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