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/namei.h>
25 #include <linux/debugfs.h>
27 #define DEBUGFS_MAGIC 0x64626720
29 /* declared over in file.c */
30 extern struct file_operations debugfs_file_operations;
32 static struct vfsmount *debugfs_mount;
33 static int debugfs_mount_count;
35 static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev)
37 struct inode *inode = new_inode(sb);
44 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
45 switch (mode & S_IFMT) {
47 init_special_inode(inode, mode, dev);
50 inode->i_fop = &debugfs_file_operations;
53 inode->i_op = &simple_dir_inode_operations;
54 inode->i_fop = &simple_dir_operations;
56 /* directory inodes start off with i_nlink == 2 (for "." entry) */
65 static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
74 inode = debugfs_get_inode(dir->i_sb, mode, dev);
76 d_instantiate(dentry, inode);
83 static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
87 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
88 res = debugfs_mknod(dir, dentry, mode, 0);
94 static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode)
96 mode = (mode & S_IALLUGO) | S_IFREG;
97 return debugfs_mknod(dir, dentry, mode, 0);
100 static inline int debugfs_positive(struct dentry *dentry)
102 return dentry->d_inode && !d_unhashed(dentry);
105 static int debug_fill_super(struct super_block *sb, void *data, int silent)
107 static struct tree_descr debug_files[] = {{""}};
109 return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
112 static int debug_get_sb(struct file_system_type *fs_type,
113 int flags, const char *dev_name,
114 void *data, struct vfsmount *mnt)
116 return get_sb_single(fs_type, flags, data, debug_fill_super, mnt);
119 static struct file_system_type debug_fs_type = {
120 .owner = THIS_MODULE,
122 .get_sb = debug_get_sb,
123 .kill_sb = kill_litter_super,
126 static int debugfs_create_by_name(const char *name, mode_t mode,
127 struct dentry *parent,
128 struct dentry **dentry)
132 /* If the parent is not specified, we create it in the root.
133 * We need the root dentry to do this, which is in the super
134 * block. A pointer to that is in the struct vfsmount that we
138 if (debugfs_mount && debugfs_mount->mnt_sb) {
139 parent = debugfs_mount->mnt_sb->s_root;
143 pr_debug("debugfs: Ah! can not find a parent!\n");
148 mutex_lock(&parent->d_inode->i_mutex);
149 *dentry = lookup_one_len(name, parent, strlen(name));
150 if (!IS_ERR(dentry)) {
151 if ((mode & S_IFMT) == S_IFDIR)
152 error = debugfs_mkdir(parent->d_inode, *dentry, mode);
154 error = debugfs_create(parent->d_inode, *dentry, mode);
156 error = PTR_ERR(dentry);
157 mutex_unlock(&parent->d_inode->i_mutex);
163 * debugfs_create_file - create a file in the debugfs filesystem
165 * @name: a pointer to a string containing the name of the file to create.
166 * @mode: the permission that the file should have
167 * @parent: a pointer to the parent dentry for this file. This should be a
168 * directory dentry if set. If this paramater is NULL, then the
169 * file will be created in the root of the debugfs filesystem.
170 * @data: a pointer to something that the caller will want to get to later
171 * on. The inode.i_private pointer will point to this value on
173 * @fops: a pointer to a struct file_operations that should be used for
176 * This is the basic "create a file" function for debugfs. It allows for a
177 * wide range of flexibility in createing a file, or a directory (if you
178 * want to create a directory, the debugfs_create_dir() function is
179 * recommended to be used instead.)
181 * This function will return a pointer to a dentry if it succeeds. This
182 * pointer must be passed to the debugfs_remove() function when the file is
183 * to be removed (no automatic cleanup happens if your module is unloaded,
184 * you are responsible here.) If an error occurs, NULL will be returned.
186 * If debugfs is not enabled in the kernel, the value -ENODEV will be
187 * returned. It is not wise to check for this value, but rather, check for
188 * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
191 struct dentry *debugfs_create_file(const char *name, mode_t mode,
192 struct dentry *parent, void *data,
193 const struct file_operations *fops)
195 struct dentry *dentry = NULL;
198 pr_debug("debugfs: creating file '%s'\n",name);
200 error = simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count);
204 error = debugfs_create_by_name(name, mode, parent, &dentry);
210 if (dentry->d_inode) {
212 dentry->d_inode->i_private = data;
214 dentry->d_inode->i_fop = fops;
219 EXPORT_SYMBOL_GPL(debugfs_create_file);
222 * debugfs_create_dir - create a directory in the debugfs filesystem
224 * @name: a pointer to a string containing the name of the directory to
226 * @parent: a pointer to the parent dentry for this file. This should be a
227 * directory dentry if set. If this paramater is NULL, then the
228 * directory will be created in the root of the debugfs filesystem.
230 * This function creates a directory in debugfs with the given name.
232 * This function will return a pointer to a dentry if it succeeds. This
233 * pointer must be passed to the debugfs_remove() function when the file is
234 * to be removed (no automatic cleanup happens if your module is unloaded,
235 * you are responsible here.) If an error occurs, NULL will be returned.
237 * If debugfs is not enabled in the kernel, the value -ENODEV will be
238 * returned. It is not wise to check for this value, but rather, check for
239 * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
242 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
244 return debugfs_create_file(name,
245 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
248 EXPORT_SYMBOL_GPL(debugfs_create_dir);
251 * debugfs_remove - removes a file or directory from the debugfs filesystem
253 * @dentry: a pointer to a the dentry of the file or directory to be
256 * This function removes a file or directory in debugfs that was previously
257 * created with a call to another debugfs function (like
258 * debufs_create_file() or variants thereof.)
260 * This function is required to be called in order for the file to be
261 * removed, no automatic cleanup of files will happen when a module is
262 * removed, you are responsible here.
264 void debugfs_remove(struct dentry *dentry)
266 struct dentry *parent;
271 parent = dentry->d_parent;
272 if (!parent || !parent->d_inode)
275 mutex_lock(&parent->d_inode->i_mutex);
276 if (debugfs_positive(dentry)) {
277 if (dentry->d_inode) {
278 if (S_ISDIR(dentry->d_inode->i_mode))
279 simple_rmdir(parent->d_inode, dentry);
281 simple_unlink(parent->d_inode, dentry);
285 mutex_unlock(&parent->d_inode->i_mutex);
286 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
288 EXPORT_SYMBOL_GPL(debugfs_remove);
290 static decl_subsys(debug, NULL, NULL);
292 static int __init debugfs_init(void)
296 kset_set_kset_s(&debug_subsys, kernel_subsys);
297 retval = subsystem_register(&debug_subsys);
301 retval = register_filesystem(&debug_fs_type);
303 subsystem_unregister(&debug_subsys);
307 static void __exit debugfs_exit(void)
309 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
310 unregister_filesystem(&debug_fs_type);
311 subsystem_unregister(&debug_subsys);
314 core_initcall(debugfs_init);
315 module_exit(debugfs_exit);
316 MODULE_LICENSE("GPL");