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 inode->i_atime = inode->i_mtime = inode_set_ctime_current(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)
247 static struct vfsmount *debugfs_automount(struct path *path)
249 struct debugfs_fsdata *fsd = path->dentry->d_fsdata;
251 return fsd->automount(path->dentry, d_inode(path->dentry)->i_private);
254 static const struct dentry_operations debugfs_dops = {
255 .d_delete = always_delete_dentry,
256 .d_release = debugfs_release_dentry,
257 .d_automount = debugfs_automount,
260 static int debug_fill_super(struct super_block *sb, void *data, int silent)
262 static const struct tree_descr debug_files[] = {{""}};
263 struct debugfs_fs_info *fsi;
266 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
273 err = debugfs_parse_options(data, &fsi->mount_opts);
277 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
281 sb->s_op = &debugfs_super_operations;
282 sb->s_d_op = &debugfs_dops;
284 debugfs_apply_options(sb);
290 sb->s_fs_info = NULL;
294 static struct dentry *debug_mount(struct file_system_type *fs_type,
295 int flags, const char *dev_name,
298 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
299 return ERR_PTR(-EPERM);
301 return mount_single(fs_type, flags, data, debug_fill_super);
304 static struct file_system_type debug_fs_type = {
305 .owner = THIS_MODULE,
307 .mount = debug_mount,
308 .kill_sb = kill_litter_super,
310 MODULE_ALIAS_FS("debugfs");
313 * debugfs_lookup() - look up an existing debugfs file
314 * @name: a pointer to a string containing the name of the file to look up.
315 * @parent: a pointer to the parent dentry of the file.
317 * This function will return a pointer to a dentry if it succeeds. If the file
318 * doesn't exist or an error occurs, %NULL will be returned. The returned
319 * dentry must be passed to dput() when it is no longer needed.
321 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
324 struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
326 struct dentry *dentry;
328 if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent))
332 parent = debugfs_mount->mnt_root;
334 dentry = lookup_positive_unlocked(name, parent, strlen(name));
339 EXPORT_SYMBOL_GPL(debugfs_lookup);
341 static struct dentry *start_creating(const char *name, struct dentry *parent)
343 struct dentry *dentry;
346 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
347 return ERR_PTR(-EPERM);
349 if (!debugfs_initialized())
350 return ERR_PTR(-ENOENT);
352 pr_debug("creating file '%s'\n", name);
357 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
358 &debugfs_mount_count);
360 pr_err("Unable to pin filesystem for file '%s'\n", name);
361 return ERR_PTR(error);
364 /* If the parent is not specified, we create it in the root.
365 * We need the root dentry to do this, which is in the super
366 * block. A pointer to that is in the struct vfsmount that we
370 parent = debugfs_mount->mnt_root;
372 inode_lock(d_inode(parent));
373 if (unlikely(IS_DEADDIR(d_inode(parent))))
374 dentry = ERR_PTR(-ENOENT);
376 dentry = lookup_one_len(name, parent, strlen(name));
377 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
378 if (d_is_dir(dentry))
379 pr_err("Directory '%s' with parent '%s' already present!\n",
380 name, parent->d_name.name);
382 pr_err("File '%s' in directory '%s' already present!\n",
383 name, parent->d_name.name);
385 dentry = ERR_PTR(-EEXIST);
388 if (IS_ERR(dentry)) {
389 inode_unlock(d_inode(parent));
390 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
396 static struct dentry *failed_creating(struct dentry *dentry)
398 inode_unlock(d_inode(dentry->d_parent));
400 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
401 return ERR_PTR(-ENOMEM);
404 static struct dentry *end_creating(struct dentry *dentry)
406 inode_unlock(d_inode(dentry->d_parent));
410 static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
411 struct dentry *parent, void *data,
412 const struct file_operations *proxy_fops,
413 const struct file_operations *real_fops)
415 struct dentry *dentry;
418 if (!(mode & S_IFMT))
420 BUG_ON(!S_ISREG(mode));
421 dentry = start_creating(name, parent);
426 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
427 failed_creating(dentry);
428 return ERR_PTR(-EPERM);
431 inode = debugfs_get_inode(dentry->d_sb);
432 if (unlikely(!inode)) {
433 pr_err("out of free dentries, can not create file '%s'\n",
435 return failed_creating(dentry);
438 inode->i_mode = mode;
439 inode->i_private = data;
441 inode->i_op = &debugfs_file_inode_operations;
442 inode->i_fop = proxy_fops;
443 dentry->d_fsdata = (void *)((unsigned long)real_fops |
444 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
446 d_instantiate(dentry, inode);
447 fsnotify_create(d_inode(dentry->d_parent), dentry);
448 return end_creating(dentry);
452 * debugfs_create_file - create a file in the debugfs filesystem
453 * @name: a pointer to a string containing the name of the file to create.
454 * @mode: the permission that the file should have.
455 * @parent: a pointer to the parent dentry for this file. This should be a
456 * directory dentry if set. If this parameter is NULL, then the
457 * file will be created in the root of the debugfs filesystem.
458 * @data: a pointer to something that the caller will want to get to later
459 * on. The inode.i_private pointer will point to this value on
461 * @fops: a pointer to a struct file_operations that should be used for
464 * This is the basic "create a file" function for debugfs. It allows for a
465 * wide range of flexibility in creating a file, or a directory (if you want
466 * to create a directory, the debugfs_create_dir() function is
467 * recommended to be used instead.)
469 * This function will return a pointer to a dentry if it succeeds. This
470 * pointer must be passed to the debugfs_remove() function when the file is
471 * to be removed (no automatic cleanup happens if your module is unloaded,
472 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
475 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
478 * NOTE: it's expected that most callers should _ignore_ the errors returned
479 * by this function. Other debugfs functions handle the fact that the "dentry"
480 * passed to them could be an error and they don't crash in that case.
481 * Drivers should generally work fine even if debugfs fails to init anyway.
483 struct dentry *debugfs_create_file(const char *name, umode_t mode,
484 struct dentry *parent, void *data,
485 const struct file_operations *fops)
488 return __debugfs_create_file(name, mode, parent, data,
489 fops ? &debugfs_full_proxy_file_operations :
490 &debugfs_noop_file_operations,
493 EXPORT_SYMBOL_GPL(debugfs_create_file);
496 * debugfs_create_file_unsafe - create a file in the debugfs filesystem
497 * @name: a pointer to a string containing the name of the file to create.
498 * @mode: the permission that the file should have.
499 * @parent: a pointer to the parent dentry for this file. This should be a
500 * directory dentry if set. If this parameter is NULL, then the
501 * file will be created in the root of the debugfs filesystem.
502 * @data: a pointer to something that the caller will want to get to later
503 * on. The inode.i_private pointer will point to this value on
505 * @fops: a pointer to a struct file_operations that should be used for
508 * debugfs_create_file_unsafe() is completely analogous to
509 * debugfs_create_file(), the only difference being that the fops
510 * handed it will not get protected against file removals by the
513 * It is your responsibility to protect your struct file_operation
514 * methods against file removals by means of debugfs_file_get()
515 * and debugfs_file_put(). ->open() is still protected by
518 * Any struct file_operations defined by means of
519 * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
520 * thus, may be used here.
522 struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
523 struct dentry *parent, void *data,
524 const struct file_operations *fops)
527 return __debugfs_create_file(name, mode, parent, data,
528 fops ? &debugfs_open_proxy_file_operations :
529 &debugfs_noop_file_operations,
532 EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
535 * debugfs_create_file_size - create a file in the debugfs filesystem
536 * @name: a pointer to a string containing the name of the file to create.
537 * @mode: the permission that the file should have.
538 * @parent: a pointer to the parent dentry for this file. This should be a
539 * directory dentry if set. If this parameter is NULL, then the
540 * file will be created in the root of the debugfs filesystem.
541 * @data: a pointer to something that the caller will want to get to later
542 * on. The inode.i_private pointer will point to this value on
544 * @fops: a pointer to a struct file_operations that should be used for
546 * @file_size: initial file size
548 * This is the basic "create a file" function for debugfs. It allows for a
549 * wide range of flexibility in creating a file, or a directory (if you want
550 * to create a directory, the debugfs_create_dir() function is
551 * recommended to be used instead.)
553 void debugfs_create_file_size(const char *name, umode_t mode,
554 struct dentry *parent, void *data,
555 const struct file_operations *fops,
558 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
561 d_inode(de)->i_size = file_size;
563 EXPORT_SYMBOL_GPL(debugfs_create_file_size);
566 * debugfs_create_dir - create a directory in the debugfs filesystem
567 * @name: a pointer to a string containing the name of the directory to
569 * @parent: a pointer to the parent dentry for this file. This should be a
570 * directory dentry if set. If this parameter is NULL, then the
571 * directory will be created in the root of the debugfs filesystem.
573 * This function creates a directory in debugfs with the given name.
575 * This function will return a pointer to a dentry if it succeeds. This
576 * pointer must be passed to the debugfs_remove() function when the file is
577 * to be removed (no automatic cleanup happens if your module is unloaded,
578 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
581 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
584 * NOTE: it's expected that most callers should _ignore_ the errors returned
585 * by this function. Other debugfs functions handle the fact that the "dentry"
586 * passed to them could be an error and they don't crash in that case.
587 * Drivers should generally work fine even if debugfs fails to init anyway.
589 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
591 struct dentry *dentry = start_creating(name, parent);
597 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
598 failed_creating(dentry);
599 return ERR_PTR(-EPERM);
602 inode = debugfs_get_inode(dentry->d_sb);
603 if (unlikely(!inode)) {
604 pr_err("out of free dentries, can not create directory '%s'\n",
606 return failed_creating(dentry);
609 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
610 inode->i_op = &debugfs_dir_inode_operations;
611 inode->i_fop = &simple_dir_operations;
613 /* directory inodes start off with i_nlink == 2 (for "." entry) */
615 d_instantiate(dentry, inode);
616 inc_nlink(d_inode(dentry->d_parent));
617 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
618 return end_creating(dentry);
620 EXPORT_SYMBOL_GPL(debugfs_create_dir);
623 * debugfs_create_automount - create automount point in the debugfs filesystem
624 * @name: a pointer to a string containing the name of the file to create.
625 * @parent: a pointer to the parent dentry for this file. This should be a
626 * directory dentry if set. If this parameter is NULL, then the
627 * file will be created in the root of the debugfs filesystem.
628 * @f: function to be called when pathname resolution steps on that one.
629 * @data: opaque argument to pass to f().
631 * @f should return what ->d_automount() would.
633 struct dentry *debugfs_create_automount(const char *name,
634 struct dentry *parent,
635 debugfs_automount_t f,
638 struct dentry *dentry = start_creating(name, parent);
639 struct debugfs_fsdata *fsd;
645 fsd = kzalloc(sizeof(*fsd), GFP_KERNEL);
647 failed_creating(dentry);
648 return ERR_PTR(-ENOMEM);
653 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
654 failed_creating(dentry);
656 return ERR_PTR(-EPERM);
659 inode = debugfs_get_inode(dentry->d_sb);
660 if (unlikely(!inode)) {
661 pr_err("out of free dentries, can not create automount '%s'\n",
664 return failed_creating(dentry);
667 make_empty_dir_inode(inode);
668 inode->i_flags |= S_AUTOMOUNT;
669 inode->i_private = data;
670 dentry->d_fsdata = fsd;
671 /* directory inodes start off with i_nlink == 2 (for "." entry) */
673 d_instantiate(dentry, inode);
674 inc_nlink(d_inode(dentry->d_parent));
675 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
676 return end_creating(dentry);
678 EXPORT_SYMBOL(debugfs_create_automount);
681 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
682 * @name: a pointer to a string containing the name of the symbolic link to
684 * @parent: a pointer to the parent dentry for this symbolic link. This
685 * should be a directory dentry if set. If this parameter is NULL,
686 * then the symbolic link will be created in the root of the debugfs
688 * @target: a pointer to a string containing the path to the target of the
691 * This function creates a symbolic link with the given name in debugfs that
692 * links to the given target path.
694 * This function will return a pointer to a dentry if it succeeds. This
695 * pointer must be passed to the debugfs_remove() function when the symbolic
696 * link is to be removed (no automatic cleanup happens if your module is
697 * unloaded, you are responsible here.) If an error occurs, ERR_PTR(-ERROR)
700 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
703 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
706 struct dentry *dentry;
708 char *link = kstrdup(target, GFP_KERNEL);
710 return ERR_PTR(-ENOMEM);
712 dentry = start_creating(name, parent);
713 if (IS_ERR(dentry)) {
718 inode = debugfs_get_inode(dentry->d_sb);
719 if (unlikely(!inode)) {
720 pr_err("out of free dentries, can not create symlink '%s'\n",
723 return failed_creating(dentry);
725 inode->i_mode = S_IFLNK | S_IRWXUGO;
726 inode->i_op = &debugfs_symlink_inode_operations;
727 inode->i_link = link;
728 d_instantiate(dentry, inode);
729 return end_creating(dentry);
731 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
733 static void __debugfs_file_removed(struct dentry *dentry)
735 struct debugfs_fsdata *fsd;
738 * Paired with the closing smp_mb() implied by a successful
739 * cmpxchg() in debugfs_file_get(): either
740 * debugfs_file_get() must see a dead dentry or we must see a
741 * debugfs_fsdata instance at ->d_fsdata here (or both).
744 fsd = READ_ONCE(dentry->d_fsdata);
745 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
747 if (!refcount_dec_and_test(&fsd->active_users))
748 wait_for_completion(&fsd->active_users_drained);
751 static void remove_one(struct dentry *victim)
753 if (d_is_reg(victim))
754 __debugfs_file_removed(victim);
755 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
759 * debugfs_remove - recursively removes a directory
760 * @dentry: a pointer to a the dentry of the directory to be removed. If this
761 * parameter is NULL or an error value, nothing will be done.
763 * This function recursively removes a directory tree in debugfs that
764 * was previously created with a call to another debugfs function
765 * (like debugfs_create_file() or variants thereof.)
767 * This function is required to be called in order for the file to be
768 * removed, no automatic cleanup of files will happen when a module is
769 * removed, you are responsible here.
771 void debugfs_remove(struct dentry *dentry)
773 if (IS_ERR_OR_NULL(dentry))
776 simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
777 simple_recursive_removal(dentry, remove_one);
778 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
780 EXPORT_SYMBOL_GPL(debugfs_remove);
783 * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it
784 * @name: a pointer to a string containing the name of the item to look up.
785 * @parent: a pointer to the parent dentry of the item.
787 * This is the equlivant of doing something like
788 * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting
789 * handled for the directory being looked up.
791 void debugfs_lookup_and_remove(const char *name, struct dentry *parent)
793 struct dentry *dentry;
795 dentry = debugfs_lookup(name, parent);
799 debugfs_remove(dentry);
802 EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove);
805 * debugfs_rename - rename a file/directory in the debugfs filesystem
806 * @old_dir: a pointer to the parent dentry for the renamed object. This
807 * should be a directory dentry.
808 * @old_dentry: dentry of an object to be renamed.
809 * @new_dir: a pointer to the parent dentry where the object should be
810 * moved. This should be a directory dentry.
811 * @new_name: a pointer to a string containing the target name.
813 * This function renames a file/directory in debugfs. The target must not
814 * exist for rename to succeed.
816 * This function will return a pointer to old_dentry (which is updated to
817 * reflect renaming) if it succeeds. If an error occurs, ERR_PTR(-ERROR)
820 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
823 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
824 struct dentry *new_dir, const char *new_name)
827 struct dentry *dentry = NULL, *trap;
828 struct name_snapshot old_name;
834 if (IS_ERR_OR_NULL(old_dentry))
837 trap = lock_rename(new_dir, old_dir);
838 /* Source or destination directories don't exist? */
839 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
841 /* Source does not exist, cyclic rename, or mountpoint? */
842 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
843 d_mountpoint(old_dentry))
845 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
846 /* Lookup failed, cyclic rename or target exists? */
847 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
850 take_dentry_name_snapshot(&old_name, old_dentry);
852 error = simple_rename(&nop_mnt_idmap, d_inode(old_dir), old_dentry,
853 d_inode(new_dir), dentry, 0);
855 release_dentry_name_snapshot(&old_name);
858 d_move(old_dentry, dentry);
859 fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
860 d_is_dir(old_dentry),
862 release_dentry_name_snapshot(&old_name);
863 unlock_rename(new_dir, old_dir);
867 if (dentry && !IS_ERR(dentry))
869 unlock_rename(new_dir, old_dir);
872 return ERR_PTR(-EINVAL);
874 EXPORT_SYMBOL_GPL(debugfs_rename);
877 * debugfs_initialized - Tells whether debugfs has been registered
879 bool debugfs_initialized(void)
881 return debugfs_registered;
883 EXPORT_SYMBOL_GPL(debugfs_initialized);
885 static int __init debugfs_kernel(char *str)
888 if (!strcmp(str, "on"))
889 debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT;
890 else if (!strcmp(str, "no-mount"))
891 debugfs_allow = DEBUGFS_ALLOW_API;
892 else if (!strcmp(str, "off"))
898 early_param("debugfs", debugfs_kernel);
899 static int __init debugfs_init(void)
903 if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT))
906 retval = sysfs_create_mount_point(kernel_kobj, "debug");
910 retval = register_filesystem(&debug_fs_type);
912 sysfs_remove_mount_point(kernel_kobj, "debug");
914 debugfs_registered = true;
918 core_initcall(debugfs_init);