Version:  2.0.40 2.2.26 2.4.37 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2

Linux/fs/debugfs/inode.c

  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 
 33 static struct vfsmount *debugfs_mount;
 34 static int debugfs_mount_count;
 35 static bool debugfs_registered;
 36 
 37 static 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 
 47 struct debugfs_mount_opts {
 48         kuid_t uid;
 49         kgid_t gid;
 50         umode_t mode;
 51 };
 52 
 53 enum {
 54         Opt_uid,
 55         Opt_gid,
 56         Opt_mode,
 57         Opt_err
 58 };
 59 
 60 static 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 
 67 struct debugfs_fs_info {
 68         struct debugfs_mount_opts mount_opts;
 69 };
 70 
 71 static 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 
119 static 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 
134 static 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 
146 fail:
147         return err;
148 }
149 
150 static 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 
167 static 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 
175 static 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 
182 static 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 
189 static const struct dentry_operations debugfs_dops = {
190         .d_delete = always_delete_dentry,
191         .d_automount = debugfs_automount,
192 };
193 
194 static 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 
224 fail:
225         kfree(fsi);
226         sb->s_fs_info = NULL;
227         return err;
228 }
229 
230 static 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 
237 static 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 };
243 MODULE_ALIAS_FS("debugfs");
244 
245 static 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         mutex_lock(&d_inode(parent)->i_mutex);
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         if (IS_ERR(dentry))
275                 mutex_unlock(&d_inode(parent)->i_mutex);
276         return dentry;
277 }
278 
279 static struct dentry *failed_creating(struct dentry *dentry)
280 {
281         mutex_unlock(&d_inode(dentry->d_parent)->i_mutex);
282         dput(dentry);
283         simple_release_fs(&debugfs_mount, &debugfs_mount_count);
284         return NULL;
285 }
286 
287 static struct dentry *end_creating(struct dentry *dentry)
288 {
289         mutex_unlock(&d_inode(dentry->d_parent)->i_mutex);
290         return dentry;
291 }
292 
293 /**
294  * debugfs_create_file - create a file in the debugfs filesystem
295  * @name: a pointer to a string containing the name of the file to create.
296  * @mode: the permission that the file should have.
297  * @parent: a pointer to the parent dentry for this file.  This should be a
298  *          directory dentry if set.  If this parameter is NULL, then the
299  *          file will be created in the root of the debugfs filesystem.
300  * @data: a pointer to something that the caller will want to get to later
301  *        on.  The inode.i_private pointer will point to this value on
302  *        the open() call.
303  * @fops: a pointer to a struct file_operations that should be used for
304  *        this file.
305  *
306  * This is the basic "create a file" function for debugfs.  It allows for a
307  * wide range of flexibility in creating a file, or a directory (if you want
308  * to create a directory, the debugfs_create_dir() function is
309  * recommended to be used instead.)
310  *
311  * This function will return a pointer to a dentry if it succeeds.  This
312  * pointer must be passed to the debugfs_remove() function when the file is
313  * to be removed (no automatic cleanup happens if your module is unloaded,
314  * you are responsible here.)  If an error occurs, %NULL will be returned.
315  *
316  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
317  * returned.
318  */
319 struct dentry *debugfs_create_file(const char *name, umode_t mode,
320                                    struct dentry *parent, void *data,
321                                    const struct file_operations *fops)
322 {
323         struct dentry *dentry;
324         struct inode *inode;
325 
326         if (!(mode & S_IFMT))
327                 mode |= S_IFREG;
328         BUG_ON(!S_ISREG(mode));
329         dentry = start_creating(name, parent);
330 
331         if (IS_ERR(dentry))
332                 return NULL;
333 
334         inode = debugfs_get_inode(dentry->d_sb);
335         if (unlikely(!inode))
336                 return failed_creating(dentry);
337 
338         inode->i_mode = mode;
339         inode->i_fop = fops ? fops : &debugfs_file_operations;
340         inode->i_private = data;
341         d_instantiate(dentry, inode);
342         fsnotify_create(d_inode(dentry->d_parent), dentry);
343         return end_creating(dentry);
344 }
345 EXPORT_SYMBOL_GPL(debugfs_create_file);
346 
347 /**
348  * debugfs_create_file_size - create a file in the debugfs filesystem
349  * @name: a pointer to a string containing the name of the file to create.
350  * @mode: the permission that the file should have.
351  * @parent: a pointer to the parent dentry for this file.  This should be a
352  *          directory dentry if set.  If this parameter is NULL, then the
353  *          file will be created in the root of the debugfs filesystem.
354  * @data: a pointer to something that the caller will want to get to later
355  *        on.  The inode.i_private pointer will point to this value on
356  *        the open() call.
357  * @fops: a pointer to a struct file_operations that should be used for
358  *        this file.
359  * @file_size: initial file size
360  *
361  * This is the basic "create a file" function for debugfs.  It allows for a
362  * wide range of flexibility in creating a file, or a directory (if you want
363  * to create a directory, the debugfs_create_dir() function is
364  * recommended to be used instead.)
365  *
366  * This function will return a pointer to a dentry if it succeeds.  This
367  * pointer must be passed to the debugfs_remove() function when the file is
368  * to be removed (no automatic cleanup happens if your module is unloaded,
369  * you are responsible here.)  If an error occurs, %NULL will be returned.
370  *
371  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
372  * returned.
373  */
374 struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
375                                         struct dentry *parent, void *data,
376                                         const struct file_operations *fops,
377                                         loff_t file_size)
378 {
379         struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
380 
381         if (de)
382                 d_inode(de)->i_size = file_size;
383         return de;
384 }
385 EXPORT_SYMBOL_GPL(debugfs_create_file_size);
386 
387 /**
388  * debugfs_create_dir - create a directory in the debugfs filesystem
389  * @name: a pointer to a string containing the name of the directory to
390  *        create.
391  * @parent: a pointer to the parent dentry for this file.  This should be a
392  *          directory dentry if set.  If this parameter is NULL, then the
393  *          directory will be created in the root of the debugfs filesystem.
394  *
395  * This function creates a directory in debugfs with the given name.
396  *
397  * This function will return a pointer to a dentry if it succeeds.  This
398  * pointer must be passed to the debugfs_remove() function when the file is
399  * to be removed (no automatic cleanup happens if your module is unloaded,
400  * you are responsible here.)  If an error occurs, %NULL will be returned.
401  *
402  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
403  * returned.
404  */
405 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
406 {
407         struct dentry *dentry = start_creating(name, parent);
408         struct inode *inode;
409 
410         if (IS_ERR(dentry))
411                 return NULL;
412 
413         inode = debugfs_get_inode(dentry->d_sb);
414         if (unlikely(!inode))
415                 return failed_creating(dentry);
416 
417         inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
418         inode->i_op = &simple_dir_inode_operations;
419         inode->i_fop = &simple_dir_operations;
420 
421         /* directory inodes start off with i_nlink == 2 (for "." entry) */
422         inc_nlink(inode);
423         d_instantiate(dentry, inode);
424         inc_nlink(d_inode(dentry->d_parent));
425         fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
426         return end_creating(dentry);
427 }
428 EXPORT_SYMBOL_GPL(debugfs_create_dir);
429 
430 /**
431  * debugfs_create_automount - create automount point in the debugfs filesystem
432  * @name: a pointer to a string containing the name of the file to create.
433  * @parent: a pointer to the parent dentry for this file.  This should be a
434  *          directory dentry if set.  If this parameter is NULL, then the
435  *          file will be created in the root of the debugfs filesystem.
436  * @f: function to be called when pathname resolution steps on that one.
437  * @data: opaque argument to pass to f().
438  *
439  * @f should return what ->d_automount() would.
440  */
441 struct dentry *debugfs_create_automount(const char *name,
442                                         struct dentry *parent,
443                                         struct vfsmount *(*f)(void *),
444                                         void *data)
445 {
446         struct dentry *dentry = start_creating(name, parent);
447         struct inode *inode;
448 
449         if (IS_ERR(dentry))
450                 return NULL;
451 
452         inode = debugfs_get_inode(dentry->d_sb);
453         if (unlikely(!inode))
454                 return failed_creating(dentry);
455 
456         inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
457         inode->i_flags |= S_AUTOMOUNT;
458         inode->i_private = data;
459         dentry->d_fsdata = (void *)f;
460         d_instantiate(dentry, inode);
461         return end_creating(dentry);
462 }
463 EXPORT_SYMBOL(debugfs_create_automount);
464 
465 /**
466  * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
467  * @name: a pointer to a string containing the name of the symbolic link to
468  *        create.
469  * @parent: a pointer to the parent dentry for this symbolic link.  This
470  *          should be a directory dentry if set.  If this parameter is NULL,
471  *          then the symbolic link will be created in the root of the debugfs
472  *          filesystem.
473  * @target: a pointer to a string containing the path to the target of the
474  *          symbolic link.
475  *
476  * This function creates a symbolic link with the given name in debugfs that
477  * links to the given target path.
478  *
479  * This function will return a pointer to a dentry if it succeeds.  This
480  * pointer must be passed to the debugfs_remove() function when the symbolic
481  * link is to be removed (no automatic cleanup happens if your module is
482  * unloaded, you are responsible here.)  If an error occurs, %NULL will be
483  * returned.
484  *
485  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
486  * returned.
487  */
488 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
489                                       const char *target)
490 {
491         struct dentry *dentry;
492         struct inode *inode;
493         char *link = kstrdup(target, GFP_KERNEL);
494         if (!link)
495                 return NULL;
496 
497         dentry = start_creating(name, parent);
498         if (IS_ERR(dentry)) {
499                 kfree(link);
500                 return NULL;
501         }
502 
503         inode = debugfs_get_inode(dentry->d_sb);
504         if (unlikely(!inode)) {
505                 kfree(link);
506                 return failed_creating(dentry);
507         }
508         inode->i_mode = S_IFLNK | S_IRWXUGO;
509         inode->i_op = &simple_symlink_inode_operations;
510         inode->i_link = link;
511         d_instantiate(dentry, inode);
512         return end_creating(dentry);
513 }
514 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
515 
516 static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
517 {
518         int ret = 0;
519 
520         if (simple_positive(dentry)) {
521                 dget(dentry);
522                 if (d_is_dir(dentry))
523                         ret = simple_rmdir(d_inode(parent), dentry);
524                 else
525                         simple_unlink(d_inode(parent), dentry);
526                 if (!ret)
527                         d_delete(dentry);
528                 dput(dentry);
529         }
530         return ret;
531 }
532 
533 /**
534  * debugfs_remove - removes a file or directory from the debugfs filesystem
535  * @dentry: a pointer to a the dentry of the file or directory to be
536  *          removed.
537  *
538  * This function removes a file or directory in debugfs that was previously
539  * created with a call to another debugfs function (like
540  * debugfs_create_file() or variants thereof.)
541  *
542  * This function is required to be called in order for the file to be
543  * removed, no automatic cleanup of files will happen when a module is
544  * removed, you are responsible here.
545  */
546 void debugfs_remove(struct dentry *dentry)
547 {
548         struct dentry *parent;
549         int ret;
550 
551         if (IS_ERR_OR_NULL(dentry))
552                 return;
553 
554         parent = dentry->d_parent;
555         if (!parent || d_really_is_negative(parent))
556                 return;
557 
558         mutex_lock(&d_inode(parent)->i_mutex);
559         ret = __debugfs_remove(dentry, parent);
560         mutex_unlock(&d_inode(parent)->i_mutex);
561         if (!ret)
562                 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
563 }
564 EXPORT_SYMBOL_GPL(debugfs_remove);
565 
566 /**
567  * debugfs_remove_recursive - recursively removes a directory
568  * @dentry: a pointer to a the dentry of the directory to be removed.
569  *
570  * This function recursively removes a directory tree in debugfs that
571  * was previously created with a call to another debugfs function
572  * (like debugfs_create_file() or variants thereof.)
573  *
574  * This function is required to be called in order for the file to be
575  * removed, no automatic cleanup of files will happen when a module is
576  * removed, you are responsible here.
577  */
578 void debugfs_remove_recursive(struct dentry *dentry)
579 {
580         struct dentry *child, *parent;
581 
582         if (IS_ERR_OR_NULL(dentry))
583                 return;
584 
585         parent = dentry->d_parent;
586         if (!parent || d_really_is_negative(parent))
587                 return;
588 
589         parent = dentry;
590  down:
591         mutex_lock(&d_inode(parent)->i_mutex);
592  loop:
593         /*
594          * The parent->d_subdirs is protected by the d_lock. Outside that
595          * lock, the child can be unlinked and set to be freed which can
596          * use the d_u.d_child as the rcu head and corrupt this list.
597          */
598         spin_lock(&parent->d_lock);
599         list_for_each_entry(child, &parent->d_subdirs, d_child) {
600                 if (!simple_positive(child))
601                         continue;
602 
603                 /* perhaps simple_empty(child) makes more sense */
604                 if (!list_empty(&child->d_subdirs)) {
605                         spin_unlock(&parent->d_lock);
606                         mutex_unlock(&d_inode(parent)->i_mutex);
607                         parent = child;
608                         goto down;
609                 }
610 
611                 spin_unlock(&parent->d_lock);
612 
613                 if (!__debugfs_remove(child, parent))
614                         simple_release_fs(&debugfs_mount, &debugfs_mount_count);
615 
616                 /*
617                  * The parent->d_lock protects agaist child from unlinking
618                  * from d_subdirs. When releasing the parent->d_lock we can
619                  * no longer trust that the next pointer is valid.
620                  * Restart the loop. We'll skip this one with the
621                  * simple_positive() check.
622                  */
623                 goto loop;
624         }
625         spin_unlock(&parent->d_lock);
626 
627         mutex_unlock(&d_inode(parent)->i_mutex);
628         child = parent;
629         parent = parent->d_parent;
630         mutex_lock(&d_inode(parent)->i_mutex);
631 
632         if (child != dentry)
633                 /* go up */
634                 goto loop;
635 
636         if (!__debugfs_remove(child, parent))
637                 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
638         mutex_unlock(&d_inode(parent)->i_mutex);
639 }
640 EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
641 
642 /**
643  * debugfs_rename - rename a file/directory in the debugfs filesystem
644  * @old_dir: a pointer to the parent dentry for the renamed object. This
645  *          should be a directory dentry.
646  * @old_dentry: dentry of an object to be renamed.
647  * @new_dir: a pointer to the parent dentry where the object should be
648  *          moved. This should be a directory dentry.
649  * @new_name: a pointer to a string containing the target name.
650  *
651  * This function renames a file/directory in debugfs.  The target must not
652  * exist for rename to succeed.
653  *
654  * This function will return a pointer to old_dentry (which is updated to
655  * reflect renaming) if it succeeds. If an error occurs, %NULL will be
656  * returned.
657  *
658  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
659  * returned.
660  */
661 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
662                 struct dentry *new_dir, const char *new_name)
663 {
664         int error;
665         struct dentry *dentry = NULL, *trap;
666         const char *old_name;
667 
668         trap = lock_rename(new_dir, old_dir);
669         /* Source or destination directories don't exist? */
670         if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
671                 goto exit;
672         /* Source does not exist, cyclic rename, or mountpoint? */
673         if (d_really_is_negative(old_dentry) || old_dentry == trap ||
674             d_mountpoint(old_dentry))
675                 goto exit;
676         dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
677         /* Lookup failed, cyclic rename or target exists? */
678         if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry))
679                 goto exit;
680 
681         old_name = fsnotify_oldname_init(old_dentry->d_name.name);
682 
683         error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
684                 dentry);
685         if (error) {
686                 fsnotify_oldname_free(old_name);
687                 goto exit;
688         }
689         d_move(old_dentry, dentry);
690         fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name,
691                 d_is_dir(old_dentry),
692                 NULL, old_dentry);
693         fsnotify_oldname_free(old_name);
694         unlock_rename(new_dir, old_dir);
695         dput(dentry);
696         return old_dentry;
697 exit:
698         if (dentry && !IS_ERR(dentry))
699                 dput(dentry);
700         unlock_rename(new_dir, old_dir);
701         return NULL;
702 }
703 EXPORT_SYMBOL_GPL(debugfs_rename);
704 
705 /**
706  * debugfs_initialized - Tells whether debugfs has been registered
707  */
708 bool debugfs_initialized(void)
709 {
710         return debugfs_registered;
711 }
712 EXPORT_SYMBOL_GPL(debugfs_initialized);
713 
714 static int __init debugfs_init(void)
715 {
716         int retval;
717 
718         retval = sysfs_create_mount_point(kernel_kobj, "debug");
719         if (retval)
720                 return retval;
721 
722         retval = register_filesystem(&debug_fs_type);
723         if (retval)
724                 sysfs_remove_mount_point(kernel_kobj, "debug");
725         else
726                 debugfs_registered = true;
727 
728         return retval;
729 }
730 core_initcall(debugfs_init);
731 
732 

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