2 * file.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 /* uncomment to get debug messages from the debug filesystem, ah the irony. */
19 #include <linux/module.h>
21 #include <linux/mount.h>
22 #include <linux/pagemap.h>
23 #include <linux/init.h>
24 #include <linux/kobject.h>
25 #include <linux/namei.h>
26 #include <linux/debugfs.h>
27 #include <linux/fsnotify.h>
28 #include <linux/string.h>
29 #include <linux/magic.h>
30 #include <linux/slab.h>
32 static struct vfsmount *debugfs_mount;
33 static int debugfs_mount_count;
34 static bool debugfs_registered;
36 static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev,
37 void *data, const struct file_operations *fops)
40 struct inode *inode = new_inode(sb);
43 inode->i_ino = get_next_ino();
45 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
46 switch (mode & S_IFMT) {
48 init_special_inode(inode, mode, dev);
51 inode->i_fop = fops ? fops : &debugfs_file_operations;
52 inode->i_private = data;
55 inode->i_op = &debugfs_link_operations;
57 inode->i_private = data;
60 inode->i_op = &simple_dir_inode_operations;
61 inode->i_fop = fops ? fops : &simple_dir_operations;
62 inode->i_private = data;
64 /* directory inodes start off with i_nlink == 2
74 static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
75 int mode, dev_t dev, void *data,
76 const struct file_operations *fops)
84 inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops);
86 d_instantiate(dentry, inode);
93 static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode,
94 void *data, const struct file_operations *fops)
98 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
99 res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
102 fsnotify_mkdir(dir, dentry);
107 static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode,
108 void *data, const struct file_operations *fops)
110 mode = (mode & S_IALLUGO) | S_IFLNK;
111 return debugfs_mknod(dir, dentry, mode, 0, data, fops);
114 static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode,
115 void *data, const struct file_operations *fops)
119 mode = (mode & S_IALLUGO) | S_IFREG;
120 res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
122 fsnotify_create(dir, dentry);
126 static inline int debugfs_positive(struct dentry *dentry)
128 return dentry->d_inode && !d_unhashed(dentry);
131 static int debug_fill_super(struct super_block *sb, void *data, int silent)
133 static struct tree_descr debug_files[] = {{""}};
135 return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
138 static int debug_get_sb(struct file_system_type *fs_type,
139 int flags, const char *dev_name,
140 void *data, struct vfsmount *mnt)
142 return get_sb_single(fs_type, flags, data, debug_fill_super, mnt);
145 static struct file_system_type debug_fs_type = {
146 .owner = THIS_MODULE,
148 .get_sb = debug_get_sb,
149 .kill_sb = kill_litter_super,
152 static int debugfs_create_by_name(const char *name, mode_t mode,
153 struct dentry *parent,
154 struct dentry **dentry,
156 const struct file_operations *fops)
160 /* If the parent is not specified, we create it in the root.
161 * We need the root dentry to do this, which is in the super
162 * block. A pointer to that is in the struct vfsmount that we
166 parent = debugfs_mount->mnt_sb->s_root;
169 mutex_lock(&parent->d_inode->i_mutex);
170 *dentry = lookup_one_len(name, parent, strlen(name));
171 if (!IS_ERR(*dentry)) {
172 switch (mode & S_IFMT) {
174 error = debugfs_mkdir(parent->d_inode, *dentry, mode,
178 error = debugfs_link(parent->d_inode, *dentry, mode,
182 error = debugfs_create(parent->d_inode, *dentry, mode,
188 error = PTR_ERR(*dentry);
189 mutex_unlock(&parent->d_inode->i_mutex);
195 * debugfs_create_file - create a file in the debugfs filesystem
196 * @name: a pointer to a string containing the name of the file to create.
197 * @mode: the permission that the file should have.
198 * @parent: a pointer to the parent dentry for this file. This should be a
199 * directory dentry if set. If this paramater is NULL, then the
200 * file will be created in the root of the debugfs filesystem.
201 * @data: a pointer to something that the caller will want to get to later
202 * on. The inode.i_private pointer will point to this value on
204 * @fops: a pointer to a struct file_operations that should be used for
207 * This is the basic "create a file" function for debugfs. It allows for a
208 * wide range of flexibility in creating a file, or a directory (if you want
209 * to create a directory, the debugfs_create_dir() function is
210 * recommended to be used instead.)
212 * This function will return a pointer to a dentry if it succeeds. This
213 * pointer must be passed to the debugfs_remove() function when the file is
214 * to be removed (no automatic cleanup happens if your module is unloaded,
215 * you are responsible here.) If an error occurs, %NULL will be returned.
217 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
220 struct dentry *debugfs_create_file(const char *name, mode_t mode,
221 struct dentry *parent, void *data,
222 const struct file_operations *fops)
224 struct dentry *dentry = NULL;
227 pr_debug("debugfs: creating file '%s'\n",name);
229 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
230 &debugfs_mount_count);
234 error = debugfs_create_by_name(name, mode, parent, &dentry,
238 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
244 EXPORT_SYMBOL_GPL(debugfs_create_file);
247 * debugfs_create_dir - create a directory in the debugfs filesystem
248 * @name: a pointer to a string containing the name of the directory to
250 * @parent: a pointer to the parent dentry for this file. This should be a
251 * directory dentry if set. If this paramater is NULL, then the
252 * directory will be created in the root of the debugfs filesystem.
254 * This function creates a directory in debugfs with the given name.
256 * This function will return a pointer to a dentry if it succeeds. This
257 * pointer must be passed to the debugfs_remove() function when the file is
258 * to be removed (no automatic cleanup happens if your module is unloaded,
259 * you are responsible here.) If an error occurs, %NULL will be returned.
261 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
264 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
266 return debugfs_create_file(name,
267 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
270 EXPORT_SYMBOL_GPL(debugfs_create_dir);
273 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
274 * @name: a pointer to a string containing the name of the symbolic link to
276 * @parent: a pointer to the parent dentry for this symbolic link. This
277 * should be a directory dentry if set. If this paramater is NULL,
278 * then the symbolic link will be created in the root of the debugfs
280 * @target: a pointer to a string containing the path to the target of the
283 * This function creates a symbolic link with the given name in debugfs that
284 * links to the given target path.
286 * This function will return a pointer to a dentry if it succeeds. This
287 * pointer must be passed to the debugfs_remove() function when the symbolic
288 * link is to be removed (no automatic cleanup happens if your module is
289 * unloaded, you are responsible here.) If an error occurs, %NULL will be
292 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
295 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
298 struct dentry *result;
301 link = kstrdup(target, GFP_KERNEL);
305 result = debugfs_create_file(name, S_IFLNK | S_IRWXUGO, parent, link,
311 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
313 static void __debugfs_remove(struct dentry *dentry, struct dentry *parent)
317 if (debugfs_positive(dentry)) {
318 if (dentry->d_inode) {
320 switch (dentry->d_inode->i_mode & S_IFMT) {
322 ret = simple_rmdir(parent->d_inode, dentry);
325 kfree(dentry->d_inode->i_private);
328 simple_unlink(parent->d_inode, dentry);
339 * debugfs_remove - removes a file or directory from the debugfs filesystem
340 * @dentry: a pointer to a the dentry of the file or directory to be
343 * This function removes a file or directory in debugfs that was previously
344 * created with a call to another debugfs function (like
345 * debugfs_create_file() or variants thereof.)
347 * This function is required to be called in order for the file to be
348 * removed, no automatic cleanup of files will happen when a module is
349 * removed, you are responsible here.
351 void debugfs_remove(struct dentry *dentry)
353 struct dentry *parent;
358 parent = dentry->d_parent;
359 if (!parent || !parent->d_inode)
362 mutex_lock(&parent->d_inode->i_mutex);
363 __debugfs_remove(dentry, parent);
364 mutex_unlock(&parent->d_inode->i_mutex);
365 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
367 EXPORT_SYMBOL_GPL(debugfs_remove);
370 * debugfs_remove_recursive - recursively removes a directory
371 * @dentry: a pointer to a the dentry of the directory to be removed.
373 * This function recursively removes a directory tree in debugfs that
374 * was previously created with a call to another debugfs function
375 * (like debugfs_create_file() or variants thereof.)
377 * This function is required to be called in order for the file to be
378 * removed, no automatic cleanup of files will happen when a module is
379 * removed, you are responsible here.
381 void debugfs_remove_recursive(struct dentry *dentry)
383 struct dentry *child;
384 struct dentry *parent;
389 parent = dentry->d_parent;
390 if (!parent || !parent->d_inode)
394 mutex_lock(&parent->d_inode->i_mutex);
398 * When all dentries under "parent" has been removed,
399 * walk up the tree until we reach our starting point.
401 if (list_empty(&parent->d_subdirs)) {
402 mutex_unlock(&parent->d_inode->i_mutex);
403 if (parent == dentry)
405 parent = parent->d_parent;
406 mutex_lock(&parent->d_inode->i_mutex);
408 child = list_entry(parent->d_subdirs.next, struct dentry,
413 * If "child" isn't empty, walk down the tree and
414 * remove all its descendants first.
416 if (!list_empty(&child->d_subdirs)) {
417 mutex_unlock(&parent->d_inode->i_mutex);
419 mutex_lock(&parent->d_inode->i_mutex);
422 __debugfs_remove(child, parent);
423 if (parent->d_subdirs.next == &child->d_u.d_child) {
425 * Try the next sibling.
427 if (child->d_u.d_child.next != &parent->d_subdirs) {
428 child = list_entry(child->d_u.d_child.next,
435 * Avoid infinite loop if we fail to remove
438 mutex_unlock(&parent->d_inode->i_mutex);
441 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
444 parent = dentry->d_parent;
445 mutex_lock(&parent->d_inode->i_mutex);
446 __debugfs_remove(dentry, parent);
447 mutex_unlock(&parent->d_inode->i_mutex);
448 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
450 EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
453 * debugfs_rename - rename a file/directory in the debugfs filesystem
454 * @old_dir: a pointer to the parent dentry for the renamed object. This
455 * should be a directory dentry.
456 * @old_dentry: dentry of an object to be renamed.
457 * @new_dir: a pointer to the parent dentry where the object should be
458 * moved. This should be a directory dentry.
459 * @new_name: a pointer to a string containing the target name.
461 * This function renames a file/directory in debugfs. The target must not
462 * exist for rename to succeed.
464 * This function will return a pointer to old_dentry (which is updated to
465 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
468 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
471 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
472 struct dentry *new_dir, const char *new_name)
475 struct dentry *dentry = NULL, *trap;
476 const char *old_name;
478 trap = lock_rename(new_dir, old_dir);
479 /* Source or destination directories don't exist? */
480 if (!old_dir->d_inode || !new_dir->d_inode)
482 /* Source does not exist, cyclic rename, or mountpoint? */
483 if (!old_dentry->d_inode || old_dentry == trap ||
484 d_mountpoint(old_dentry))
486 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
487 /* Lookup failed, cyclic rename or target exists? */
488 if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
491 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
493 error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
496 fsnotify_oldname_free(old_name);
499 d_move(old_dentry, dentry);
500 fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
501 S_ISDIR(old_dentry->d_inode->i_mode),
503 fsnotify_oldname_free(old_name);
504 unlock_rename(new_dir, old_dir);
508 if (dentry && !IS_ERR(dentry))
510 unlock_rename(new_dir, old_dir);
513 EXPORT_SYMBOL_GPL(debugfs_rename);
516 * debugfs_initialized - Tells whether debugfs has been registered
518 bool debugfs_initialized(void)
520 return debugfs_registered;
522 EXPORT_SYMBOL_GPL(debugfs_initialized);
525 static struct kobject *debug_kobj;
527 static int __init debugfs_init(void)
531 debug_kobj = kobject_create_and_add("debug", kernel_kobj);
535 retval = register_filesystem(&debug_fs_type);
537 kobject_put(debug_kobj);
539 debugfs_registered = true;
544 static void __exit debugfs_exit(void)
546 debugfs_registered = false;
548 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
549 unregister_filesystem(&debug_fs_type);
550 kobject_put(debug_kobj);
553 core_initcall(debugfs_init);
554 module_exit(debugfs_exit);
555 MODULE_LICENSE("GPL");