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/fs_context.h>
18 #include <linux/fs_parser.h>
19 #include <linux/pagemap.h>
20 #include <linux/init.h>
21 #include <linux/kobject.h>
22 #include <linux/namei.h>
23 #include <linux/debugfs.h>
24 #include <linux/fsnotify.h>
25 #include <linux/string.h>
26 #include <linux/seq_file.h>
27 #include <linux/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_fs_info {
94 static const struct fs_parameter_spec debugfs_param_specs[] = {
95 fsparam_u32 ("gid", Opt_gid),
96 fsparam_u32oct ("mode", Opt_mode),
97 fsparam_u32 ("uid", Opt_uid),
101 static int debugfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
103 struct debugfs_fs_info *opts = fc->s_fs_info;
104 struct fs_parse_result result;
109 opt = fs_parse(fc, debugfs_param_specs, param, &result);
115 uid = make_kuid(current_user_ns(), result.uint_32);
117 return invalf(fc, "Unknown uid");
121 gid = make_kgid(current_user_ns(), result.uint_32);
123 return invalf(fc, "Unknown gid");
127 opts->mode = result.uint_32 & S_IALLUGO;
130 * We might like to report bad mount options here;
131 * but traditionally debugfs has ignored all mount options
135 opts->opts |= BIT(opt);
140 static void _debugfs_apply_options(struct super_block *sb, bool remount)
142 struct debugfs_fs_info *fsi = sb->s_fs_info;
143 struct inode *inode = d_inode(sb->s_root);
146 * On remount, only reset mode/uid/gid if they were provided as mount
150 if (!remount || fsi->opts & BIT(Opt_mode)) {
151 inode->i_mode &= ~S_IALLUGO;
152 inode->i_mode |= fsi->mode;
155 if (!remount || fsi->opts & BIT(Opt_uid))
156 inode->i_uid = fsi->uid;
158 if (!remount || fsi->opts & BIT(Opt_gid))
159 inode->i_gid = fsi->gid;
162 static void debugfs_apply_options(struct super_block *sb)
164 _debugfs_apply_options(sb, false);
167 static void debugfs_apply_options_remount(struct super_block *sb)
169 _debugfs_apply_options(sb, true);
172 static int debugfs_reconfigure(struct fs_context *fc)
174 struct super_block *sb = fc->root->d_sb;
175 struct debugfs_fs_info *sb_opts = sb->s_fs_info;
176 struct debugfs_fs_info *new_opts = fc->s_fs_info;
180 /* structure copy of new mount options to sb */
181 *sb_opts = *new_opts;
182 debugfs_apply_options_remount(sb);
187 static int debugfs_show_options(struct seq_file *m, struct dentry *root)
189 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
191 if (!uid_eq(fsi->uid, GLOBAL_ROOT_UID))
192 seq_printf(m, ",uid=%u",
193 from_kuid_munged(&init_user_ns, fsi->uid));
194 if (!gid_eq(fsi->gid, GLOBAL_ROOT_GID))
195 seq_printf(m, ",gid=%u",
196 from_kgid_munged(&init_user_ns, fsi->gid));
197 if (fsi->mode != DEBUGFS_DEFAULT_MODE)
198 seq_printf(m, ",mode=%o", fsi->mode);
203 static void debugfs_free_inode(struct inode *inode)
205 if (S_ISLNK(inode->i_mode))
206 kfree(inode->i_link);
207 free_inode_nonrcu(inode);
210 static const struct super_operations debugfs_super_operations = {
211 .statfs = simple_statfs,
212 .show_options = debugfs_show_options,
213 .free_inode = debugfs_free_inode,
216 static void debugfs_release_dentry(struct dentry *dentry)
218 struct debugfs_fsdata *fsd = dentry->d_fsdata;
220 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
223 /* check it wasn't a dir (no fsdata) or automount (no real_fops) */
224 if (fsd && fsd->real_fops) {
225 WARN_ON(!list_empty(&fsd->cancellations));
226 mutex_destroy(&fsd->cancellations_mtx);
232 static struct vfsmount *debugfs_automount(struct path *path)
234 struct debugfs_fsdata *fsd = path->dentry->d_fsdata;
236 return fsd->automount(path->dentry, d_inode(path->dentry)->i_private);
239 static const struct dentry_operations debugfs_dops = {
240 .d_delete = always_delete_dentry,
241 .d_release = debugfs_release_dentry,
242 .d_automount = debugfs_automount,
245 static int debugfs_fill_super(struct super_block *sb, struct fs_context *fc)
247 static const struct tree_descr debug_files[] = {{""}};
250 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
254 sb->s_op = &debugfs_super_operations;
255 sb->s_d_op = &debugfs_dops;
257 debugfs_apply_options(sb);
262 static int debugfs_get_tree(struct fs_context *fc)
264 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
267 return get_tree_single(fc, debugfs_fill_super);
270 static void debugfs_free_fc(struct fs_context *fc)
272 kfree(fc->s_fs_info);
275 static const struct fs_context_operations debugfs_context_ops = {
276 .free = debugfs_free_fc,
277 .parse_param = debugfs_parse_param,
278 .get_tree = debugfs_get_tree,
279 .reconfigure = debugfs_reconfigure,
282 static int debugfs_init_fs_context(struct fs_context *fc)
284 struct debugfs_fs_info *fsi;
286 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
290 fsi->mode = DEBUGFS_DEFAULT_MODE;
293 fc->ops = &debugfs_context_ops;
297 static struct file_system_type debug_fs_type = {
298 .owner = THIS_MODULE,
300 .init_fs_context = debugfs_init_fs_context,
301 .parameters = debugfs_param_specs,
302 .kill_sb = kill_litter_super,
304 MODULE_ALIAS_FS("debugfs");
307 * debugfs_lookup() - look up an existing debugfs file
308 * @name: a pointer to a string containing the name of the file to look up.
309 * @parent: a pointer to the parent dentry of the file.
311 * This function will return a pointer to a dentry if it succeeds. If the file
312 * doesn't exist or an error occurs, %NULL will be returned. The returned
313 * dentry must be passed to dput() when it is no longer needed.
315 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
318 struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
320 struct dentry *dentry;
322 if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent))
326 parent = debugfs_mount->mnt_root;
328 dentry = lookup_positive_unlocked(name, parent, strlen(name));
333 EXPORT_SYMBOL_GPL(debugfs_lookup);
335 static struct dentry *start_creating(const char *name, struct dentry *parent)
337 struct dentry *dentry;
340 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
341 return ERR_PTR(-EPERM);
343 if (!debugfs_initialized())
344 return ERR_PTR(-ENOENT);
346 pr_debug("creating file '%s'\n", name);
351 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
352 &debugfs_mount_count);
354 pr_err("Unable to pin filesystem for file '%s'\n", name);
355 return ERR_PTR(error);
358 /* If the parent is not specified, we create it in the root.
359 * We need the root dentry to do this, which is in the super
360 * block. A pointer to that is in the struct vfsmount that we
364 parent = debugfs_mount->mnt_root;
366 inode_lock(d_inode(parent));
367 if (unlikely(IS_DEADDIR(d_inode(parent))))
368 dentry = ERR_PTR(-ENOENT);
370 dentry = lookup_one_len(name, parent, strlen(name));
371 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
372 if (d_is_dir(dentry))
373 pr_err("Directory '%s' with parent '%s' already present!\n",
374 name, parent->d_name.name);
376 pr_err("File '%s' in directory '%s' already present!\n",
377 name, parent->d_name.name);
379 dentry = ERR_PTR(-EEXIST);
382 if (IS_ERR(dentry)) {
383 inode_unlock(d_inode(parent));
384 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
390 static struct dentry *failed_creating(struct dentry *dentry)
392 inode_unlock(d_inode(dentry->d_parent));
394 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
395 return ERR_PTR(-ENOMEM);
398 static struct dentry *end_creating(struct dentry *dentry)
400 inode_unlock(d_inode(dentry->d_parent));
404 static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
405 struct dentry *parent, void *data,
406 const struct file_operations *proxy_fops,
407 const struct file_operations *real_fops)
409 struct dentry *dentry;
412 if (!(mode & S_IFMT))
414 BUG_ON(!S_ISREG(mode));
415 dentry = start_creating(name, parent);
420 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
421 failed_creating(dentry);
422 return ERR_PTR(-EPERM);
425 inode = debugfs_get_inode(dentry->d_sb);
426 if (unlikely(!inode)) {
427 pr_err("out of free dentries, can not create file '%s'\n",
429 return failed_creating(dentry);
432 inode->i_mode = mode;
433 inode->i_private = data;
435 inode->i_op = &debugfs_file_inode_operations;
436 inode->i_fop = proxy_fops;
437 dentry->d_fsdata = (void *)((unsigned long)real_fops |
438 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
440 d_instantiate(dentry, inode);
441 fsnotify_create(d_inode(dentry->d_parent), dentry);
442 return end_creating(dentry);
446 * debugfs_create_file - create a file in the debugfs filesystem
447 * @name: a pointer to a string containing the name of the file to create.
448 * @mode: the permission that the file should have.
449 * @parent: a pointer to the parent dentry for this file. This should be a
450 * directory dentry if set. If this parameter is NULL, then the
451 * file will be created in the root of the debugfs filesystem.
452 * @data: a pointer to something that the caller will want to get to later
453 * on. The inode.i_private pointer will point to this value on
455 * @fops: a pointer to a struct file_operations that should be used for
458 * This is the basic "create a file" function for debugfs. It allows for a
459 * wide range of flexibility in creating a file, or a directory (if you want
460 * to create a directory, the debugfs_create_dir() function is
461 * recommended to be used instead.)
463 * This function will return a pointer to a dentry if it succeeds. This
464 * pointer must be passed to the debugfs_remove() function when the file is
465 * to be removed (no automatic cleanup happens if your module is unloaded,
466 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
469 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
472 * NOTE: it's expected that most callers should _ignore_ the errors returned
473 * by this function. Other debugfs functions handle the fact that the "dentry"
474 * passed to them could be an error and they don't crash in that case.
475 * Drivers should generally work fine even if debugfs fails to init anyway.
477 struct dentry *debugfs_create_file(const char *name, umode_t mode,
478 struct dentry *parent, void *data,
479 const struct file_operations *fops)
482 return __debugfs_create_file(name, mode, parent, data,
483 fops ? &debugfs_full_proxy_file_operations :
484 &debugfs_noop_file_operations,
487 EXPORT_SYMBOL_GPL(debugfs_create_file);
490 * debugfs_create_file_unsafe - create a file in the debugfs filesystem
491 * @name: a pointer to a string containing the name of the file to create.
492 * @mode: the permission that the file should have.
493 * @parent: a pointer to the parent dentry for this file. This should be a
494 * directory dentry if set. If this parameter is NULL, then the
495 * file will be created in the root of the debugfs filesystem.
496 * @data: a pointer to something that the caller will want to get to later
497 * on. The inode.i_private pointer will point to this value on
499 * @fops: a pointer to a struct file_operations that should be used for
502 * debugfs_create_file_unsafe() is completely analogous to
503 * debugfs_create_file(), the only difference being that the fops
504 * handed it will not get protected against file removals by the
507 * It is your responsibility to protect your struct file_operation
508 * methods against file removals by means of debugfs_file_get()
509 * and debugfs_file_put(). ->open() is still protected by
512 * Any struct file_operations defined by means of
513 * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
514 * thus, may be used here.
516 struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
517 struct dentry *parent, void *data,
518 const struct file_operations *fops)
521 return __debugfs_create_file(name, mode, parent, data,
522 fops ? &debugfs_open_proxy_file_operations :
523 &debugfs_noop_file_operations,
526 EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
529 * debugfs_create_file_size - create a file in the debugfs filesystem
530 * @name: a pointer to a string containing the name of the file to create.
531 * @mode: the permission that the file should have.
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 * file will be created in the root of the debugfs filesystem.
535 * @data: a pointer to something that the caller will want to get to later
536 * on. The inode.i_private pointer will point to this value on
538 * @fops: a pointer to a struct file_operations that should be used for
540 * @file_size: initial file size
542 * This is the basic "create a file" function for debugfs. It allows for a
543 * wide range of flexibility in creating a file, or a directory (if you want
544 * to create a directory, the debugfs_create_dir() function is
545 * recommended to be used instead.)
547 void debugfs_create_file_size(const char *name, umode_t mode,
548 struct dentry *parent, void *data,
549 const struct file_operations *fops,
552 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
555 d_inode(de)->i_size = file_size;
557 EXPORT_SYMBOL_GPL(debugfs_create_file_size);
560 * debugfs_create_dir - create a directory in the debugfs filesystem
561 * @name: a pointer to a string containing the name of the directory to
563 * @parent: a pointer to the parent dentry for this file. This should be a
564 * directory dentry if set. If this parameter is NULL, then the
565 * directory will be created in the root of the debugfs filesystem.
567 * This function creates a directory in debugfs with the given name.
569 * This function will return a pointer to a dentry if it succeeds. This
570 * pointer must be passed to the debugfs_remove() function when the file is
571 * to be removed (no automatic cleanup happens if your module is unloaded,
572 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
575 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
578 * NOTE: it's expected that most callers should _ignore_ the errors returned
579 * by this function. Other debugfs functions handle the fact that the "dentry"
580 * passed to them could be an error and they don't crash in that case.
581 * Drivers should generally work fine even if debugfs fails to init anyway.
583 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
585 struct dentry *dentry = start_creating(name, parent);
591 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
592 failed_creating(dentry);
593 return ERR_PTR(-EPERM);
596 inode = debugfs_get_inode(dentry->d_sb);
597 if (unlikely(!inode)) {
598 pr_err("out of free dentries, can not create directory '%s'\n",
600 return failed_creating(dentry);
603 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
604 inode->i_op = &debugfs_dir_inode_operations;
605 inode->i_fop = &simple_dir_operations;
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_GPL(debugfs_create_dir);
617 * debugfs_create_automount - create automount point in the debugfs filesystem
618 * @name: a pointer to a string containing the name of the file to create.
619 * @parent: a pointer to the parent dentry for this file. This should be a
620 * directory dentry if set. If this parameter is NULL, then the
621 * file will be created in the root of the debugfs filesystem.
622 * @f: function to be called when pathname resolution steps on that one.
623 * @data: opaque argument to pass to f().
625 * @f should return what ->d_automount() would.
627 struct dentry *debugfs_create_automount(const char *name,
628 struct dentry *parent,
629 debugfs_automount_t f,
632 struct dentry *dentry = start_creating(name, parent);
633 struct debugfs_fsdata *fsd;
639 fsd = kzalloc(sizeof(*fsd), GFP_KERNEL);
641 failed_creating(dentry);
642 return ERR_PTR(-ENOMEM);
647 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
648 failed_creating(dentry);
650 return ERR_PTR(-EPERM);
653 inode = debugfs_get_inode(dentry->d_sb);
654 if (unlikely(!inode)) {
655 pr_err("out of free dentries, can not create automount '%s'\n",
658 return failed_creating(dentry);
661 make_empty_dir_inode(inode);
662 inode->i_flags |= S_AUTOMOUNT;
663 inode->i_private = data;
664 dentry->d_fsdata = fsd;
665 /* directory inodes start off with i_nlink == 2 (for "." entry) */
667 d_instantiate(dentry, inode);
668 inc_nlink(d_inode(dentry->d_parent));
669 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
670 return end_creating(dentry);
672 EXPORT_SYMBOL(debugfs_create_automount);
675 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
676 * @name: a pointer to a string containing the name of the symbolic link to
678 * @parent: a pointer to the parent dentry for this symbolic link. This
679 * should be a directory dentry if set. If this parameter is NULL,
680 * then the symbolic link will be created in the root of the debugfs
682 * @target: a pointer to a string containing the path to the target of the
685 * This function creates a symbolic link with the given name in debugfs that
686 * links to the given target path.
688 * This function will return a pointer to a dentry if it succeeds. This
689 * pointer must be passed to the debugfs_remove() function when the symbolic
690 * link is to be removed (no automatic cleanup happens if your module is
691 * unloaded, you are responsible here.) If an error occurs, ERR_PTR(-ERROR)
694 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
697 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
700 struct dentry *dentry;
702 char *link = kstrdup(target, GFP_KERNEL);
704 return ERR_PTR(-ENOMEM);
706 dentry = start_creating(name, parent);
707 if (IS_ERR(dentry)) {
712 inode = debugfs_get_inode(dentry->d_sb);
713 if (unlikely(!inode)) {
714 pr_err("out of free dentries, can not create symlink '%s'\n",
717 return failed_creating(dentry);
719 inode->i_mode = S_IFLNK | S_IRWXUGO;
720 inode->i_op = &debugfs_symlink_inode_operations;
721 inode->i_link = link;
722 d_instantiate(dentry, inode);
723 return end_creating(dentry);
725 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
727 static void __debugfs_file_removed(struct dentry *dentry)
729 struct debugfs_fsdata *fsd;
732 * Paired with the closing smp_mb() implied by a successful
733 * cmpxchg() in debugfs_file_get(): either
734 * debugfs_file_get() must see a dead dentry or we must see a
735 * debugfs_fsdata instance at ->d_fsdata here (or both).
738 fsd = READ_ONCE(dentry->d_fsdata);
739 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
742 /* if this was the last reference, we're done */
743 if (refcount_dec_and_test(&fsd->active_users))
747 * If there's still a reference, the code that obtained it can
748 * be in different states:
749 * - The common case of not using cancellations, or already
750 * after debugfs_leave_cancellation(), where we just need
751 * to wait for debugfs_file_put() which signals the completion;
752 * - inside a cancellation section, i.e. between
753 * debugfs_enter_cancellation() and debugfs_leave_cancellation(),
754 * in which case we need to trigger the ->cancel() function,
755 * and then wait for debugfs_file_put() just like in the
757 * - before debugfs_enter_cancellation() (but obviously after
758 * debugfs_file_get()), in which case we may not see the
759 * cancellation in the list on the first round of the loop,
760 * but debugfs_enter_cancellation() signals the completion
761 * after adding it, so this code gets woken up to call the
762 * ->cancel() function.
764 while (refcount_read(&fsd->active_users)) {
765 struct debugfs_cancellation *c;
768 * Lock the cancellations. Note that the cancellations
769 * structs are meant to be on the stack, so we need to
770 * ensure we either use them here or don't touch them,
771 * and debugfs_leave_cancellation() will wait for this
772 * to be finished processing before exiting one. It may
773 * of course win and remove the cancellation, but then
774 * chances are we never even got into this bit, we only
775 * do if the refcount isn't zero already.
777 mutex_lock(&fsd->cancellations_mtx);
778 while ((c = list_first_entry_or_null(&fsd->cancellations,
779 typeof(*c), list))) {
780 list_del_init(&c->list);
781 c->cancel(dentry, c->cancel_data);
783 mutex_unlock(&fsd->cancellations_mtx);
785 wait_for_completion(&fsd->active_users_drained);
789 static void remove_one(struct dentry *victim)
791 if (d_is_reg(victim))
792 __debugfs_file_removed(victim);
793 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
797 * debugfs_remove - recursively removes a directory
798 * @dentry: a pointer to a the dentry of the directory to be removed. If this
799 * parameter is NULL or an error value, nothing will be done.
801 * This function recursively removes a directory tree in debugfs that
802 * was previously created with a call to another debugfs function
803 * (like debugfs_create_file() or variants thereof.)
805 * This function is required to be called in order for the file to be
806 * removed, no automatic cleanup of files will happen when a module is
807 * removed, you are responsible here.
809 void debugfs_remove(struct dentry *dentry)
811 if (IS_ERR_OR_NULL(dentry))
814 simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
815 simple_recursive_removal(dentry, remove_one);
816 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
818 EXPORT_SYMBOL_GPL(debugfs_remove);
821 * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it
822 * @name: a pointer to a string containing the name of the item to look up.
823 * @parent: a pointer to the parent dentry of the item.
825 * This is the equlivant of doing something like
826 * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting
827 * handled for the directory being looked up.
829 void debugfs_lookup_and_remove(const char *name, struct dentry *parent)
831 struct dentry *dentry;
833 dentry = debugfs_lookup(name, parent);
837 debugfs_remove(dentry);
840 EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove);
843 * debugfs_rename - rename a file/directory in the debugfs filesystem
844 * @old_dir: a pointer to the parent dentry for the renamed object. This
845 * should be a directory dentry.
846 * @old_dentry: dentry of an object to be renamed.
847 * @new_dir: a pointer to the parent dentry where the object should be
848 * moved. This should be a directory dentry.
849 * @new_name: a pointer to a string containing the target name.
851 * This function renames a file/directory in debugfs. The target must not
852 * exist for rename to succeed.
854 * This function will return a pointer to old_dentry (which is updated to
855 * reflect renaming) if it succeeds. If an error occurs, ERR_PTR(-ERROR)
858 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
861 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
862 struct dentry *new_dir, const char *new_name)
865 struct dentry *dentry = NULL, *trap;
866 struct name_snapshot old_name;
872 if (IS_ERR_OR_NULL(old_dentry))
875 trap = lock_rename(new_dir, old_dir);
876 /* Source or destination directories don't exist? */
877 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
879 /* Source does not exist, cyclic rename, or mountpoint? */
880 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
881 d_mountpoint(old_dentry))
883 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
884 /* Lookup failed, cyclic rename or target exists? */
885 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
888 take_dentry_name_snapshot(&old_name, old_dentry);
890 error = simple_rename(&nop_mnt_idmap, d_inode(old_dir), old_dentry,
891 d_inode(new_dir), dentry, 0);
893 release_dentry_name_snapshot(&old_name);
896 d_move(old_dentry, dentry);
897 fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
898 d_is_dir(old_dentry),
900 release_dentry_name_snapshot(&old_name);
901 unlock_rename(new_dir, old_dir);
905 if (dentry && !IS_ERR(dentry))
907 unlock_rename(new_dir, old_dir);
910 return ERR_PTR(-EINVAL);
912 EXPORT_SYMBOL_GPL(debugfs_rename);
915 * debugfs_initialized - Tells whether debugfs has been registered
917 bool debugfs_initialized(void)
919 return debugfs_registered;
921 EXPORT_SYMBOL_GPL(debugfs_initialized);
923 static int __init debugfs_kernel(char *str)
926 if (!strcmp(str, "on"))
927 debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT;
928 else if (!strcmp(str, "no-mount"))
929 debugfs_allow = DEBUGFS_ALLOW_API;
930 else if (!strcmp(str, "off"))
936 early_param("debugfs", debugfs_kernel);
937 static int __init debugfs_init(void)
941 if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT))
944 retval = sysfs_create_mount_point(kernel_kobj, "debug");
948 retval = register_filesystem(&debug_fs_type);
950 sysfs_remove_mount_point(kernel_kobj, "debug");
952 debugfs_registered = true;
956 core_initcall(debugfs_init);