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
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>
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
31 static struct vfsmount *debugfs_mount;
32 static int debugfs_mount_count;
33 static bool debugfs_registered;
34
35 static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev,
36 void *data, const struct file_operations *fops)
37
38 {
39 struct inode *inode = new_inode(sb);
40
41 if (inode) {
42 inode->i_mode = mode;
43 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
44 switch (mode & S_IFMT) {
45 default:
46 init_special_inode(inode, mode, dev);
47 break;
48 case S_IFREG:
49 inode->i_fop = fops ? fops : &debugfs_file_operations;
50 inode->i_private = data;
51 break;
52 case S_IFLNK:
53 inode->i_op = &debugfs_link_operations;
54 inode->i_fop = fops;
55 inode->i_private = data;
56 break;
57 case S_IFDIR:
58 inode->i_op = &simple_dir_inode_operations;
59 inode->i_fop = fops ? fops : &simple_dir_operations;
60 inode->i_private = data;
61
62 /* directory inodes start off with i_nlink == 2
63 * (for "." entry) */
64 inc_nlink(inode);
65 break;
66 }
67 }
68 return inode;
69 }
70
71 /* SMP-safe */
72 static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
73 int mode, dev_t dev, void *data,
74 const struct file_operations *fops)
75 {
76 struct inode *inode;
77 int error = -EPERM;
78
79 if (dentry->d_inode)
80 return -EEXIST;
81
82 inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops);
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 void *data, const struct file_operations *fops)
93 {
94 int res;
95
96 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
97 res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
98 if (!res) {
99 inc_nlink(dir);
100 fsnotify_mkdir(dir, dentry);
101 }
102 return res;
103 }
104
105 static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode,
106 void *data, const struct file_operations *fops)
107 {
108 mode = (mode & S_IALLUGO) | S_IFLNK;
109 return debugfs_mknod(dir, dentry, mode, 0, data, fops);
110 }
111
112 static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode,
113 void *data, const struct file_operations *fops)
114 {
115 int res;
116
117 mode = (mode & S_IALLUGO) | S_IFREG;
118 res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
119 if (!res)
120 fsnotify_create(dir, dentry);
121 return res;
122 }
123
124 static inline int debugfs_positive(struct dentry *dentry)
125 {
126 return dentry->d_inode && !d_unhashed(dentry);
127 }
128
129 static int debug_fill_super(struct super_block *sb, void *data, int silent)
130 {
131 static struct tree_descr debug_files[] = {{""}};
132
133 return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
134 }
135
136 static int debug_get_sb(struct file_system_type *fs_type,
137 int flags, const char *dev_name,
138 void *data, struct vfsmount *mnt)
139 {
140 return get_sb_single(fs_type, flags, data, debug_fill_super, mnt);
141 }
142
143 static struct file_system_type debug_fs_type = {
144 .owner = THIS_MODULE,
145 .name = "debugfs",
146 .get_sb = debug_get_sb,
147 .kill_sb = kill_litter_super,
148 };
149
150 static int debugfs_create_by_name(const char *name, mode_t mode,
151 struct dentry *parent,
152 struct dentry **dentry,
153 void *data,
154 const struct file_operations *fops)
155 {
156 int error = 0;
157
158 /* If the parent is not specified, we create it in the root.
159 * We need the root dentry to do this, which is in the super
160 * block. A pointer to that is in the struct vfsmount that we
161 * have around.
162 */
163 if (!parent) {
164 if (debugfs_mount && debugfs_mount->mnt_sb) {
165 parent = debugfs_mount->mnt_sb->s_root;
166 }
167 }
168 if (!parent) {
169 pr_debug("debugfs: Ah! can not find a parent!\n");
170 return -EFAULT;
171 }
172
173 *dentry = NULL;
174 mutex_lock(&parent->d_inode->i_mutex);
175 *dentry = lookup_one_len(name, parent, strlen(name));
176 if (!IS_ERR(*dentry)) {
177 switch (mode & S_IFMT) {
178 case S_IFDIR:
179 error = debugfs_mkdir(parent->d_inode, *dentry, mode,
180 data, fops);
181 break;
182 case S_IFLNK:
183 error = debugfs_link(parent->d_inode, *dentry, mode,
184 data, fops);
185 break;
186 default:
187 error = debugfs_create(parent->d_inode, *dentry, mode,
188 data, fops);
189 break;
190 }
191 dput(*dentry);
192 } else
193 error = PTR_ERR(*dentry);
194 mutex_unlock(&parent->d_inode->i_mutex);
195
196 return error;
197 }
198
199 /**
200 * debugfs_create_file - create a file in the debugfs filesystem
201 * @name: a pointer to a string containing the name of the file to create.
202 * @mode: the permission that the file should have
203 * @parent: a pointer to the parent dentry for this file. This should be a
204 * directory dentry if set. If this paramater is NULL, then the
205 * file will be created in the root of the debugfs filesystem.
206 * @data: a pointer to something that the caller will want to get to later
207 * on. The inode.i_private pointer will point to this value on
208 * the open() call.
209 * @fops: a pointer to a struct file_operations that should be used for
210 * this file.
211 *
212 * This is the basic "create a file" function for debugfs. It allows for a
213 * wide range of flexibility in createing a file, or a directory (if you
214 * want to create a directory, the debugfs_create_dir() function is
215 * recommended to be used instead.)
216 *
217 * This function will return a pointer to a dentry if it succeeds. This
218 * pointer must be passed to the debugfs_remove() function when the file is
219 * to be removed (no automatic cleanup happens if your module is unloaded,
220 * you are responsible here.) If an error occurs, %NULL will be returned.
221 *
222 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
223 * returned.
224 */
225 struct dentry *debugfs_create_file(const char *name, mode_t mode,
226 struct dentry *parent, void *data,
227 const struct file_operations *fops)
228 {
229 struct dentry *dentry = NULL;
230 int error;
231
232 pr_debug("debugfs: creating file '%s'\n",name);
233
234 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
235 &debugfs_mount_count);
236 if (error)
237 goto exit;
238
239 error = debugfs_create_by_name(name, mode, parent, &dentry,
240 data, fops);
241 if (error) {
242 dentry = NULL;
243 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
244 goto exit;
245 }
246 exit:
247 return dentry;
248 }
249 EXPORT_SYMBOL_GPL(debugfs_create_file);
250
251 /**
252 * debugfs_create_dir - create a directory in the debugfs filesystem
253 * @name: a pointer to a string containing the name of the directory to
254 * create.
255 * @parent: a pointer to the parent dentry for this file. This should be a
256 * directory dentry if set. If this paramater is NULL, then the
257 * directory will be created in the root of the debugfs filesystem.
258 *
259 * This function creates a directory in debugfs with the given name.
260 *
261 * This function will return a pointer to a dentry if it succeeds. This
262 * pointer must be passed to the debugfs_remove() function when the file is
263 * to be removed (no automatic cleanup happens if your module is unloaded,
264 * you are responsible here.) If an error occurs, %NULL will be returned.
265 *
266 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
267 * returned.
268 */
269 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
270 {
271 return debugfs_create_file(name,
272 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
273 parent, NULL, NULL);
274 }
275 EXPORT_SYMBOL_GPL(debugfs_create_dir);
276
277 /**
278 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
279 * @name: a pointer to a string containing the name of the symbolic link to
280 * create.
281 * @parent: a pointer to the parent dentry for this symbolic link. This
282 * should be a directory dentry if set. If this paramater is NULL,
283 * then the symbolic link will be created in the root of the debugfs
284 * filesystem.
285 * @target: a pointer to a string containing the path to the target of the
286 * symbolic link.
287 *
288 * This function creates a symbolic link with the given name in debugfs that
289 * links to the given target path.
290 *
291 * This function will return a pointer to a dentry if it succeeds. This
292 * pointer must be passed to the debugfs_remove() function when the symbolic
293 * link is to be removed (no automatic cleanup happens if your module is
294 * unloaded, you are responsible here.) If an error occurs, %NULL will be
295 * returned.
296 *
297 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
298 * returned.
299 */
300 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
301 const char *target)
302 {
303 struct dentry *result;
304 char *link;
305
306 link = kstrdup(target, GFP_KERNEL);
307 if (!link)
308 return NULL;
309
310 result = debugfs_create_file(name, S_IFLNK | S_IRWXUGO, parent, link,
311 NULL);
312 if (!result)
313 kfree(link);
314 return result;
315 }
316 EXPORT_SYMBOL_GPL(debugfs_create_symlink);
317
318 static void __debugfs_remove(struct dentry *dentry, struct dentry *parent)
319 {
320 int ret = 0;
321
322 if (debugfs_positive(dentry)) {
323 if (dentry->d_inode) {
324 dget(dentry);
325 switch (dentry->d_inode->i_mode & S_IFMT) {
326 case S_IFDIR:
327 ret = simple_rmdir(parent->d_inode, dentry);
328 break;
329 case S_IFLNK:
330 kfree(dentry->d_inode->i_private);
331 /* fall through */
332 default:
333 simple_unlink(parent->d_inode, dentry);
334 break;
335 }
336 if (!ret)
337 d_delete(dentry);
338 dput(dentry);
339 }
340 }
341 }
342
343 /**
344 * debugfs_remove - removes a file or directory from the debugfs filesystem
345 * @dentry: a pointer to a the dentry of the file or directory to be
346 * removed.
347 *
348 * This function removes a file or directory in debugfs that was previously
349 * created with a call to another debugfs function (like
350 * debugfs_create_file() or variants thereof.)
351 *
352 * This function is required to be called in order for the file to be
353 * removed, no automatic cleanup of files will happen when a module is
354 * removed, you are responsible here.
355 */
356 void debugfs_remove(struct dentry *dentry)
357 {
358 struct dentry *parent;
359
360 if (!dentry)
361 return;
362
363 parent = dentry->d_parent;
364 if (!parent || !parent->d_inode)
365 return;
366
367 mutex_lock(&parent->d_inode->i_mutex);
368 __debugfs_remove(dentry, parent);
369 mutex_unlock(&parent->d_inode->i_mutex);
370 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
371 }
372 EXPORT_SYMBOL_GPL(debugfs_remove);
373
374 /**
375 * debugfs_remove_recursive - recursively removes a directory
376 * @dentry: a pointer to a the dentry of the directory to be removed.
377 *
378 * This function recursively removes a directory tree in debugfs that
379 * was previously created with a call to another debugfs function
380 * (like debugfs_create_file() or variants thereof.)
381 *
382 * This function is required to be called in order for the file to be
383 * removed, no automatic cleanup of files will happen when a module is
384 * removed, you are responsible here.
385 */
386 void debugfs_remove_recursive(struct dentry *dentry)
387 {
388 struct dentry *child;
389 struct dentry *parent;
390
391 if (!dentry)
392 return;
393
394 parent = dentry->d_parent;
395 if (!parent || !parent->d_inode)
396 return;
397
398 parent = dentry;
399 mutex_lock(&parent->d_inode->i_mutex);
400
401 while (1) {
402 /*
403 * When all dentries under "parent" has been removed,
404 * walk up the tree until we reach our starting point.
405 */
406 if (list_empty(&parent->d_subdirs)) {
407 mutex_unlock(&parent->d_inode->i_mutex);
408 if (parent == dentry)
409 break;
410 parent = parent->d_parent;
411 mutex_lock(&parent->d_inode->i_mutex);
412 }
413 child = list_entry(parent->d_subdirs.next, struct dentry,
414 d_u.d_child);
415 next_sibling:
416
417 /*
418 * If "child" isn't empty, walk down the tree and
419 * remove all its descendants first.
420 */
421 if (!list_empty(&child->d_subdirs)) {
422 mutex_unlock(&parent->d_inode->i_mutex);
423 parent = child;
424 mutex_lock(&parent->d_inode->i_mutex);
425 continue;
426 }
427 __debugfs_remove(child, parent);
428 if (parent->d_subdirs.next == &child->d_u.d_child) {
429 /*
430 * Try the next sibling.
431 */
432 if (child->d_u.d_child.next != &parent->d_subdirs) {
433 child = list_entry(child->d_u.d_child.next,
434 struct dentry,
435 d_u.d_child);
436 goto next_sibling;
437 }
438
439 /*
440 * Avoid infinite loop if we fail to remove
441 * one dentry.
442 */
443 mutex_unlock(&parent->d_inode->i_mutex);
444 break;
445 }
446 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
447 }
448
449 parent = dentry->d_parent;
450 mutex_lock(&parent->d_inode->i_mutex);
451 __debugfs_remove(dentry, parent);
452 mutex_unlock(&parent->d_inode->i_mutex);
453 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
454 }
455 EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
456
457 /**
458 * debugfs_rename - rename a file/directory in the debugfs filesystem
459 * @old_dir: a pointer to the parent dentry for the renamed object. This
460 * should be a directory dentry.
461 * @old_dentry: dentry of an object to be renamed.
462 * @new_dir: a pointer to the parent dentry where the object should be
463 * moved. This should be a directory dentry.
464 * @new_name: a pointer to a string containing the target name.
465 *
466 * This function renames a file/directory in debugfs. The target must not
467 * exist for rename to succeed.
468 *
469 * This function will return a pointer to old_dentry (which is updated to
470 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
471 * returned.
472 *
473 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
474 * returned.
475 */
476 struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
477 struct dentry *new_dir, const char *new_name)
478 {
479 int error;
480 struct dentry *dentry = NULL, *trap;
481 const char *old_name;
482
483 trap = lock_rename(new_dir, old_dir);
484 /* Source or destination directories don't exist? */
485 if (!old_dir->d_inode || !new_dir->d_inode)
486 goto exit;
487 /* Source does not exist, cyclic rename, or mountpoint? */
488 if (!old_dentry->d_inode || old_dentry == trap ||
489 d_mountpoint(old_dentry))
490 goto exit;
491 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
492 /* Lookup failed, cyclic rename or target exists? */
493 if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
494 goto exit;
495
496 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
497
498 error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
499 dentry);
500 if (error) {
501 fsnotify_oldname_free(old_name);
502 goto exit;
503 }
504 d_move(old_dentry, dentry);
505 fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
506 old_dentry->d_name.name, S_ISDIR(old_dentry->d_inode->i_mode),
507 NULL, old_dentry);
508 fsnotify_oldname_free(old_name);
509 unlock_rename(new_dir, old_dir);
510 dput(dentry);
511 return old_dentry;
512 exit:
513 if (dentry && !IS_ERR(dentry))
514 dput(dentry);
515 unlock_rename(new_dir, old_dir);
516 return NULL;
517 }
518 EXPORT_SYMBOL_GPL(debugfs_rename);
519
520 /**
521 * debugfs_initialized - Tells whether debugfs has been registered
522 */
523 bool debugfs_initialized(void)
524 {
525 return debugfs_registered;
526 }
527 EXPORT_SYMBOL_GPL(debugfs_initialized);
528
529
530 static struct kobject *debug_kobj;
531
532 static int __init debugfs_init(void)
533 {
534 int retval;
535
536 debug_kobj = kobject_create_and_add("debug", kernel_kobj);
537 if (!debug_kobj)
538 return -EINVAL;
539
540 retval = register_filesystem(&debug_fs_type);
541 if (retval)
542 kobject_put(debug_kobj);
543 else
544 debugfs_registered = true;
545
546 return retval;
547 }
548
549 static void __exit debugfs_exit(void)
550 {
551 debugfs_registered = false;
552
553 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
554 unregister_filesystem(&debug_fs_type);
555 kobject_put(debug_kobj);
556 }
557
558 core_initcall(debugfs_init);
559 module_exit(debugfs_exit);
560 MODULE_LICENSE("GPL");
561
562
|
This page was automatically generated by the
LXR engine.
|