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;
38 static unsigned int debugfs_allow __ro_after_init = DEFAULT_DEBUGFS_ALLOW_BITS;
41 * Don't allow access attributes to be changed whilst the kernel is locked down
42 * so that we can use the file mode as part of a heuristic to determine whether
43 * to lock down individual files.
45 static int debugfs_setattr(struct mnt_idmap *idmap,
46 struct dentry *dentry, struct iattr *ia)
50 if (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) {
51 ret = security_locked_down(LOCKDOWN_DEBUGFS);
55 return simple_setattr(&nop_mnt_idmap, dentry, ia);
58 static const struct inode_operations debugfs_file_inode_operations = {
59 .setattr = debugfs_setattr,
61 static const struct inode_operations debugfs_dir_inode_operations = {
62 .lookup = simple_lookup,
63 .setattr = debugfs_setattr,
65 static const struct inode_operations debugfs_symlink_inode_operations = {
66 .get_link = simple_get_link,
67 .setattr = debugfs_setattr,
70 static struct inode *debugfs_get_inode(struct super_block *sb)
72 struct inode *inode = new_inode(sb);
74 inode->i_ino = get_next_ino();
75 simple_inode_init_ts(inode);
80 struct debugfs_mount_opts {
95 static const match_table_t tokens = {
98 {Opt_mode, "mode=%o"},
102 struct debugfs_fs_info {
103 struct debugfs_mount_opts mount_opts;
106 static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
108 substring_t args[MAX_OPT_ARGS];
116 opts->mode = DEBUGFS_DEFAULT_MODE;
118 while ((p = strsep(&data, ",")) != NULL) {
122 token = match_token(p, tokens, args);
125 if (match_int(&args[0], &option))
127 uid = make_kuid(current_user_ns(), option);
133 if (match_int(&args[0], &option))
135 gid = make_kgid(current_user_ns(), option);
141 if (match_octal(&args[0], &option))
143 opts->mode = option & S_IALLUGO;
146 * We might like to report bad mount options here;
147 * but traditionally debugfs has ignored all mount options
151 opts->opts |= BIT(token);
157 static void _debugfs_apply_options(struct super_block *sb, bool remount)
159 struct debugfs_fs_info *fsi = sb->s_fs_info;
160 struct inode *inode = d_inode(sb->s_root);
161 struct debugfs_mount_opts *opts = &fsi->mount_opts;
164 * On remount, only reset mode/uid/gid if they were provided as mount
168 if (!remount || opts->opts & BIT(Opt_mode)) {
169 inode->i_mode &= ~S_IALLUGO;
170 inode->i_mode |= opts->mode;
173 if (!remount || opts->opts & BIT(Opt_uid))
174 inode->i_uid = opts->uid;
176 if (!remount || opts->opts & BIT(Opt_gid))
177 inode->i_gid = opts->gid;
180 static void debugfs_apply_options(struct super_block *sb)
182 _debugfs_apply_options(sb, false);
185 static void debugfs_apply_options_remount(struct super_block *sb)
187 _debugfs_apply_options(sb, true);
190 static int debugfs_remount(struct super_block *sb, int *flags, char *data)
193 struct debugfs_fs_info *fsi = sb->s_fs_info;
196 err = debugfs_parse_options(data, &fsi->mount_opts);
200 debugfs_apply_options_remount(sb);
206 static int debugfs_show_options(struct seq_file *m, struct dentry *root)
208 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
209 struct debugfs_mount_opts *opts = &fsi->mount_opts;
211 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
212 seq_printf(m, ",uid=%u",
213 from_kuid_munged(&init_user_ns, opts->uid));
214 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
215 seq_printf(m, ",gid=%u",
216 from_kgid_munged(&init_user_ns, opts->gid));
217 if (opts->mode != DEBUGFS_DEFAULT_MODE)
218 seq_printf(m, ",mode=%o", opts->mode);
223 static void debugfs_free_inode(struct inode *inode)
225 if (S_ISLNK(inode->i_mode))
226 kfree(inode->i_link);
227 free_inode_nonrcu(inode);
230 static const struct super_operations debugfs_super_operations = {
231 .statfs = simple_statfs,
232 .remount_fs = debugfs_remount,
233 .show_options = debugfs_show_options,
234 .free_inode = debugfs_free_inode,
237 static void debugfs_release_dentry(struct dentry *dentry)
239 struct debugfs_fsdata *fsd = dentry->d_fsdata;
241 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
244 /* check it wasn't a dir (no fsdata) or automount (no real_fops) */
245 if (fsd && fsd->real_fops) {
246 #ifdef CONFIG_LOCKDEP
247 lockdep_unregister_key(&fsd->key);
248 kfree(fsd->lock_name);
250 WARN_ON(!list_empty(&fsd->cancellations));
251 mutex_destroy(&fsd->cancellations_mtx);
257 static struct vfsmount *debugfs_automount(struct path *path)
259 struct debugfs_fsdata *fsd = path->dentry->d_fsdata;
261 return fsd->automount(path->dentry, d_inode(path->dentry)->i_private);
264 static const struct dentry_operations debugfs_dops = {
265 .d_delete = always_delete_dentry,
266 .d_release = debugfs_release_dentry,
267 .d_automount = debugfs_automount,
270 static int debug_fill_super(struct super_block *sb, void *data, int silent)
272 static const struct tree_descr debug_files[] = {{""}};
273 struct debugfs_fs_info *fsi;
276 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
283 err = debugfs_parse_options(data, &fsi->mount_opts);
287 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
291 sb->s_op = &debugfs_super_operations;
292 sb->s_d_op = &debugfs_dops;
294 debugfs_apply_options(sb);
300 sb->s_fs_info = NULL;
304 static struct dentry *debug_mount(struct file_system_type *fs_type,
305 int flags, const char *dev_name,
308 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
309 return ERR_PTR(-EPERM);
311 return mount_single(fs_type, flags, data, debug_fill_super);
314 static struct file_system_type debug_fs_type = {
315 .owner = THIS_MODULE,
317 .mount = debug_mount,
318 .kill_sb = kill_litter_super,
320 MODULE_ALIAS_FS("debugfs");
323 * debugfs_lookup() - look up an existing debugfs file
324 * @name: a pointer to a string containing the name of the file to look up.
325 * @parent: a pointer to the parent dentry of the file.
327 * This function will return a pointer to a dentry if it succeeds. If the file
328 * doesn't exist or an error occurs, %NULL will be returned. The returned
329 * dentry must be passed to dput() when it is no longer needed.
331 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
334 struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
336 struct dentry *dentry;
338 if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent))
342 parent = debugfs_mount->mnt_root;
344 dentry = lookup_positive_unlocked(name, parent, strlen(name));
349 EXPORT_SYMBOL_GPL(debugfs_lookup);
351 static struct dentry *start_creating(const char *name, struct dentry *parent)
353 struct dentry *dentry;
356 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
357 return ERR_PTR(-EPERM);
359 if (!debugfs_initialized())
360 return ERR_PTR(-ENOENT);
362 pr_debug("creating file '%s'\n", name);
367 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
368 &debugfs_mount_count);
370 pr_err("Unable to pin filesystem for file '%s'\n", name);
371 return ERR_PTR(error);
374 /* If the parent is not specified, we create it in the root.
375 * We need the root dentry to do this, which is in the super
376 * block. A pointer to that is in the struct vfsmount that we
380 parent = debugfs_mount->mnt_root;
382 inode_lock(d_inode(parent));
383 if (unlikely(IS_DEADDIR(d_inode(parent))))
384 dentry = ERR_PTR(-ENOENT);
386 dentry = lookup_one_len(name, parent, strlen(name));
387 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
388 if (d_is_dir(dentry))
389 pr_err("Directory '%s' with parent '%s' already present!\n",
390 name, parent->d_name.name);
392 pr_err("File '%s' in directory '%s' already present!\n",
393 name, parent->d_name.name);
395 dentry = ERR_PTR(-EEXIST);
398 if (IS_ERR(dentry)) {
399 inode_unlock(d_inode(parent));
400 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
406 static struct dentry *failed_creating(struct dentry *dentry)
408 inode_unlock(d_inode(dentry->d_parent));
410 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
411 return ERR_PTR(-ENOMEM);
414 static struct dentry *end_creating(struct dentry *dentry)
416 inode_unlock(d_inode(dentry->d_parent));
420 static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
421 struct dentry *parent, void *data,
422 const struct file_operations *proxy_fops,
423 const struct file_operations *real_fops)
425 struct dentry *dentry;
428 if (!(mode & S_IFMT))
430 BUG_ON(!S_ISREG(mode));
431 dentry = start_creating(name, parent);
436 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
437 failed_creating(dentry);
438 return ERR_PTR(-EPERM);
441 inode = debugfs_get_inode(dentry->d_sb);
442 if (unlikely(!inode)) {
443 pr_err("out of free dentries, can not create file '%s'\n",
445 return failed_creating(dentry);
448 inode->i_mode = mode;
449 inode->i_private = data;
451 inode->i_op = &debugfs_file_inode_operations;
452 inode->i_fop = proxy_fops;
453 dentry->d_fsdata = (void *)((unsigned long)real_fops |
454 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
456 d_instantiate(dentry, inode);
457 fsnotify_create(d_inode(dentry->d_parent), dentry);
458 return end_creating(dentry);
462 * debugfs_create_file - create a file in the debugfs filesystem
463 * @name: a pointer to a string containing the name of the file to create.
464 * @mode: the permission that the file should have.
465 * @parent: a pointer to the parent dentry for this file. This should be a
466 * directory dentry if set. If this parameter is NULL, then the
467 * file will be created in the root of the debugfs filesystem.
468 * @data: a pointer to something that the caller will want to get to later
469 * on. The inode.i_private pointer will point to this value on
471 * @fops: a pointer to a struct file_operations that should be used for
474 * This is the basic "create a file" function for debugfs. It allows for a
475 * wide range of flexibility in creating a file, or a directory (if you want
476 * to create a directory, the debugfs_create_dir() function is
477 * recommended to be used instead.)
479 * This function will return a pointer to a dentry if it succeeds. This
480 * pointer must be passed to the debugfs_remove() function when the file is
481 * to be removed (no automatic cleanup happens if your module is unloaded,
482 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
485 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
488 * NOTE: it's expected that most callers should _ignore_ the errors returned
489 * by this function. Other debugfs functions handle the fact that the "dentry"
490 * passed to them could be an error and they don't crash in that case.
491 * Drivers should generally work fine even if debugfs fails to init anyway.
493 struct dentry *debugfs_create_file(const char *name, umode_t mode,
494 struct dentry *parent, void *data,
495 const struct file_operations *fops)
498 return __debugfs_create_file(name, mode, parent, data,
499 fops ? &debugfs_full_proxy_file_operations :
500 &debugfs_noop_file_operations,
503 EXPORT_SYMBOL_GPL(debugfs_create_file);
506 * debugfs_create_file_unsafe - create a file in the debugfs filesystem
507 * @name: a pointer to a string containing the name of the file to create.
508 * @mode: the permission that the file should have.
509 * @parent: a pointer to the parent dentry for this file. This should be a
510 * directory dentry if set. If this parameter is NULL, then the
511 * file will be created in the root of the debugfs filesystem.
512 * @data: a pointer to something that the caller will want to get to later
513 * on. The inode.i_private pointer will point to this value on
515 * @fops: a pointer to a struct file_operations that should be used for
518 * debugfs_create_file_unsafe() is completely analogous to
519 * debugfs_create_file(), the only difference being that the fops
520 * handed it will not get protected against file removals by the
523 * It is your responsibility to protect your struct file_operation
524 * methods against file removals by means of debugfs_file_get()
525 * and debugfs_file_put(). ->open() is still protected by
528 * Any struct file_operations defined by means of
529 * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
530 * thus, may be used here.
532 struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
533 struct dentry *parent, void *data,
534 const struct file_operations *fops)
537 return __debugfs_create_file(name, mode, parent, data,
538 fops ? &debugfs_open_proxy_file_operations :
539 &debugfs_noop_file_operations,
542 EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
545 * debugfs_create_file_size - create a file in the debugfs filesystem
546 * @name: a pointer to a string containing the name of the file to create.
547 * @mode: the permission that the file should have.
548 * @parent: a pointer to the parent dentry for this file. This should be a
549 * directory dentry if set. If this parameter is NULL, then the
550 * file will be created in the root of the debugfs filesystem.
551 * @data: a pointer to something that the caller will want to get to later
552 * on. The inode.i_private pointer will point to this value on
554 * @fops: a pointer to a struct file_operations that should be used for
556 * @file_size: initial file size
558 * This is the basic "create a file" function for debugfs. It allows for a
559 * wide range of flexibility in creating a file, or a directory (if you want
560 * to create a directory, the debugfs_create_dir() function is
561 * recommended to be used instead.)
563 void debugfs_create_file_size(const char *name, umode_t mode,
564 struct dentry *parent, void *data,
565 const struct file_operations *fops,
568 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
571 d_inode(de)->i_size = file_size;
573 EXPORT_SYMBOL_GPL(debugfs_create_file_size);
576 * debugfs_create_dir - create a directory in the debugfs filesystem
577 * @name: a pointer to a string containing the name of the directory to
579 * @parent: a pointer to the parent dentry for this file. This should be a
580 * directory dentry if set. If this parameter is NULL, then the
581 * directory will be created in the root of the debugfs filesystem.
583 * This function creates a directory in debugfs with the given name.
585 * This function will return a pointer to a dentry if it succeeds. This
586 * pointer must be passed to the debugfs_remove() function when the file is
587 * to be removed (no automatic cleanup happens if your module is unloaded,
588 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
591 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
594 * NOTE: it's expected that most callers should _ignore_ the errors returned
595 * by this function. Other debugfs functions handle the fact that the "dentry"
596 * passed to them could be an error and they don't crash in that case.
597 * Drivers should generally work fine even if debugfs fails to init anyway.
599 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
601 struct dentry *dentry = start_creating(name, parent);
607 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
608 failed_creating(dentry);
609 return ERR_PTR(-EPERM);
612 inode = debugfs_get_inode(dentry->d_sb);
613 if (unlikely(!inode)) {
614 pr_err("out of free dentries, can not create directory '%s'\n",
616 return failed_creating(dentry);
619 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
620 inode->i_op = &debugfs_dir_inode_operations;
621 inode->i_fop = &simple_dir_operations;
623 /* directory inodes start off with i_nlink == 2 (for "." entry) */
625 d_instantiate(dentry, inode);
626 inc_nlink(d_inode(dentry->d_parent));
627 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
628 return end_creating(dentry);
630 EXPORT_SYMBOL_GPL(debugfs_create_dir);
633 * debugfs_create_automount - create automount point in the debugfs filesystem
634 * @name: a pointer to a string containing the name of the file to create.
635 * @parent: a pointer to the parent dentry for this file. This should be a
636 * directory dentry if set. If this parameter is NULL, then the
637 * file will be created in the root of the debugfs filesystem.
638 * @f: function to be called when pathname resolution steps on that one.
639 * @data: opaque argument to pass to f().
641 * @f should return what ->d_automount() would.
643 struct dentry *debugfs_create_automount(const char *name,
644 struct dentry *parent,
645 debugfs_automount_t f,
648 struct dentry *dentry = start_creating(name, parent);
649 struct debugfs_fsdata *fsd;
655 fsd = kzalloc(sizeof(*fsd), GFP_KERNEL);
657 failed_creating(dentry);
658 return ERR_PTR(-ENOMEM);
663 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
664 failed_creating(dentry);
666 return ERR_PTR(-EPERM);
669 inode = debugfs_get_inode(dentry->d_sb);
670 if (unlikely(!inode)) {
671 pr_err("out of free dentries, can not create automount '%s'\n",
674 return failed_creating(dentry);
677 make_empty_dir_inode(inode);
678 inode->i_flags |= S_AUTOMOUNT;
679 inode->i_private = data;
680 dentry->d_fsdata = fsd;
681 /* directory inodes start off with i_nlink == 2 (for "." entry) */
683 d_instantiate(dentry, inode);
684 inc_nlink(d_inode(dentry->d_parent));
685 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
686 return end_creating(dentry);
688 EXPORT_SYMBOL(debugfs_create_automount);
691 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
692 * @name: a pointer to a string containing the name of the symbolic link to
694 * @parent: a pointer to the parent dentry for this symbolic link. This
695 * should be a directory dentry if set. If this parameter is NULL,
696 * then the symbolic link will be created in the root of the debugfs
698 * @target: a pointer to a string containing the path to the target of the
701 * This function creates a symbolic link with the given name in debugfs that
702 * links to the given target path.
704 * This function will return a pointer to a dentry if it succeeds. This
705 * pointer must be passed to the debugfs_remove() function when the symbolic
706 * link is to be removed (no automatic cleanup happens if your module is
707 * unloaded, you are responsible here.) If an error occurs, ERR_PTR(-ERROR)
710 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
713 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
716 struct dentry *dentry;
718 char *link = kstrdup(target, GFP_KERNEL);
720 return ERR_PTR(-ENOMEM);
722 dentry = start_creating(name, parent);
723 if (IS_ERR(dentry)) {
728 inode = debugfs_get_inode(dentry->d_sb);
729 if (unlikely(!inode)) {
730 pr_err("out of free dentries, can not create symlink '%s'\n",
733 return failed_creating(dentry);
735 inode->i_mode = S_IFLNK | S_IRWXUGO;
736 inode->i_op = &debugfs_symlink_inode_operations;
737 inode->i_link = link;
738 d_instantiate(dentry, inode);
739 return end_creating(dentry);
741 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
743 static void __debugfs_file_removed(struct dentry *dentry)
745 struct debugfs_fsdata *fsd;
748 * Paired with the closing smp_mb() implied by a successful
749 * cmpxchg() in debugfs_file_get(): either
750 * debugfs_file_get() must see a dead dentry or we must see a
751 * debugfs_fsdata instance at ->d_fsdata here (or both).
754 fsd = READ_ONCE(dentry->d_fsdata);
755 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
758 lock_map_acquire(&fsd->lockdep_map);
759 lock_map_release(&fsd->lockdep_map);
761 /* if we hit zero, just wait for all to finish */
762 if (!refcount_dec_and_test(&fsd->active_users)) {
763 wait_for_completion(&fsd->active_users_drained);
767 /* if we didn't hit zero, try to cancel any we can */
768 while (refcount_read(&fsd->active_users)) {
769 struct debugfs_cancellation *c;
772 * Lock the cancellations. Note that the cancellations
773 * structs are meant to be on the stack, so we need to
774 * ensure we either use them here or don't touch them,
775 * and debugfs_leave_cancellation() will wait for this
776 * to be finished processing before exiting one. It may
777 * of course win and remove the cancellation, but then
778 * chances are we never even got into this bit, we only
779 * do if the refcount isn't zero already.
781 mutex_lock(&fsd->cancellations_mtx);
782 while ((c = list_first_entry_or_null(&fsd->cancellations,
783 typeof(*c), list))) {
784 list_del_init(&c->list);
785 c->cancel(dentry, c->cancel_data);
787 mutex_unlock(&fsd->cancellations_mtx);
789 wait_for_completion(&fsd->active_users_drained);
793 static void remove_one(struct dentry *victim)
795 if (d_is_reg(victim))
796 __debugfs_file_removed(victim);
797 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
801 * debugfs_remove - recursively removes a directory
802 * @dentry: a pointer to a the dentry of the directory to be removed. If this
803 * parameter is NULL or an error value, nothing will be done.
805 * This function recursively removes a directory tree in debugfs that
806 * was previously created with a call to another debugfs function
807 * (like debugfs_create_file() or variants thereof.)
809 * This function is required to be called in order for the file to be
810 * removed, no automatic cleanup of files will happen when a module is
811 * removed, you are responsible here.
813 void debugfs_remove(struct dentry *dentry)
815 if (IS_ERR_OR_NULL(dentry))
818 simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
819 simple_recursive_removal(dentry, remove_one);
820 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
822 EXPORT_SYMBOL_GPL(debugfs_remove);
825 * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it
826 * @name: a pointer to a string containing the name of the item to look up.
827 * @parent: a pointer to the parent dentry of the item.
829 * This is the equlivant of doing something like
830 * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting
831 * handled for the directory being looked up.
833 void debugfs_lookup_and_remove(const char *name, struct dentry *parent)
835 struct dentry *dentry;
837 dentry = debugfs_lookup(name, parent);
841 debugfs_remove(dentry);
844 EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove);
847 * debugfs_rename - rename a file/directory in the debugfs filesystem
848 * @old_dir: a pointer to the parent dentry for the renamed object. This
849 * should be a directory dentry.
850 * @old_dentry: dentry of an object to be renamed.
851 * @new_dir: a pointer to the parent dentry where the object should be
852 * moved. This should be a directory dentry.
853 * @new_name: a pointer to a string containing the target name.
855 * This function renames a file/directory in debugfs. The target must not
856 * exist for rename to succeed.
858 * This function will return a pointer to old_dentry (which is updated to
859 * reflect renaming) if it succeeds. If an error occurs, ERR_PTR(-ERROR)
862 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
865 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
866 struct dentry *new_dir, const char *new_name)
869 struct dentry *dentry = NULL, *trap;
870 struct name_snapshot old_name;
876 if (IS_ERR_OR_NULL(old_dentry))
879 trap = lock_rename(new_dir, old_dir);
880 /* Source or destination directories don't exist? */
881 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
883 /* Source does not exist, cyclic rename, or mountpoint? */
884 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
885 d_mountpoint(old_dentry))
887 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
888 /* Lookup failed, cyclic rename or target exists? */
889 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
892 take_dentry_name_snapshot(&old_name, old_dentry);
894 error = simple_rename(&nop_mnt_idmap, d_inode(old_dir), old_dentry,
895 d_inode(new_dir), dentry, 0);
897 release_dentry_name_snapshot(&old_name);
900 d_move(old_dentry, dentry);
901 fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
902 d_is_dir(old_dentry),
904 release_dentry_name_snapshot(&old_name);
905 unlock_rename(new_dir, old_dir);
909 if (dentry && !IS_ERR(dentry))
911 unlock_rename(new_dir, old_dir);
914 return ERR_PTR(-EINVAL);
916 EXPORT_SYMBOL_GPL(debugfs_rename);
919 * debugfs_initialized - Tells whether debugfs has been registered
921 bool debugfs_initialized(void)
923 return debugfs_registered;
925 EXPORT_SYMBOL_GPL(debugfs_initialized);
927 static int __init debugfs_kernel(char *str)
930 if (!strcmp(str, "on"))
931 debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT;
932 else if (!strcmp(str, "no-mount"))
933 debugfs_allow = DEBUGFS_ALLOW_API;
934 else if (!strcmp(str, "off"))
940 early_param("debugfs", debugfs_kernel);
941 static int __init debugfs_init(void)
945 if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT))
948 retval = sysfs_create_mount_point(kernel_kobj, "debug");
952 retval = register_filesystem(&debug_fs_type);
954 sysfs_remove_mount_point(kernel_kobj, "debug");
956 debugfs_registered = true;
960 core_initcall(debugfs_init);