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/magic.h>
27 #include <linux/slab.h>
29 static struct vfsmount *debugfs_mount;
30 static int debugfs_mount_count;
31 static bool debugfs_registered;
33 static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev,
34 void *data, const struct file_operations *fops)
37 struct inode *inode = new_inode(sb);
40 inode->i_ino = get_next_ino();
42 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
43 switch (mode & S_IFMT) {
45 init_special_inode(inode, mode, dev);
48 inode->i_fop = fops ? fops : &debugfs_file_operations;
49 inode->i_private = data;
52 inode->i_op = &debugfs_link_operations;
54 inode->i_private = data;
57 inode->i_op = &simple_dir_inode_operations;
58 inode->i_fop = fops ? fops : &simple_dir_operations;
59 inode->i_private = data;
61 /* directory inodes start off with i_nlink == 2
71 static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
72 int mode, dev_t dev, void *data,
73 const struct file_operations *fops)
81 inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops);
83 d_instantiate(dentry, inode);
90 static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode,
91 void *data, const struct file_operations *fops)
95 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
96 res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
99 fsnotify_mkdir(dir, dentry);
104 static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode,
105 void *data, const struct file_operations *fops)
107 mode = (mode & S_IALLUGO) | S_IFLNK;
108 return debugfs_mknod(dir, dentry, mode, 0, data, fops);
111 static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode,
112 void *data, const struct file_operations *fops)
116 mode = (mode & S_IALLUGO) | S_IFREG;
117 res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
119 fsnotify_create(dir, dentry);
123 static inline int debugfs_positive(struct dentry *dentry)
125 return dentry->d_inode && !d_unhashed(dentry);
128 static void debugfs_evict_inode(struct inode *inode)
130 truncate_inode_pages(&inode->i_data, 0);
131 end_writeback(inode);
132 if (S_ISLNK(inode->i_mode))
133 kfree(inode->i_private);
136 static const struct super_operations debugfs_super_operations = {
137 .evict_inode = debugfs_evict_inode,
140 static int debug_fill_super(struct super_block *sb, void *data, int silent)
142 static struct tree_descr debug_files[] = {{""}};
145 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
149 sb->s_op = &debugfs_super_operations;
154 static struct dentry *debug_mount(struct file_system_type *fs_type,
155 int flags, const char *dev_name,
158 return mount_single(fs_type, flags, data, debug_fill_super);
161 static struct file_system_type debug_fs_type = {
162 .owner = THIS_MODULE,
164 .mount = debug_mount,
165 .kill_sb = kill_litter_super,
168 static int debugfs_create_by_name(const char *name, mode_t mode,
169 struct dentry *parent,
170 struct dentry **dentry,
172 const struct file_operations *fops)
176 /* If the parent is not specified, we create it in the root.
177 * We need the root dentry to do this, which is in the super
178 * block. A pointer to that is in the struct vfsmount that we
182 parent = debugfs_mount->mnt_sb->s_root;
185 mutex_lock(&parent->d_inode->i_mutex);
186 *dentry = lookup_one_len(name, parent, strlen(name));
187 if (!IS_ERR(*dentry)) {
188 switch (mode & S_IFMT) {
190 error = debugfs_mkdir(parent->d_inode, *dentry, mode,
194 error = debugfs_link(parent->d_inode, *dentry, mode,
198 error = debugfs_create(parent->d_inode, *dentry, mode,
204 error = PTR_ERR(*dentry);
205 mutex_unlock(&parent->d_inode->i_mutex);
211 * debugfs_create_file - create a file in the debugfs filesystem
212 * @name: a pointer to a string containing the name of the file to create.
213 * @mode: the permission that the file should have.
214 * @parent: a pointer to the parent dentry for this file. This should be a
215 * directory dentry if set. If this paramater is NULL, then the
216 * file will be created in the root of the debugfs filesystem.
217 * @data: a pointer to something that the caller will want to get to later
218 * on. The inode.i_private pointer will point to this value on
220 * @fops: a pointer to a struct file_operations that should be used for
223 * This is the basic "create a file" function for debugfs. It allows for a
224 * wide range of flexibility in creating a file, or a directory (if you want
225 * to create a directory, the debugfs_create_dir() function is
226 * recommended to be used instead.)
228 * This function will return a pointer to a dentry if it succeeds. This
229 * pointer must be passed to the debugfs_remove() function when the file is
230 * to be removed (no automatic cleanup happens if your module is unloaded,
231 * you are responsible here.) If an error occurs, %NULL will be returned.
233 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
236 struct dentry *debugfs_create_file(const char *name, mode_t mode,
237 struct dentry *parent, void *data,
238 const struct file_operations *fops)
240 struct dentry *dentry = NULL;
243 pr_debug("debugfs: creating file '%s'\n",name);
245 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
246 &debugfs_mount_count);
250 error = debugfs_create_by_name(name, mode, parent, &dentry,
254 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
260 EXPORT_SYMBOL_GPL(debugfs_create_file);
263 * debugfs_create_dir - create a directory in the debugfs filesystem
264 * @name: a pointer to a string containing the name of the directory to
266 * @parent: a pointer to the parent dentry for this file. This should be a
267 * directory dentry if set. If this paramater is NULL, then the
268 * directory will be created in the root of the debugfs filesystem.
270 * This function creates a directory in debugfs with the given name.
272 * This function will return a pointer to a dentry if it succeeds. This
273 * pointer must be passed to the debugfs_remove() function when the file is
274 * to be removed (no automatic cleanup happens if your module is unloaded,
275 * you are responsible here.) If an error occurs, %NULL will be returned.
277 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
280 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
282 return debugfs_create_file(name,
283 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
286 EXPORT_SYMBOL_GPL(debugfs_create_dir);
289 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
290 * @name: a pointer to a string containing the name of the symbolic link to
292 * @parent: a pointer to the parent dentry for this symbolic link. This
293 * should be a directory dentry if set. If this paramater is NULL,
294 * then the symbolic link will be created in the root of the debugfs
296 * @target: a pointer to a string containing the path to the target of the
299 * This function creates a symbolic link with the given name in debugfs that
300 * links to the given target path.
302 * This function will return a pointer to a dentry if it succeeds. This
303 * pointer must be passed to the debugfs_remove() function when the symbolic
304 * link is to be removed (no automatic cleanup happens if your module is
305 * unloaded, you are responsible here.) If an error occurs, %NULL will be
308 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
311 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
314 struct dentry *result;
317 link = kstrdup(target, GFP_KERNEL);
321 result = debugfs_create_file(name, S_IFLNK | S_IRWXUGO, parent, link,
327 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
329 static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
333 if (debugfs_positive(dentry)) {
335 if (S_ISDIR(dentry->d_inode->i_mode))
336 ret = simple_rmdir(parent->d_inode, dentry);
338 simple_unlink(parent->d_inode, dentry);
347 * debugfs_remove - removes a file or directory from the debugfs filesystem
348 * @dentry: a pointer to a the dentry of the file or directory to be
351 * This function removes a file or directory in debugfs that was previously
352 * created with a call to another debugfs function (like
353 * debugfs_create_file() or variants thereof.)
355 * This function is required to be called in order for the file to be
356 * removed, no automatic cleanup of files will happen when a module is
357 * removed, you are responsible here.
359 void debugfs_remove(struct dentry *dentry)
361 struct dentry *parent;
367 parent = dentry->d_parent;
368 if (!parent || !parent->d_inode)
371 mutex_lock(&parent->d_inode->i_mutex);
372 ret = __debugfs_remove(dentry, parent);
373 mutex_unlock(&parent->d_inode->i_mutex);
375 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
377 EXPORT_SYMBOL_GPL(debugfs_remove);
380 * debugfs_remove_recursive - recursively removes a directory
381 * @dentry: a pointer to a the dentry of the directory to be removed.
383 * This function recursively removes a directory tree in debugfs that
384 * was previously created with a call to another debugfs function
385 * (like debugfs_create_file() or variants thereof.)
387 * This function is required to be called in order for the file to be
388 * removed, no automatic cleanup of files will happen when a module is
389 * removed, you are responsible here.
391 void debugfs_remove_recursive(struct dentry *dentry)
393 struct dentry *child, *parent;
398 parent = dentry->d_parent;
399 if (!parent || !parent->d_inode)
404 mutex_lock(&parent->d_inode->i_mutex);
407 * The parent->d_subdirs is protected by the d_lock. Outside that
408 * lock, the child can be unlinked and set to be freed which can
409 * use the d_u.d_child as the rcu head and corrupt this list.
411 spin_lock(&parent->d_lock);
412 list_for_each_entry(child, &parent->d_subdirs, d_child) {
413 if (!debugfs_positive(child))
416 /* perhaps simple_empty(child) makes more sense */
417 if (!list_empty(&child->d_subdirs)) {
418 spin_unlock(&parent->d_lock);
419 mutex_unlock(&parent->d_inode->i_mutex);
424 spin_unlock(&parent->d_lock);
426 if (!__debugfs_remove(child, parent))
427 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
430 * The parent->d_lock protects agaist child from unlinking
431 * from d_subdirs. When releasing the parent->d_lock we can
432 * no longer trust that the next pointer is valid.
433 * Restart the loop. We'll skip this one with the
434 * debugfs_positive() check.
438 spin_unlock(&parent->d_lock);
440 mutex_unlock(&parent->d_inode->i_mutex);
442 parent = parent->d_parent;
443 mutex_lock(&parent->d_inode->i_mutex);
449 if (!__debugfs_remove(child, parent))
450 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
451 mutex_unlock(&parent->d_inode->i_mutex);
453 EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
456 * debugfs_rename - rename a file/directory in the debugfs filesystem
457 * @old_dir: a pointer to the parent dentry for the renamed object. This
458 * should be a directory dentry.
459 * @old_dentry: dentry of an object to be renamed.
460 * @new_dir: a pointer to the parent dentry where the object should be
461 * moved. This should be a directory dentry.
462 * @new_name: a pointer to a string containing the target name.
464 * This function renames a file/directory in debugfs. The target must not
465 * exist for rename to succeed.
467 * This function will return a pointer to old_dentry (which is updated to
468 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
471 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
474 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
475 struct dentry *new_dir, const char *new_name)
478 struct dentry *dentry = NULL, *trap;
479 const char *old_name;
481 trap = lock_rename(new_dir, old_dir);
482 /* Source or destination directories don't exist? */
483 if (!old_dir->d_inode || !new_dir->d_inode)
485 /* Source does not exist, cyclic rename, or mountpoint? */
486 if (!old_dentry->d_inode || old_dentry == trap ||
487 d_mountpoint(old_dentry))
489 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
490 /* Lookup failed, cyclic rename or target exists? */
491 if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
494 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
496 error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
499 fsnotify_oldname_free(old_name);
502 d_move(old_dentry, dentry);
503 fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
504 S_ISDIR(old_dentry->d_inode->i_mode),
506 fsnotify_oldname_free(old_name);
507 unlock_rename(new_dir, old_dir);
511 if (dentry && !IS_ERR(dentry))
513 unlock_rename(new_dir, old_dir);
516 EXPORT_SYMBOL_GPL(debugfs_rename);
519 * debugfs_initialized - Tells whether debugfs has been registered
521 bool debugfs_initialized(void)
523 return debugfs_registered;
525 EXPORT_SYMBOL_GPL(debugfs_initialized);
528 static struct kobject *debug_kobj;
530 static int __init debugfs_init(void)
534 debug_kobj = kobject_create_and_add("debug", kernel_kobj);
538 retval = register_filesystem(&debug_fs_type);
540 kobject_put(debug_kobj);
542 debugfs_registered = true;
546 core_initcall(debugfs_init);