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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * inode.c - part of debugfs, a tiny little debug file system
4 *
5 * Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com>
6 * Copyright (C) 2004 IBM Inc.
7 * Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org>
8 *
9 * debugfs is for people to use instead of /proc or /sys.
10 * See ./Documentation/core-api/kernel-api.rst for more details.
11 */
12
13#define pr_fmt(fmt) "debugfs: " fmt
14
15#include <linux/module.h>
16#include <linux/fs.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>
30
31#include "internal.h"
32
33#define DEBUGFS_DEFAULT_MODE 0700
34
35static struct vfsmount *debugfs_mount;
36static int debugfs_mount_count;
37static bool debugfs_registered;
38static unsigned int debugfs_allow __ro_after_init = DEFAULT_DEBUGFS_ALLOW_BITS;
39
40/*
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.
44 */
45static int debugfs_setattr(struct mnt_idmap *idmap,
46 struct dentry *dentry, struct iattr *ia)
47{
48 int ret;
49
50 if (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) {
51 ret = security_locked_down(LOCKDOWN_DEBUGFS);
52 if (ret)
53 return ret;
54 }
55 return simple_setattr(&nop_mnt_idmap, dentry, ia);
56}
57
58static const struct inode_operations debugfs_file_inode_operations = {
59 .setattr = debugfs_setattr,
60};
61static const struct inode_operations debugfs_dir_inode_operations = {
62 .lookup = simple_lookup,
63 .setattr = debugfs_setattr,
64};
65static const struct inode_operations debugfs_symlink_inode_operations = {
66 .get_link = simple_get_link,
67 .setattr = debugfs_setattr,
68};
69
70static struct inode *debugfs_get_inode(struct super_block *sb)
71{
72 struct inode *inode = new_inode(sb);
73 if (inode) {
74 inode->i_ino = get_next_ino();
75 simple_inode_init_ts(inode);
76 }
77 return inode;
78}
79
80struct debugfs_mount_opts {
81 kuid_t uid;
82 kgid_t gid;
83 umode_t mode;
84 /* Opt_* bitfield. */
85 unsigned int opts;
86};
87
88enum {
89 Opt_uid,
90 Opt_gid,
91 Opt_mode,
92 Opt_err
93};
94
95static const match_table_t tokens = {
96 {Opt_uid, "uid=%u"},
97 {Opt_gid, "gid=%u"},
98 {Opt_mode, "mode=%o"},
99 {Opt_err, NULL}
100};
101
102struct debugfs_fs_info {
103 struct debugfs_mount_opts mount_opts;
104};
105
106static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
107{
108 substring_t args[MAX_OPT_ARGS];
109 int option;
110 int token;
111 kuid_t uid;
112 kgid_t gid;
113 char *p;
114
115 opts->opts = 0;
116 opts->mode = DEBUGFS_DEFAULT_MODE;
117
118 while ((p = strsep(&data, ",")) != NULL) {
119 if (!*p)
120 continue;
121
122 token = match_token(p, tokens, args);
123 switch (token) {
124 case Opt_uid:
125 if (match_int(&args[0], &option))
126 return -EINVAL;
127 uid = make_kuid(current_user_ns(), option);
128 if (!uid_valid(uid))
129 return -EINVAL;
130 opts->uid = uid;
131 break;
132 case Opt_gid:
133 if (match_int(&args[0], &option))
134 return -EINVAL;
135 gid = make_kgid(current_user_ns(), option);
136 if (!gid_valid(gid))
137 return -EINVAL;
138 opts->gid = gid;
139 break;
140 case Opt_mode:
141 if (match_octal(&args[0], &option))
142 return -EINVAL;
143 opts->mode = option & S_IALLUGO;
144 break;
145 /*
146 * We might like to report bad mount options here;
147 * but traditionally debugfs has ignored all mount options
148 */
149 }
150
151 opts->opts |= BIT(token);
152 }
153
154 return 0;
155}
156
157static void _debugfs_apply_options(struct super_block *sb, bool remount)
158{
159 struct debugfs_fs_info *fsi = sb->s_fs_info;
160 struct inode *inode = d_inode(sb->s_root);
161 struct debugfs_mount_opts *opts = &fsi->mount_opts;
162
163 /*
164 * On remount, only reset mode/uid/gid if they were provided as mount
165 * options.
166 */
167
168 if (!remount || opts->opts & BIT(Opt_mode)) {
169 inode->i_mode &= ~S_IALLUGO;
170 inode->i_mode |= opts->mode;
171 }
172
173 if (!remount || opts->opts & BIT(Opt_uid))
174 inode->i_uid = opts->uid;
175
176 if (!remount || opts->opts & BIT(Opt_gid))
177 inode->i_gid = opts->gid;
178}
179
180static void debugfs_apply_options(struct super_block *sb)
181{
182 _debugfs_apply_options(sb, false);
183}
184
185static void debugfs_apply_options_remount(struct super_block *sb)
186{
187 _debugfs_apply_options(sb, true);
188}
189
190static int debugfs_remount(struct super_block *sb, int *flags, char *data)
191{
192 int err;
193 struct debugfs_fs_info *fsi = sb->s_fs_info;
194
195 sync_filesystem(sb);
196 err = debugfs_parse_options(data, &fsi->mount_opts);
197 if (err)
198 goto fail;
199
200 debugfs_apply_options_remount(sb);
201
202fail:
203 return err;
204}
205
206static int debugfs_show_options(struct seq_file *m, struct dentry *root)
207{
208 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
209 struct debugfs_mount_opts *opts = &fsi->mount_opts;
210
211 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
212 seq_printf(m, ",uid=%u",
213 from_kuid_munged(&init_user_ns, opts->uid));
214 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
215 seq_printf(m, ",gid=%u",
216 from_kgid_munged(&init_user_ns, opts->gid));
217 if (opts->mode != DEBUGFS_DEFAULT_MODE)
218 seq_printf(m, ",mode=%o", opts->mode);
219
220 return 0;
221}
222
223static void debugfs_free_inode(struct inode *inode)
224{
225 if (S_ISLNK(inode->i_mode))
226 kfree(inode->i_link);
227 free_inode_nonrcu(inode);
228}
229
230static const struct super_operations debugfs_super_operations = {
231 .statfs = simple_statfs,
232 .remount_fs = debugfs_remount,
233 .show_options = debugfs_show_options,
234 .free_inode = debugfs_free_inode,
235};
236
237static void debugfs_release_dentry(struct dentry *dentry)
238{
239 struct debugfs_fsdata *fsd = dentry->d_fsdata;
240
241 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
242 return;
243
244 /* check it wasn't a dir (no fsdata) or automount (no real_fops) */
245 if (fsd && fsd->real_fops) {
246 WARN_ON(!list_empty(&fsd->cancellations));
247 mutex_destroy(&fsd->cancellations_mtx);
248 }
249
250 kfree(fsd);
251}
252
253static struct vfsmount *debugfs_automount(struct path *path)
254{
255 struct debugfs_fsdata *fsd = path->dentry->d_fsdata;
256
257 return fsd->automount(path->dentry, d_inode(path->dentry)->i_private);
258}
259
260static const struct dentry_operations debugfs_dops = {
261 .d_delete = always_delete_dentry,
262 .d_release = debugfs_release_dentry,
263 .d_automount = debugfs_automount,
264};
265
266static int debug_fill_super(struct super_block *sb, void *data, int silent)
267{
268 static const struct tree_descr debug_files[] = {{""}};
269 struct debugfs_fs_info *fsi;
270 int err;
271
272 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
273 sb->s_fs_info = fsi;
274 if (!fsi) {
275 err = -ENOMEM;
276 goto fail;
277 }
278
279 err = debugfs_parse_options(data, &fsi->mount_opts);
280 if (err)
281 goto fail;
282
283 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
284 if (err)
285 goto fail;
286
287 sb->s_op = &debugfs_super_operations;
288 sb->s_d_op = &debugfs_dops;
289
290 debugfs_apply_options(sb);
291
292 return 0;
293
294fail:
295 kfree(fsi);
296 sb->s_fs_info = NULL;
297 return err;
298}
299
300static struct dentry *debug_mount(struct file_system_type *fs_type,
301 int flags, const char *dev_name,
302 void *data)
303{
304 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
305 return ERR_PTR(-EPERM);
306
307 return mount_single(fs_type, flags, data, debug_fill_super);
308}
309
310static struct file_system_type debug_fs_type = {
311 .owner = THIS_MODULE,
312 .name = "debugfs",
313 .mount = debug_mount,
314 .kill_sb = kill_litter_super,
315};
316MODULE_ALIAS_FS("debugfs");
317
318/**
319 * debugfs_lookup() - look up an existing debugfs file
320 * @name: a pointer to a string containing the name of the file to look up.
321 * @parent: a pointer to the parent dentry of the file.
322 *
323 * This function will return a pointer to a dentry if it succeeds. If the file
324 * doesn't exist or an error occurs, %NULL will be returned. The returned
325 * dentry must be passed to dput() when it is no longer needed.
326 *
327 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
328 * returned.
329 */
330struct dentry *debugfs_lookup(const char *name, struct dentry *parent)
331{
332 struct dentry *dentry;
333
334 if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent))
335 return NULL;
336
337 if (!parent)
338 parent = debugfs_mount->mnt_root;
339
340 dentry = lookup_positive_unlocked(name, parent, strlen(name));
341 if (IS_ERR(dentry))
342 return NULL;
343 return dentry;
344}
345EXPORT_SYMBOL_GPL(debugfs_lookup);
346
347static struct dentry *start_creating(const char *name, struct dentry *parent)
348{
349 struct dentry *dentry;
350 int error;
351
352 if (!(debugfs_allow & DEBUGFS_ALLOW_API))
353 return ERR_PTR(-EPERM);
354
355 if (!debugfs_initialized())
356 return ERR_PTR(-ENOENT);
357
358 pr_debug("creating file '%s'\n", name);
359
360 if (IS_ERR(parent))
361 return parent;
362
363 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
364 &debugfs_mount_count);
365 if (error) {
366 pr_err("Unable to pin filesystem for file '%s'\n", name);
367 return ERR_PTR(error);
368 }
369
370 /* If the parent is not specified, we create it in the root.
371 * We need the root dentry to do this, which is in the super
372 * block. A pointer to that is in the struct vfsmount that we
373 * have around.
374 */
375 if (!parent)
376 parent = debugfs_mount->mnt_root;
377
378 inode_lock(d_inode(parent));
379 if (unlikely(IS_DEADDIR(d_inode(parent))))
380 dentry = ERR_PTR(-ENOENT);
381 else
382 dentry = lookup_one_len(name, parent, strlen(name));
383 if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
384 if (d_is_dir(dentry))
385 pr_err("Directory '%s' with parent '%s' already present!\n",
386 name, parent->d_name.name);
387 else
388 pr_err("File '%s' in directory '%s' already present!\n",
389 name, parent->d_name.name);
390 dput(dentry);
391 dentry = ERR_PTR(-EEXIST);
392 }
393
394 if (IS_ERR(dentry)) {
395 inode_unlock(d_inode(parent));
396 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
397 }
398
399 return dentry;
400}
401
402static struct dentry *failed_creating(struct dentry *dentry)
403{
404 inode_unlock(d_inode(dentry->d_parent));
405 dput(dentry);
406 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
407 return ERR_PTR(-ENOMEM);
408}
409
410static struct dentry *end_creating(struct dentry *dentry)
411{
412 inode_unlock(d_inode(dentry->d_parent));
413 return dentry;
414}
415
416static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
417 struct dentry *parent, void *data,
418 const struct file_operations *proxy_fops,
419 const struct file_operations *real_fops)
420{
421 struct dentry *dentry;
422 struct inode *inode;
423
424 if (!(mode & S_IFMT))
425 mode |= S_IFREG;
426 BUG_ON(!S_ISREG(mode));
427 dentry = start_creating(name, parent);
428
429 if (IS_ERR(dentry))
430 return dentry;
431
432 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
433 failed_creating(dentry);
434 return ERR_PTR(-EPERM);
435 }
436
437 inode = debugfs_get_inode(dentry->d_sb);
438 if (unlikely(!inode)) {
439 pr_err("out of free dentries, can not create file '%s'\n",
440 name);
441 return failed_creating(dentry);
442 }
443
444 inode->i_mode = mode;
445 inode->i_private = data;
446
447 inode->i_op = &debugfs_file_inode_operations;
448 inode->i_fop = proxy_fops;
449 dentry->d_fsdata = (void *)((unsigned long)real_fops |
450 DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
451
452 d_instantiate(dentry, inode);
453 fsnotify_create(d_inode(dentry->d_parent), dentry);
454 return end_creating(dentry);
455}
456
457/**
458 * debugfs_create_file - create a file in the debugfs filesystem
459 * @name: a pointer to a string containing the name of the file to create.
460 * @mode: the permission that the file should have.
461 * @parent: a pointer to the parent dentry for this file. This should be a
462 * directory dentry if set. If this parameter is NULL, then the
463 * file will be created in the root of the debugfs filesystem.
464 * @data: a pointer to something that the caller will want to get to later
465 * on. The inode.i_private pointer will point to this value on
466 * the open() call.
467 * @fops: a pointer to a struct file_operations that should be used for
468 * this file.
469 *
470 * This is the basic "create a file" function for debugfs. It allows for a
471 * wide range of flexibility in creating a file, or a directory (if you want
472 * to create a directory, the debugfs_create_dir() function is
473 * recommended to be used instead.)
474 *
475 * This function will return a pointer to a dentry if it succeeds. This
476 * pointer must be passed to the debugfs_remove() function when the file is
477 * to be removed (no automatic cleanup happens if your module is unloaded,
478 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
479 * returned.
480 *
481 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
482 * returned.
483 *
484 * NOTE: it's expected that most callers should _ignore_ the errors returned
485 * by this function. Other debugfs functions handle the fact that the "dentry"
486 * passed to them could be an error and they don't crash in that case.
487 * Drivers should generally work fine even if debugfs fails to init anyway.
488 */
489struct dentry *debugfs_create_file(const char *name, umode_t mode,
490 struct dentry *parent, void *data,
491 const struct file_operations *fops)
492{
493
494 return __debugfs_create_file(name, mode, parent, data,
495 fops ? &debugfs_full_proxy_file_operations :
496 &debugfs_noop_file_operations,
497 fops);
498}
499EXPORT_SYMBOL_GPL(debugfs_create_file);
500
501/**
502 * debugfs_create_file_unsafe - create a file in the debugfs filesystem
503 * @name: a pointer to a string containing the name of the file to create.
504 * @mode: the permission that the file should have.
505 * @parent: a pointer to the parent dentry for this file. This should be a
506 * directory dentry if set. If this parameter is NULL, then the
507 * file will be created in the root of the debugfs filesystem.
508 * @data: a pointer to something that the caller will want to get to later
509 * on. The inode.i_private pointer will point to this value on
510 * the open() call.
511 * @fops: a pointer to a struct file_operations that should be used for
512 * this file.
513 *
514 * debugfs_create_file_unsafe() is completely analogous to
515 * debugfs_create_file(), the only difference being that the fops
516 * handed it will not get protected against file removals by the
517 * debugfs core.
518 *
519 * It is your responsibility to protect your struct file_operation
520 * methods against file removals by means of debugfs_file_get()
521 * and debugfs_file_put(). ->open() is still protected by
522 * debugfs though.
523 *
524 * Any struct file_operations defined by means of
525 * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and
526 * thus, may be used here.
527 */
528struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
529 struct dentry *parent, void *data,
530 const struct file_operations *fops)
531{
532
533 return __debugfs_create_file(name, mode, parent, data,
534 fops ? &debugfs_open_proxy_file_operations :
535 &debugfs_noop_file_operations,
536 fops);
537}
538EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe);
539
540/**
541 * debugfs_create_file_size - create a file in the debugfs filesystem
542 * @name: a pointer to a string containing the name of the file to create.
543 * @mode: the permission that the file should have.
544 * @parent: a pointer to the parent dentry for this file. This should be a
545 * directory dentry if set. If this parameter is NULL, then the
546 * file will be created in the root of the debugfs filesystem.
547 * @data: a pointer to something that the caller will want to get to later
548 * on. The inode.i_private pointer will point to this value on
549 * the open() call.
550 * @fops: a pointer to a struct file_operations that should be used for
551 * this file.
552 * @file_size: initial file size
553 *
554 * This is the basic "create a file" function for debugfs. It allows for a
555 * wide range of flexibility in creating a file, or a directory (if you want
556 * to create a directory, the debugfs_create_dir() function is
557 * recommended to be used instead.)
558 */
559void debugfs_create_file_size(const char *name, umode_t mode,
560 struct dentry *parent, void *data,
561 const struct file_operations *fops,
562 loff_t file_size)
563{
564 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
565
566 if (!IS_ERR(de))
567 d_inode(de)->i_size = file_size;
568}
569EXPORT_SYMBOL_GPL(debugfs_create_file_size);
570
571/**
572 * debugfs_create_dir - create a directory in the debugfs filesystem
573 * @name: a pointer to a string containing the name of the directory to
574 * create.
575 * @parent: a pointer to the parent dentry for this file. This should be a
576 * directory dentry if set. If this parameter is NULL, then the
577 * directory will be created in the root of the debugfs filesystem.
578 *
579 * This function creates a directory in debugfs with the given name.
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 file is
583 * to be removed (no automatic cleanup happens if your module is unloaded,
584 * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be
585 * returned.
586 *
587 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
588 * returned.
589 *
590 * NOTE: it's expected that most callers should _ignore_ the errors returned
591 * by this function. Other debugfs functions handle the fact that the "dentry"
592 * passed to them could be an error and they don't crash in that case.
593 * Drivers should generally work fine even if debugfs fails to init anyway.
594 */
595struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
596{
597 struct dentry *dentry = start_creating(name, parent);
598 struct inode *inode;
599
600 if (IS_ERR(dentry))
601 return dentry;
602
603 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
604 failed_creating(dentry);
605 return ERR_PTR(-EPERM);
606 }
607
608 inode = debugfs_get_inode(dentry->d_sb);
609 if (unlikely(!inode)) {
610 pr_err("out of free dentries, can not create directory '%s'\n",
611 name);
612 return failed_creating(dentry);
613 }
614
615 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
616 inode->i_op = &debugfs_dir_inode_operations;
617 inode->i_fop = &simple_dir_operations;
618
619 /* directory inodes start off with i_nlink == 2 (for "." entry) */
620 inc_nlink(inode);
621 d_instantiate(dentry, inode);
622 inc_nlink(d_inode(dentry->d_parent));
623 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
624 return end_creating(dentry);
625}
626EXPORT_SYMBOL_GPL(debugfs_create_dir);
627
628/**
629 * debugfs_create_automount - create automount point in the debugfs filesystem
630 * @name: a pointer to a string containing the name of the file to create.
631 * @parent: a pointer to the parent dentry for this file. This should be a
632 * directory dentry if set. If this parameter is NULL, then the
633 * file will be created in the root of the debugfs filesystem.
634 * @f: function to be called when pathname resolution steps on that one.
635 * @data: opaque argument to pass to f().
636 *
637 * @f should return what ->d_automount() would.
638 */
639struct dentry *debugfs_create_automount(const char *name,
640 struct dentry *parent,
641 debugfs_automount_t f,
642 void *data)
643{
644 struct dentry *dentry = start_creating(name, parent);
645 struct debugfs_fsdata *fsd;
646 struct inode *inode;
647
648 if (IS_ERR(dentry))
649 return dentry;
650
651 fsd = kzalloc(sizeof(*fsd), GFP_KERNEL);
652 if (!fsd) {
653 failed_creating(dentry);
654 return ERR_PTR(-ENOMEM);
655 }
656
657 fsd->automount = f;
658
659 if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
660 failed_creating(dentry);
661 kfree(fsd);
662 return ERR_PTR(-EPERM);
663 }
664
665 inode = debugfs_get_inode(dentry->d_sb);
666 if (unlikely(!inode)) {
667 pr_err("out of free dentries, can not create automount '%s'\n",
668 name);
669 kfree(fsd);
670 return failed_creating(dentry);
671 }
672
673 make_empty_dir_inode(inode);
674 inode->i_flags |= S_AUTOMOUNT;
675 inode->i_private = data;
676 dentry->d_fsdata = fsd;
677 /* directory inodes start off with i_nlink == 2 (for "." entry) */
678 inc_nlink(inode);
679 d_instantiate(dentry, inode);
680 inc_nlink(d_inode(dentry->d_parent));
681 fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
682 return end_creating(dentry);
683}
684EXPORT_SYMBOL(debugfs_create_automount);
685
686/**
687 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
688 * @name: a pointer to a string containing the name of the symbolic link to
689 * create.
690 * @parent: a pointer to the parent dentry for this symbolic link. This
691 * should be a directory dentry if set. If this parameter is NULL,
692 * then the symbolic link will be created in the root of the debugfs
693 * filesystem.
694 * @target: a pointer to a string containing the path to the target of the
695 * symbolic link.
696 *
697 * This function creates a symbolic link with the given name in debugfs that
698 * links to the given target path.
699 *
700 * This function will return a pointer to a dentry if it succeeds. This
701 * pointer must be passed to the debugfs_remove() function when the symbolic
702 * link is to be removed (no automatic cleanup happens if your module is
703 * unloaded, you are responsible here.) If an error occurs, ERR_PTR(-ERROR)
704 * will be returned.
705 *
706 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
707 * returned.
708 */
709struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
710 const char *target)
711{
712 struct dentry *dentry;
713 struct inode *inode;
714 char *link = kstrdup(target, GFP_KERNEL);
715 if (!link)
716 return ERR_PTR(-ENOMEM);
717
718 dentry = start_creating(name, parent);
719 if (IS_ERR(dentry)) {
720 kfree(link);
721 return dentry;
722 }
723
724 inode = debugfs_get_inode(dentry->d_sb);
725 if (unlikely(!inode)) {
726 pr_err("out of free dentries, can not create symlink '%s'\n",
727 name);
728 kfree(link);
729 return failed_creating(dentry);
730 }
731 inode->i_mode = S_IFLNK | S_IRWXUGO;
732 inode->i_op = &debugfs_symlink_inode_operations;
733 inode->i_link = link;
734 d_instantiate(dentry, inode);
735 return end_creating(dentry);
736}
737EXPORT_SYMBOL_GPL(debugfs_create_symlink);
738
739static void __debugfs_file_removed(struct dentry *dentry)
740{
741 struct debugfs_fsdata *fsd;
742
743 /*
744 * Paired with the closing smp_mb() implied by a successful
745 * cmpxchg() in debugfs_file_get(): either
746 * debugfs_file_get() must see a dead dentry or we must see a
747 * debugfs_fsdata instance at ->d_fsdata here (or both).
748 */
749 smp_mb();
750 fsd = READ_ONCE(dentry->d_fsdata);
751 if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
752 return;
753
754 /* if we hit zero, just wait for all to finish */
755 if (!refcount_dec_and_test(&fsd->active_users)) {
756 wait_for_completion(&fsd->active_users_drained);
757 return;
758 }
759
760 /* if we didn't hit zero, try to cancel any we can */
761 while (refcount_read(&fsd->active_users)) {
762 struct debugfs_cancellation *c;
763
764 /*
765 * Lock the cancellations. Note that the cancellations
766 * structs are meant to be on the stack, so we need to
767 * ensure we either use them here or don't touch them,
768 * and debugfs_leave_cancellation() will wait for this
769 * to be finished processing before exiting one. It may
770 * of course win and remove the cancellation, but then
771 * chances are we never even got into this bit, we only
772 * do if the refcount isn't zero already.
773 */
774 mutex_lock(&fsd->cancellations_mtx);
775 while ((c = list_first_entry_or_null(&fsd->cancellations,
776 typeof(*c), list))) {
777 list_del_init(&c->list);
778 c->cancel(dentry, c->cancel_data);
779 }
780 mutex_unlock(&fsd->cancellations_mtx);
781
782 wait_for_completion(&fsd->active_users_drained);
783 }
784}
785
786static void remove_one(struct dentry *victim)
787{
788 if (d_is_reg(victim))
789 __debugfs_file_removed(victim);
790 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
791}
792
793/**
794 * debugfs_remove - recursively removes a directory
795 * @dentry: a pointer to a the dentry of the directory to be removed. If this
796 * parameter is NULL or an error value, nothing will be done.
797 *
798 * This function recursively removes a directory tree in debugfs that
799 * was previously created with a call to another debugfs function
800 * (like debugfs_create_file() or variants thereof.)
801 *
802 * This function is required to be called in order for the file to be
803 * removed, no automatic cleanup of files will happen when a module is
804 * removed, you are responsible here.
805 */
806void debugfs_remove(struct dentry *dentry)
807{
808 if (IS_ERR_OR_NULL(dentry))
809 return;
810
811 simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
812 simple_recursive_removal(dentry, remove_one);
813 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
814}
815EXPORT_SYMBOL_GPL(debugfs_remove);
816
817/**
818 * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it
819 * @name: a pointer to a string containing the name of the item to look up.
820 * @parent: a pointer to the parent dentry of the item.
821 *
822 * This is the equlivant of doing something like
823 * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting
824 * handled for the directory being looked up.
825 */
826void debugfs_lookup_and_remove(const char *name, struct dentry *parent)
827{
828 struct dentry *dentry;
829
830 dentry = debugfs_lookup(name, parent);
831 if (!dentry)
832 return;
833
834 debugfs_remove(dentry);
835 dput(dentry);
836}
837EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove);
838
839/**
840 * debugfs_rename - rename a file/directory in the debugfs filesystem
841 * @old_dir: a pointer to the parent dentry for the renamed object. This
842 * should be a directory dentry.
843 * @old_dentry: dentry of an object to be renamed.
844 * @new_dir: a pointer to the parent dentry where the object should be
845 * moved. This should be a directory dentry.
846 * @new_name: a pointer to a string containing the target name.
847 *
848 * This function renames a file/directory in debugfs. The target must not
849 * exist for rename to succeed.
850 *
851 * This function will return a pointer to old_dentry (which is updated to
852 * reflect renaming) if it succeeds. If an error occurs, ERR_PTR(-ERROR)
853 * will be returned.
854 *
855 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
856 * returned.
857 */
858struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
859 struct dentry *new_dir, const char *new_name)
860{
861 int error;
862 struct dentry *dentry = NULL, *trap;
863 struct name_snapshot old_name;
864
865 if (IS_ERR(old_dir))
866 return old_dir;
867 if (IS_ERR(new_dir))
868 return new_dir;
869 if (IS_ERR_OR_NULL(old_dentry))
870 return old_dentry;
871
872 trap = lock_rename(new_dir, old_dir);
873 /* Source or destination directories don't exist? */
874 if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
875 goto exit;
876 /* Source does not exist, cyclic rename, or mountpoint? */
877 if (d_really_is_negative(old_dentry) || old_dentry == trap ||
878 d_mountpoint(old_dentry))
879 goto exit;
880 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
881 /* Lookup failed, cyclic rename or target exists? */
882 if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
883 goto exit;
884
885 take_dentry_name_snapshot(&old_name, old_dentry);
886
887 error = simple_rename(&nop_mnt_idmap, d_inode(old_dir), old_dentry,
888 d_inode(new_dir), dentry, 0);
889 if (error) {
890 release_dentry_name_snapshot(&old_name);
891 goto exit;
892 }
893 d_move(old_dentry, dentry);
894 fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
895 d_is_dir(old_dentry),
896 NULL, old_dentry);
897 release_dentry_name_snapshot(&old_name);
898 unlock_rename(new_dir, old_dir);
899 dput(dentry);
900 return old_dentry;
901exit:
902 if (dentry && !IS_ERR(dentry))
903 dput(dentry);
904 unlock_rename(new_dir, old_dir);
905 if (IS_ERR(dentry))
906 return dentry;
907 return ERR_PTR(-EINVAL);
908}
909EXPORT_SYMBOL_GPL(debugfs_rename);
910
911/**
912 * debugfs_initialized - Tells whether debugfs has been registered
913 */
914bool debugfs_initialized(void)
915{
916 return debugfs_registered;
917}
918EXPORT_SYMBOL_GPL(debugfs_initialized);
919
920static int __init debugfs_kernel(char *str)
921{
922 if (str) {
923 if (!strcmp(str, "on"))
924 debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT;
925 else if (!strcmp(str, "no-mount"))
926 debugfs_allow = DEBUGFS_ALLOW_API;
927 else if (!strcmp(str, "off"))
928 debugfs_allow = 0;
929 }
930
931 return 0;
932}
933early_param("debugfs", debugfs_kernel);
934static int __init debugfs_init(void)
935{
936 int retval;
937
938 if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT))
939 return -EPERM;
940
941 retval = sysfs_create_mount_point(kernel_kobj, "debug");
942 if (retval)
943 return retval;
944
945 retval = register_filesystem(&debug_fs_type);
946 if (retval)
947 sysfs_remove_mount_point(kernel_kobj, "debug");
948 else
949 debugfs_registered = true;
950
951 return retval;
952}
953core_initcall(debugfs_init);
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 0755
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, umode_t mode, dev_t dev,
38 void *data, const struct file_operations *fops)
39
40{
41 struct inode *inode = new_inode(sb);
42
43 if (inode) {
44 inode->i_ino = get_next_ino();
45 inode->i_mode = mode;
46 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
47 switch (mode & S_IFMT) {
48 default:
49 init_special_inode(inode, mode, dev);
50 break;
51 case S_IFREG:
52 inode->i_fop = fops ? fops : &debugfs_file_operations;
53 inode->i_private = data;
54 break;
55 case S_IFLNK:
56 inode->i_op = &debugfs_link_operations;
57 inode->i_fop = fops;
58 inode->i_private = data;
59 break;
60 case S_IFDIR:
61 inode->i_op = &simple_dir_inode_operations;
62 inode->i_fop = fops ? fops : &simple_dir_operations;
63 inode->i_private = data;
64
65 /* directory inodes start off with i_nlink == 2
66 * (for "." entry) */
67 inc_nlink(inode);
68 break;
69 }
70 }
71 return inode;
72}
73
74/* SMP-safe */
75static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
76 umode_t mode, dev_t dev, void *data,
77 const struct file_operations *fops)
78{
79 struct inode *inode;
80 int error = -EPERM;
81
82 if (dentry->d_inode)
83 return -EEXIST;
84
85 inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops);
86 if (inode) {
87 d_instantiate(dentry, inode);
88 dget(dentry);
89 error = 0;
90 }
91 return error;
92}
93
94static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode,
95 void *data, const struct file_operations *fops)
96{
97 int res;
98
99 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
100 res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
101 if (!res) {
102 inc_nlink(dir);
103 fsnotify_mkdir(dir, dentry);
104 }
105 return res;
106}
107
108static int debugfs_link(struct inode *dir, struct dentry *dentry, umode_t mode,
109 void *data, const struct file_operations *fops)
110{
111 mode = (mode & S_IALLUGO) | S_IFLNK;
112 return debugfs_mknod(dir, dentry, mode, 0, data, fops);
113}
114
115static int debugfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
116 void *data, const struct file_operations *fops)
117{
118 int res;
119
120 mode = (mode & S_IALLUGO) | S_IFREG;
121 res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
122 if (!res)
123 fsnotify_create(dir, dentry);
124 return res;
125}
126
127static inline int debugfs_positive(struct dentry *dentry)
128{
129 return dentry->d_inode && !d_unhashed(dentry);
130}
131
132struct debugfs_mount_opts {
133 uid_t uid;
134 gid_t gid;
135 umode_t mode;
136};
137
138enum {
139 Opt_uid,
140 Opt_gid,
141 Opt_mode,
142 Opt_err
143};
144
145static const match_table_t tokens = {
146 {Opt_uid, "uid=%u"},
147 {Opt_gid, "gid=%u"},
148 {Opt_mode, "mode=%o"},
149 {Opt_err, NULL}
150};
151
152struct debugfs_fs_info {
153 struct debugfs_mount_opts mount_opts;
154};
155
156static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
157{
158 substring_t args[MAX_OPT_ARGS];
159 int option;
160 int token;
161 char *p;
162
163 opts->mode = DEBUGFS_DEFAULT_MODE;
164
165 while ((p = strsep(&data, ",")) != NULL) {
166 if (!*p)
167 continue;
168
169 token = match_token(p, tokens, args);
170 switch (token) {
171 case Opt_uid:
172 if (match_int(&args[0], &option))
173 return -EINVAL;
174 opts->uid = option;
175 break;
176 case Opt_gid:
177 if (match_octal(&args[0], &option))
178 return -EINVAL;
179 opts->gid = option;
180 break;
181 case Opt_mode:
182 if (match_octal(&args[0], &option))
183 return -EINVAL;
184 opts->mode = option & S_IALLUGO;
185 break;
186 /*
187 * We might like to report bad mount options here;
188 * but traditionally debugfs has ignored all mount options
189 */
190 }
191 }
192
193 return 0;
194}
195
196static int debugfs_apply_options(struct super_block *sb)
197{
198 struct debugfs_fs_info *fsi = sb->s_fs_info;
199 struct inode *inode = sb->s_root->d_inode;
200 struct debugfs_mount_opts *opts = &fsi->mount_opts;
201
202 inode->i_mode &= ~S_IALLUGO;
203 inode->i_mode |= opts->mode;
204
205 inode->i_uid = opts->uid;
206 inode->i_gid = opts->gid;
207
208 return 0;
209}
210
211static int debugfs_remount(struct super_block *sb, int *flags, char *data)
212{
213 int err;
214 struct debugfs_fs_info *fsi = sb->s_fs_info;
215
216 err = debugfs_parse_options(data, &fsi->mount_opts);
217 if (err)
218 goto fail;
219
220 debugfs_apply_options(sb);
221
222fail:
223 return err;
224}
225
226static int debugfs_show_options(struct seq_file *m, struct dentry *root)
227{
228 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
229 struct debugfs_mount_opts *opts = &fsi->mount_opts;
230
231 if (opts->uid != 0)
232 seq_printf(m, ",uid=%u", opts->uid);
233 if (opts->gid != 0)
234 seq_printf(m, ",gid=%u", opts->gid);
235 if (opts->mode != DEBUGFS_DEFAULT_MODE)
236 seq_printf(m, ",mode=%o", opts->mode);
237
238 return 0;
239}
240
241static const struct super_operations debugfs_super_operations = {
242 .statfs = simple_statfs,
243 .remount_fs = debugfs_remount,
244 .show_options = debugfs_show_options,
245};
246
247static int debug_fill_super(struct super_block *sb, void *data, int silent)
248{
249 static struct tree_descr debug_files[] = {{""}};
250 struct debugfs_fs_info *fsi;
251 int err;
252
253 save_mount_options(sb, data);
254
255 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
256 sb->s_fs_info = fsi;
257 if (!fsi) {
258 err = -ENOMEM;
259 goto fail;
260 }
261
262 err = debugfs_parse_options(data, &fsi->mount_opts);
263 if (err)
264 goto fail;
265
266 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
267 if (err)
268 goto fail;
269
270 sb->s_op = &debugfs_super_operations;
271
272 debugfs_apply_options(sb);
273
274 return 0;
275
276fail:
277 kfree(fsi);
278 sb->s_fs_info = NULL;
279 return err;
280}
281
282static struct dentry *debug_mount(struct file_system_type *fs_type,
283 int flags, const char *dev_name,
284 void *data)
285{
286 return mount_single(fs_type, flags, data, debug_fill_super);
287}
288
289static struct file_system_type debug_fs_type = {
290 .owner = THIS_MODULE,
291 .name = "debugfs",
292 .mount = debug_mount,
293 .kill_sb = kill_litter_super,
294};
295
296static int debugfs_create_by_name(const char *name, umode_t mode,
297 struct dentry *parent,
298 struct dentry **dentry,
299 void *data,
300 const struct file_operations *fops)
301{
302 int error = 0;
303
304 /* If the parent is not specified, we create it in the root.
305 * We need the root dentry to do this, which is in the super
306 * block. A pointer to that is in the struct vfsmount that we
307 * have around.
308 */
309 if (!parent)
310 parent = debugfs_mount->mnt_root;
311
312 *dentry = NULL;
313 mutex_lock(&parent->d_inode->i_mutex);
314 *dentry = lookup_one_len(name, parent, strlen(name));
315 if (!IS_ERR(*dentry)) {
316 switch (mode & S_IFMT) {
317 case S_IFDIR:
318 error = debugfs_mkdir(parent->d_inode, *dentry, mode,
319 data, fops);
320 break;
321 case S_IFLNK:
322 error = debugfs_link(parent->d_inode, *dentry, mode,
323 data, fops);
324 break;
325 default:
326 error = debugfs_create(parent->d_inode, *dentry, mode,
327 data, fops);
328 break;
329 }
330 dput(*dentry);
331 } else
332 error = PTR_ERR(*dentry);
333 mutex_unlock(&parent->d_inode->i_mutex);
334
335 return error;
336}
337
338/**
339 * debugfs_create_file - create a file in the debugfs filesystem
340 * @name: a pointer to a string containing the name of the file to create.
341 * @mode: the permission that the file should have.
342 * @parent: a pointer to the parent dentry for this file. This should be a
343 * directory dentry if set. If this paramater is NULL, then the
344 * file will be created in the root of the debugfs filesystem.
345 * @data: a pointer to something that the caller will want to get to later
346 * on. The inode.i_private pointer will point to this value on
347 * the open() call.
348 * @fops: a pointer to a struct file_operations that should be used for
349 * this file.
350 *
351 * This is the basic "create a file" function for debugfs. It allows for a
352 * wide range of flexibility in creating a file, or a directory (if you want
353 * to create a directory, the debugfs_create_dir() function is
354 * recommended to be used instead.)
355 *
356 * This function will return a pointer to a dentry if it succeeds. This
357 * pointer must be passed to the debugfs_remove() function when the file is
358 * to be removed (no automatic cleanup happens if your module is unloaded,
359 * you are responsible here.) If an error occurs, %NULL will be returned.
360 *
361 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
362 * returned.
363 */
364struct dentry *debugfs_create_file(const char *name, umode_t mode,
365 struct dentry *parent, void *data,
366 const struct file_operations *fops)
367{
368 struct dentry *dentry = NULL;
369 int error;
370
371 pr_debug("debugfs: creating file '%s'\n",name);
372
373 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
374 &debugfs_mount_count);
375 if (error)
376 goto exit;
377
378 error = debugfs_create_by_name(name, mode, parent, &dentry,
379 data, fops);
380 if (error) {
381 dentry = NULL;
382 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
383 goto exit;
384 }
385exit:
386 return dentry;
387}
388EXPORT_SYMBOL_GPL(debugfs_create_file);
389
390/**
391 * debugfs_create_dir - create a directory in the debugfs filesystem
392 * @name: a pointer to a string containing the name of the directory to
393 * create.
394 * @parent: a pointer to the parent dentry for this file. This should be a
395 * directory dentry if set. If this paramater is NULL, then the
396 * directory will be created in the root of the debugfs filesystem.
397 *
398 * This function creates a directory in debugfs with the given name.
399 *
400 * This function will return a pointer to a dentry if it succeeds. This
401 * pointer must be passed to the debugfs_remove() function when the file is
402 * to be removed (no automatic cleanup happens if your module is unloaded,
403 * you are responsible here.) If an error occurs, %NULL will be returned.
404 *
405 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
406 * returned.
407 */
408struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
409{
410 return debugfs_create_file(name,
411 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
412 parent, NULL, NULL);
413}
414EXPORT_SYMBOL_GPL(debugfs_create_dir);
415
416/**
417 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
418 * @name: a pointer to a string containing the name of the symbolic link to
419 * create.
420 * @parent: a pointer to the parent dentry for this symbolic link. This
421 * should be a directory dentry if set. If this paramater is NULL,
422 * then the symbolic link will be created in the root of the debugfs
423 * filesystem.
424 * @target: a pointer to a string containing the path to the target of the
425 * symbolic link.
426 *
427 * This function creates a symbolic link with the given name in debugfs that
428 * links to the given target path.
429 *
430 * This function will return a pointer to a dentry if it succeeds. This
431 * pointer must be passed to the debugfs_remove() function when the symbolic
432 * link is to be removed (no automatic cleanup happens if your module is
433 * unloaded, you are responsible here.) If an error occurs, %NULL will be
434 * returned.
435 *
436 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
437 * returned.
438 */
439struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
440 const char *target)
441{
442 struct dentry *result;
443 char *link;
444
445 link = kstrdup(target, GFP_KERNEL);
446 if (!link)
447 return NULL;
448
449 result = debugfs_create_file(name, S_IFLNK | S_IRWXUGO, parent, link,
450 NULL);
451 if (!result)
452 kfree(link);
453 return result;
454}
455EXPORT_SYMBOL_GPL(debugfs_create_symlink);
456
457static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
458{
459 int ret = 0;
460
461 if (debugfs_positive(dentry)) {
462 if (dentry->d_inode) {
463 dget(dentry);
464 switch (dentry->d_inode->i_mode & S_IFMT) {
465 case S_IFDIR:
466 ret = simple_rmdir(parent->d_inode, dentry);
467 break;
468 case S_IFLNK:
469 kfree(dentry->d_inode->i_private);
470 /* fall through */
471 default:
472 simple_unlink(parent->d_inode, dentry);
473 break;
474 }
475 if (!ret)
476 d_delete(dentry);
477 dput(dentry);
478 }
479 }
480 return ret;
481}
482
483/**
484 * debugfs_remove - removes a file or directory from the debugfs filesystem
485 * @dentry: a pointer to a the dentry of the file or directory to be
486 * removed.
487 *
488 * This function removes a file or directory in debugfs that was previously
489 * created with a call to another debugfs function (like
490 * debugfs_create_file() or variants thereof.)
491 *
492 * This function is required to be called in order for the file to be
493 * removed, no automatic cleanup of files will happen when a module is
494 * removed, you are responsible here.
495 */
496void debugfs_remove(struct dentry *dentry)
497{
498 struct dentry *parent;
499 int ret;
500
501 if (!dentry)
502 return;
503
504 parent = dentry->d_parent;
505 if (!parent || !parent->d_inode)
506 return;
507
508 mutex_lock(&parent->d_inode->i_mutex);
509 ret = __debugfs_remove(dentry, parent);
510 mutex_unlock(&parent->d_inode->i_mutex);
511 if (!ret)
512 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
513}
514EXPORT_SYMBOL_GPL(debugfs_remove);
515
516/**
517 * debugfs_remove_recursive - recursively removes a directory
518 * @dentry: a pointer to a the dentry of the directory to be removed.
519 *
520 * This function recursively removes a directory tree in debugfs that
521 * was previously created with a call to another debugfs function
522 * (like debugfs_create_file() or variants thereof.)
523 *
524 * This function is required to be called in order for the file to be
525 * removed, no automatic cleanup of files will happen when a module is
526 * removed, you are responsible here.
527 */
528void debugfs_remove_recursive(struct dentry *dentry)
529{
530 struct dentry *child;
531 struct dentry *parent;
532
533 if (!dentry)
534 return;
535
536 parent = dentry->d_parent;
537 if (!parent || !parent->d_inode)
538 return;
539
540 parent = dentry;
541 mutex_lock(&parent->d_inode->i_mutex);
542
543 while (1) {
544 /*
545 * When all dentries under "parent" has been removed,
546 * walk up the tree until we reach our starting point.
547 */
548 if (list_empty(&parent->d_subdirs)) {
549 mutex_unlock(&parent->d_inode->i_mutex);
550 if (parent == dentry)
551 break;
552 parent = parent->d_parent;
553 mutex_lock(&parent->d_inode->i_mutex);
554 }
555 child = list_entry(parent->d_subdirs.next, struct dentry,
556 d_u.d_child);
557 next_sibling:
558
559 /*
560 * If "child" isn't empty, walk down the tree and
561 * remove all its descendants first.
562 */
563 if (!list_empty(&child->d_subdirs)) {
564 mutex_unlock(&parent->d_inode->i_mutex);
565 parent = child;
566 mutex_lock(&parent->d_inode->i_mutex);
567 continue;
568 }
569 __debugfs_remove(child, parent);
570 if (parent->d_subdirs.next == &child->d_u.d_child) {
571 /*
572 * Try the next sibling.
573 */
574 if (child->d_u.d_child.next != &parent->d_subdirs) {
575 child = list_entry(child->d_u.d_child.next,
576 struct dentry,
577 d_u.d_child);
578 goto next_sibling;
579 }
580
581 /*
582 * Avoid infinite loop if we fail to remove
583 * one dentry.
584 */
585 mutex_unlock(&parent->d_inode->i_mutex);
586 break;
587 }
588 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
589 }
590
591 parent = dentry->d_parent;
592 mutex_lock(&parent->d_inode->i_mutex);
593 __debugfs_remove(dentry, parent);
594 mutex_unlock(&parent->d_inode->i_mutex);
595 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
596}
597EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
598
599/**
600 * debugfs_rename - rename a file/directory in the debugfs filesystem
601 * @old_dir: a pointer to the parent dentry for the renamed object. This
602 * should be a directory dentry.
603 * @old_dentry: dentry of an object to be renamed.
604 * @new_dir: a pointer to the parent dentry where the object should be
605 * moved. This should be a directory dentry.
606 * @new_name: a pointer to a string containing the target name.
607 *
608 * This function renames a file/directory in debugfs. The target must not
609 * exist for rename to succeed.
610 *
611 * This function will return a pointer to old_dentry (which is updated to
612 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
613 * returned.
614 *
615 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
616 * returned.
617 */
618struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
619 struct dentry *new_dir, const char *new_name)
620{
621 int error;
622 struct dentry *dentry = NULL, *trap;
623 const char *old_name;
624
625 trap = lock_rename(new_dir, old_dir);
626 /* Source or destination directories don't exist? */
627 if (!old_dir->d_inode || !new_dir->d_inode)
628 goto exit;
629 /* Source does not exist, cyclic rename, or mountpoint? */
630 if (!old_dentry->d_inode || old_dentry == trap ||
631 d_mountpoint(old_dentry))
632 goto exit;
633 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
634 /* Lookup failed, cyclic rename or target exists? */
635 if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
636 goto exit;
637
638 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
639
640 error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
641 dentry);
642 if (error) {
643 fsnotify_oldname_free(old_name);
644 goto exit;
645 }
646 d_move(old_dentry, dentry);
647 fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
648 S_ISDIR(old_dentry->d_inode->i_mode),
649 NULL, old_dentry);
650 fsnotify_oldname_free(old_name);
651 unlock_rename(new_dir, old_dir);
652 dput(dentry);
653 return old_dentry;
654exit:
655 if (dentry && !IS_ERR(dentry))
656 dput(dentry);
657 unlock_rename(new_dir, old_dir);
658 return NULL;
659}
660EXPORT_SYMBOL_GPL(debugfs_rename);
661
662/**
663 * debugfs_initialized - Tells whether debugfs has been registered
664 */
665bool debugfs_initialized(void)
666{
667 return debugfs_registered;
668}
669EXPORT_SYMBOL_GPL(debugfs_initialized);
670
671
672static struct kobject *debug_kobj;
673
674static int __init debugfs_init(void)
675{
676 int retval;
677
678 debug_kobj = kobject_create_and_add("debug", kernel_kobj);
679 if (!debug_kobj)
680 return -EINVAL;
681
682 retval = register_filesystem(&debug_fs_type);
683 if (retval)
684 kobject_put(debug_kobj);
685 else
686 debugfs_registered = true;
687
688 return retval;
689}
690core_initcall(debugfs_init);
691