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>
29 #define DEBUGFS_MAGIC 0x64626720
31 /* declared over in file.c */
32 extern struct file_operations debugfs_file_operations;
34 static struct vfsmount *debugfs_mount;
35 static int debugfs_mount_count;
37 static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev)
39 struct inode *inode = new_inode(sb);
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 = &debugfs_file_operations;
55 inode->i_op = &simple_dir_inode_operations;
56 inode->i_fop = &simple_dir_operations;
58 /* directory inodes start off with i_nlink == 2 (for "." entry) */
67 static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
76 inode = debugfs_get_inode(dir->i_sb, mode, dev);
78 d_instantiate(dentry, inode);
85 static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
89 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
90 res = debugfs_mknod(dir, dentry, mode, 0);
93 fsnotify_mkdir(dir, dentry);
98 static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode)
102 mode = (mode & S_IALLUGO) | S_IFREG;
103 res = debugfs_mknod(dir, dentry, mode, 0);
105 fsnotify_create(dir, dentry);
109 static inline int debugfs_positive(struct dentry *dentry)
111 return dentry->d_inode && !d_unhashed(dentry);
114 static int debug_fill_super(struct super_block *sb, void *data, int silent)
116 static struct tree_descr debug_files[] = {{""}};
118 return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
121 static int debug_get_sb(struct file_system_type *fs_type,
122 int flags, const char *dev_name,
123 void *data, struct vfsmount *mnt)
125 return get_sb_single(fs_type, flags, data, debug_fill_super, mnt);
128 static struct file_system_type debug_fs_type = {
129 .owner = THIS_MODULE,
131 .get_sb = debug_get_sb,
132 .kill_sb = kill_litter_super,
135 static int debugfs_create_by_name(const char *name, mode_t mode,
136 struct dentry *parent,
137 struct dentry **dentry)
141 /* If the parent is not specified, we create it in the root.
142 * We need the root dentry to do this, which is in the super
143 * block. A pointer to that is in the struct vfsmount that we
147 if (debugfs_mount && debugfs_mount->mnt_sb) {
148 parent = debugfs_mount->mnt_sb->s_root;
152 pr_debug("debugfs: Ah! can not find a parent!\n");
157 mutex_lock(&parent->d_inode->i_mutex);
158 *dentry = lookup_one_len(name, parent, strlen(name));
159 if (!IS_ERR(*dentry)) {
160 if ((mode & S_IFMT) == S_IFDIR)
161 error = debugfs_mkdir(parent->d_inode, *dentry, mode);
163 error = debugfs_create(parent->d_inode, *dentry, mode);
165 error = PTR_ERR(*dentry);
166 mutex_unlock(&parent->d_inode->i_mutex);
172 * debugfs_create_file - create a file in the debugfs filesystem
173 * @name: a pointer to a string containing the name of the file to create.
174 * @mode: the permission that the file should have
175 * @parent: a pointer to the parent dentry for this file. This should be a
176 * directory dentry if set. If this paramater is NULL, then the
177 * file will be created in the root of the debugfs filesystem.
178 * @data: a pointer to something that the caller will want to get to later
179 * on. The inode.i_private pointer will point to this value on
181 * @fops: a pointer to a struct file_operations that should be used for
184 * This is the basic "create a file" function for debugfs. It allows for a
185 * wide range of flexibility in createing a file, or a directory (if you
186 * want to create a directory, the debugfs_create_dir() function is
187 * recommended to be used instead.)
189 * This function will return a pointer to a dentry if it succeeds. This
190 * pointer must be passed to the debugfs_remove() function when the file is
191 * to be removed (no automatic cleanup happens if your module is unloaded,
192 * you are responsible here.) If an error occurs, %NULL will be returned.
194 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
195 * returned. It is not wise to check for this value, but rather, check for
196 * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
199 struct dentry *debugfs_create_file(const char *name, mode_t mode,
200 struct dentry *parent, void *data,
201 const struct file_operations *fops)
203 struct dentry *dentry = NULL;
206 pr_debug("debugfs: creating file '%s'\n",name);
208 error = simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
212 error = debugfs_create_by_name(name, mode, parent, &dentry);
218 if (dentry->d_inode) {
220 dentry->d_inode->i_private = data;
222 dentry->d_inode->i_fop = fops;
227 EXPORT_SYMBOL_GPL(debugfs_create_file);
230 * debugfs_create_dir - create a directory in the debugfs filesystem
231 * @name: a pointer to a string containing the name of the directory to
233 * @parent: a pointer to the parent dentry for this file. This should be a
234 * directory dentry if set. If this paramater is NULL, then the
235 * directory will be created in the root of the debugfs filesystem.
237 * This function creates a directory in debugfs with the given name.
239 * This function will return a pointer to a dentry if it succeeds. This
240 * pointer must be passed to the debugfs_remove() function when the file is
241 * to be removed (no automatic cleanup happens if your module is unloaded,
242 * you are responsible here.) If an error occurs, %NULL will be returned.
244 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
245 * returned. It is not wise to check for this value, but rather, check for
246 * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
249 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
251 return debugfs_create_file(name,
252 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
255 EXPORT_SYMBOL_GPL(debugfs_create_dir);
258 * debugfs_remove - removes a file or directory from the debugfs filesystem
259 * @dentry: a pointer to a the dentry of the file or directory to be
262 * This function removes a file or directory in debugfs that was previously
263 * created with a call to another debugfs function (like
264 * debugfs_create_file() or variants thereof.)
266 * This function is required to be called in order for the file to be
267 * removed, no automatic cleanup of files will happen when a module is
268 * removed, you are responsible here.
270 void debugfs_remove(struct dentry *dentry)
272 struct dentry *parent;
277 parent = dentry->d_parent;
278 if (!parent || !parent->d_inode)
281 mutex_lock(&parent->d_inode->i_mutex);
282 if (debugfs_positive(dentry)) {
283 if (dentry->d_inode) {
284 if (S_ISDIR(dentry->d_inode->i_mode))
285 simple_rmdir(parent->d_inode, dentry);
287 simple_unlink(parent->d_inode, dentry);
291 mutex_unlock(&parent->d_inode->i_mutex);
292 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
294 EXPORT_SYMBOL_GPL(debugfs_remove);
296 static decl_subsys(debug, NULL, NULL);
298 static int __init debugfs_init(void)
302 kset_set_kset_s(&debug_subsys, kernel_subsys);
303 retval = subsystem_register(&debug_subsys);
307 retval = register_filesystem(&debug_fs_type);
309 subsystem_unregister(&debug_subsys);
313 static void __exit debugfs_exit(void)
315 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
316 unregister_filesystem(&debug_fs_type);
317 subsystem_unregister(&debug_subsys);
320 core_initcall(debugfs_init);
321 module_exit(debugfs_exit);
322 MODULE_LICENSE("GPL");