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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * file.c - part of debugfs, a tiny little debug file system | |
3 | * | |
4 | * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com> | |
5 | * Copyright (C) 2004 IBM Inc. | |
6 | * | |
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. | |
10 | * | |
11 | * debugfs is for people to use instead of /proc or /sys. | |
12 | * See Documentation/DocBook/kernel-api for more details. | |
13 | * | |
14 | */ | |
15 | ||
16 | /* uncomment to get debug messages from the debug filesystem, ah the irony. */ | |
17 | /* #define DEBUG */ | |
18 | ||
1da177e4 LT |
19 | #include <linux/module.h> |
20 | #include <linux/fs.h> | |
21 | #include <linux/mount.h> | |
22 | #include <linux/pagemap.h> | |
23 | #include <linux/init.h> | |
4d8ebddc | 24 | #include <linux/kobject.h> |
1da177e4 LT |
25 | #include <linux/namei.h> |
26 | #include <linux/debugfs.h> | |
4f36557f | 27 | #include <linux/fsnotify.h> |
66f54963 | 28 | #include <linux/string.h> |
1da177e4 LT |
29 | |
30 | #define DEBUGFS_MAGIC 0x64626720 | |
31 | ||
32 | /* declared over in file.c */ | |
33 | extern struct file_operations debugfs_file_operations; | |
66f54963 | 34 | extern struct inode_operations debugfs_link_operations; |
1da177e4 LT |
35 | |
36 | static struct vfsmount *debugfs_mount; | |
37 | static int debugfs_mount_count; | |
38 | ||
39 | static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev) | |
40 | { | |
41 | struct inode *inode = new_inode(sb); | |
42 | ||
43 | if (inode) { | |
44 | inode->i_mode = mode; | |
45 | inode->i_uid = 0; | |
46 | inode->i_gid = 0; | |
1da177e4 LT |
47 | inode->i_blocks = 0; |
48 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
49 | switch (mode & S_IFMT) { | |
50 | default: | |
51 | init_special_inode(inode, mode, dev); | |
52 | break; | |
53 | case S_IFREG: | |
54 | inode->i_fop = &debugfs_file_operations; | |
55 | break; | |
66f54963 PO |
56 | case S_IFLNK: |
57 | inode->i_op = &debugfs_link_operations; | |
58 | break; | |
1da177e4 LT |
59 | case S_IFDIR: |
60 | inode->i_op = &simple_dir_inode_operations; | |
61 | inode->i_fop = &simple_dir_operations; | |
62 | ||
bafb232e MD |
63 | /* directory inodes start off with i_nlink == 2 |
64 | * (for "." entry) */ | |
d8c76e6f | 65 | inc_nlink(inode); |
1da177e4 LT |
66 | break; |
67 | } | |
68 | } | |
69 | return inode; | |
70 | } | |
71 | ||
72 | /* SMP-safe */ | |
73 | static int debugfs_mknod(struct inode *dir, struct dentry *dentry, | |
74 | int mode, dev_t dev) | |
75 | { | |
71601e2b | 76 | struct inode *inode; |
1da177e4 LT |
77 | int error = -EPERM; |
78 | ||
79 | if (dentry->d_inode) | |
80 | return -EEXIST; | |
81 | ||
71601e2b | 82 | inode = debugfs_get_inode(dir->i_sb, mode, dev); |
1da177e4 LT |
83 | if (inode) { |
84 | d_instantiate(dentry, inode); | |
85 | dget(dentry); | |
86 | error = 0; | |
87 | } | |
88 | return error; | |
89 | } | |
90 | ||
91 | static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) | |
92 | { | |
93 | int res; | |
94 | ||
95 | mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR; | |
96 | res = debugfs_mknod(dir, dentry, mode, 0); | |
4f36557f | 97 | if (!res) { |
d8c76e6f | 98 | inc_nlink(dir); |
4f36557f MD |
99 | fsnotify_mkdir(dir, dentry); |
100 | } | |
1da177e4 LT |
101 | return res; |
102 | } | |
103 | ||
66f54963 PO |
104 | static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode) |
105 | { | |
106 | mode = (mode & S_IALLUGO) | S_IFLNK; | |
107 | return debugfs_mknod(dir, dentry, mode, 0); | |
108 | } | |
109 | ||
1da177e4 LT |
110 | static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode) |
111 | { | |
4f36557f MD |
112 | int res; |
113 | ||
1da177e4 | 114 | mode = (mode & S_IALLUGO) | S_IFREG; |
4f36557f MD |
115 | res = debugfs_mknod(dir, dentry, mode, 0); |
116 | if (!res) | |
117 | fsnotify_create(dir, dentry); | |
118 | return res; | |
1da177e4 LT |
119 | } |
120 | ||
121 | static inline int debugfs_positive(struct dentry *dentry) | |
122 | { | |
123 | return dentry->d_inode && !d_unhashed(dentry); | |
124 | } | |
125 | ||
126 | static int debug_fill_super(struct super_block *sb, void *data, int silent) | |
127 | { | |
128 | static struct tree_descr debug_files[] = {{""}}; | |
129 | ||
130 | return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files); | |
131 | } | |
132 | ||
454e2398 DH |
133 | static int debug_get_sb(struct file_system_type *fs_type, |
134 | int flags, const char *dev_name, | |
135 | void *data, struct vfsmount *mnt) | |
1da177e4 | 136 | { |
454e2398 | 137 | return get_sb_single(fs_type, flags, data, debug_fill_super, mnt); |
1da177e4 LT |
138 | } |
139 | ||
140 | static struct file_system_type debug_fs_type = { | |
141 | .owner = THIS_MODULE, | |
142 | .name = "debugfs", | |
143 | .get_sb = debug_get_sb, | |
144 | .kill_sb = kill_litter_super, | |
145 | }; | |
146 | ||
147 | static int debugfs_create_by_name(const char *name, mode_t mode, | |
148 | struct dentry *parent, | |
149 | struct dentry **dentry) | |
150 | { | |
151 | int error = 0; | |
152 | ||
153 | /* If the parent is not specified, we create it in the root. | |
154 | * We need the root dentry to do this, which is in the super | |
155 | * block. A pointer to that is in the struct vfsmount that we | |
156 | * have around. | |
157 | */ | |
bafb232e | 158 | if (!parent) { |
1da177e4 LT |
159 | if (debugfs_mount && debugfs_mount->mnt_sb) { |
160 | parent = debugfs_mount->mnt_sb->s_root; | |
161 | } | |
162 | } | |
163 | if (!parent) { | |
164 | pr_debug("debugfs: Ah! can not find a parent!\n"); | |
165 | return -EFAULT; | |
166 | } | |
167 | ||
168 | *dentry = NULL; | |
1b1dcc1b | 169 | mutex_lock(&parent->d_inode->i_mutex); |
5f45f1a7 | 170 | *dentry = lookup_one_len(name, parent, strlen(name)); |
7bb0386f | 171 | if (!IS_ERR(*dentry)) { |
66f54963 PO |
172 | switch (mode & S_IFMT) { |
173 | case S_IFDIR: | |
1da177e4 | 174 | error = debugfs_mkdir(parent->d_inode, *dentry, mode); |
66f54963 PO |
175 | break; |
176 | case S_IFLNK: | |
177 | error = debugfs_link(parent->d_inode, *dentry, mode); | |
178 | break; | |
179 | default: | |
1da177e4 | 180 | error = debugfs_create(parent->d_inode, *dentry, mode); |
66f54963 PO |
181 | break; |
182 | } | |
65c33336 | 183 | dput(*dentry); |
1da177e4 | 184 | } else |
7bb0386f | 185 | error = PTR_ERR(*dentry); |
1b1dcc1b | 186 | mutex_unlock(&parent->d_inode->i_mutex); |
1da177e4 LT |
187 | |
188 | return error; | |
189 | } | |
190 | ||
191 | /** | |
192 | * debugfs_create_file - create a file in the debugfs filesystem | |
1da177e4 LT |
193 | * @name: a pointer to a string containing the name of the file to create. |
194 | * @mode: the permission that the file should have | |
195 | * @parent: a pointer to the parent dentry for this file. This should be a | |
196 | * directory dentry if set. If this paramater is NULL, then the | |
197 | * file will be created in the root of the debugfs filesystem. | |
198 | * @data: a pointer to something that the caller will want to get to later | |
8e18e294 | 199 | * on. The inode.i_private pointer will point to this value on |
1da177e4 LT |
200 | * the open() call. |
201 | * @fops: a pointer to a struct file_operations that should be used for | |
202 | * this file. | |
203 | * | |
204 | * This is the basic "create a file" function for debugfs. It allows for a | |
205 | * wide range of flexibility in createing a file, or a directory (if you | |
206 | * want to create a directory, the debugfs_create_dir() function is | |
207 | * recommended to be used instead.) | |
208 | * | |
209 | * This function will return a pointer to a dentry if it succeeds. This | |
210 | * pointer must be passed to the debugfs_remove() function when the file is | |
211 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
6468b3af | 212 | * you are responsible here.) If an error occurs, %NULL will be returned. |
1da177e4 | 213 | * |
6468b3af | 214 | * If debugfs is not enabled in the kernel, the value -%ENODEV will be |
873760fb | 215 | * returned. |
1da177e4 LT |
216 | */ |
217 | struct dentry *debugfs_create_file(const char *name, mode_t mode, | |
218 | struct dentry *parent, void *data, | |
99ac48f5 | 219 | const struct file_operations *fops) |
1da177e4 LT |
220 | { |
221 | struct dentry *dentry = NULL; | |
222 | int error; | |
223 | ||
224 | pr_debug("debugfs: creating file '%s'\n",name); | |
225 | ||
63223a06 MD |
226 | error = simple_pin_fs(&debug_fs_type, &debugfs_mount, |
227 | &debugfs_mount_count); | |
1da177e4 LT |
228 | if (error) |
229 | goto exit; | |
230 | ||
231 | error = debugfs_create_by_name(name, mode, parent, &dentry); | |
232 | if (error) { | |
233 | dentry = NULL; | |
63223a06 | 234 | simple_release_fs(&debugfs_mount, &debugfs_mount_count); |
1da177e4 LT |
235 | goto exit; |
236 | } | |
237 | ||
238 | if (dentry->d_inode) { | |
239 | if (data) | |
8e18e294 | 240 | dentry->d_inode->i_private = data; |
1da177e4 LT |
241 | if (fops) |
242 | dentry->d_inode->i_fop = fops; | |
243 | } | |
244 | exit: | |
245 | return dentry; | |
246 | } | |
247 | EXPORT_SYMBOL_GPL(debugfs_create_file); | |
248 | ||
249 | /** | |
250 | * debugfs_create_dir - create a directory in the debugfs filesystem | |
1da177e4 LT |
251 | * @name: a pointer to a string containing the name of the directory to |
252 | * create. | |
253 | * @parent: a pointer to the parent dentry for this file. This should be a | |
254 | * directory dentry if set. If this paramater is NULL, then the | |
255 | * directory will be created in the root of the debugfs filesystem. | |
256 | * | |
257 | * This function creates a directory in debugfs with the given name. | |
258 | * | |
259 | * This function will return a pointer to a dentry if it succeeds. This | |
260 | * pointer must be passed to the debugfs_remove() function when the file is | |
261 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
6468b3af | 262 | * you are responsible here.) If an error occurs, %NULL will be returned. |
1da177e4 | 263 | * |
6468b3af | 264 | * If debugfs is not enabled in the kernel, the value -%ENODEV will be |
873760fb | 265 | * returned. |
1da177e4 LT |
266 | */ |
267 | struct dentry *debugfs_create_dir(const char *name, struct dentry *parent) | |
268 | { | |
269 | return debugfs_create_file(name, | |
270 | S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, | |
271 | parent, NULL, NULL); | |
272 | } | |
273 | EXPORT_SYMBOL_GPL(debugfs_create_dir); | |
274 | ||
66f54963 PO |
275 | /** |
276 | * debugfs_create_symlink- create a symbolic link in the debugfs filesystem | |
277 | * @name: a pointer to a string containing the name of the symbolic link to | |
278 | * create. | |
279 | * @parent: a pointer to the parent dentry for this symbolic link. This | |
280 | * should be a directory dentry if set. If this paramater is NULL, | |
281 | * then the symbolic link will be created in the root of the debugfs | |
282 | * filesystem. | |
283 | * @target: a pointer to a string containing the path to the target of the | |
284 | * symbolic link. | |
285 | * | |
286 | * This function creates a symbolic link with the given name in debugfs that | |
287 | * links to the given target path. | |
288 | * | |
289 | * This function will return a pointer to a dentry if it succeeds. This | |
290 | * pointer must be passed to the debugfs_remove() function when the symbolic | |
291 | * link is to be removed (no automatic cleanup happens if your module is | |
292 | * unloaded, you are responsible here.) If an error occurs, %NULL will be | |
293 | * returned. | |
294 | * | |
295 | * If debugfs is not enabled in the kernel, the value -%ENODEV will be | |
873760fb | 296 | * returned. |
66f54963 PO |
297 | */ |
298 | struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent, | |
299 | const char *target) | |
300 | { | |
301 | struct dentry *result; | |
302 | char *link; | |
303 | ||
304 | link = kstrdup(target, GFP_KERNEL); | |
305 | if (!link) | |
306 | return NULL; | |
307 | ||
308 | result = debugfs_create_file(name, S_IFLNK | S_IRWXUGO, parent, link, | |
309 | NULL); | |
310 | if (!result) | |
311 | kfree(link); | |
312 | return result; | |
313 | } | |
314 | EXPORT_SYMBOL_GPL(debugfs_create_symlink); | |
315 | ||
1da177e4 LT |
316 | /** |
317 | * debugfs_remove - removes a file or directory from the debugfs filesystem | |
1da177e4 LT |
318 | * @dentry: a pointer to a the dentry of the file or directory to be |
319 | * removed. | |
320 | * | |
321 | * This function removes a file or directory in debugfs that was previously | |
322 | * created with a call to another debugfs function (like | |
5a65980e | 323 | * debugfs_create_file() or variants thereof.) |
1da177e4 LT |
324 | * |
325 | * This function is required to be called in order for the file to be | |
326 | * removed, no automatic cleanup of files will happen when a module is | |
327 | * removed, you are responsible here. | |
328 | */ | |
329 | void debugfs_remove(struct dentry *dentry) | |
330 | { | |
331 | struct dentry *parent; | |
65c33336 | 332 | int ret = 0; |
1da177e4 LT |
333 | |
334 | if (!dentry) | |
335 | return; | |
336 | ||
337 | parent = dentry->d_parent; | |
338 | if (!parent || !parent->d_inode) | |
339 | return; | |
340 | ||
1b1dcc1b | 341 | mutex_lock(&parent->d_inode->i_mutex); |
1da177e4 LT |
342 | if (debugfs_positive(dentry)) { |
343 | if (dentry->d_inode) { | |
29a7f3ad | 344 | dget(dentry); |
66f54963 PO |
345 | switch (dentry->d_inode->i_mode & S_IFMT) { |
346 | case S_IFDIR: | |
65c33336 | 347 | ret = simple_rmdir(parent->d_inode, dentry); |
66f54963 PO |
348 | break; |
349 | case S_IFLNK: | |
350 | kfree(dentry->d_inode->i_private); | |
351 | /* fall through */ | |
352 | default: | |
1da177e4 | 353 | simple_unlink(parent->d_inode, dentry); |
66f54963 PO |
354 | break; |
355 | } | |
29a7f3ad MD |
356 | if (!ret) |
357 | d_delete(dentry); | |
358 | dput(dentry); | |
1da177e4 LT |
359 | } |
360 | } | |
1b1dcc1b | 361 | mutex_unlock(&parent->d_inode->i_mutex); |
1da177e4 LT |
362 | simple_release_fs(&debugfs_mount, &debugfs_mount_count); |
363 | } | |
364 | EXPORT_SYMBOL_GPL(debugfs_remove); | |
365 | ||
cfc94cdf JK |
366 | /** |
367 | * debugfs_rename - rename a file/directory in the debugfs filesystem | |
368 | * @old_dir: a pointer to the parent dentry for the renamed object. This | |
369 | * should be a directory dentry. | |
370 | * @old_dentry: dentry of an object to be renamed. | |
371 | * @new_dir: a pointer to the parent dentry where the object should be | |
372 | * moved. This should be a directory dentry. | |
373 | * @new_name: a pointer to a string containing the target name. | |
374 | * | |
375 | * This function renames a file/directory in debugfs. The target must not | |
376 | * exist for rename to succeed. | |
377 | * | |
378 | * This function will return a pointer to old_dentry (which is updated to | |
379 | * reflect renaming) if it succeeds. If an error occurs, %NULL will be | |
380 | * returned. | |
381 | * | |
382 | * If debugfs is not enabled in the kernel, the value -%ENODEV will be | |
383 | * returned. | |
384 | */ | |
385 | struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry, | |
386 | struct dentry *new_dir, const char *new_name) | |
387 | { | |
388 | int error; | |
389 | struct dentry *dentry = NULL, *trap; | |
390 | const char *old_name; | |
391 | ||
392 | trap = lock_rename(new_dir, old_dir); | |
393 | /* Source or destination directories don't exist? */ | |
394 | if (!old_dir->d_inode || !new_dir->d_inode) | |
395 | goto exit; | |
396 | /* Source does not exist, cyclic rename, or mountpoint? */ | |
397 | if (!old_dentry->d_inode || old_dentry == trap || | |
398 | d_mountpoint(old_dentry)) | |
399 | goto exit; | |
400 | dentry = lookup_one_len(new_name, new_dir, strlen(new_name)); | |
401 | /* Lookup failed, cyclic rename or target exists? */ | |
402 | if (IS_ERR(dentry) || dentry == trap || dentry->d_inode) | |
403 | goto exit; | |
404 | ||
405 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); | |
406 | ||
407 | error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode, | |
408 | dentry); | |
409 | if (error) { | |
410 | fsnotify_oldname_free(old_name); | |
411 | goto exit; | |
412 | } | |
413 | d_move(old_dentry, dentry); | |
414 | fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name, | |
415 | old_dentry->d_name.name, S_ISDIR(old_dentry->d_inode->i_mode), | |
416 | NULL, old_dentry->d_inode); | |
417 | fsnotify_oldname_free(old_name); | |
418 | unlock_rename(new_dir, old_dir); | |
419 | dput(dentry); | |
420 | return old_dentry; | |
421 | exit: | |
422 | if (dentry && !IS_ERR(dentry)) | |
423 | dput(dentry); | |
424 | unlock_rename(new_dir, old_dir); | |
425 | return NULL; | |
426 | } | |
427 | EXPORT_SYMBOL_GPL(debugfs_rename); | |
428 | ||
1da177e4 LT |
429 | static decl_subsys(debug, NULL, NULL); |
430 | ||
431 | static int __init debugfs_init(void) | |
432 | { | |
433 | int retval; | |
434 | ||
823bccfc | 435 | kobj_set_kset_s(&debug_subsys, kernel_subsys); |
1da177e4 LT |
436 | retval = subsystem_register(&debug_subsys); |
437 | if (retval) | |
438 | return retval; | |
439 | ||
440 | retval = register_filesystem(&debug_fs_type); | |
441 | if (retval) | |
442 | subsystem_unregister(&debug_subsys); | |
443 | return retval; | |
444 | } | |
445 | ||
446 | static void __exit debugfs_exit(void) | |
447 | { | |
448 | simple_release_fs(&debugfs_mount, &debugfs_mount_count); | |
449 | unregister_filesystem(&debug_fs_type); | |
450 | subsystem_unregister(&debug_subsys); | |
451 | } | |
452 | ||
453 | core_initcall(debugfs_init); | |
454 | module_exit(debugfs_exit); | |
455 | MODULE_LICENSE("GPL"); | |
456 |