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1/*
2 * inode.c - part of debugfs, a tiny little debug file system
3 *
4 * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
5 * Copyright (C) 2004 IBM Inc.
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License version
9 * 2 as published by the Free Software Foundation.
10 *
11 * debugfs is for people to use instead of /proc or /sys.
12 * See Documentation/DocBook/kernel-api for more details.
13 *
14 */
15
16#include <linux/module.h>
17#include <linux/fs.h>
18#include <linux/mount.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/parser.h>
28#include <linux/magic.h>
29#include <linux/slab.h>
30
31#define DEBUGFS_DEFAULT_MODE 0700
32
33static struct vfsmount *debugfs_mount;
34static int debugfs_mount_count;
35static bool debugfs_registered;
36
37static struct inode *debugfs_get_inode(struct super_block *sb)
38{
39 struct inode *inode = new_inode(sb);
40 if (inode) {
41 inode->i_ino = get_next_ino();
42 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
43 }
44 return inode;
45}
46
47struct debugfs_mount_opts {
48 kuid_t uid;
49 kgid_t gid;
50 umode_t mode;
51};
52
53enum {
54 Opt_uid,
55 Opt_gid,
56 Opt_mode,
57 Opt_err
58};
59
60static const match_table_t tokens = {
61 {Opt_uid, "uid=%u"},
62 {Opt_gid, "gid=%u"},
63 {Opt_mode, "mode=%o"},
64 {Opt_err, NULL}
65};
66
67struct debugfs_fs_info {
68 struct debugfs_mount_opts mount_opts;
69};
70
71static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
72{
73 substring_t args[MAX_OPT_ARGS];
74 int option;
75 int token;
76 kuid_t uid;
77 kgid_t gid;
78 char *p;
79
80 opts->mode = DEBUGFS_DEFAULT_MODE;
81
82 while ((p = strsep(&data, ",")) != NULL) {
83 if (!*p)
84 continue;
85
86 token = match_token(p, tokens, args);
87 switch (token) {
88 case Opt_uid:
89 if (match_int(&args[0], &option))
90 return -EINVAL;
91 uid = make_kuid(current_user_ns(), option);
92 if (!uid_valid(uid))
93 return -EINVAL;
94 opts->uid = uid;
95 break;
96 case Opt_gid:
97 if (match_int(&args[0], &option))
98 return -EINVAL;
99 gid = make_kgid(current_user_ns(), option);
100 if (!gid_valid(gid))
101 return -EINVAL;
102 opts->gid = gid;
103 break;
104 case Opt_mode:
105 if (match_octal(&args[0], &option))
106 return -EINVAL;
107 opts->mode = option & S_IALLUGO;
108 break;
109 /*
110 * We might like to report bad mount options here;
111 * but traditionally debugfs has ignored all mount options
112 */
113 }
114 }
115
116 return 0;
117}
118
119static int debugfs_apply_options(struct super_block *sb)
120{
121 struct debugfs_fs_info *fsi = sb->s_fs_info;
122 struct inode *inode = d_inode(sb->s_root);
123 struct debugfs_mount_opts *opts = &fsi->mount_opts;
124
125 inode->i_mode &= ~S_IALLUGO;
126 inode->i_mode |= opts->mode;
127
128 inode->i_uid = opts->uid;
129 inode->i_gid = opts->gid;
130
131 return 0;
132}
133
134static int debugfs_remount(struct super_block *sb, int *flags, char *data)
135{
136 int err;
137 struct debugfs_fs_info *fsi = sb->s_fs_info;
138
139 sync_filesystem(sb);
140 err = debugfs_parse_options(data, &fsi->mount_opts);
141 if (err)
142 goto fail;
143
144 debugfs_apply_options(sb);
145
146fail:
147 return err;
148}
149
150static int debugfs_show_options(struct seq_file *m, struct dentry *root)
151{
152 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
153 struct debugfs_mount_opts *opts = &fsi->mount_opts;
154
155 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
156 seq_printf(m, ",uid=%u",
157 from_kuid_munged(&init_user_ns, opts->uid));
158 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
159 seq_printf(m, ",gid=%u",
160 from_kgid_munged(&init_user_ns, opts->gid));
161 if (opts->mode != DEBUGFS_DEFAULT_MODE)
162 seq_printf(m, ",mode=%o", opts->mode);
163
164 return 0;
165}
166
167static void debugfs_evict_inode(struct inode *inode)
168{
169 truncate_inode_pages_final(&inode->i_data);
170 clear_inode(inode);
171 if (S_ISLNK(inode->i_mode))
172 kfree(inode->i_link);
173}
174
175static const struct super_operations debugfs_super_operations = {
176 .statfs = simple_statfs,
177 .remount_fs = debugfs_remount,
178 .show_options = debugfs_show_options,
179 .evict_inode = debugfs_evict_inode,
180};
181
182static struct vfsmount *debugfs_automount(struct path *path)
183{
184 struct vfsmount *(*f)(void *);
185 f = (struct vfsmount *(*)(void *))path->dentry->d_fsdata;
186 return f(d_inode(path->dentry)->i_private);
187}
188
189static const struct dentry_operations debugfs_dops = {
190 .d_delete = always_delete_dentry,
191 .d_automount = debugfs_automount,
192};
193
194static int debug_fill_super(struct super_block *sb, void *data, int silent)
195{
196 static struct tree_descr debug_files[] = {{""}};
197 struct debugfs_fs_info *fsi;
198 int err;
199
200 save_mount_options(sb, data);
201
202 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
203 sb->s_fs_info = fsi;
204 if (!fsi) {
205 err = -ENOMEM;
206 goto fail;
207 }
208
209 err = debugfs_parse_options(data, &fsi->mount_opts);
210 if (err)
211 goto fail;
212
213 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
214 if (err)
215 goto fail;
216
217 sb->s_op = &debugfs_super_operations;
218 sb->s_d_op = &debugfs_dops;
219
220 debugfs_apply_options(sb);
221
222 return 0;
223
224fail:
225 kfree(fsi);
226 sb->s_fs_info = NULL;
227 return err;
228}
229
230static struct dentry *debug_mount(struct file_system_type *fs_type,
231 int flags, const char *dev_name,
232 void *data)
233{
234 return mount_single(fs_type, flags, data, debug_fill_super);
235}
236
237static struct file_system_type debug_fs_type = {
238 .owner = THIS_MODULE,
239 .name = "debugfs",
240 .mount = debug_mount,
241 .kill_sb = kill_litter_super,
242};
243MODULE_ALIAS_FS("debugfs");
244
245static struct dentry *start_creating(const char *name, struct dentry *parent)
246{
247 struct dentry *dentry;
248 int error;
249
250 pr_debug("debugfs: creating file '%s'\n",name);
251
252 if (IS_ERR(parent))
253 return parent;
254
255 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
256 &debugfs_mount_count);
257 if (error)
258 return ERR_PTR(error);
259
260 /* If the parent is not specified, we create it in the root.
261 * We need the root dentry to do this, which is in the super
262 * block. A pointer to that is in the struct vfsmount that we
263 * have around.
264 */
265 if (!parent)
266 parent = debugfs_mount->mnt_root;
267
268 inode_lock(d_inode(parent));
269 dentry = lookup_one_len(name, parent, strlen(name));
270 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
271 dput(dentry);
272 dentry = ERR_PTR(-EEXIST);
273 }
274
275 if (IS_ERR(dentry)) {
276 inode_unlock(d_inode(parent));
277 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
278 }
279
280 return dentry;
281}
282
283static struct dentry *failed_creating(struct dentry *dentry)
284{
285 inode_unlock(d_inode(dentry->d_parent));
286 dput(dentry);
287 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
288 return NULL;
289}
290
291static struct dentry *end_creating(struct dentry *dentry)
292{
293 inode_unlock(d_inode(dentry->d_parent));
294 return dentry;
295}
296
297/**
298 * debugfs_create_file - create a file in the debugfs filesystem
299 * @name: a pointer to a string containing the name of the file to create.
300 * @mode: the permission that the file should have.
301 * @parent: a pointer to the parent dentry for this file. This should be a
302 * directory dentry if set. If this parameter is NULL, then the
303 * file will be created in the root of the debugfs filesystem.
304 * @data: a pointer to something that the caller will want to get to later
305 * on. The inode.i_private pointer will point to this value on
306 * the open() call.
307 * @fops: a pointer to a struct file_operations that should be used for
308 * this file.
309 *
310 * This is the basic "create a file" function for debugfs. It allows for a
311 * wide range of flexibility in creating a file, or a directory (if you want
312 * to create a directory, the debugfs_create_dir() function is
313 * recommended to be used instead.)
314 *
315 * This function will return a pointer to a dentry if it succeeds. This
316 * pointer must be passed to the debugfs_remove() function when the file is
317 * to be removed (no automatic cleanup happens if your module is unloaded,
318 * you are responsible here.) If an error occurs, %NULL will be returned.
319 *
320 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
321 * returned.
322 */
323struct dentry *debugfs_create_file(const char *name, umode_t mode,
324 struct dentry *parent, void *data,
325 const struct file_operations *fops)
326{
327 struct dentry *dentry;
328 struct inode *inode;
329
330 if (!(mode & S_IFMT))
331 mode |= S_IFREG;
332 BUG_ON(!S_ISREG(mode));
333 dentry = start_creating(name, parent);
334
335 if (IS_ERR(dentry))
336 return NULL;
337
338 inode = debugfs_get_inode(dentry->d_sb);
339 if (unlikely(!inode))
340 return failed_creating(dentry);
341
342 inode->i_mode = mode;
343 inode->i_fop = fops ? fops : &debugfs_file_operations;
344 inode->i_private = data;
345 d_instantiate(dentry, inode);
346 fsnotify_create(d_inode(dentry->d_parent), dentry);
347 return end_creating(dentry);
348}
349EXPORT_SYMBOL_GPL(debugfs_create_file);
350
351/**
352 * debugfs_create_file_size - create a file in the debugfs filesystem
353 * @name: a pointer to a string containing the name of the file to create.
354 * @mode: the permission that the file should have.
355 * @parent: a pointer to the parent dentry for this file. This should be a
356 * directory dentry if set. If this parameter is NULL, then the
357 * file will be created in the root of the debugfs filesystem.
358 * @data: a pointer to something that the caller will want to get to later
359 * on. The inode.i_private pointer will point to this value on
360 * the open() call.
361 * @fops: a pointer to a struct file_operations that should be used for
362 * this file.
363 * @file_size: initial file size
364 *
365 * This is the basic "create a file" function for debugfs. It allows for a
366 * wide range of flexibility in creating a file, or a directory (if you want
367 * to create a directory, the debugfs_create_dir() function is
368 * recommended to be used instead.)
369 *
370 * This function will return a pointer to a dentry if it succeeds. This
371 * pointer must be passed to the debugfs_remove() function when the file is
372 * to be removed (no automatic cleanup happens if your module is unloaded,
373 * you are responsible here.) If an error occurs, %NULL will be returned.
374 *
375 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
376 * returned.
377 */
378struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
379 struct dentry *parent, void *data,
380 const struct file_operations *fops,
381 loff_t file_size)
382{
383 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
384
385 if (de)
386 d_inode(de)->i_size = file_size;
387 return de;
388}
389EXPORT_SYMBOL_GPL(debugfs_create_file_size);
390
391/**
392 * debugfs_create_dir - create a directory in the debugfs filesystem
393 * @name: a pointer to a string containing the name of the directory to
394 * create.
395 * @parent: a pointer to the parent dentry for this file. This should be a
396 * directory dentry if set. If this parameter is NULL, then the
397 * directory will be created in the root of the debugfs filesystem.
398 *
399 * This function creates a directory in debugfs with the given name.
400 *
401 * This function will return a pointer to a dentry if it succeeds. This
402 * pointer must be passed to the debugfs_remove() function when the file is
403 * to be removed (no automatic cleanup happens if your module is unloaded,
404 * you are responsible here.) If an error occurs, %NULL will be returned.
405 *
406 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
407 * returned.
408 */
409struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
410{
411 struct dentry *dentry = start_creating(name, parent);
412 struct inode *inode;
413
414 if (IS_ERR(dentry))
415 return NULL;
416
417 inode = debugfs_get_inode(dentry->d_sb);
418 if (unlikely(!inode))
419 return failed_creating(dentry);
420
421 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
422 inode->i_op = &simple_dir_inode_operations;
423 inode->i_fop = &simple_dir_operations;
424
425 /* directory inodes start off with i_nlink == 2 (for "." entry) */
426 inc_nlink(inode);
427 d_instantiate(dentry, inode);
428 inc_nlink(d_inode(dentry->d_parent));
429 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
430 return end_creating(dentry);
431}
432EXPORT_SYMBOL_GPL(debugfs_create_dir);
433
434/**
435 * debugfs_create_automount - create automount point in the debugfs filesystem
436 * @name: a pointer to a string containing the name of the file to create.
437 * @parent: a pointer to the parent dentry for this file. This should be a
438 * directory dentry if set. If this parameter is NULL, then the
439 * file will be created in the root of the debugfs filesystem.
440 * @f: function to be called when pathname resolution steps on that one.
441 * @data: opaque argument to pass to f().
442 *
443 * @f should return what ->d_automount() would.
444 */
445struct dentry *debugfs_create_automount(const char *name,
446 struct dentry *parent,
447 struct vfsmount *(*f)(void *),
448 void *data)
449{
450 struct dentry *dentry = start_creating(name, parent);
451 struct inode *inode;
452
453 if (IS_ERR(dentry))
454 return NULL;
455
456 inode = debugfs_get_inode(dentry->d_sb);
457 if (unlikely(!inode))
458 return failed_creating(dentry);
459
460 make_empty_dir_inode(inode);
461 inode->i_flags |= S_AUTOMOUNT;
462 inode->i_private = data;
463 dentry->d_fsdata = (void *)f;
464 d_instantiate(dentry, inode);
465 return end_creating(dentry);
466}
467EXPORT_SYMBOL(debugfs_create_automount);
468
469/**
470 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
471 * @name: a pointer to a string containing the name of the symbolic link to
472 * create.
473 * @parent: a pointer to the parent dentry for this symbolic link. This
474 * should be a directory dentry if set. If this parameter is NULL,
475 * then the symbolic link will be created in the root of the debugfs
476 * filesystem.
477 * @target: a pointer to a string containing the path to the target of the
478 * symbolic link.
479 *
480 * This function creates a symbolic link with the given name in debugfs that
481 * links to the given target path.
482 *
483 * This function will return a pointer to a dentry if it succeeds. This
484 * pointer must be passed to the debugfs_remove() function when the symbolic
485 * link is to be removed (no automatic cleanup happens if your module is
486 * unloaded, you are responsible here.) If an error occurs, %NULL will be
487 * returned.
488 *
489 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
490 * returned.
491 */
492struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
493 const char *target)
494{
495 struct dentry *dentry;
496 struct inode *inode;
497 char *link = kstrdup(target, GFP_KERNEL);
498 if (!link)
499 return NULL;
500
501 dentry = start_creating(name, parent);
502 if (IS_ERR(dentry)) {
503 kfree(link);
504 return NULL;
505 }
506
507 inode = debugfs_get_inode(dentry->d_sb);
508 if (unlikely(!inode)) {
509 kfree(link);
510 return failed_creating(dentry);
511 }
512 inode->i_mode = S_IFLNK | S_IRWXUGO;
513 inode->i_op = &simple_symlink_inode_operations;
514 inode->i_link = link;
515 d_instantiate(dentry, inode);
516 return end_creating(dentry);
517}
518EXPORT_SYMBOL_GPL(debugfs_create_symlink);
519
520static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
521{
522 int ret = 0;
523
524 if (simple_positive(dentry)) {
525 dget(dentry);
526 if (d_is_dir(dentry))
527 ret = simple_rmdir(d_inode(parent), dentry);
528 else
529 simple_unlink(d_inode(parent), dentry);
530 if (!ret)
531 d_delete(dentry);
532 dput(dentry);
533 }
534 return ret;
535}
536
537/**
538 * debugfs_remove - removes a file or directory from the debugfs filesystem
539 * @dentry: a pointer to a the dentry of the file or directory to be
540 * removed. If this parameter is NULL or an error value, nothing
541 * will be done.
542 *
543 * This function removes a file or directory in debugfs that was previously
544 * created with a call to another debugfs function (like
545 * debugfs_create_file() or variants thereof.)
546 *
547 * This function is required to be called in order for the file to be
548 * removed, no automatic cleanup of files will happen when a module is
549 * removed, you are responsible here.
550 */
551void debugfs_remove(struct dentry *dentry)
552{
553 struct dentry *parent;
554 int ret;
555
556 if (IS_ERR_OR_NULL(dentry))
557 return;
558
559 parent = dentry->d_parent;
560 if (!parent || d_really_is_negative(parent))
561 return;
562
563 inode_lock(d_inode(parent));
564 ret = __debugfs_remove(dentry, parent);
565 inode_unlock(d_inode(parent));
566 if (!ret)
567 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
568}
569EXPORT_SYMBOL_GPL(debugfs_remove);
570
571/**
572 * debugfs_remove_recursive - recursively removes a directory
573 * @dentry: a pointer to a the dentry of the directory to be removed. If this
574 * parameter is NULL or an error value, nothing will be done.
575 *
576 * This function recursively removes a directory tree in debugfs that
577 * was previously created with a call to another debugfs function
578 * (like debugfs_create_file() or variants thereof.)
579 *
580 * This function is required to be called in order for the file to be
581 * removed, no automatic cleanup of files will happen when a module is
582 * removed, you are responsible here.
583 */
584void debugfs_remove_recursive(struct dentry *dentry)
585{
586 struct dentry *child, *parent;
587
588 if (IS_ERR_OR_NULL(dentry))
589 return;
590
591 parent = dentry->d_parent;
592 if (!parent || d_really_is_negative(parent))
593 return;
594
595 parent = dentry;
596 down:
597 inode_lock(d_inode(parent));
598 loop:
599 /*
600 * The parent->d_subdirs is protected by the d_lock. Outside that
601 * lock, the child can be unlinked and set to be freed which can
602 * use the d_u.d_child as the rcu head and corrupt this list.
603 */
604 spin_lock(&parent->d_lock);
605 list_for_each_entry(child, &parent->d_subdirs, d_child) {
606 if (!simple_positive(child))
607 continue;
608
609 /* perhaps simple_empty(child) makes more sense */
610 if (!list_empty(&child->d_subdirs)) {
611 spin_unlock(&parent->d_lock);
612 inode_unlock(d_inode(parent));
613 parent = child;
614 goto down;
615 }
616
617 spin_unlock(&parent->d_lock);
618
619 if (!__debugfs_remove(child, parent))
620 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
621
622 /*
623 * The parent->d_lock protects agaist child from unlinking
624 * from d_subdirs. When releasing the parent->d_lock we can
625 * no longer trust that the next pointer is valid.
626 * Restart the loop. We'll skip this one with the
627 * simple_positive() check.
628 */
629 goto loop;
630 }
631 spin_unlock(&parent->d_lock);
632
633 inode_unlock(d_inode(parent));
634 child = parent;
635 parent = parent->d_parent;
636 inode_lock(d_inode(parent));
637
638 if (child != dentry)
639 /* go up */
640 goto loop;
641
642 if (!__debugfs_remove(child, parent))
643 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
644 inode_unlock(d_inode(parent));
645}
646EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
647
648/**
649 * debugfs_rename - rename a file/directory in the debugfs filesystem
650 * @old_dir: a pointer to the parent dentry for the renamed object. This
651 * should be a directory dentry.
652 * @old_dentry: dentry of an object to be renamed.
653 * @new_dir: a pointer to the parent dentry where the object should be
654 * moved. This should be a directory dentry.
655 * @new_name: a pointer to a string containing the target name.
656 *
657 * This function renames a file/directory in debugfs. The target must not
658 * exist for rename to succeed.
659 *
660 * This function will return a pointer to old_dentry (which is updated to
661 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
662 * returned.
663 *
664 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
665 * returned.
666 */
667struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
668 struct dentry *new_dir, const char *new_name)
669{
670 int error;
671 struct dentry *dentry = NULL, *trap;
672 const char *old_name;
673
674 trap = lock_rename(new_dir, old_dir);
675 /* Source or destination directories don't exist? */
676 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
677 goto exit;
678 /* Source does not exist, cyclic rename, or mountpoint? */
679 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
680 d_mountpoint(old_dentry))
681 goto exit;
682 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
683 /* Lookup failed, cyclic rename or target exists? */
684 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
685 goto exit;
686
687 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
688
689 error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
690 dentry);
691 if (error) {
692 fsnotify_oldname_free(old_name);
693 goto exit;
694 }
695 d_move(old_dentry, dentry);
696 fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name,
697 d_is_dir(old_dentry),
698 NULL, old_dentry);
699 fsnotify_oldname_free(old_name);
700 unlock_rename(new_dir, old_dir);
701 dput(dentry);
702 return old_dentry;
703exit:
704 if (dentry && !IS_ERR(dentry))
705 dput(dentry);
706 unlock_rename(new_dir, old_dir);
707 return NULL;
708}
709EXPORT_SYMBOL_GPL(debugfs_rename);
710
711/**
712 * debugfs_initialized - Tells whether debugfs has been registered
713 */
714bool debugfs_initialized(void)
715{
716 return debugfs_registered;
717}
718EXPORT_SYMBOL_GPL(debugfs_initialized);
719
720static int __init debugfs_init(void)
721{
722 int retval;
723
724 retval = sysfs_create_mount_point(kernel_kobj, "debug");
725 if (retval)
726 return retval;
727
728 retval = register_filesystem(&debug_fs_type);
729 if (retval)
730 sysfs_remove_mount_point(kernel_kobj, "debug");
731 else
732 debugfs_registered = true;
733
734 return retval;
735}
736core_initcall(debugfs_init);
737
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * inode.c - part of debugfs, a tiny little debug file system
4 *
5 * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
6 * Copyright (C) 2004 IBM Inc.
7 *
8 * debugfs is for people to use instead of /proc or /sys.
9 * See ./Documentation/core-api/kernel-api.rst for more details.
10 */
11
12#include <linux/module.h>
13#include <linux/fs.h>
14#include <linux/mount.h>
15#include <linux/pagemap.h>
16#include <linux/init.h>
17#include <linux/kobject.h>
18#include <linux/namei.h>
19#include <linux/debugfs.h>
20#include <linux/fsnotify.h>
21#include <linux/string.h>
22#include <linux/seq_file.h>
23#include <linux/parser.h>
24#include <linux/magic.h>
25#include <linux/slab.h>
26
27#include "internal.h"
28
29#define DEBUGFS_DEFAULT_MODE 0700
30
31static struct vfsmount *debugfs_mount;
32static int debugfs_mount_count;
33static bool debugfs_registered;
34
35static struct inode *debugfs_get_inode(struct super_block *sb)
36{
37 struct inode *inode = new_inode(sb);
38 if (inode) {
39 inode->i_ino = get_next_ino();
40 inode->i_atime = inode->i_mtime =
41 inode->i_ctime = current_time(inode);
42 }
43 return inode;
44}
45
46struct debugfs_mount_opts {
47 kuid_t uid;
48 kgid_t gid;
49 umode_t mode;
50};
51
52enum {
53 Opt_uid,
54 Opt_gid,
55 Opt_mode,
56 Opt_err
57};
58
59static const match_table_t tokens = {
60 {Opt_uid, "uid=%u"},
61 {Opt_gid, "gid=%u"},
62 {Opt_mode, "mode=%o"},
63 {Opt_err, NULL}
64};
65
66struct debugfs_fs_info {
67 struct debugfs_mount_opts mount_opts;
68};
69
70static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
71{
72 substring_t args[MAX_OPT_ARGS];
73 int option;
74 int token;
75 kuid_t uid;
76 kgid_t gid;
77 char *p;
78
79 opts->mode = DEBUGFS_DEFAULT_MODE;
80
81 while ((p = strsep(&data, ",")) != NULL) {
82 if (!*p)
83 continue;
84
85 token = match_token(p, tokens, args);
86 switch (token) {
87 case Opt_uid:
88 if (match_int(&args[0], &option))
89 return -EINVAL;
90 uid = make_kuid(current_user_ns(), option);
91 if (!uid_valid(uid))
92 return -EINVAL;
93 opts->uid = uid;
94 break;
95 case Opt_gid:
96 if (match_int(&args[0], &option))
97 return -EINVAL;
98 gid = make_kgid(current_user_ns(), option);
99 if (!gid_valid(gid))
100 return -EINVAL;
101 opts->gid = gid;
102 break;
103 case Opt_mode:
104 if (match_octal(&args[0], &option))
105 return -EINVAL;
106 opts->mode = option & S_IALLUGO;
107 break;
108 /*
109 * We might like to report bad mount options here;
110 * but traditionally debugfs has ignored all mount options
111 */
112 }
113 }
114
115 return 0;
116}
117
118static int debugfs_apply_options(struct super_block *sb)
119{
120 struct debugfs_fs_info *fsi = sb->s_fs_info;
121 struct inode *inode = d_inode(sb->s_root);
122 struct debugfs_mount_opts *opts = &fsi->mount_opts;
123
124 inode->i_mode &= ~S_IALLUGO;
125 inode->i_mode |= opts->mode;
126
127 inode->i_uid = opts->uid;
128 inode->i_gid = opts->gid;
129
130 return 0;
131}
132
133static int debugfs_remount(struct super_block *sb, int *flags, char *data)
134{
135 int err;
136 struct debugfs_fs_info *fsi = sb->s_fs_info;
137
138 sync_filesystem(sb);
139 err = debugfs_parse_options(data, &fsi->mount_opts);
140 if (err)
141 goto fail;
142
143 debugfs_apply_options(sb);
144
145fail:
146 return err;
147}
148
149static int debugfs_show_options(struct seq_file *m, struct dentry *root)
150{
151 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
152 struct debugfs_mount_opts *opts = &fsi->mount_opts;
153
154 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
155 seq_printf(m, ",uid=%u",
156 from_kuid_munged(&init_user_ns, opts->uid));
157 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
158 seq_printf(m, ",gid=%u",
159 from_kgid_munged(&init_user_ns, opts->gid));
160 if (opts->mode != DEBUGFS_DEFAULT_MODE)
161 seq_printf(m, ",mode=%o", opts->mode);
162
163 return 0;
164}
165
166static void debugfs_evict_inode(struct inode *inode)
167{
168 truncate_inode_pages_final(&inode->i_data);
169 clear_inode(inode);
170 if (S_ISLNK(inode->i_mode))
171 kfree(inode->i_link);
172}
173
174static const struct super_operations debugfs_super_operations = {
175 .statfs = simple_statfs,
176 .remount_fs = debugfs_remount,
177 .show_options = debugfs_show_options,
178 .evict_inode = debugfs_evict_inode,
179};
180
181static void debugfs_release_dentry(struct dentry *dentry)
182{
183 void *fsd = dentry->d_fsdata;
184
185 if (!((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
186 kfree(dentry->d_fsdata);
187}
188
189static struct vfsmount *debugfs_automount(struct path *path)
190{
191 debugfs_automount_t f;
192 f = (debugfs_automount_t)path->dentry->d_fsdata;
193 return f(path->dentry, d_inode(path->dentry)->i_private);
194}
195
196static const struct dentry_operations debugfs_dops = {
197 .d_delete = always_delete_dentry,
198 .d_release = debugfs_release_dentry,
199 .d_automount = debugfs_automount,
200};
201
202static int debug_fill_super(struct super_block *sb, void *data, int silent)
203{
204 static const struct tree_descr debug_files[] = {{""}};
205 struct debugfs_fs_info *fsi;
206 int err;
207
208 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
209 sb->s_fs_info = fsi;
210 if (!fsi) {
211 err = -ENOMEM;
212 goto fail;
213 }
214
215 err = debugfs_parse_options(data, &fsi->mount_opts);
216 if (err)
217 goto fail;
218
219 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
220 if (err)
221 goto fail;
222
223 sb->s_op = &debugfs_super_operations;
224 sb->s_d_op = &debugfs_dops;
225
226 debugfs_apply_options(sb);
227
228 return 0;
229
230fail:
231 kfree(fsi);
232 sb->s_fs_info = NULL;
233 return err;
234}
235
236static struct dentry *debug_mount(struct file_system_type *fs_type,
237 int flags, const char *dev_name,
238 void *data)
239{
240 return mount_single(fs_type, flags, data, debug_fill_super);
241}
242
243static struct file_system_type debug_fs_type = {
244 .owner = THIS_MODULE,
245 .name = "debugfs",
246 .mount = debug_mount,
247 .kill_sb = kill_litter_super,
248};
249MODULE_ALIAS_FS("debugfs");
250
251/**
252 * debugfs_lookup() - look up an existing debugfs file
253 * @name: a pointer to a string containing the name of the file to look up.
254 * @parent: a pointer to the parent dentry of the file.
255 *
256 * This function will return a pointer to a dentry if it succeeds. If the file
257 * doesn't exist or an error occurs, %NULL will be returned. The returned
258 * dentry must be passed to dput() when it is no longer needed.
259 *
260 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
261 * returned.
262 */
263struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
264{
265 struct dentry *dentry;
266
267 if (IS_ERR(parent))
268 return NULL;
269
270 if (!parent)
271 parent = debugfs_mount->mnt_root;
272
273 dentry = lookup_one_len_unlocked(name, parent, strlen(name));
274 if (IS_ERR(dentry))
275 return NULL;
276 if (!d_really_is_positive(dentry)) {
277 dput(dentry);
278 return NULL;
279 }
280 return dentry;
281}
282EXPORT_SYMBOL_GPL(debugfs_lookup);
283
284static struct dentry *start_creating(const char *name, struct dentry *parent)
285{
286 struct dentry *dentry;
287 int error;
288
289 pr_debug("debugfs: creating file '%s'\n",name);
290
291 if (IS_ERR(parent))
292 return parent;
293
294 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
295 &debugfs_mount_count);
296 if (error)
297 return ERR_PTR(error);
298
299 /* If the parent is not specified, we create it in the root.
300 * We need the root dentry to do this, which is in the super
301 * block. A pointer to that is in the struct vfsmount that we
302 * have around.
303 */
304 if (!parent)
305 parent = debugfs_mount->mnt_root;
306
307 inode_lock(d_inode(parent));
308 dentry = lookup_one_len(name, parent, strlen(name));
309 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
310 dput(dentry);
311 dentry = ERR_PTR(-EEXIST);
312 }
313
314 if (IS_ERR(dentry)) {
315 inode_unlock(d_inode(parent));
316 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
317 }
318
319 return dentry;
320}
321
322static struct dentry *failed_creating(struct dentry *dentry)
323{
324 inode_unlock(d_inode(dentry->d_parent));
325 dput(dentry);
326 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
327 return NULL;
328}
329
330static struct dentry *end_creating(struct dentry *dentry)
331{
332 inode_unlock(d_inode(dentry->d_parent));
333 return dentry;
334}
335
336static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
337 struct dentry *parent, void *data,
338 const struct file_operations *proxy_fops,
339 const struct file_operations *real_fops)
340{
341 struct dentry *dentry;
342 struct inode *inode;
343
344 if (!(mode & S_IFMT))
345 mode |= S_IFREG;
346 BUG_ON(!S_ISREG(mode));
347 dentry = start_creating(name, parent);
348
349 if (IS_ERR(dentry))
350 return NULL;
351
352 inode = debugfs_get_inode(dentry->d_sb);
353 if (unlikely(!inode))
354 return failed_creating(dentry);
355
356 inode->i_mode = mode;
357 inode->i_private = data;
358
359 inode->i_fop = proxy_fops;
360 dentry->d_fsdata = (void *)((unsigned long)real_fops |
361 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
362
363 d_instantiate(dentry, inode);
364 fsnotify_create(d_inode(dentry->d_parent), dentry);
365 return end_creating(dentry);
366}
367
368/**
369 * debugfs_create_file - create a file in the debugfs filesystem
370 * @name: a pointer to a string containing the name of the file to create.
371 * @mode: the permission that the file should have.
372 * @parent: a pointer to the parent dentry for this file. This should be a
373 * directory dentry if set. If this parameter is NULL, then the
374 * file will be created in the root of the debugfs filesystem.
375 * @data: a pointer to something that the caller will want to get to later
376 * on. The inode.i_private pointer will point to this value on
377 * the open() call.
378 * @fops: a pointer to a struct file_operations that should be used for
379 * this file.
380 *
381 * This is the basic "create a file" function for debugfs. It allows for a
382 * wide range of flexibility in creating a file, or a directory (if you want
383 * to create a directory, the debugfs_create_dir() function is
384 * recommended to be used instead.)
385 *
386 * This function will return a pointer to a dentry if it succeeds. This
387 * pointer must be passed to the debugfs_remove() function when the file is
388 * to be removed (no automatic cleanup happens if your module is unloaded,
389 * you are responsible here.) If an error occurs, %NULL will be returned.
390 *
391 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
392 * returned.
393 */
394struct dentry *debugfs_create_file(const char *name, umode_t mode,
395 struct dentry *parent, void *data,
396 const struct file_operations *fops)
397{
398
399 return __debugfs_create_file(name, mode, parent, data,
400 fops ? &debugfs_full_proxy_file_operations :
401 &debugfs_noop_file_operations,
402 fops);
403}
404EXPORT_SYMBOL_GPL(debugfs_create_file);
405
406/**
407 * debugfs_create_file_unsafe - create a file in the debugfs filesystem
408 * @name: a pointer to a string containing the name of the file to create.
409 * @mode: the permission that the file should have.
410 * @parent: a pointer to the parent dentry for this file. This should be a
411 * directory dentry if set. If this parameter is NULL, then the
412 * file will be created in the root of the debugfs filesystem.
413 * @data: a pointer to something that the caller will want to get to later
414 * on. The inode.i_private pointer will point to this value on
415 * the open() call.
416 * @fops: a pointer to a struct file_operations that should be used for
417 * this file.
418 *
419 * debugfs_create_file_unsafe() is completely analogous to
420 * debugfs_create_file(), the only difference being that the fops
421 * handed it will not get protected against file removals by the
422 * debugfs core.
423 *
424 * It is your responsibility to protect your struct file_operation
425 * methods against file removals by means of debugfs_use_file_start()
426 * and debugfs_use_file_finish(). ->open() is still protected by
427 * debugfs though.
428 *
429 * Any struct file_operations defined by means of
430 * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
431 * thus, may be used here.
432 */
433struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
434 struct dentry *parent, void *data,
435 const struct file_operations *fops)
436{
437
438 return __debugfs_create_file(name, mode, parent, data,
439 fops ? &debugfs_open_proxy_file_operations :
440 &debugfs_noop_file_operations,
441 fops);
442}
443EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
444
445/**
446 * debugfs_create_file_size - 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
454 * the open() call.
455 * @fops: a pointer to a struct file_operations that should be used for
456 * this file.
457 * @file_size: initial file size
458 *
459 * This is the basic "create a file" function for debugfs. It allows for a
460 * wide range of flexibility in creating a file, or a directory (if you want
461 * to create a directory, the debugfs_create_dir() function is
462 * recommended to be used instead.)
463 *
464 * This function will return a pointer to a dentry if it succeeds. This
465 * pointer must be passed to the debugfs_remove() function when the file is
466 * to be removed (no automatic cleanup happens if your module is unloaded,
467 * you are responsible here.) If an error occurs, %NULL will be returned.
468 *
469 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
470 * returned.
471 */
472struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
473 struct dentry *parent, void *data,
474 const struct file_operations *fops,
475 loff_t file_size)
476{
477 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
478
479 if (de)
480 d_inode(de)->i_size = file_size;
481 return de;
482}
483EXPORT_SYMBOL_GPL(debugfs_create_file_size);
484
485/**
486 * debugfs_create_dir - create a directory in the debugfs filesystem
487 * @name: a pointer to a string containing the name of the directory to
488 * create.
489 * @parent: a pointer to the parent dentry for this file. This should be a
490 * directory dentry if set. If this parameter is NULL, then the
491 * directory will be created in the root of the debugfs filesystem.
492 *
493 * This function creates a directory in debugfs with the given name.
494 *
495 * This function will return a pointer to a dentry if it succeeds. This
496 * pointer must be passed to the debugfs_remove() function when the file is
497 * to be removed (no automatic cleanup happens if your module is unloaded,
498 * you are responsible here.) If an error occurs, %NULL will be returned.
499 *
500 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
501 * returned.
502 */
503struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
504{
505 struct dentry *dentry = start_creating(name, parent);
506 struct inode *inode;
507
508 if (IS_ERR(dentry))
509 return NULL;
510
511 inode = debugfs_get_inode(dentry->d_sb);
512 if (unlikely(!inode))
513 return failed_creating(dentry);
514
515 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
516 inode->i_op = &simple_dir_inode_operations;
517 inode->i_fop = &simple_dir_operations;
518
519 /* directory inodes start off with i_nlink == 2 (for "." entry) */
520 inc_nlink(inode);
521 d_instantiate(dentry, inode);
522 inc_nlink(d_inode(dentry->d_parent));
523 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
524 return end_creating(dentry);
525}
526EXPORT_SYMBOL_GPL(debugfs_create_dir);
527
528/**
529 * debugfs_create_automount - create automount point in the debugfs filesystem
530 * @name: a pointer to a string containing the name of the file to create.
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 * file will be created in the root of the debugfs filesystem.
534 * @f: function to be called when pathname resolution steps on that one.
535 * @data: opaque argument to pass to f().
536 *
537 * @f should return what ->d_automount() would.
538 */
539struct dentry *debugfs_create_automount(const char *name,
540 struct dentry *parent,
541 debugfs_automount_t f,
542 void *data)
543{
544 struct dentry *dentry = start_creating(name, parent);
545 struct inode *inode;
546
547 if (IS_ERR(dentry))
548 return NULL;
549
550 inode = debugfs_get_inode(dentry->d_sb);
551 if (unlikely(!inode))
552 return failed_creating(dentry);
553
554 make_empty_dir_inode(inode);
555 inode->i_flags |= S_AUTOMOUNT;
556 inode->i_private = data;
557 dentry->d_fsdata = (void *)f;
558 /* directory inodes start off with i_nlink == 2 (for "." entry) */
559 inc_nlink(inode);
560 d_instantiate(dentry, inode);
561 inc_nlink(d_inode(dentry->d_parent));
562 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
563 return end_creating(dentry);
564}
565EXPORT_SYMBOL(debugfs_create_automount);
566
567/**
568 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
569 * @name: a pointer to a string containing the name of the symbolic link to
570 * create.
571 * @parent: a pointer to the parent dentry for this symbolic link. This
572 * should be a directory dentry if set. If this parameter is NULL,
573 * then the symbolic link will be created in the root of the debugfs
574 * filesystem.
575 * @target: a pointer to a string containing the path to the target of the
576 * symbolic link.
577 *
578 * This function creates a symbolic link with the given name in debugfs that
579 * links to the given target path.
580 *
581 * This function will return a pointer to a dentry if it succeeds. This
582 * pointer must be passed to the debugfs_remove() function when the symbolic
583 * link is to be removed (no automatic cleanup happens if your module is
584 * unloaded, you are responsible here.) If an error occurs, %NULL will be
585 * returned.
586 *
587 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
588 * returned.
589 */
590struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
591 const char *target)
592{
593 struct dentry *dentry;
594 struct inode *inode;
595 char *link = kstrdup(target, GFP_KERNEL);
596 if (!link)
597 return NULL;
598
599 dentry = start_creating(name, parent);
600 if (IS_ERR(dentry)) {
601 kfree(link);
602 return NULL;
603 }
604
605 inode = debugfs_get_inode(dentry->d_sb);
606 if (unlikely(!inode)) {
607 kfree(link);
608 return failed_creating(dentry);
609 }
610 inode->i_mode = S_IFLNK | S_IRWXUGO;
611 inode->i_op = &simple_symlink_inode_operations;
612 inode->i_link = link;
613 d_instantiate(dentry, inode);
614 return end_creating(dentry);
615}
616EXPORT_SYMBOL_GPL(debugfs_create_symlink);
617
618static void __debugfs_remove_file(struct dentry *dentry, struct dentry *parent)
619{
620 struct debugfs_fsdata *fsd;
621
622 simple_unlink(d_inode(parent), dentry);
623 d_delete(dentry);
624
625 /*
626 * Paired with the closing smp_mb() implied by a successful
627 * cmpxchg() in debugfs_file_get(): either
628 * debugfs_file_get() must see a dead dentry or we must see a
629 * debugfs_fsdata instance at ->d_fsdata here (or both).
630 */
631 smp_mb();
632 fsd = READ_ONCE(dentry->d_fsdata);
633 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
634 return;
635 if (!refcount_dec_and_test(&fsd->active_users))
636 wait_for_completion(&fsd->active_users_drained);
637}
638
639static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
640{
641 int ret = 0;
642
643 if (simple_positive(dentry)) {
644 dget(dentry);
645 if (!d_is_reg(dentry)) {
646 if (d_is_dir(dentry))
647 ret = simple_rmdir(d_inode(parent), dentry);
648 else
649 simple_unlink(d_inode(parent), dentry);
650 if (!ret)
651 d_delete(dentry);
652 } else {
653 __debugfs_remove_file(dentry, parent);
654 }
655 dput(dentry);
656 }
657 return ret;
658}
659
660/**
661 * debugfs_remove - removes a file or directory from the debugfs filesystem
662 * @dentry: a pointer to a the dentry of the file or directory to be
663 * removed. If this parameter is NULL or an error value, nothing
664 * will be done.
665 *
666 * This function removes a file or directory in debugfs that was previously
667 * created with a call to another debugfs function (like
668 * debugfs_create_file() or variants thereof.)
669 *
670 * This function is required to be called in order for the file to be
671 * removed, no automatic cleanup of files will happen when a module is
672 * removed, you are responsible here.
673 */
674void debugfs_remove(struct dentry *dentry)
675{
676 struct dentry *parent;
677 int ret;
678
679 if (IS_ERR_OR_NULL(dentry))
680 return;
681
682 parent = dentry->d_parent;
683 inode_lock(d_inode(parent));
684 ret = __debugfs_remove(dentry, parent);
685 inode_unlock(d_inode(parent));
686 if (!ret)
687 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
688}
689EXPORT_SYMBOL_GPL(debugfs_remove);
690
691/**
692 * debugfs_remove_recursive - recursively removes a directory
693 * @dentry: a pointer to a the dentry of the directory to be removed. If this
694 * parameter is NULL or an error value, nothing will be done.
695 *
696 * This function recursively removes a directory tree in debugfs that
697 * was previously created with a call to another debugfs function
698 * (like debugfs_create_file() or variants thereof.)
699 *
700 * This function is required to be called in order for the file to be
701 * removed, no automatic cleanup of files will happen when a module is
702 * removed, you are responsible here.
703 */
704void debugfs_remove_recursive(struct dentry *dentry)
705{
706 struct dentry *child, *parent;
707
708 if (IS_ERR_OR_NULL(dentry))
709 return;
710
711 parent = dentry;
712 down:
713 inode_lock(d_inode(parent));
714 loop:
715 /*
716 * The parent->d_subdirs is protected by the d_lock. Outside that
717 * lock, the child can be unlinked and set to be freed which can
718 * use the d_u.d_child as the rcu head and corrupt this list.
719 */
720 spin_lock(&parent->d_lock);
721 list_for_each_entry(child, &parent->d_subdirs, d_child) {
722 if (!simple_positive(child))
723 continue;
724
725 /* perhaps simple_empty(child) makes more sense */
726 if (!list_empty(&child->d_subdirs)) {
727 spin_unlock(&parent->d_lock);
728 inode_unlock(d_inode(parent));
729 parent = child;
730 goto down;
731 }
732
733 spin_unlock(&parent->d_lock);
734
735 if (!__debugfs_remove(child, parent))
736 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
737
738 /*
739 * The parent->d_lock protects agaist child from unlinking
740 * from d_subdirs. When releasing the parent->d_lock we can
741 * no longer trust that the next pointer is valid.
742 * Restart the loop. We'll skip this one with the
743 * simple_positive() check.
744 */
745 goto loop;
746 }
747 spin_unlock(&parent->d_lock);
748
749 inode_unlock(d_inode(parent));
750 child = parent;
751 parent = parent->d_parent;
752 inode_lock(d_inode(parent));
753
754 if (child != dentry)
755 /* go up */
756 goto loop;
757
758 if (!__debugfs_remove(child, parent))
759 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
760 inode_unlock(d_inode(parent));
761}
762EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
763
764/**
765 * debugfs_rename - rename a file/directory in the debugfs filesystem
766 * @old_dir: a pointer to the parent dentry for the renamed object. This
767 * should be a directory dentry.
768 * @old_dentry: dentry of an object to be renamed.
769 * @new_dir: a pointer to the parent dentry where the object should be
770 * moved. This should be a directory dentry.
771 * @new_name: a pointer to a string containing the target name.
772 *
773 * This function renames a file/directory in debugfs. The target must not
774 * exist for rename to succeed.
775 *
776 * This function will return a pointer to old_dentry (which is updated to
777 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
778 * returned.
779 *
780 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
781 * returned.
782 */
783struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
784 struct dentry *new_dir, const char *new_name)
785{
786 int error;
787 struct dentry *dentry = NULL, *trap;
788 struct name_snapshot old_name;
789
790 trap = lock_rename(new_dir, old_dir);
791 /* Source or destination directories don't exist? */
792 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
793 goto exit;
794 /* Source does not exist, cyclic rename, or mountpoint? */
795 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
796 d_mountpoint(old_dentry))
797 goto exit;
798 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
799 /* Lookup failed, cyclic rename or target exists? */
800 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
801 goto exit;
802
803 take_dentry_name_snapshot(&old_name, old_dentry);
804
805 error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
806 dentry, 0);
807 if (error) {
808 release_dentry_name_snapshot(&old_name);
809 goto exit;
810 }
811 d_move(old_dentry, dentry);
812 fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name.name,
813 d_is_dir(old_dentry),
814 NULL, old_dentry);
815 release_dentry_name_snapshot(&old_name);
816 unlock_rename(new_dir, old_dir);
817 dput(dentry);
818 return old_dentry;
819exit:
820 if (dentry && !IS_ERR(dentry))
821 dput(dentry);
822 unlock_rename(new_dir, old_dir);
823 return NULL;
824}
825EXPORT_SYMBOL_GPL(debugfs_rename);
826
827/**
828 * debugfs_initialized - Tells whether debugfs has been registered
829 */
830bool debugfs_initialized(void)
831{
832 return debugfs_registered;
833}
834EXPORT_SYMBOL_GPL(debugfs_initialized);
835
836static int __init debugfs_init(void)
837{
838 int retval;
839
840 retval = sysfs_create_mount_point(kernel_kobj, "debug");
841 if (retval)
842 return retval;
843
844 retval = register_filesystem(&debug_fs_type);
845 if (retval)
846 sysfs_remove_mount_point(kernel_kobj, "debug");
847 else
848 debugfs_registered = true;
849
850 return retval;
851}
852core_initcall(debugfs_init);
853