2 * inode.c - part of debugfs, a tiny little debug file system
4 * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
5 * Copyright (C) 2004 IBM Inc.
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.
11 * debugfs is for people to use instead of /proc or /sys.
12 * See Documentation/DocBook/kernel-api for more details.
16 #include <linux/module.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>
31 #define DEBUGFS_DEFAULT_MODE 0700
33 static struct vfsmount *debugfs_mount;
34 static int debugfs_mount_count;
35 static bool debugfs_registered;
37 static struct inode *debugfs_get_inode(struct super_block *sb, umode_t mode, dev_t dev,
38 void *data, const struct file_operations *fops)
41 struct inode *inode = new_inode(sb);
44 inode->i_ino = get_next_ino();
46 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
47 switch (mode & S_IFMT) {
49 init_special_inode(inode, mode, dev);
52 inode->i_fop = fops ? fops : &debugfs_file_operations;
53 inode->i_private = data;
56 inode->i_op = &debugfs_link_operations;
57 inode->i_private = data;
60 inode->i_op = &simple_dir_inode_operations;
61 inode->i_fop = &simple_dir_operations;
63 /* directory inodes start off with i_nlink == 2
73 static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
74 umode_t mode, dev_t dev, void *data,
75 const struct file_operations *fops)
83 inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops);
85 d_instantiate(dentry, inode);
92 static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
96 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
97 res = debugfs_mknod(dir, dentry, mode, 0, NULL, NULL);
100 fsnotify_mkdir(dir, dentry);
105 static int debugfs_link(struct inode *dir, struct dentry *dentry, umode_t mode,
108 mode = (mode & S_IALLUGO) | S_IFLNK;
109 return debugfs_mknod(dir, dentry, mode, 0, data, NULL);
112 static int debugfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
113 void *data, const struct file_operations *fops)
117 mode = (mode & S_IALLUGO) | S_IFREG;
118 res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
120 fsnotify_create(dir, dentry);
124 static inline int debugfs_positive(struct dentry *dentry)
126 return dentry->d_inode && !d_unhashed(dentry);
129 struct debugfs_mount_opts {
142 static const match_table_t tokens = {
145 {Opt_mode, "mode=%o"},
149 struct debugfs_fs_info {
150 struct debugfs_mount_opts mount_opts;
153 static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
155 substring_t args[MAX_OPT_ARGS];
162 opts->mode = DEBUGFS_DEFAULT_MODE;
164 while ((p = strsep(&data, ",")) != NULL) {
168 token = match_token(p, tokens, args);
171 if (match_int(&args[0], &option))
173 uid = make_kuid(current_user_ns(), option);
179 if (match_int(&args[0], &option))
181 gid = make_kgid(current_user_ns(), option);
187 if (match_octal(&args[0], &option))
189 opts->mode = option & S_IALLUGO;
192 * We might like to report bad mount options here;
193 * but traditionally debugfs has ignored all mount options
201 static int debugfs_apply_options(struct super_block *sb)
203 struct debugfs_fs_info *fsi = sb->s_fs_info;
204 struct inode *inode = sb->s_root->d_inode;
205 struct debugfs_mount_opts *opts = &fsi->mount_opts;
207 inode->i_mode &= ~S_IALLUGO;
208 inode->i_mode |= opts->mode;
210 inode->i_uid = opts->uid;
211 inode->i_gid = opts->gid;
216 static int debugfs_remount(struct super_block *sb, int *flags, char *data)
219 struct debugfs_fs_info *fsi = sb->s_fs_info;
221 err = debugfs_parse_options(data, &fsi->mount_opts);
225 debugfs_apply_options(sb);
231 static int debugfs_show_options(struct seq_file *m, struct dentry *root)
233 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
234 struct debugfs_mount_opts *opts = &fsi->mount_opts;
236 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
237 seq_printf(m, ",uid=%u",
238 from_kuid_munged(&init_user_ns, opts->uid));
239 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
240 seq_printf(m, ",gid=%u",
241 from_kgid_munged(&init_user_ns, opts->gid));
242 if (opts->mode != DEBUGFS_DEFAULT_MODE)
243 seq_printf(m, ",mode=%o", opts->mode);
248 static const struct super_operations debugfs_super_operations = {
249 .statfs = simple_statfs,
250 .remount_fs = debugfs_remount,
251 .show_options = debugfs_show_options,
254 static int debug_fill_super(struct super_block *sb, void *data, int silent)
256 static struct tree_descr debug_files[] = {{""}};
257 struct debugfs_fs_info *fsi;
260 save_mount_options(sb, data);
262 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
269 err = debugfs_parse_options(data, &fsi->mount_opts);
273 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
277 sb->s_op = &debugfs_super_operations;
279 debugfs_apply_options(sb);
285 sb->s_fs_info = NULL;
289 static struct dentry *debug_mount(struct file_system_type *fs_type,
290 int flags, const char *dev_name,
293 return mount_single(fs_type, flags, data, debug_fill_super);
296 static struct file_system_type debug_fs_type = {
297 .owner = THIS_MODULE,
299 .mount = debug_mount,
300 .kill_sb = kill_litter_super,
303 static struct dentry *__create_file(const char *name, umode_t mode,
304 struct dentry *parent, void *data,
305 const struct file_operations *fops)
307 struct dentry *dentry = NULL;
310 pr_debug("debugfs: creating file '%s'\n",name);
312 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
313 &debugfs_mount_count);
317 /* If the parent is not specified, we create it in the root.
318 * We need the root dentry to do this, which is in the super
319 * block. A pointer to that is in the struct vfsmount that we
323 parent = debugfs_mount->mnt_root;
325 mutex_lock(&parent->d_inode->i_mutex);
326 dentry = lookup_one_len(name, parent, strlen(name));
327 if (!IS_ERR(dentry)) {
328 switch (mode & S_IFMT) {
330 error = debugfs_mkdir(parent->d_inode, dentry, mode);
334 error = debugfs_link(parent->d_inode, dentry, mode,
338 error = debugfs_create(parent->d_inode, dentry, mode,
344 error = PTR_ERR(dentry);
345 mutex_unlock(&parent->d_inode->i_mutex);
349 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
356 * debugfs_create_file - create a file in the debugfs filesystem
357 * @name: a pointer to a string containing the name of the file to create.
358 * @mode: the permission that the file should have.
359 * @parent: a pointer to the parent dentry for this file. This should be a
360 * directory dentry if set. If this paramater is NULL, then the
361 * file will be created in the root of the debugfs filesystem.
362 * @data: a pointer to something that the caller will want to get to later
363 * on. The inode.i_private pointer will point to this value on
365 * @fops: a pointer to a struct file_operations that should be used for
368 * This is the basic "create a file" function for debugfs. It allows for a
369 * wide range of flexibility in creating a file, or a directory (if you want
370 * to create a directory, the debugfs_create_dir() function is
371 * recommended to be used instead.)
373 * This function will return a pointer to a dentry if it succeeds. This
374 * pointer must be passed to the debugfs_remove() function when the file is
375 * to be removed (no automatic cleanup happens if your module is unloaded,
376 * you are responsible here.) If an error occurs, %NULL will be returned.
378 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
381 struct dentry *debugfs_create_file(const char *name, umode_t mode,
382 struct dentry *parent, void *data,
383 const struct file_operations *fops)
385 switch (mode & S_IFMT) {
393 return __create_file(name, mode, parent, data, fops);
395 EXPORT_SYMBOL_GPL(debugfs_create_file);
398 * debugfs_create_dir - create a directory in the debugfs filesystem
399 * @name: a pointer to a string containing the name of the directory to
401 * @parent: a pointer to the parent dentry for this file. This should be a
402 * directory dentry if set. If this paramater is NULL, then the
403 * directory will be created in the root of the debugfs filesystem.
405 * This function creates a directory in debugfs with the given name.
407 * This function will return a pointer to a dentry if it succeeds. This
408 * pointer must be passed to the debugfs_remove() function when the file is
409 * to be removed (no automatic cleanup happens if your module is unloaded,
410 * you are responsible here.) If an error occurs, %NULL will be returned.
412 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
415 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
417 return __create_file(name, S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
420 EXPORT_SYMBOL_GPL(debugfs_create_dir);
423 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
424 * @name: a pointer to a string containing the name of the symbolic link to
426 * @parent: a pointer to the parent dentry for this symbolic link. This
427 * should be a directory dentry if set. If this paramater is NULL,
428 * then the symbolic link will be created in the root of the debugfs
430 * @target: a pointer to a string containing the path to the target of the
433 * This function creates a symbolic link with the given name in debugfs that
434 * links to the given target path.
436 * This function will return a pointer to a dentry if it succeeds. This
437 * pointer must be passed to the debugfs_remove() function when the symbolic
438 * link is to be removed (no automatic cleanup happens if your module is
439 * unloaded, you are responsible here.) If an error occurs, %NULL will be
442 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
445 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
448 struct dentry *result;
451 link = kstrdup(target, GFP_KERNEL);
455 result = __create_file(name, S_IFLNK | S_IRWXUGO, parent, link, NULL);
460 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
462 static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
466 if (debugfs_positive(dentry)) {
467 if (dentry->d_inode) {
469 switch (dentry->d_inode->i_mode & S_IFMT) {
471 ret = simple_rmdir(parent->d_inode, dentry);
474 kfree(dentry->d_inode->i_private);
477 simple_unlink(parent->d_inode, dentry);
489 * debugfs_remove - removes a file or directory from the debugfs filesystem
490 * @dentry: a pointer to a the dentry of the file or directory to be
493 * This function removes a file or directory in debugfs that was previously
494 * created with a call to another debugfs function (like
495 * debugfs_create_file() or variants thereof.)
497 * This function is required to be called in order for the file to be
498 * removed, no automatic cleanup of files will happen when a module is
499 * removed, you are responsible here.
501 void debugfs_remove(struct dentry *dentry)
503 struct dentry *parent;
506 if (IS_ERR_OR_NULL(dentry))
509 parent = dentry->d_parent;
510 if (!parent || !parent->d_inode)
513 mutex_lock(&parent->d_inode->i_mutex);
514 ret = __debugfs_remove(dentry, parent);
515 mutex_unlock(&parent->d_inode->i_mutex);
517 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
519 EXPORT_SYMBOL_GPL(debugfs_remove);
522 * debugfs_remove_recursive - recursively removes a directory
523 * @dentry: a pointer to a the dentry of the directory to be removed.
525 * This function recursively removes a directory tree in debugfs that
526 * was previously created with a call to another debugfs function
527 * (like debugfs_create_file() or variants thereof.)
529 * This function is required to be called in order for the file to be
530 * removed, no automatic cleanup of files will happen when a module is
531 * removed, you are responsible here.
533 void debugfs_remove_recursive(struct dentry *dentry)
535 struct dentry *child;
536 struct dentry *parent;
538 if (IS_ERR_OR_NULL(dentry))
541 parent = dentry->d_parent;
542 if (!parent || !parent->d_inode)
546 mutex_lock(&parent->d_inode->i_mutex);
550 * When all dentries under "parent" has been removed,
551 * walk up the tree until we reach our starting point.
553 if (list_empty(&parent->d_subdirs)) {
554 mutex_unlock(&parent->d_inode->i_mutex);
555 if (parent == dentry)
557 parent = parent->d_parent;
558 mutex_lock(&parent->d_inode->i_mutex);
560 child = list_entry(parent->d_subdirs.next, struct dentry,
565 * If "child" isn't empty, walk down the tree and
566 * remove all its descendants first.
568 if (!list_empty(&child->d_subdirs)) {
569 mutex_unlock(&parent->d_inode->i_mutex);
571 mutex_lock(&parent->d_inode->i_mutex);
574 __debugfs_remove(child, parent);
575 if (parent->d_subdirs.next == &child->d_u.d_child) {
577 * Try the next sibling.
579 if (child->d_u.d_child.next != &parent->d_subdirs) {
580 child = list_entry(child->d_u.d_child.next,
587 * Avoid infinite loop if we fail to remove
590 mutex_unlock(&parent->d_inode->i_mutex);
593 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
596 parent = dentry->d_parent;
597 mutex_lock(&parent->d_inode->i_mutex);
598 __debugfs_remove(dentry, parent);
599 mutex_unlock(&parent->d_inode->i_mutex);
600 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
602 EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
605 * debugfs_rename - rename a file/directory in the debugfs filesystem
606 * @old_dir: a pointer to the parent dentry for the renamed object. This
607 * should be a directory dentry.
608 * @old_dentry: dentry of an object to be renamed.
609 * @new_dir: a pointer to the parent dentry where the object should be
610 * moved. This should be a directory dentry.
611 * @new_name: a pointer to a string containing the target name.
613 * This function renames a file/directory in debugfs. The target must not
614 * exist for rename to succeed.
616 * This function will return a pointer to old_dentry (which is updated to
617 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
620 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
623 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
624 struct dentry *new_dir, const char *new_name)
627 struct dentry *dentry = NULL, *trap;
628 const char *old_name;
630 trap = lock_rename(new_dir, old_dir);
631 /* Source or destination directories don't exist? */
632 if (!old_dir->d_inode || !new_dir->d_inode)
634 /* Source does not exist, cyclic rename, or mountpoint? */
635 if (!old_dentry->d_inode || old_dentry == trap ||
636 d_mountpoint(old_dentry))
638 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
639 /* Lookup failed, cyclic rename or target exists? */
640 if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
643 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
645 error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
648 fsnotify_oldname_free(old_name);
651 d_move(old_dentry, dentry);
652 fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
653 S_ISDIR(old_dentry->d_inode->i_mode),
655 fsnotify_oldname_free(old_name);
656 unlock_rename(new_dir, old_dir);
660 if (dentry && !IS_ERR(dentry))
662 unlock_rename(new_dir, old_dir);
665 EXPORT_SYMBOL_GPL(debugfs_rename);
668 * debugfs_initialized - Tells whether debugfs has been registered
670 bool debugfs_initialized(void)
672 return debugfs_registered;
674 EXPORT_SYMBOL_GPL(debugfs_initialized);
677 static struct kobject *debug_kobj;
679 static int __init debugfs_init(void)
683 debug_kobj = kobject_create_and_add("debug", kernel_kobj);
687 retval = register_filesystem(&debug_fs_type);
689 kobject_put(debug_kobj);
691 debugfs_registered = true;
695 core_initcall(debugfs_init);