projects/linux·blob v3.13 · refs

671 lines · 17.5 KiB

1/*
2 * inode.c - part of debugfs, a tiny little debug file system
3 *
4 * Copyright (C) 2004 Greg Kroah-Hartman <[email protected]>
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#include <linux/module.h>
17#include <linux/fs.h>
18#include <linux/mount.h>
19#include <linux/pagemap.h>
20#include <linux/init.h>
21#include <linux/kobject.h>
22#include <linux/namei.h>
23#include <linux/debugfs.h>
24#include <linux/fsnotify.h>
25#include <linux/string.h>
26#include <linux/seq_file.h>
27#include <linux/parser.h>
28#include <linux/magic.h>
29#include <linux/slab.h>
30
31#define DEBUGFS_DEFAULT_MODE 0700
32
33static struct vfsmount *debugfs_mount;
34static int debugfs_mount_count;
35static bool debugfs_registered;
36
37static struct inode *debugfs_get_inode(struct super_block *sb, umode_t mode, dev_t dev,
38 void *data, const struct file_operations *fops)
39
40{
41 struct inode *inode = new_inode(sb);
42
43 if (inode) {
44 inode->i_ino = get_next_ino();
45 inode->i_mode = mode;
46 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
47 switch (mode & S_IFMT) {
48 default:
49 init_special_inode(inode, mode, dev);
50 break;
51 case S_IFREG:
52 inode->i_fop = fops ? fops : &debugfs_file_operations;
53 inode->i_private = data;
54 break;
55 case S_IFLNK:
56 inode->i_op = &debugfs_link_operations;
57 inode->i_private = data;
58 break;
59 case S_IFDIR:
60 inode->i_op = &simple_dir_inode_operations;
61 inode->i_fop = &simple_dir_operations;
62
63 /* directory inodes start off with i_nlink == 2
64 * (for "." entry) */
65 inc_nlink(inode);
66 break;
67 }
68 }
69 return inode;
70}
71
72/* SMP-safe */
73static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
74 umode_t mode, dev_t dev, void *data,
75 const struct file_operations *fops)
76{
77 struct inode *inode;
78 int error = -EPERM;
79
80 if (dentry->d_inode)
81 return -EEXIST;
82
83 inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops);
84 if (inode) {
85 d_instantiate(dentry, inode);
86 dget(dentry);
87 error = 0;
88 }
89 return error;
90}
91
92static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
93{
94 int res;
95
96 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
97 res = debugfs_mknod(dir, dentry, mode, 0, NULL, NULL);
98 if (!res) {
99 inc_nlink(dir);
100 fsnotify_mkdir(dir, dentry);
101 }
102 return res;
103}
104
105static int debugfs_link(struct inode *dir, struct dentry *dentry, umode_t mode,
106 void *data)
107{
108 mode = (mode & S_IALLUGO) | S_IFLNK;
109 return debugfs_mknod(dir, dentry, mode, 0, data, NULL);
110}
111
112static int debugfs_create(struct inode *dir, struct dentry *dentry, umode_t 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
124static inline int debugfs_positive(struct dentry *dentry)
125{
126 return dentry->d_inode && !d_unhashed(dentry);
127}
128
129struct debugfs_mount_opts {
130 kuid_t uid;
131 kgid_t gid;
132 umode_t mode;
133};
134
135enum {
136 Opt_uid,
137 Opt_gid,
138 Opt_mode,
139 Opt_err
140};
141
142static const match_table_t tokens = {
143 {Opt_uid, "uid=%u"},
144 {Opt_gid, "gid=%u"},
145 {Opt_mode, "mode=%o"},
146 {Opt_err, NULL}
147};
148
149struct debugfs_fs_info {
150 struct debugfs_mount_opts mount_opts;
151};
152
153static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
154{
155 substring_t args[MAX_OPT_ARGS];
156 int option;
157 int token;
158 kuid_t uid;
159 kgid_t gid;
160 char *p;
161
162 opts->mode = DEBUGFS_DEFAULT_MODE;
163
164 while ((p = strsep(&data, ",")) != NULL) {
165 if (!*p)
166 continue;
167
168 token = match_token(p, tokens, args);
169 switch (token) {
170 case Opt_uid:
171 if (match_int(&args[0], &option))
172 return -EINVAL;
173 uid = make_kuid(current_user_ns(), option);
174 if (!uid_valid(uid))
175 return -EINVAL;
176 opts->uid = uid;
177 break;
178 case Opt_gid:
179 if (match_int(&args[0], &option))
180 return -EINVAL;
181 gid = make_kgid(current_user_ns(), option);
182 if (!gid_valid(gid))
183 return -EINVAL;
184 opts->gid = gid;
185 break;
186 case Opt_mode:
187 if (match_octal(&args[0], &option))
188 return -EINVAL;
189 opts->mode = option & S_IALLUGO;
190 break;
191 /*
192 * We might like to report bad mount options here;
193 * but traditionally debugfs has ignored all mount options
194 */
195 }
196 }
197
198 return 0;
199}
200
201static int debugfs_apply_options(struct super_block *sb)
202{
203 struct debugfs_fs_info *fsi = sb->s_fs_info;
204 struct inode *inode = sb->s_root->d_inode;
205 struct debugfs_mount_opts *opts = &fsi->mount_opts;
206
207 inode->i_mode &= ~S_IALLUGO;
208 inode->i_mode |= opts->mode;
209
210 inode->i_uid = opts->uid;
211 inode->i_gid = opts->gid;
212
213 return 0;
214}
215
216static int debugfs_remount(struct super_block *sb, int *flags, char *data)
217{
218 int err;
219 struct debugfs_fs_info *fsi = sb->s_fs_info;
220
221 err = debugfs_parse_options(data, &fsi->mount_opts);
222 if (err)
223 goto fail;
224
225 debugfs_apply_options(sb);
226
227fail:
228 return err;
229}
230
231static int debugfs_show_options(struct seq_file *m, struct dentry *root)
232{
233 struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
234 struct debugfs_mount_opts *opts = &fsi->mount_opts;
235
236 if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
237 seq_printf(m, ",uid=%u",
238 from_kuid_munged(&init_user_ns, opts->uid));
239 if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
240 seq_printf(m, ",gid=%u",
241 from_kgid_munged(&init_user_ns, opts->gid));
242 if (opts->mode != DEBUGFS_DEFAULT_MODE)
243 seq_printf(m, ",mode=%o", opts->mode);
244
245 return 0;
246}
247
248static const struct super_operations debugfs_super_operations = {
249 .statfs = simple_statfs,
250 .remount_fs = debugfs_remount,
251 .show_options = debugfs_show_options,
252};
253
254static int debug_fill_super(struct super_block *sb, void *data, int silent)
255{
256 static struct tree_descr debug_files[] = {{""}};
257 struct debugfs_fs_info *fsi;
258 int err;
259
260 save_mount_options(sb, data);
261
262 fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
263 sb->s_fs_info = fsi;
264 if (!fsi) {
265 err = -ENOMEM;
266 goto fail;
267 }
268
269 err = debugfs_parse_options(data, &fsi->mount_opts);
270 if (err)
271 goto fail;
272
273 err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
274 if (err)
275 goto fail;
276
277 sb->s_op = &debugfs_super_operations;
278
279 debugfs_apply_options(sb);
280
281 return 0;
282
283fail:
284 kfree(fsi);
285 sb->s_fs_info = NULL;
286 return err;
287}
288
289static struct dentry *debug_mount(struct file_system_type *fs_type,
290 int flags, const char *dev_name,
291 void *data)
292{
293 return mount_single(fs_type, flags, data, debug_fill_super);
294}
295
296static struct file_system_type debug_fs_type = {
297 .owner = THIS_MODULE,
298 .name = "debugfs",
299 .mount = debug_mount,
300 .kill_sb = kill_litter_super,
301};
302MODULE_ALIAS_FS("debugfs");
303
304static struct dentry *__create_file(const char *name, umode_t mode,
305 struct dentry *parent, void *data,
306 const struct file_operations *fops)
307{
308 struct dentry *dentry = NULL;
309 int error;
310
311 pr_debug("debugfs: creating file '%s'\n",name);
312
313 error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
314 &debugfs_mount_count);
315 if (error)
316 goto exit;
317
318 /* If the parent is not specified, we create it in the root.
319 * We need the root dentry to do this, which is in the super
320 * block. A pointer to that is in the struct vfsmount that we
321 * have around.
322 */
323 if (!parent)
324 parent = debugfs_mount->mnt_root;
325
326 mutex_lock(&parent->d_inode->i_mutex);
327 dentry = lookup_one_len(name, parent, strlen(name));
328 if (!IS_ERR(dentry)) {
329 switch (mode & S_IFMT) {
330 case S_IFDIR:
331 error = debugfs_mkdir(parent->d_inode, dentry, mode);
332
333 break;
334 case S_IFLNK:
335 error = debugfs_link(parent->d_inode, dentry, mode,
336 data);
337 break;
338 default:
339 error = debugfs_create(parent->d_inode, dentry, mode,
340 data, fops);
341 break;
342 }
343 dput(dentry);
344 } else
345 error = PTR_ERR(dentry);
346 mutex_unlock(&parent->d_inode->i_mutex);
347
348 if (error) {
349 dentry = NULL;
350 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
351 }
352exit:
353 return dentry;
354}
355
356/**
357 * debugfs_create_file - create a file in the debugfs filesystem
358 * @name: a pointer to a string containing the name of the file to create.
359 * @mode: the permission that the file should have.
360 * @parent: a pointer to the parent dentry for this file. This should be a
361 * directory dentry if set. If this paramater is NULL, then the
362 * file will be created in the root of the debugfs filesystem.
363 * @data: a pointer to something that the caller will want to get to later
364 * on. The inode.i_private pointer will point to this value on
365 * the open() call.
366 * @fops: a pointer to a struct file_operations that should be used for
367 * this file.
368 *
369 * This is the basic "create a file" function for debugfs. It allows for a
370 * wide range of flexibility in creating a file, or a directory (if you want
371 * to create a directory, the debugfs_create_dir() function is
372 * recommended to be used instead.)
373 *
374 * This function will return a pointer to a dentry if it succeeds. This
375 * pointer must be passed to the debugfs_remove() function when the file is
376 * to be removed (no automatic cleanup happens if your module is unloaded,
377 * you are responsible here.) If an error occurs, %NULL will be returned.
378 *
379 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
380 * returned.
381 */
382struct dentry *debugfs_create_file(const char *name, umode_t mode,
383 struct dentry *parent, void *data,
384 const struct file_operations *fops)
385{
386 switch (mode & S_IFMT) {
387 case S_IFREG:
388 case 0:
389 break;
390 default:
391 BUG();
392 }
393
394 return __create_file(name, mode, parent, data, fops);
395}
396EXPORT_SYMBOL_GPL(debugfs_create_file);
397
398/**
399 * debugfs_create_dir - create a directory in the debugfs filesystem
400 * @name: a pointer to a string containing the name of the directory to
401 * create.
402 * @parent: a pointer to the parent dentry for this file. This should be a
403 * directory dentry if set. If this paramater is NULL, then the
404 * directory will be created in the root of the debugfs filesystem.
405 *
406 * This function creates a directory in debugfs with the given name.
407 *
408 * This function will return a pointer to a dentry if it succeeds. This
409 * pointer must be passed to the debugfs_remove() function when the file is
410 * to be removed (no automatic cleanup happens if your module is unloaded,
411 * you are responsible here.) If an error occurs, %NULL will be returned.
412 *
413 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
414 * returned.
415 */
416struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
417{
418 return __create_file(name, S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
419 parent, NULL, NULL);
420}
421EXPORT_SYMBOL_GPL(debugfs_create_dir);
422
423/**
424 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
425 * @name: a pointer to a string containing the name of the symbolic link to
426 * create.
427 * @parent: a pointer to the parent dentry for this symbolic link. This
428 * should be a directory dentry if set. If this paramater is NULL,
429 * then the symbolic link will be created in the root of the debugfs
430 * filesystem.
431 * @target: a pointer to a string containing the path to the target of the
432 * symbolic link.
433 *
434 * This function creates a symbolic link with the given name in debugfs that
435 * links to the given target path.
436 *
437 * This function will return a pointer to a dentry if it succeeds. This
438 * pointer must be passed to the debugfs_remove() function when the symbolic
439 * link is to be removed (no automatic cleanup happens if your module is
440 * unloaded, you are responsible here.) If an error occurs, %NULL will be
441 * returned.
442 *
443 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
444 * returned.
445 */
446struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
447 const char *target)
448{
449 struct dentry *result;
450 char *link;
451
452 link = kstrdup(target, GFP_KERNEL);
453 if (!link)
454 return NULL;
455
456 result = __create_file(name, S_IFLNK | S_IRWXUGO, parent, link, NULL);
457 if (!result)
458 kfree(link);
459 return result;
460}
461EXPORT_SYMBOL_GPL(debugfs_create_symlink);
462
463static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
464{
465 int ret = 0;
466
467 if (debugfs_positive(dentry)) {
468 if (dentry->d_inode) {
469 dget(dentry);
470 switch (dentry->d_inode->i_mode & S_IFMT) {
471 case S_IFDIR:
472 ret = simple_rmdir(parent->d_inode, dentry);
473 break;
474 case S_IFLNK:
475 kfree(dentry->d_inode->i_private);
476 /* fall through */
477 default:
478 simple_unlink(parent->d_inode, dentry);
479 break;
480 }
481 if (!ret)
482 d_delete(dentry);
483 dput(dentry);
484 }
485 }
486 return ret;
487}
488
489/**
490 * debugfs_remove - removes a file or directory from the debugfs filesystem
491 * @dentry: a pointer to a the dentry of the file or directory to be
492 * removed.
493 *
494 * This function removes a file or directory in debugfs that was previously
495 * created with a call to another debugfs function (like
496 * debugfs_create_file() or variants thereof.)
497 *
498 * This function is required to be called in order for the file to be
499 * removed, no automatic cleanup of files will happen when a module is
500 * removed, you are responsible here.
501 */
502void debugfs_remove(struct dentry *dentry)
503{
504 struct dentry *parent;
505 int ret;
506
507 if (IS_ERR_OR_NULL(dentry))
508 return;
509
510 parent = dentry->d_parent;
511 if (!parent || !parent->d_inode)
512 return;
513
514 mutex_lock(&parent->d_inode->i_mutex);
515 ret = __debugfs_remove(dentry, parent);
516 mutex_unlock(&parent->d_inode->i_mutex);
517 if (!ret)
518 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
519}
520EXPORT_SYMBOL_GPL(debugfs_remove);
521
522/**
523 * debugfs_remove_recursive - recursively removes a directory
524 * @dentry: a pointer to a the dentry of the directory to be removed.
525 *
526 * This function recursively removes a directory tree in debugfs that
527 * was previously created with a call to another debugfs function
528 * (like debugfs_create_file() or variants thereof.)
529 *
530 * This function is required to be called in order for the file to be
531 * removed, no automatic cleanup of files will happen when a module is
532 * removed, you are responsible here.
533 */
534void debugfs_remove_recursive(struct dentry *dentry)
535{
536 struct dentry *child, *next, *parent;
537
538 if (IS_ERR_OR_NULL(dentry))
539 return;
540
541 parent = dentry->d_parent;
542 if (!parent || !parent->d_inode)
543 return;
544
545 parent = dentry;
546 down:
547 mutex_lock(&parent->d_inode->i_mutex);
548 list_for_each_entry_safe(child, next, &parent->d_subdirs, d_u.d_child) {
549 if (!debugfs_positive(child))
550 continue;
551
552 /* perhaps simple_empty(child) makes more sense */
553 if (!list_empty(&child->d_subdirs)) {
554 mutex_unlock(&parent->d_inode->i_mutex);
555 parent = child;
556 goto down;
557 }
558 up:
559 if (!__debugfs_remove(child, parent))
560 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
561 }
562
563 mutex_unlock(&parent->d_inode->i_mutex);
564 child = parent;
565 parent = parent->d_parent;
566 mutex_lock(&parent->d_inode->i_mutex);
567
568 if (child != dentry) {
569 next = list_next_entry(child, d_u.d_child);
570 goto up;
571 }
572
573 if (!__debugfs_remove(child, parent))
574 simple_release_fs(&debugfs_mount, &debugfs_mount_count);
575 mutex_unlock(&parent->d_inode->i_mutex);
576}
577EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
578
579/**
580 * debugfs_rename - rename a file/directory in the debugfs filesystem
581 * @old_dir: a pointer to the parent dentry for the renamed object. This
582 * should be a directory dentry.
583 * @old_dentry: dentry of an object to be renamed.
584 * @new_dir: a pointer to the parent dentry where the object should be
585 * moved. This should be a directory dentry.
586 * @new_name: a pointer to a string containing the target name.
587 *
588 * This function renames a file/directory in debugfs. The target must not
589 * exist for rename to succeed.
590 *
591 * This function will return a pointer to old_dentry (which is updated to
592 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
593 * returned.
594 *
595 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
596 * returned.
597 */
598struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
599 struct dentry *new_dir, const char *new_name)
600{
601 int error;
602 struct dentry *dentry = NULL, *trap;
603 const char *old_name;
604
605 trap = lock_rename(new_dir, old_dir);
606 /* Source or destination directories don't exist? */
607 if (!old_dir->d_inode || !new_dir->d_inode)
608 goto exit;
609 /* Source does not exist, cyclic rename, or mountpoint? */
610 if (!old_dentry->d_inode || old_dentry == trap ||
611 d_mountpoint(old_dentry))
612 goto exit;
613 dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
614 /* Lookup failed, cyclic rename or target exists? */
615 if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
616 goto exit;
617
618 old_name = fsnotify_oldname_init(old_dentry->d_name.name);
619
620 error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
621 dentry);
622 if (error) {
623 fsnotify_oldname_free(old_name);
624 goto exit;
625 }
626 d_move(old_dentry, dentry);
627 fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
628 S_ISDIR(old_dentry->d_inode->i_mode),
629 NULL, old_dentry);
630 fsnotify_oldname_free(old_name);
631 unlock_rename(new_dir, old_dir);
632 dput(dentry);
633 return old_dentry;
634exit:
635 if (dentry && !IS_ERR(dentry))
636 dput(dentry);
637 unlock_rename(new_dir, old_dir);
638 return NULL;
639}
640EXPORT_SYMBOL_GPL(debugfs_rename);
641
642/**
643 * debugfs_initialized - Tells whether debugfs has been registered
644 */
645bool debugfs_initialized(void)
646{
647 return debugfs_registered;
648}
649EXPORT_SYMBOL_GPL(debugfs_initialized);
650
651
652static struct kobject *debug_kobj;
653
654static int __init debugfs_init(void)
655{
656 int retval;
657
658 debug_kobj = kobject_create_and_add("debug", kernel_kobj);
659 if (!debug_kobj)
660 return -EINVAL;
661
662 retval = register_filesystem(&debug_fs_type);
663 if (retval)
664 kobject_put(debug_kobj);
665 else
666 debugfs_registered = true;
667
668 return retval;
669}
670core_initcall(debugfs_init);
671