data
, ",")) != NULL
) {
115 token
= match_token(p
, tokens
, args
);
118 if (match_int(&args
[0], &option
))
120 uid
= make_kuid(current_user_ns(), option
);
126 if (match_int(&args
[0], &option
))
128 gid
= make_kgid(current_user_ns(), option
);
134 if (match_octal(&args
[0], &option
))
136 opts
->mode
= option
& S_IALLUGO
;
139 * We might like to report bad mount options here;
140 * but traditionally debugfs has ignored all mount options
148 static int debugfs_apply_options(struct super_block
*sb
)
150 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
151 struct inode
*inode
= d_inode(sb
->s_root
);
152 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
154 inode
->i_mode
&= ~S_IALLUGO
;
155 inode
->i_mode
|= opts
->mode
;
157 inode
->i_uid
= opts
->uid
;
158 inode
->i_gid
= opts
->gid
;
163 static int debugfs_remount(struct super_block
*sb
, int *flags
, char *data
)
166 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
169 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
173 debugfs_apply_options(sb
);
179 static int debugfs_show_options(struct seq_file
*m
, struct dentry
*root
)
181 struct debugfs_fs_info
*fsi
= root
->d_sb
->s_fs_info
;
182 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
184 if (!uid_eq(opts
->uid
, GLOBAL_ROOT_UID
))
185 seq_printf(m
, ",uid=%u",
186 from_kuid_munged(&init_user_ns
, opts
->uid
));
187 if (!gid_eq(opts
->gid
, GLOBAL_ROOT_GID
))
188 seq_printf(m
, ",gid=%u",
189 from_kgid_munged(&init_user_ns
, opts
->gid
));
190 if (opts
->mode
!= DEBUGFS_DEFAULT_MODE
)
191 seq_printf(m
, ",mode=%o", opts
->mode
);
196 static void debugfs_free_inode(struct inode
*inode
)
198 if (S_ISLNK(inode
->i_mode
))
199 kfree(inode
->i_link
);
200 free_inode_nonrcu(inode
);
203 static const struct super_operations debugfs_super_operations
= {
204 .statfs
= simple_statfs
,
205 .remount_fs
= debugfs_remount
,
206 .show_options
= debugfs_show_options
,
207 .free_inode
= debugfs_free_inode
,
210 static void debugfs_release_dentry(struct dentry
*dentry
)
212 void *fsd
= dentry
->d_fsdata
;
214 if (!((unsigned long)fsd
& DEBUGFS_FSDATA_IS_REAL_FOPS_BIT
))
215 kfree(dentry
->d_fsdata
);
218 static struct vfsmount
*debugfs_automount(struct path
*path
)
220 debugfs_automount_t f
;
221 f
= (debugfs_automount_t
)path
->dentry
->d_fsdata
;
222 return f(path
->dentry
, d_inode(path
->dentry
)->i_private
);
225 static const struct dentry_operations debugfs_dops
= {
226 .d_delete
= always_delete_dentry
,
227 .d_release
= debugfs_release_dentry
,
228 .d_automount
= debugfs_automount
,
231 static int debug_fill_super(struct super_block
*sb
, void *data
, int silent
)
233 static const struct tree_descr debug_files
[] = {{""}};
234 struct debugfs_fs_info
*fsi
;
237 fsi
= kzalloc(sizeof(struct debugfs_fs_info
), GFP_KERNEL
);
244 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
248 err
= simple_fill_super(sb
, DEBUGFS_MAGIC
, debug_files
);
252 sb
->s_op
= &debugfs_super_operations
;
253 sb
->s_d_op
= &debugfs_dops
;
255 debugfs_apply_options(sb
);
261 sb
->s_fs_info
= NULL
;
265 static struct dentry
*debug_mount(struct file_system_type
*fs_type
,
266 int flags
, const char *dev_name
,
269 return mount_single(fs_type
, flags
, data
, debug_fill_super
);
272 static struct file_system_type debug_fs_type
= {
273 .owner
= THIS_MODULE
,
275 .mount
= debug_mount
,
276 .kill_sb
= kill_litter_super
,
278 MODULE_ALIAS_FS("debugfs");
281 * debugfs_lookup() - look up an existing debugfs file
282 * @name: a pointer to a string containing the name of the file to look up.
283 * @parent: a pointer to the parent dentry of the file.
285 * This function will return a pointer to a dentry if it succeeds. If the file
286 * doesn't exist or an error occurs, %NULL will be returned. The returned
287 * dentry must be passed to dput() when it is no longer needed.
289 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
292 struct dentry
*debugfs_lookup(const char *name
, struct dentry
*parent
)
294 struct dentry
*dentry
;
300 parent
= debugfs_mount
->mnt_root
;
302 dentry
= lookup_one_len_unlocked(name
, parent
, strlen(name
));
305 if (!d_really_is_positive(dentry
)) {
311 EXPORT_SYMBOL_GPL(debugfs_lookup
);
313 static struct dentry
*start_creating(const char *name
, struct dentry
*parent
)
315 struct dentry
*dentry
;
318 pr_debug("creating file '%s'\n", name
);
323 error
= simple_pin_fs(&debug_fs_type
, &debugfs_mount
,
324 &debugfs_mount_count
);
326 pr_err("Unable to pin filesystem for file '%s'\n", name
);
327 return ERR_PTR(error
);
330 /* If the parent is not specified, we create it in the root.
331 * We need the root dentry to do this, which is in the super
332 * block. A pointer to that is in the struct vfsmount that we
336 parent
= debugfs_mount
->mnt_root
;
338 inode_lock(d_inode(parent
));
339 dentry
= lookup_one_len(name
, parent
, strlen(name
));
340 if (!IS_ERR(dentry
) && d_really_is_positive(dentry
)) {
341 if (d_is_dir(dentry
))
342 pr_err("Directory '%s' with parent '%s' already present!\n",
343 name
, parent
->d_name
.name
);
345 pr_err("File '%s' in directory '%s' already present!\n",
346 name
, parent
->d_name
.name
);
348 dentry
= ERR_PTR(-EEXIST
);
351 if (IS_ERR(dentry
)) {
352 inode_unlock(d_inode(parent
));
353 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
359 static struct dentry
*failed_creating(struct dentry
*dentry
)
361 inode_unlock(d_inode(dentry
->d_parent
));
363 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
364 return ERR_PTR(-ENOMEM
);
367 static struct dentry
*end_creating(struct dentry
*dentry
)
369 inode_unlock(d_inode(dentry
->d_parent
));
373 static struct dentry
*__debugfs_create_file(const char *name
, umode_t mode
,
374 struct dentry
*parent
, void *data
,
375 const struct file_operations
*proxy_fops
,
376 const struct file_operations
*real_fops
)
378 struct dentry
*dentry
;
381 if (!(mode
& S_IFMT
))
383 BUG_ON(!S_ISREG(mode
));
384 dentry
= start_creating(name
, parent
);
389 inode
= debugfs_get_inode(dentry
->d_sb
);
390 if (unlikely(!inode
)) {
391 pr_err("out of free dentries, can not create file '%s'\n",
393 return failed_creating(dentry
);
396 inode
->i_mode
= mode
;
397 inode
->i_private
= data
;
399 inode
->i_op
= &debugfs_file_inode_operations
;
400 inode
->i_fop
= proxy_fops
;
401 dentry
->d_fsdata
= (void *)((unsigned long)real_fops
|
402 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT
);
404 d_instantiate(dentry
, inode
);
405 fsnotify_create(d_inode(dentry
->d_parent
), dentry
);
406 return end_creating(dentry
);
410 * debugfs_create_file - create a file in the debugfs filesystem
411 * @name: a pointer to a string containing the name of the file to create.
412 * @mode: the permission that the file should have.
413 * @parent: a pointer to the parent dentry for this file. This should be a
414 * directory dentry if set. If this parameter is NULL, then the
415 * file will be created in the root of the debugfs filesystem.
416 * @data: a pointer to something that the caller will want to get to later
417 * on. The inode.i_private pointer will point to this value on
419 * @fops: a pointer to a struct file_operations that should be used for
422 * This is the basic "create a file" function for debugfs. It allows for a
423 * wide range of flexibility in creating a file, or a directory (if you want
424 * to create a directory, the debugfs_create_dir() function is
425 * recommended to be used instead.)
427 * This function will return a pointer to a dentry if it succeeds. This
428 * pointer must be passed to the debugfs_remove() function when the file is
429 * to be removed (no automatic cleanup happens if your module is unloaded,
430 * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be
433 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
436 struct dentry
*debugfs_create_file(const char *name
, umode_t mode
,
437 struct dentry
*parent
, void *data
,
438 const struct file_operations
*fops
)
441 return __debugfs_create_file(name
, mode
, parent
, data
,
442 fops
? &debugfs_full_proxy_file_operations
:
443 &debugfs_noop_file_operations
,
446 EXPORT_SYMBOL_GPL(debugfs_create_file
);
449 * debugfs_create_file_unsafe - create a file in the debugfs filesystem
450 * @name: a pointer to a string containing the name of the file to create.
451 * @mode: the permission that the file should have.
452 * @parent: a pointer to the parent dentry for this file. This should be a
453 * directory dentry if set. If this parameter is NULL, then the
454 * file will be created in the root of the debugfs filesystem.
455 * @data: a pointer to something that the caller will want to get to later
456 * on. The inode.i_private pointer will point to this value on
458 * @fops: a pointer to a struct file_operations that should be used for
461 * debugfs_create_file_unsafe() is completely analogous to
462 * debugfs_create_file(), the only difference being that the fops
463 * handed it will not get protected against file removals by the
466 * It is your responsibility to protect your struct file_operation
467 * methods against file removals by means of debugfs_file_get()
468 * and debugfs_file_put(). ->open() is still protected by
471 * Any struct file_operations defined by means of
472 * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
473 * thus, may be used here.
475 struct dentry
*debugfs_create_file_unsafe(const char *name
, umode_t mode
,
476 struct dentry
*parent
, void *data
,
477 const struct file_operations
*fops
)
480 return __debugfs_create_file(name
, mode
, parent
, data
,
481 fops
? &debugfs_open_proxy_file_operations
:
482 &debugfs_noop_file_operations
,
485 EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe
);
488 * debugfs_create_file_size - create a file in the debugfs filesystem
489 * @name: a pointer to a string containing the name of the file to create.
490 * @mode: the permission that the file should have.
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 * file will be created in the root of the debugfs filesystem.
494 * @data: a pointer to something that the caller will want to get to later
495 * on. The inode.i_private pointer will point to this value on
497 * @fops: a pointer to a struct file_operations that should be used for
499 * @file_size: initial file size
501 * This is the basic "create a file" function for debugfs. It allows for a
502 * wide range of flexibility in creating a file, or a directory (if you want
503 * to create a directory, the debugfs_create_dir() function is
504 * recommended to be used instead.)
506 * This function will return a pointer to a dentry if it succeeds. This
507 * pointer must be passed to the debugfs_remove() function when the file is
508 * to be removed (no automatic cleanup happens if your module is unloaded,
509 * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be
512 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
515 struct dentry
*debugfs_create_file_size(const char *name
, umode_t mode
,
516 struct dentry
*parent
, void *data
,
517 const struct file_operations
*fops
,
520 struct dentry
*de
= debugfs_create_file(name
, mode
, parent
, data
, fops
);
523 d_inode(de
)->i_size
= file_size
;
526 EXPORT_SYMBOL_GPL(debugfs_create_file_size
);
529 * debugfs_create_dir - create a directory in the debugfs filesystem
530 * @name: a pointer to a string containing the name of the directory to
532 * @parent: a pointer to the parent dentry for this file. This should be a
533 * directory dentry if set. If this parameter is NULL, then the
534 * directory will be created in the root of the debugfs filesystem.
536 * This function creates a directory in debugfs with the given name.
538 * This function will return a pointer to a dentry if it succeeds. This
539 * pointer must be passed to the debugfs_remove() function when the file is
540 * to be removed (no automatic cleanup happens if your module is unloaded,
541 * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be
544 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
547 struct dentry
*debugfs_create_dir(const char *name
, struct dentry
*parent
)
549 struct dentry
*dentry
= start_creating(name
, parent
);
555 inode
= debugfs_get_inode(dentry
->d_sb
);
556 if (unlikely(!inode
)) {
557 pr_err("out of free dentries, can not create directory '%s'\n",
559 return failed_creating(dentry
);
562 inode
->i_mode
= S_IFDIR
| S_IRWXU
| S_IRUGO
| S_IXUGO
;
563 inode
->i_op
= &debugfs_dir_inode_operations
;
564 inode
->i_fop
= &simple_dir_operations
;
566 /* directory inodes start off with i_nlink == 2 (for "." entry) */
568 d_instantiate(dentry
, inode
);
569 inc_nlink(d_inode(dentry
->d_parent
));
570 fsnotify_mkdir(d_inode(dentry
->d_parent
), dentry
);
571 return end_creating(dentry
);
573 EXPORT_SYMBOL_GPL(debugfs_create_dir
);
576 * debugfs_create_automount - create automount point in the debugfs filesystem
577 * @name: a pointer to a string containing the name of the file to create.
578 * @parent: a pointer to the parent dentry for this file. This should be a
579 * directory dentry if set. If this parameter is NULL, then the
580 * file will be created in the root of the debugfs filesystem.
581 * @f: function to be called when pathname resolution steps on that one.
582 * @data: opaque argument to pass to f().
584 * @f should return what ->d_automount() would.
586 struct dentry
*debugfs_create_automount(const char *name
,
587 struct dentry
*parent
,
588 debugfs_automount_t f
,
591 struct dentry
*dentry
= start_creating(name
, parent
);
597 inode
= debugfs_get_inode(dentry
->d_sb
);
598 if (unlikely(!inode
)) {
599 pr_err("out of free dentries, can not create automount '%s'\n",
601 return failed_creating(dentry
);
604 make_empty_dir_inode(inode
);
605 inode
->i_flags
|= S_AUTOMOUNT
;
606 inode
->i_private
= data
;
607 dentry
->d_fsdata
= (void *)f
;
608 /* directory inodes start off with i_nlink == 2 (for "." entry) */
610 d_instantiate(dentry
, inode
);
611 inc_nlink(d_inode(dentry
->d_parent
));
612 fsnotify_mkdir(d_inode(dentry
->d_parent
), dentry
);
613 return end_creating(dentry
);
615 EXPORT_SYMBOL(debugfs_create_automount
);
618 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
619 * @name: a pointer to a string containing the name of the symbolic link to
621 * @parent: a pointer to the parent dentry for this symbolic link. This
622 * should be a directory dentry if set. If this parameter is NULL,
623 * then the symbolic link will be created in the root of the debugfs
625 * @target: a pointer to a string containing the path to the target of the
628 * This function creates a symbolic link with the given name in debugfs that
629 * links to the given target path.
631 * This function will return a pointer to a dentry if it succeeds. This
632 * pointer must be passed to the debugfs_remove() function when the symbolic
633 * link is to be removed (no automatic cleanup happens if your module is
634 * unloaded, you are responsible here.) If an error occurs, %ERR_PTR(-ERROR)
637 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
640 struct dentry
*debugfs_create_symlink(const char *name
, struct dentry
*parent
,
643 struct dentry
*dentry
;
645 char *link
= kstrdup(target
, GFP_KERNEL
);
647 return ERR_PTR(-ENOMEM
);
649 dentry
= start_creating(name
, parent
);
650 if (IS_ERR(dentry
)) {
655 inode
= debugfs_get_inode(dentry
->d_sb
);
656 if (unlikely(!inode
)) {
657 pr_err("out of free dentries, can not create symlink '%s'\n",
660 return failed_creating(dentry
);
662 inode
->i_mode
= S_IFLNK
| S_IRWXUGO
;
663 inode
->i_op
= &debugfs_symlink_inode_operations
;
664 inode
->i_link
= link
;
665 d_instantiate(dentry
, inode
);
666 return end_creating(dentry
);
668 EXPORT_SYMBOL_GPL(debugfs_create_symlink
);
670 static void __debugfs_file_removed(struct dentry
*dentry
)
672 struct debugfs_fsdata
*fsd
;
675 * Paired with the closing smp_mb() implied by a successful
676 * cmpxchg() in debugfs_file_get(): either
677 * debugfs_file_get() must see a dead dentry or we must see a
678 * debugfs_fsdata instance at ->d_fsdata here (or both).
681 fsd
= READ_ONCE(dentry
->d_fsdata
);
682 if ((unsigned long)fsd
& DEBUGFS_FSDATA_IS_REAL_FOPS_BIT
)
684 if (!refcount_dec_and_test(&fsd
->active_users
))
685 wait_for_completion(&fsd
->active_users_drained
);
688 static int __debugfs_remove(struct dentry
*dentry
, struct dentry
*parent
)
692 if (simple_positive(dentry
)) {
694 if (d_is_dir(dentry
)) {
695 ret
= simple_rmdir(d_inode(parent
), dentry
);
697 fsnotify_rmdir(d_inode(parent
), dentry
);
699 simple_unlink(d_inode(parent
), dentry
);
700 fsnotify_unlink(d_inode(parent
), dentry
);
704 if (d_is_reg(dentry
))
705 __debugfs_file_removed(dentry
);
712 * debugfs_remove - removes a file or directory from the debugfs filesystem
713 * @dentry: a pointer to a the dentry of the file or directory to be
714 * removed. If this parameter is NULL or an error value, nothing
717 * This function removes a file or directory in debugfs that was previously
718 * created with a call to another debugfs function (like
719 * debugfs_create_file() or variants thereof.)
721 * This function is required to be called in order for the file to be
722 * removed, no automatic cleanup of files will happen when a module is
723 * removed, you are responsible here.
725 void debugfs_remove(struct dentry
*dentry
)
727 struct dentry
*parent
;
730 if (IS_ERR_OR_NULL(dentry
))
733 parent
= dentry
->d_parent
;
734 inode_lock(d_inode(parent
));
735 ret
= __debugfs_remove(dentry
, parent
);
736 inode_unlock(d_inode(parent
));
738 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
740 EXPORT_SYMBOL_GPL(debugfs_remove
);
743 * debugfs_remove_recursive - recursively removes a directory
744 * @dentry: a pointer to a the dentry of the directory to be removed. If this
745 * parameter is NULL or an error value, nothing will be done.
747 * This function recursively removes a directory tree in debugfs that
748 * was previously created with a call to another debugfs function
749 * (like debugfs_create_file() or variants thereof.)
751 * This function is required to be called in order for the file to be
752 * removed, no automatic cleanup of files will happen when a module is
753 * removed, you are responsible here.
755 void debugfs_remove_recursive(struct dentry
*dentry
)
757 struct dentry
*child
, *parent
;
759 if (IS_ERR_OR_NULL(dentry
))
764 inode_lock(d_inode(parent
));
767 * The parent->d_subdirs is protected by the d_lock. Outside that
768 * lock, the child can be unlinked and set to be freed which can
769 * use the d_u.d_child as the rcu head and corrupt this list.
771 spin_lock(&parent
->d_lock
);
772 list_for_each_entry(child
, &parent
->d_subdirs
, d_child
) {
773 if (!simple_positive(child
))
776 /* perhaps simple_empty(child) makes more sense */
777 if (!list_empty(&child
->d_subdirs
)) {
778 spin_unlock(&parent
->d_lock
);
779 inode_unlock(d_inode(parent
));
784 spin_unlock(&parent
->d_lock
);
786 if (!__debugfs_remove(child
, parent
))
787 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
790 * The parent->d_lock protects agaist child from unlinking
791 * from d_subdirs. When releasing the parent->d_lock we can
792 * no longer trust that the next pointer is valid.
793 * Restart the loop. We'll skip this one with the
794 * simple_positive() check.
798 spin_unlock(&parent
->d_lock
);
800 inode_unlock(d_inode(parent
));
802 parent
= parent
->d_parent
;
803 inode_lock(d_inode(parent
));
809 if (!__debugfs_remove(child
, parent
))
810 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
811 inode_unlock(d_inode(parent
));
813 EXPORT_SYMBOL_GPL(debugfs_remove_recursive
);
816 * debugfs_rename - rename a file/directory in the debugfs filesystem
817 * @old_dir: a pointer to the parent dentry for the renamed object. This
818 * should be a directory dentry.
819 * @old_dentry: dentry of an object to be renamed.
820 * @new_dir: a pointer to the parent dentry where the object should be
821 * moved. This should be a directory dentry.
822 * @new_name: a pointer to a string containing the target name.
824 * This function renames a file/directory in debugfs. The target must not
825 * exist for rename to succeed.
827 * This function will return a pointer to old_dentry (which is updated to
828 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
831 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
834 struct dentry
*debugfs_rename(struct dentry
*old_dir
, struct dentry
*old_dentry
,
835 struct dentry
*new_dir
, const char *new_name
)
838 struct dentry
*dentry
= NULL
, *trap
;
839 struct name_snapshot old_name
;
845 if (IS_ERR_OR_NULL(old_dentry
))
848 trap
= lock_rename(new_dir
, old_dir
);
849 /* Source or destination directories don't exist? */
850 if (d_really_is_negative(old_dir
) || d_really_is_negative(new_dir
))
852 /* Source does not exist, cyclic rename, or mountpoint? */
853 if (d_really_is_negative(old_dentry
) || old_dentry
== trap
||
854 d_mountpoint(old_dentry
))
856 dentry
= lookup_one_len(new_name
, new_dir
, strlen(new_name
));
857 /* Lookup failed, cyclic rename or target exists? */
858 if (IS_ERR(dentry
) || dentry
== trap
|| d_really_is_positive(dentry
))
861 take_dentry_name_snapshot(&old_name
, old_dentry
);
863 error
= simple_rename(d_inode(old_dir
), old_dentry
, d_inode(new_dir
),
866 release_dentry_name_snapshot(&old_name
);
869 d_move(old_dentry
, dentry
);
870 fsnotify_move(d_inode(old_dir
), d_inode(new_dir
), &old_name
.name
,
871 d_is_dir(old_dentry
),
873 release_dentry_name_snapshot(&old_name
);
874 unlock_rename(new_dir
, old_dir
);
878 if (dentry
&& !IS_ERR(dentry
))
880 unlock_rename(new_dir
, old_dir
);
883 return ERR_PTR(-EINVAL
);
885 EXPORT_SYMBOL_GPL(debugfs_rename
);
888 * debugfs_initialized - Tells whether debugfs has been registered
890 bool debugfs_initialized(void)
892 return debugfs_registered
;
894 EXPORT_SYMBOL_GPL(debugfs_initialized
);
896 static int __init
debugfs_init(void)
900 retval
= sysfs_create_mount_point(kernel_kobj
, "debug");
904 retval
= register_filesystem(&debug_fs_type
);
906 sysfs_remove_mount_point(kernel_kobj
, "debug");
908 debugfs_registered
= true;
912 core_initcall(debugfs_init
);