Version:  2.0.40 2.2.26 2.4.37 3.4 3.5 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

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

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