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 struct debugfs_mount_opts {
60 static const match_table_t tokens = {
63 {Opt_mode, "mode=%o"},
67 struct debugfs_fs_info {
68 struct debugfs_mount_opts mount_opts;
71 static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
73 substring_t args[MAX_OPT_ARGS];
80 opts->mode = DEBUGFS_DEFAULT_MODE;
82 while ((p = strsep(&data, ",")) != NULL) {
86 token = match_token(p, tokens, args);
89 if (match_int(&args[0], &option))
91 uid = make_kuid(current_user_ns(), option);
97 if (match_int(&args[0], &option))
99 gid = make_kgid(current_user_ns(), option);
105 if (match_octal(&args[0], &option))
107 opts->mode = option & S_IALLUGO;
110 * We might like to report bad mount options here;
111 * but traditionally debugfs has ignored all mount options
119 static int debugfs_apply_options(struct super_block *sb)
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;
125 inode->i_mode &= ~S_IALLUGO;
126 inode->i_mode |= opts->mode;
128 inode->i_uid = opts->uid;
129 inode->i_gid = opts->gid;
134 static int debugfs_remount(struct super_block *sb, int *flags, char *data)
137 struct debugfs_fs_info *fsi = sb->s_fs_info;
140 err = debugfs_parse_options(data, &fsi->mount_opts);
144 debugfs_apply_options(sb);
150 static int debugfs_show_options(struct seq_file *m, struct dentry *root)
152 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
153 struct debugfs_mount_opts *opts = &fsi->mount_opts;
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);
167 static void debugfs_evict_inode(struct inode *inode)
169 truncate_inode_pages_final(&inode->i_data);
171 if (S_ISLNK(inode->i_mode))
172 kfree(inode->i_link);
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,
182 static struct vfsmount *debugfs_automount(struct path *path)
184 struct vfsmount *(*f)(void *);
185 f = (struct vfsmount *(*)(void *))path->dentry->d_fsdata;
186 return f(d_inode(path->dentry)->i_private);
189 static const struct dentry_operations debugfs_dops = {
190 .d_delete = always_delete_dentry,
191 .d_automount = debugfs_automount,
194 static int debug_fill_super(struct super_block *sb, void *data, int silent)
196 static struct tree_descr debug_files[] = {{""}};
197 struct debugfs_fs_info *fsi;
200 save_mount_options(sb, data);
202 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
209 err = debugfs_parse_options(data, &fsi->mount_opts);
213 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
217 sb->s_op = &debugfs_super_operations;
218 sb->s_d_op = &debugfs_dops;
220 debugfs_apply_options(sb);
226 sb->s_fs_info = NULL;
230 static struct dentry *debug_mount(struct file_system_type *fs_type,
231 int flags, const char *dev_name,
234 return mount_single(fs_type, flags, data, debug_fill_super);
237 static struct file_system_type debug_fs_type = {
238 .owner = THIS_MODULE,
240 .mount = debug_mount,
241 .kill_sb = kill_litter_super,
243 MODULE_ALIAS_FS("debugfs");
245 static struct dentry *start_creating(const char *name, struct dentry *parent)
247 struct dentry *dentry;
250 pr_debug("debugfs: creating file '%s'\n",name);
255 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
256 &debugfs_mount_count);
258 return ERR_PTR(error);
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
266 parent = debugfs_mount->mnt_root;
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)) {
272 dentry = ERR_PTR(-EEXIST);
275 mutex_unlock(&d_inode(parent)->i_mutex);
279 static struct dentry *failed_creating(struct dentry *dentry)
281 mutex_unlock(&d_inode(dentry->d_parent)->i_mutex);
283 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
287 static struct dentry *end_creating(struct dentry *dentry)
289 mutex_unlock(&d_inode(dentry->d_parent)->i_mutex);
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
303 * @fops: a pointer to a struct file_operations that should be used for
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.)
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.
316 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
319 struct dentry *debugfs_create_file(const char *name, umode_t mode,
320 struct dentry *parent, void *data,
321 const struct file_operations *fops)
323 struct dentry *dentry;
326 if (!(mode & S_IFMT))
328 BUG_ON(!S_ISREG(mode));
329 dentry = start_creating(name, parent);
334 inode = debugfs_get_inode(dentry->d_sb);
335 if (unlikely(!inode))
336 return failed_creating(dentry);
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);
345 EXPORT_SYMBOL_GPL(debugfs_create_file);
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
357 * @fops: a pointer to a struct file_operations that should be used for
359 * @file_size: initial file size
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.)
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.
371 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
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,
379 struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
382 d_inode(de)->i_size = file_size;
385 EXPORT_SYMBOL_GPL(debugfs_create_file_size);
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
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.
395 * This function creates a directory in debugfs with the given name.
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.
402 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
405 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
407 struct dentry *dentry = start_creating(name, parent);
413 inode = debugfs_get_inode(dentry->d_sb);
414 if (unlikely(!inode))
415 return failed_creating(dentry);
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;
421 /* directory inodes start off with i_nlink == 2 (for "." entry) */
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);
428 EXPORT_SYMBOL_GPL(debugfs_create_dir);
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().
439 * @f should return what ->d_automount() would.
441 struct dentry *debugfs_create_automount(const char *name,
442 struct dentry *parent,
443 struct vfsmount *(*f)(void *),
446 struct dentry *dentry = start_creating(name, parent);
452 inode = debugfs_get_inode(dentry->d_sb);
453 if (unlikely(!inode))
454 return failed_creating(dentry);
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);
463 EXPORT_SYMBOL(debugfs_create_automount);
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
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
473 * @target: a pointer to a string containing the path to the target of the
476 * This function creates a symbolic link with the given name in debugfs that
477 * links to the given target path.
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
485 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
488 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
491 struct dentry *dentry;
493 char *link = kstrdup(target, GFP_KERNEL);
497 dentry = start_creating(name, parent);
498 if (IS_ERR(dentry)) {
503 inode = debugfs_get_inode(dentry->d_sb);
504 if (unlikely(!inode)) {
506 return failed_creating(dentry);
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);
514 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
516 static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
520 if (simple_positive(dentry)) {
522 if (d_is_dir(dentry))
523 ret = simple_rmdir(d_inode(parent), dentry);
525 simple_unlink(d_inode(parent), dentry);
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
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.)
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.
546 void debugfs_remove(struct dentry *dentry)
548 struct dentry *parent;
551 if (IS_ERR_OR_NULL(dentry))
554 parent = dentry->d_parent;
555 if (!parent || d_really_is_negative(parent))
558 mutex_lock(&d_inode(parent)->i_mutex);
559 ret = __debugfs_remove(dentry, parent);
560 mutex_unlock(&d_inode(parent)->i_mutex);
562 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
564 EXPORT_SYMBOL_GPL(debugfs_remove);
567 * debugfs_remove_recursive - recursively removes a directory
568 * @dentry: a pointer to a the dentry of the directory to be removed.
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.)
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.
578 void debugfs_remove_recursive(struct dentry *dentry)
580 struct dentry *child, *parent;
582 if (IS_ERR_OR_NULL(dentry))
585 parent = dentry->d_parent;
586 if (!parent || d_really_is_negative(parent))
591 mutex_lock(&d_inode(parent)->i_mutex);
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.
598 spin_lock(&parent->d_lock);
599 list_for_each_entry(child, &parent->d_subdirs, d_child) {
600 if (!simple_positive(child))
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);
611 spin_unlock(&parent->d_lock);
613 if (!__debugfs_remove(child, parent))
614 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
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.
625 spin_unlock(&parent->d_lock);
627 mutex_unlock(&d_inode(parent)->i_mutex);
629 parent = parent->d_parent;
630 mutex_lock(&d_inode(parent)->i_mutex);
636 if (!__debugfs_remove(child, parent))
637 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
638 mutex_unlock(&d_inode(parent)->i_mutex);
640 EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
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.
651 * This function renames a file/directory in debugfs. The target must not
652 * exist for rename to succeed.
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
658 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
661 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
662 struct dentry *new_dir, const char *new_name)
665 struct dentry *dentry = NULL, *trap;
666 const char *old_name;
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))
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))
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))
681 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
683 error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
686 fsnotify_oldname_free(old_name);
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),
693 fsnotify_oldname_free(old_name);
694 unlock_rename(new_dir, old_dir);
698 if (dentry && !IS_ERR(dentry))
700 unlock_rename(new_dir, old_dir);
703 EXPORT_SYMBOL_GPL(debugfs_rename);
706 * debugfs_initialized - Tells whether debugfs has been registered
708 bool debugfs_initialized(void)
710 return debugfs_registered;
712 EXPORT_SYMBOL_GPL(debugfs_initialized);
714 static int __init debugfs_init(void)
718 retval = sysfs_create_mount_point(kernel_kobj, "debug");
722 retval = register_filesystem(&debug_fs_type);
724 sysfs_remove_mount_point(kernel_kobj, "debug");
726 debugfs_registered = true;
730 core_initcall(debugfs_init);