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
164 * @name: a pointer to a string containing the name of the file to create.
165 * @mode: the permission that the file should have
166 * @parent: a pointer to the parent dentry for this file. This should be a
167 * directory dentry if set. If this paramater is NULL, then the
168 * file will be created in the root of the debugfs filesystem.
169 * @data: a pointer to something that the caller will want to get to later
170 * on. The inode.i_private pointer will point to this value on
172 * @fops: a pointer to a struct file_operations that should be used for
175 * This is the basic "create a file" function for debugfs. It allows for a
176 * wide range of flexibility in createing a file, or a directory (if you
177 * want to create a directory, the debugfs_create_dir() function is
178 * recommended to be used instead.)
180 * This function will return a pointer to a dentry if it succeeds. This
181 * pointer must be passed to the debugfs_remove() function when the file is
182 * to be removed (no automatic cleanup happens if your module is unloaded,
183 * you are responsible here.) If an error occurs, %NULL will be returned.
185 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
186 * returned. It is not wise to check for this value, but rather, check for
187 * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
190 struct dentry
*debugfs_create_file(const char *name
, mode_t mode
,
191 struct dentry
*parent
, void *data
,
192 const struct file_operations
*fops
)
194 struct dentry
*dentry
= NULL
;
197 pr_debug("debugfs: creating file '%s'\n",name
);
199 error
= simple_pin_fs(&debug_fs_type
, &debugfs_mount
, &debugfs_mount_count
);
203 error
= debugfs_create_by_name(name
, mode
, parent
, &dentry
);
209 if (dentry
->d_inode
) {
211 dentry
->d_inode
->i_private
= data
;
213 dentry
->d_inode
->i_fop
= fops
;
218 EXPORT_SYMBOL_GPL(debugfs_create_file
);
221 * debugfs_create_dir - create a directory in the debugfs filesystem
222 * @name: a pointer to a string containing the name of the directory to
224 * @parent: a pointer to the parent dentry for this file. This should be a
225 * directory dentry if set. If this paramater is NULL, then the
226 * directory will be created in the root of the debugfs filesystem.
228 * This function creates a directory in debugfs with the given name.
230 * This function will return a pointer to a dentry if it succeeds. This
231 * pointer must be passed to the debugfs_remove() function when the file is
232 * to be removed (no automatic cleanup happens if your module is unloaded,
233 * you are responsible here.) If an error occurs, %NULL will be returned.
235 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
236 * returned. It is not wise to check for this value, but rather, check for
237 * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
240 struct dentry
*debugfs_create_dir(const char *name
, struct dentry
*parent
)
242 return debugfs_create_file(name
,
243 S_IFDIR
| S_IRWXU
| S_IRUGO
| S_IXUGO
,
246 EXPORT_SYMBOL_GPL(debugfs_create_dir
);
249 * debugfs_remove - removes a file or directory from the debugfs filesystem
250 * @dentry: a pointer to a the dentry of the file or directory to be
253 * This function removes a file or directory in debugfs that was previously
254 * created with a call to another debugfs function (like
255 * debufs_create_file() or variants thereof.)
257 * This function is required to be called in order for the file to be
258 * removed, no automatic cleanup of files will happen when a module is
259 * removed, you are responsible here.
261 void debugfs_remove(struct dentry
*dentry
)
263 struct dentry
*parent
;
268 parent
= dentry
->d_parent
;
269 if (!parent
|| !parent
->d_inode
)
272 mutex_lock(&parent
->d_inode
->i_mutex
);
273 if (debugfs_positive(dentry
)) {
274 if (dentry
->d_inode
) {
275 if (S_ISDIR(dentry
->d_inode
->i_mode
))
276 simple_rmdir(parent
->d_inode
, dentry
);
278 simple_unlink(parent
->d_inode
, dentry
);
282 mutex_unlock(&parent
->d_inode
->i_mutex
);
283 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
285 EXPORT_SYMBOL_GPL(debugfs_remove
);
287 static decl_subsys(debug
, NULL
, NULL
);
289 static int __init
debugfs_init(void)
293 kset_set_kset_s(&debug_subsys
, kernel_subsys
);
294 retval
= subsystem_register(&debug_subsys
);
298 retval
= register_filesystem(&debug_fs_type
);
300 subsystem_unregister(&debug_subsys
);
304 static void __exit
debugfs_exit(void)
306 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
307 unregister_filesystem(&debug_fs_type
);
308 subsystem_unregister(&debug_subsys
);
311 core_initcall(debugfs_init
);
312 module_exit(debugfs_exit
);
313 MODULE_LICENSE("GPL");