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