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)
39 struct inode *inode = new_inode(sb);
41 inode->i_ino = get_next_ino();
42 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
47 static inline int debugfs_positive(struct dentry *dentry)
49 return dentry->d_inode && !d_unhashed(dentry);
52 struct debugfs_mount_opts {
65 static const match_table_t tokens = {
68 {Opt_mode, "mode=%o"},
72 struct debugfs_fs_info {
73 struct debugfs_mount_opts mount_opts;
76 static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
78 substring_t args[MAX_OPT_ARGS];
85 opts->mode = DEBUGFS_DEFAULT_MODE;
87 while ((p = strsep(&data, ",")) != NULL) {
91 token = match_token(p, tokens, args);
94 if (match_int(&args[0], &option))
96 uid = make_kuid(current_user_ns(), option);
102 if (match_int(&args[0], &option))
104 gid = make_kgid(current_user_ns(), option);
110 if (match_octal(&args[0], &option))
112 opts->mode = option & S_IALLUGO;
115 * We might like to report bad mount options here;
116 * but traditionally debugfs has ignored all mount options
124 static int debugfs_apply_options(struct super_block *sb)
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;
130 inode->i_mode &= ~S_IALLUGO;
131 inode->i_mode |= opts->mode;
133 inode->i_uid = opts->uid;
134 inode->i_gid = opts->gid;
139 static int debugfs_remount(struct super_block *sb, int *flags, char *data)
142 struct debugfs_fs_info *fsi = sb->s_fs_info;
145 err = debugfs_parse_options(data, &fsi->mount_opts);
149 debugfs_apply_options(sb);
155 static int debugfs_show_options(struct seq_file *m, struct dentry *root)
157 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
158 struct debugfs_mount_opts *opts = &fsi->mount_opts;
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);
172 static const struct super_operations debugfs_super_operations = {
173 .statfs = simple_statfs,
174 .remount_fs = debugfs_remount,
175 .show_options = debugfs_show_options,
178 static struct vfsmount *debugfs_automount(struct path *path)
180 struct vfsmount *(*f)(void *);
181 f = (struct vfsmount *(*)(void *))path->dentry->d_fsdata;
182 return f(path->dentry->d_inode->i_private);
185 static const struct dentry_operations debugfs_dops = {
186 .d_delete = always_delete_dentry,
187 .d_automount = debugfs_automount,
190 static int debug_fill_super(struct super_block *sb, void *data, int silent)
192 static struct tree_descr debug_files[] = {{""}};
193 struct debugfs_fs_info *fsi;
196 save_mount_options(sb, data);
198 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
205 err = debugfs_parse_options(data, &fsi->mount_opts);
209 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
213 sb->s_op = &debugfs_super_operations;
214 sb->s_d_op = &debugfs_dops;
216 debugfs_apply_options(sb);
222 sb->s_fs_info = NULL;
226 static struct dentry *debug_mount(struct file_system_type *fs_type,
227 int flags, const char *dev_name,
230 return mount_single(fs_type, flags, data, debug_fill_super);
233 static struct file_system_type debug_fs_type = {
234 .owner = THIS_MODULE,
236 .mount = debug_mount,
237 .kill_sb = kill_litter_super,
239 MODULE_ALIAS_FS("debugfs");
241 static struct dentry *start_creating(const char *name, struct dentry *parent)
243 struct dentry *dentry;
246 pr_debug("debugfs: creating file '%s'\n",name);
248 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
249 &debugfs_mount_count);
251 return ERR_PTR(error);
253 /* If the parent is not specified, we create it in the root.
254 * We need the root dentry to do this, which is in the super
255 * block. A pointer to that is in the struct vfsmount that we
259 parent = debugfs_mount->mnt_root;
261 mutex_lock(&parent->d_inode->i_mutex);
262 dentry = lookup_one_len(name, parent, strlen(name));
263 if (!IS_ERR(dentry) && dentry->d_inode) {
265 dentry = ERR_PTR(-EEXIST);
268 mutex_unlock(&parent->d_inode->i_mutex);
272 static struct dentry *failed_creating(struct dentry *dentry)
274 mutex_unlock(&dentry->d_parent->d_inode->i_mutex);
276 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
280 static struct dentry *end_creating(struct dentry *dentry)
282 mutex_unlock(&dentry->d_parent->d_inode->i_mutex);
287 * debugfs_create_file - create a file in the debugfs filesystem
288 * @name: a pointer to a string containing the name of the file to create.
289 * @mode: the permission that the file should have.
290 * @parent: a pointer to the parent dentry for this file. This should be a
291 * directory dentry if set. If this parameter is NULL, then the
292 * file will be created in the root of the debugfs filesystem.
293 * @data: a pointer to something that the caller will want to get to later
294 * on. The inode.i_private pointer will point to this value on
296 * @fops: a pointer to a struct file_operations that should be used for
299 * This is the basic "create a file" function for debugfs. It allows for a
300 * wide range of flexibility in creating a file, or a directory (if you want
301 * to create a directory, the debugfs_create_dir() function is
302 * recommended to be used instead.)
304 * This function will return a pointer to a dentry if it succeeds. This
305 * pointer must be passed to the debugfs_remove() function when the file is
306 * to be removed (no automatic cleanup happens if your module is unloaded,
307 * you are responsible here.) If an error occurs, %NULL will be returned.
309 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
312 struct dentry *debugfs_create_file(const char *name, umode_t mode,
313 struct dentry *parent, void *data,
314 const struct file_operations *fops)
316 struct dentry *dentry;
319 if (!(mode & S_IFMT))
321 BUG_ON(!S_ISREG(mode));
322 dentry = start_creating(name, parent);
327 inode = debugfs_get_inode(dentry->d_sb);
328 if (unlikely(!inode))
329 return failed_creating(dentry);
331 inode->i_mode = mode;
332 inode->i_fop = fops ? fops : &debugfs_file_operations;
333 inode->i_private = data;
334 d_instantiate(dentry, inode);
335 fsnotify_create(dentry->d_parent->d_inode, dentry);
336 return end_creating(dentry);
338 EXPORT_SYMBOL_GPL(debugfs_create_file);
341 * debugfs_create_file_size - create a file in the debugfs filesystem
342 * @name: a pointer to a string containing the name of the file to create.
343 * @mode: the permission that the file should have.
344 * @parent: a pointer to the parent dentry for this file. This should be a
345 * directory dentry if set. If this parameter is NULL, then the
346 * file will be created in the root of the debugfs filesystem.
347 * @data: a pointer to something that the caller will want to get to later
348 * on. The inode.i_private pointer will point to this value on
350 * @fops: a pointer to a struct file_operations that should be used for
352 * @file_size: initial file size
354 * This is the basic "create a file" function for debugfs. It allows for a
355 * wide range of flexibility in creating a file, or a directory (if you want
356 * to create a directory, the debugfs_create_dir() function is
357 * recommended to be used instead.)
359 * This function will return a pointer to a dentry if it succeeds. This
360 * pointer must be passed to the debugfs_remove() function when the file is
361 * to be removed (no automatic cleanup happens if your module is unloaded,
362 * you are responsible here.) If an error occurs, %NULL will be returned.
364 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
367 struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
368 struct dentry *parent, void *data,
369 const struct file_operations *fops,
372 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
375 de->d_inode->i_size = file_size;
378 EXPORT_SYMBOL_GPL(debugfs_create_file_size);
381 * debugfs_create_dir - create a directory in the debugfs filesystem
382 * @name: a pointer to a string containing the name of the directory to
384 * @parent: a pointer to the parent dentry for this file. This should be a
385 * directory dentry if set. If this parameter is NULL, then the
386 * directory will be created in the root of the debugfs filesystem.
388 * This function creates a directory in debugfs with the given name.
390 * This function will return a pointer to a dentry if it succeeds. This
391 * pointer must be passed to the debugfs_remove() function when the file is
392 * to be removed (no automatic cleanup happens if your module is unloaded,
393 * you are responsible here.) If an error occurs, %NULL will be returned.
395 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
398 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
400 struct dentry *dentry = start_creating(name, parent);
406 inode = debugfs_get_inode(dentry->d_sb);
407 if (unlikely(!inode))
408 return failed_creating(dentry);
410 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
411 inode->i_op = &simple_dir_inode_operations;
412 inode->i_fop = &simple_dir_operations;
414 /* directory inodes start off with i_nlink == 2 (for "." entry) */
416 d_instantiate(dentry, inode);
417 inc_nlink(dentry->d_parent->d_inode);
418 fsnotify_mkdir(dentry->d_parent->d_inode, dentry);
419 return end_creating(dentry);
421 EXPORT_SYMBOL_GPL(debugfs_create_dir);
424 * debugfs_create_automount - create automount point in the debugfs filesystem
425 * @name: a pointer to a string containing the name of the file to create.
426 * @parent: a pointer to the parent dentry for this file. This should be a
427 * directory dentry if set. If this parameter is NULL, then the
428 * file will be created in the root of the debugfs filesystem.
429 * @f: function to be called when pathname resolution steps on that one.
430 * @data: opaque argument to pass to f().
432 * @f should return what ->d_automount() would.
434 struct dentry *debugfs_create_automount(const char *name,
435 struct dentry *parent,
436 struct vfsmount *(*f)(void *),
439 struct dentry *dentry = start_creating(name, parent);
445 inode = debugfs_get_inode(dentry->d_sb);
446 if (unlikely(!inode))
447 return failed_creating(dentry);
449 inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
450 inode->i_flags |= S_AUTOMOUNT;
451 inode->i_private = data;
452 dentry->d_fsdata = (void *)f;
453 d_instantiate(dentry, inode);
454 return end_creating(dentry);
456 EXPORT_SYMBOL(debugfs_create_automount);
459 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
460 * @name: a pointer to a string containing the name of the symbolic link to
462 * @parent: a pointer to the parent dentry for this symbolic link. This
463 * should be a directory dentry if set. If this parameter is NULL,
464 * then the symbolic link will be created in the root of the debugfs
466 * @target: a pointer to a string containing the path to the target of the
469 * This function creates a symbolic link with the given name in debugfs that
470 * links to the given target path.
472 * This function will return a pointer to a dentry if it succeeds. This
473 * pointer must be passed to the debugfs_remove() function when the symbolic
474 * link is to be removed (no automatic cleanup happens if your module is
475 * unloaded, you are responsible here.) If an error occurs, %NULL will be
478 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
481 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
484 struct dentry *dentry;
486 char *link = kstrdup(target, GFP_KERNEL);
490 dentry = start_creating(name, parent);
491 if (IS_ERR(dentry)) {
496 inode = debugfs_get_inode(dentry->d_sb);
497 if (unlikely(!inode)) {
499 return failed_creating(dentry);
501 inode->i_mode = S_IFLNK | S_IRWXUGO;
502 inode->i_op = &debugfs_link_operations;
503 inode->i_private = link;
504 d_instantiate(dentry, inode);
505 return end_creating(dentry);
507 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
509 static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
513 if (debugfs_positive(dentry)) {
514 if (dentry->d_inode) {
516 switch (dentry->d_inode->i_mode & S_IFMT) {
518 ret = simple_rmdir(parent->d_inode, dentry);
521 kfree(dentry->d_inode->i_private);
524 simple_unlink(parent->d_inode, dentry);
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
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.)
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.
548 void debugfs_remove(struct dentry *dentry)
550 struct dentry *parent;
553 if (IS_ERR_OR_NULL(dentry))
556 parent = dentry->d_parent;
557 if (!parent || !parent->d_inode)
560 mutex_lock(&parent->d_inode->i_mutex);
561 ret = __debugfs_remove(dentry, parent);
562 mutex_unlock(&parent->d_inode->i_mutex);
564 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
566 EXPORT_SYMBOL_GPL(debugfs_remove);
569 * debugfs_remove_recursive - recursively removes a directory
570 * @dentry: a pointer to a the dentry of the directory to be removed.
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.)
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.
580 void debugfs_remove_recursive(struct dentry *dentry)
582 struct dentry *child, *parent;
584 if (IS_ERR_OR_NULL(dentry))
587 parent = dentry->d_parent;
588 if (!parent || !parent->d_inode)
593 mutex_lock(&parent->d_inode->i_mutex);
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.
600 spin_lock(&parent->d_lock);
601 list_for_each_entry(child, &parent->d_subdirs, d_child) {
602 if (!debugfs_positive(child))
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);
613 spin_unlock(&parent->d_lock);
615 if (!__debugfs_remove(child, parent))
616 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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.
627 spin_unlock(&parent->d_lock);
629 mutex_unlock(&parent->d_inode->i_mutex);
631 parent = parent->d_parent;
632 mutex_lock(&parent->d_inode->i_mutex);
638 if (!__debugfs_remove(child, parent))
639 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
640 mutex_unlock(&parent->d_inode->i_mutex);
642 EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
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.
653 * This function renames a file/directory in debugfs. The target must not
654 * exist for rename to succeed.
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
660 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
663 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
664 struct dentry *new_dir, const char *new_name)
667 struct dentry *dentry = NULL, *trap;
668 const char *old_name;
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)
674 /* Source does not exist, cyclic rename, or mountpoint? */
675 if (!old_dentry->d_inode || old_dentry == trap ||
676 d_mountpoint(old_dentry))
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)
683 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
685 error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
688 fsnotify_oldname_free(old_name);
691 d_move(old_dentry, dentry);
692 fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
693 S_ISDIR(old_dentry->d_inode->i_mode),
695 fsnotify_oldname_free(old_name);
696 unlock_rename(new_dir, old_dir);
700 if (dentry && !IS_ERR(dentry))
702 unlock_rename(new_dir, old_dir);
705 EXPORT_SYMBOL_GPL(debugfs_rename);
708 * debugfs_initialized - Tells whether debugfs has been registered
710 bool debugfs_initialized(void)
712 return debugfs_registered;
714 EXPORT_SYMBOL_GPL(debugfs_initialized);
717 static struct kobject *debug_kobj;
719 static int __init debugfs_init(void)
723 debug_kobj = kobject_create_and_add("debug", kernel_kobj);
727 retval = register_filesystem(&debug_fs_type);
729 kobject_put(debug_kobj);
731 debugfs_registered = true;
735 core_initcall(debugfs_init);