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;
296 if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent))
300 parent = debugfs_mount->mnt_root;
302 dentry = lookup_positive_unlocked(name, parent, strlen(name));
307 EXPORT_SYMBOL_GPL(debugfs_lookup);
309 static struct dentry *start_creating(const char *name, struct dentry *parent)
311 struct dentry *dentry;
314 if (!debugfs_initialized())
315 return ERR_PTR(-ENOENT);
317 pr_debug("creating file '%s'\n", name);
322 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
323 &debugfs_mount_count);
325 pr_err("Unable to pin filesystem for file '%s'\n", name);
326 return ERR_PTR(error);
329 /* If the parent is not specified, we create it in the root.
330 * We need the root dentry to do this, which is in the super
331 * block. A pointer to that is in the struct vfsmount that we
335 parent = debugfs_mount->mnt_root;
337 inode_lock(d_inode(parent));
338 dentry = lookup_one_len(name, parent, strlen(name));
339 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
340 if (d_is_dir(dentry))
341 pr_err("Directory '%s' with parent '%s' already present!\n",
342 name, parent->d_name.name);
344 pr_err("File '%s' in directory '%s' already present!\n",
345 name, parent->d_name.name);
347 dentry = ERR_PTR(-EEXIST);
350 if (IS_ERR(dentry)) {
351 inode_unlock(d_inode(parent));
352 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
358 static struct dentry *failed_creating(struct dentry *dentry)
360 inode_unlock(d_inode(dentry->d_parent));
362 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
363 return ERR_PTR(-ENOMEM);
366 static struct dentry *end_creating(struct dentry *dentry)
368 inode_unlock(d_inode(dentry->d_parent));
372 static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
373 struct dentry *parent, void *data,
374 const struct file_operations *proxy_fops,
375 const struct file_operations *real_fops)
377 struct dentry *dentry;
380 if (!(mode & S_IFMT))
382 BUG_ON(!S_ISREG(mode));
383 dentry = start_creating(name, parent);
388 inode = debugfs_get_inode(dentry->d_sb);
389 if (unlikely(!inode)) {
390 pr_err("out of free dentries, can not create file '%s'\n",
392 return failed_creating(dentry);
395 inode->i_mode = mode;
396 inode->i_private = data;
398 inode->i_op = &debugfs_file_inode_operations;
399 inode->i_fop = proxy_fops;
400 dentry->d_fsdata = (void *)((unsigned long)real_fops |
401 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
403 d_instantiate(dentry, inode);
404 fsnotify_create(d_inode(dentry->d_parent), dentry);
405 return end_creating(dentry);
409 * debugfs_create_file - 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 * This is the basic "create a file" function for debugfs. It allows for a
422 * wide range of flexibility in creating a file, or a directory (if you want
423 * to create a directory, the debugfs_create_dir() function is
424 * recommended to be used instead.)
426 * This function will return a pointer to a dentry if it succeeds. This
427 * pointer must be passed to the debugfs_remove() function when the file is
428 * to be removed (no automatic cleanup happens if your module is unloaded,
429 * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be
432 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
435 struct dentry *debugfs_create_file(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_full_proxy_file_operations :
442 &debugfs_noop_file_operations,
445 EXPORT_SYMBOL_GPL(debugfs_create_file);
448 * debugfs_create_file_unsafe - 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
460 * debugfs_create_file_unsafe() is completely analogous to
461 * debugfs_create_file(), the only difference being that the fops
462 * handed it will not get protected against file removals by the
465 * It is your responsibility to protect your struct file_operation
466 * methods against file removals by means of debugfs_file_get()
467 * and debugfs_file_put(). ->open() is still protected by
470 * Any struct file_operations defined by means of
471 * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
472 * thus, may be used here.
474 struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
475 struct dentry *parent, void *data,
476 const struct file_operations *fops)
479 return __debugfs_create_file(name, mode, parent, data,
480 fops ? &debugfs_open_proxy_file_operations :
481 &debugfs_noop_file_operations,
484 EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
487 * debugfs_create_file_size - create a file in the debugfs filesystem
488 * @name: a pointer to a string containing the name of the file to create.
489 * @mode: the permission that the file should have.
490 * @parent: a pointer to the parent dentry for this file. This should be a
491 * directory dentry if set. If this parameter is NULL, then the
492 * file will be created in the root of the debugfs filesystem.
493 * @data: a pointer to something that the caller will want to get to later
494 * on. The inode.i_private pointer will point to this value on
496 * @fops: a pointer to a struct file_operations that should be used for
498 * @file_size: initial file size
500 * This is the basic "create a file" function for debugfs. It allows for a
501 * wide range of flexibility in creating a file, or a directory (if you want
502 * to create a directory, the debugfs_create_dir() function is
503 * recommended to be used instead.)
505 * This function will return a pointer to a dentry if it succeeds. This
506 * pointer must be passed to the debugfs_remove() function when the file is
507 * to be removed (no automatic cleanup happens if your module is unloaded,
508 * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be
511 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
514 struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
515 struct dentry *parent, void *data,
516 const struct file_operations *fops,
519 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
522 d_inode(de)->i_size = file_size;
525 EXPORT_SYMBOL_GPL(debugfs_create_file_size);
528 * debugfs_create_dir - create a directory in the debugfs filesystem
529 * @name: a pointer to a string containing the name of the directory to
531 * @parent: a pointer to the parent dentry for this file. This should be a
532 * directory dentry if set. If this parameter is NULL, then the
533 * directory will be created in the root of the debugfs filesystem.
535 * This function creates a directory in debugfs with the given name.
537 * This function will return a pointer to a dentry if it succeeds. This
538 * pointer must be passed to the debugfs_remove() function when the file is
539 * to be removed (no automatic cleanup happens if your module is unloaded,
540 * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be
543 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
546 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
548 struct dentry *dentry = start_creating(name, parent);
554 inode = debugfs_get_inode(dentry->d_sb);
555 if (unlikely(!inode)) {
556 pr_err("out of free dentries, can not create directory '%s'\n",
558 return failed_creating(dentry);
561 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
562 inode->i_op = &debugfs_dir_inode_operations;
563 inode->i_fop = &simple_dir_operations;
565 /* directory inodes start off with i_nlink == 2 (for "." entry) */
567 d_instantiate(dentry, inode);
568 inc_nlink(d_inode(dentry->d_parent));
569 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
570 return end_creating(dentry);
572 EXPORT_SYMBOL_GPL(debugfs_create_dir);
575 * debugfs_create_automount - create automount point in the debugfs filesystem
576 * @name: a pointer to a string containing the name of the file to create.
577 * @parent: a pointer to the parent dentry for this file. This should be a
578 * directory dentry if set. If this parameter is NULL, then the
579 * file will be created in the root of the debugfs filesystem.
580 * @f: function to be called when pathname resolution steps on that one.
581 * @data: opaque argument to pass to f().
583 * @f should return what ->d_automount() would.
585 struct dentry *debugfs_create_automount(const char *name,
586 struct dentry *parent,
587 debugfs_automount_t f,
590 struct dentry *dentry = start_creating(name, parent);
596 inode = debugfs_get_inode(dentry->d_sb);
597 if (unlikely(!inode)) {
598 pr_err("out of free dentries, can not create automount '%s'\n",
600 return failed_creating(dentry);
603 make_empty_dir_inode(inode);
604 inode->i_flags |= S_AUTOMOUNT;
605 inode->i_private = data;
606 dentry->d_fsdata = (void *)f;
607 /* directory inodes start off with i_nlink == 2 (for "." entry) */
609 d_instantiate(dentry, inode);
610 inc_nlink(d_inode(dentry->d_parent));
611 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
612 return end_creating(dentry);
614 EXPORT_SYMBOL(debugfs_create_automount);
617 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
618 * @name: a pointer to a string containing the name of the symbolic link to
620 * @parent: a pointer to the parent dentry for this symbolic link. This
621 * should be a directory dentry if set. If this parameter is NULL,
622 * then the symbolic link will be created in the root of the debugfs
624 * @target: a pointer to a string containing the path to the target of the
627 * This function creates a symbolic link with the given name in debugfs that
628 * links to the given target path.
630 * This function will return a pointer to a dentry if it succeeds. This
631 * pointer must be passed to the debugfs_remove() function when the symbolic
632 * link is to be removed (no automatic cleanup happens if your module is
633 * unloaded, you are responsible here.) If an error occurs, %ERR_PTR(-ERROR)
636 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
639 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
642 struct dentry *dentry;
644 char *link = kstrdup(target, GFP_KERNEL);
646 return ERR_PTR(-ENOMEM);
648 dentry = start_creating(name, parent);
649 if (IS_ERR(dentry)) {
654 inode = debugfs_get_inode(dentry->d_sb);
655 if (unlikely(!inode)) {
656 pr_err("out of free dentries, can not create symlink '%s'\n",
659 return failed_creating(dentry);
661 inode->i_mode = S_IFLNK | S_IRWXUGO;
662 inode->i_op = &debugfs_symlink_inode_operations;
663 inode->i_link = link;
664 d_instantiate(dentry, inode);
665 return end_creating(dentry);
667 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
669 static void __debugfs_file_removed(struct dentry *dentry)
671 struct debugfs_fsdata *fsd;
674 * Paired with the closing smp_mb() implied by a successful
675 * cmpxchg() in debugfs_file_get(): either
676 * debugfs_file_get() must see a dead dentry or we must see a
677 * debugfs_fsdata instance at ->d_fsdata here (or both).
680 fsd = READ_ONCE(dentry->d_fsdata);
681 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
683 if (!refcount_dec_and_test(&fsd->active_users))
684 wait_for_completion(&fsd->active_users_drained);
687 static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
691 if (simple_positive(dentry)) {
693 if (d_is_dir(dentry)) {
694 ret = simple_rmdir(d_inode(parent), dentry);
696 fsnotify_rmdir(d_inode(parent), dentry);
698 simple_unlink(d_inode(parent), dentry);
699 fsnotify_unlink(d_inode(parent), dentry);
703 if (d_is_reg(dentry))
704 __debugfs_file_removed(dentry);
711 * debugfs_remove - removes a file or directory from the debugfs filesystem
712 * @dentry: a pointer to a the dentry of the file or directory to be
713 * removed. If this parameter is NULL or an error value, nothing
716 * This function removes a file or directory in debugfs that was previously
717 * created with a call to another debugfs function (like
718 * debugfs_create_file() or variants thereof.)
720 * This function is required to be called in order for the file to be
721 * removed, no automatic cleanup of files will happen when a module is
722 * removed, you are responsible here.
724 void debugfs_remove(struct dentry *dentry)
726 struct dentry *parent;
729 if (IS_ERR_OR_NULL(dentry))
732 parent = dentry->d_parent;
733 inode_lock(d_inode(parent));
734 ret = __debugfs_remove(dentry, parent);
735 inode_unlock(d_inode(parent));
737 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
739 EXPORT_SYMBOL_GPL(debugfs_remove);
742 * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it
743 * @name: a pointer to a string containing the name of the item to look up.
744 * @parent: a pointer to the parent dentry of the item.
746 * This is the equlivant of doing something like
747 * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting
748 * handled for the directory being looked up.
750 void debugfs_lookup_and_remove(const char *name, struct dentry *parent)
752 struct dentry *dentry;
754 dentry = debugfs_lookup(name, parent);
758 debugfs_remove(dentry);
761 EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove);
764 * debugfs_remove_recursive - recursively removes a directory
765 * @dentry: a pointer to a the dentry of the directory to be removed. If this
766 * parameter is NULL or an error value, nothing will be done.
768 * This function recursively removes a directory tree in debugfs that
769 * was previously created with a call to another debugfs function
770 * (like debugfs_create_file() or variants thereof.)
772 * This function is required to be called in order for the file to be
773 * removed, no automatic cleanup of files will happen when a module is
774 * removed, you are responsible here.
776 void debugfs_remove_recursive(struct dentry *dentry)
778 struct dentry *child, *parent;
780 if (IS_ERR_OR_NULL(dentry))
785 inode_lock(d_inode(parent));
788 * The parent->d_subdirs is protected by the d_lock. Outside that
789 * lock, the child can be unlinked and set to be freed which can
790 * use the d_u.d_child as the rcu head and corrupt this list.
792 spin_lock(&parent->d_lock);
793 list_for_each_entry(child, &parent->d_subdirs, d_child) {
794 if (!simple_positive(child))
797 /* perhaps simple_empty(child) makes more sense */
798 if (!list_empty(&child->d_subdirs)) {
799 spin_unlock(&parent->d_lock);
800 inode_unlock(d_inode(parent));
805 spin_unlock(&parent->d_lock);
807 if (!__debugfs_remove(child, parent))
808 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
811 * The parent->d_lock protects agaist child from unlinking
812 * from d_subdirs. When releasing the parent->d_lock we can
813 * no longer trust that the next pointer is valid.
814 * Restart the loop. We'll skip this one with the
815 * simple_positive() check.
819 spin_unlock(&parent->d_lock);
821 inode_unlock(d_inode(parent));
823 parent = parent->d_parent;
824 inode_lock(d_inode(parent));
830 if (!__debugfs_remove(child, parent))
831 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
832 inode_unlock(d_inode(parent));
834 EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
837 * debugfs_rename - rename a file/directory in the debugfs filesystem
838 * @old_dir: a pointer to the parent dentry for the renamed object. This
839 * should be a directory dentry.
840 * @old_dentry: dentry of an object to be renamed.
841 * @new_dir: a pointer to the parent dentry where the object should be
842 * moved. This should be a directory dentry.
843 * @new_name: a pointer to a string containing the target name.
845 * This function renames a file/directory in debugfs. The target must not
846 * exist for rename to succeed.
848 * This function will return a pointer to old_dentry (which is updated to
849 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
852 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
855 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
856 struct dentry *new_dir, const char *new_name)
859 struct dentry *dentry = NULL, *trap;
860 struct name_snapshot old_name;
866 if (IS_ERR_OR_NULL(old_dentry))
869 trap = lock_rename(new_dir, old_dir);
870 /* Source or destination directories don't exist? */
871 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
873 /* Source does not exist, cyclic rename, or mountpoint? */
874 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
875 d_mountpoint(old_dentry))
877 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
878 /* Lookup failed, cyclic rename or target exists? */
879 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
882 take_dentry_name_snapshot(&old_name, old_dentry);
884 error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
887 release_dentry_name_snapshot(&old_name);
890 d_move(old_dentry, dentry);
891 fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
892 d_is_dir(old_dentry),
894 release_dentry_name_snapshot(&old_name);
895 unlock_rename(new_dir, old_dir);
899 if (dentry && !IS_ERR(dentry))
901 unlock_rename(new_dir, old_dir);
904 return ERR_PTR(-EINVAL);
906 EXPORT_SYMBOL_GPL(debugfs_rename);
909 * debugfs_initialized - Tells whether debugfs has been registered
911 bool debugfs_initialized(void)
913 return debugfs_registered;
915 EXPORT_SYMBOL_GPL(debugfs_initialized);
917 static int __init debugfs_init(void)
921 retval = sysfs_create_mount_point(kernel_kobj, "debug");
925 retval = register_filesystem(&debug_fs_type);
927 sysfs_remove_mount_point(kernel_kobj, "debug");
929 debugfs_registered = true;
933 core_initcall(debugfs_init);