2 * inode.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 #include <linux/module.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>
31 #define DEBUGFS_DEFAULT_MODE 0755
33 static struct vfsmount
*debugfs_mount
;
34 static int debugfs_mount_count
;
35 static bool debugfs_registered
;
37 static struct inode
*debugfs_get_inode(struct super_block
*sb
, umode_t mode
, dev_t dev
,
38 void *data
, const struct file_operations
*fops
)
41 struct inode
*inode
= new_inode(sb
);
44 inode
->i_ino
= get_next_ino();
46 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
47 switch (mode
& S_IFMT
) {
49 init_special_inode(inode
, mode
, dev
);
52 inode
->i_fop
= fops
? fops
: &debugfs_file_operations
;
53 inode
->i_private
= data
;
56 inode
->i_op
= &debugfs_link_operations
;
57 inode
->i_private
= data
;
60 inode
->i_op
= &simple_dir_inode_operations
;
61 inode
->i_fop
= &simple_dir_operations
;
62 inode
->i_private
= NULL
;
64 /* directory inodes start off with i_nlink == 2
74 static int debugfs_mknod(struct inode
*dir
, struct dentry
*dentry
,
75 umode_t mode
, dev_t dev
, void *data
,
76 const struct file_operations
*fops
)
84 inode
= debugfs_get_inode(dir
->i_sb
, mode
, dev
, data
, fops
);
86 d_instantiate(dentry
, inode
);
93 static int debugfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
97 mode
= (mode
& (S_IRWXUGO
| S_ISVTX
)) | S_IFDIR
;
98 res
= debugfs_mknod(dir
, dentry
, mode
, 0, NULL
, NULL
);
101 fsnotify_mkdir(dir
, dentry
);
106 static int debugfs_link(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
109 mode
= (mode
& S_IALLUGO
) | S_IFLNK
;
110 return debugfs_mknod(dir
, dentry
, mode
, 0, data
, NULL
);
113 static int debugfs_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
114 void *data
, const struct file_operations
*fops
)
118 mode
= (mode
& S_IALLUGO
) | S_IFREG
;
119 res
= debugfs_mknod(dir
, dentry
, mode
, 0, data
, fops
);
121 fsnotify_create(dir
, dentry
);
125 static inline int debugfs_positive(struct dentry
*dentry
)
127 return dentry
->d_inode
&& !d_unhashed(dentry
);
130 struct debugfs_mount_opts
{
143 static const match_table_t tokens
= {
146 {Opt_mode
, "mode=%o"},
150 struct debugfs_fs_info
{
151 struct debugfs_mount_opts mount_opts
;
154 static int debugfs_parse_options(char *data
, struct debugfs_mount_opts
*opts
)
156 substring_t args
[MAX_OPT_ARGS
];
161 opts
->mode
= DEBUGFS_DEFAULT_MODE
;
163 while ((p
= strsep(&data
, ",")) != NULL
) {
167 token
= match_token(p
, tokens
, args
);
170 if (match_int(&args
[0], &option
))
175 if (match_octal(&args
[0], &option
))
180 if (match_octal(&args
[0], &option
))
182 opts
->mode
= option
& S_IALLUGO
;
185 * We might like to report bad mount options here;
186 * but traditionally debugfs has ignored all mount options
194 static int debugfs_apply_options(struct super_block
*sb
)
196 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
197 struct inode
*inode
= sb
->s_root
->d_inode
;
198 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
200 inode
->i_mode
&= ~S_IALLUGO
;
201 inode
->i_mode
|= opts
->mode
;
203 inode
->i_uid
= opts
->uid
;
204 inode
->i_gid
= opts
->gid
;
209 static int debugfs_remount(struct super_block
*sb
, int *flags
, char *data
)
212 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
214 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
218 debugfs_apply_options(sb
);
224 static int debugfs_show_options(struct seq_file
*m
, struct dentry
*root
)
226 struct debugfs_fs_info
*fsi
= root
->d_sb
->s_fs_info
;
227 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
230 seq_printf(m
, ",uid=%u", opts
->uid
);
232 seq_printf(m
, ",gid=%u", opts
->gid
);
233 if (opts
->mode
!= DEBUGFS_DEFAULT_MODE
)
234 seq_printf(m
, ",mode=%o", opts
->mode
);
239 static const struct super_operations debugfs_super_operations
= {
240 .statfs
= simple_statfs
,
241 .remount_fs
= debugfs_remount
,
242 .show_options
= debugfs_show_options
,
245 static int debug_fill_super(struct super_block
*sb
, void *data
, int silent
)
247 static struct tree_descr debug_files
[] = {{""}};
248 struct debugfs_fs_info
*fsi
;
251 save_mount_options(sb
, data
);
253 fsi
= kzalloc(sizeof(struct debugfs_fs_info
), GFP_KERNEL
);
260 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
264 err
= simple_fill_super(sb
, DEBUGFS_MAGIC
, debug_files
);
268 sb
->s_op
= &debugfs_super_operations
;
270 debugfs_apply_options(sb
);
276 sb
->s_fs_info
= NULL
;
280 static struct dentry
*debug_mount(struct file_system_type
*fs_type
,
281 int flags
, const char *dev_name
,
284 return mount_single(fs_type
, flags
, data
, debug_fill_super
);
287 static struct file_system_type debug_fs_type
= {
288 .owner
= THIS_MODULE
,
290 .mount
= debug_mount
,
291 .kill_sb
= kill_litter_super
,
294 struct dentry
*__create_file(const char *name
, umode_t mode
,
295 struct dentry
*parent
, void *data
,
296 const struct file_operations
*fops
)
298 struct dentry
*dentry
= NULL
;
301 pr_debug("debugfs: creating file '%s'\n",name
);
303 error
= simple_pin_fs(&debug_fs_type
, &debugfs_mount
,
304 &debugfs_mount_count
);
308 /* If the parent is not specified, we create it in the root.
309 * We need the root dentry to do this, which is in the super
310 * block. A pointer to that is in the struct vfsmount that we
314 parent
= debugfs_mount
->mnt_root
;
317 mutex_lock(&parent
->d_inode
->i_mutex
);
318 dentry
= lookup_one_len(name
, parent
, strlen(name
));
319 if (!IS_ERR(dentry
)) {
320 switch (mode
& S_IFMT
) {
322 error
= debugfs_mkdir(parent
->d_inode
, dentry
, mode
);
326 error
= debugfs_link(parent
->d_inode
, dentry
, mode
,
330 error
= debugfs_create(parent
->d_inode
, dentry
, mode
,
336 error
= PTR_ERR(dentry
);
337 mutex_unlock(&parent
->d_inode
->i_mutex
);
341 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
348 * debugfs_create_file - create a file in the debugfs filesystem
349 * @name: a pointer to a string containing the name of the file to create.
350 * @mode: the permission that the file should have.
351 * @parent: a pointer to the parent dentry for this file. This should be a
352 * directory dentry if set. If this paramater is NULL, then the
353 * file will be created in the root of the debugfs filesystem.
354 * @data: a pointer to something that the caller will want to get to later
355 * on. The inode.i_private pointer will point to this value on
357 * @fops: a pointer to a struct file_operations that should be used for
360 * This is the basic "create a file" function for debugfs. It allows for a
361 * wide range of flexibility in creating a file, or a directory (if you want
362 * to create a directory, the debugfs_create_dir() function is
363 * recommended to be used instead.)
365 * This function will return a pointer to a dentry if it succeeds. This
366 * pointer must be passed to the debugfs_remove() function when the file is
367 * to be removed (no automatic cleanup happens if your module is unloaded,
368 * you are responsible here.) If an error occurs, %NULL will be returned.
370 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
373 struct dentry
*debugfs_create_file(const char *name
, umode_t mode
,
374 struct dentry
*parent
, void *data
,
375 const struct file_operations
*fops
)
377 switch (mode
& S_IFMT
) {
385 return __create_file(name
, mode
, parent
, data
, fops
);
387 EXPORT_SYMBOL_GPL(debugfs_create_file
);
390 * debugfs_create_dir - create a directory in the debugfs filesystem
391 * @name: a pointer to a string containing the name of the directory to
393 * @parent: a pointer to the parent dentry for this file. This should be a
394 * directory dentry if set. If this paramater is NULL, then the
395 * directory will be created in the root of the debugfs filesystem.
397 * This function creates a directory in debugfs with the given name.
399 * This function will return a pointer to a dentry if it succeeds. This
400 * pointer must be passed to the debugfs_remove() function when the file is
401 * to be removed (no automatic cleanup happens if your module is unloaded,
402 * you are responsible here.) If an error occurs, %NULL will be returned.
404 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
407 struct dentry
*debugfs_create_dir(const char *name
, struct dentry
*parent
)
409 return __create_file(name
, S_IFDIR
| S_IRWXU
| S_IRUGO
| S_IXUGO
,
412 EXPORT_SYMBOL_GPL(debugfs_create_dir
);
415 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
416 * @name: a pointer to a string containing the name of the symbolic link to
418 * @parent: a pointer to the parent dentry for this symbolic link. This
419 * should be a directory dentry if set. If this paramater is NULL,
420 * then the symbolic link will be created in the root of the debugfs
422 * @target: a pointer to a string containing the path to the target of the
425 * This function creates a symbolic link with the given name in debugfs that
426 * links to the given target path.
428 * This function will return a pointer to a dentry if it succeeds. This
429 * pointer must be passed to the debugfs_remove() function when the symbolic
430 * link is to be removed (no automatic cleanup happens if your module is
431 * unloaded, you are responsible here.) If an error occurs, %NULL will be
434 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
437 struct dentry
*debugfs_create_symlink(const char *name
, struct dentry
*parent
,
440 struct dentry
*result
;
443 link
= kstrdup(target
, GFP_KERNEL
);
447 result
= __create_file(name
, S_IFLNK
| S_IRWXUGO
, parent
, link
, NULL
);
452 EXPORT_SYMBOL_GPL(debugfs_create_symlink
);
454 static int __debugfs_remove(struct dentry
*dentry
, struct dentry
*parent
)
458 if (debugfs_positive(dentry
)) {
459 if (dentry
->d_inode
) {
461 switch (dentry
->d_inode
->i_mode
& S_IFMT
) {
463 ret
= simple_rmdir(parent
->d_inode
, dentry
);
466 kfree(dentry
->d_inode
->i_private
);
469 simple_unlink(parent
->d_inode
, dentry
);
481 * debugfs_remove - removes a file or directory from the debugfs filesystem
482 * @dentry: a pointer to a the dentry of the file or directory to be
485 * This function removes a file or directory in debugfs that was previously
486 * created with a call to another debugfs function (like
487 * debugfs_create_file() or variants thereof.)
489 * This function is required to be called in order for the file to be
490 * removed, no automatic cleanup of files will happen when a module is
491 * removed, you are responsible here.
493 void debugfs_remove(struct dentry
*dentry
)
495 struct dentry
*parent
;
501 parent
= dentry
->d_parent
;
502 if (!parent
|| !parent
->d_inode
)
505 mutex_lock(&parent
->d_inode
->i_mutex
);
506 ret
= __debugfs_remove(dentry
, parent
);
507 mutex_unlock(&parent
->d_inode
->i_mutex
);
509 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
511 EXPORT_SYMBOL_GPL(debugfs_remove
);
514 * debugfs_remove_recursive - recursively removes a directory
515 * @dentry: a pointer to a the dentry of the directory to be removed.
517 * This function recursively removes a directory tree in debugfs that
518 * was previously created with a call to another debugfs function
519 * (like debugfs_create_file() or variants thereof.)
521 * This function is required to be called in order for the file to be
522 * removed, no automatic cleanup of files will happen when a module is
523 * removed, you are responsible here.
525 void debugfs_remove_recursive(struct dentry
*dentry
)
527 struct dentry
*child
;
528 struct dentry
*parent
;
533 parent
= dentry
->d_parent
;
534 if (!parent
|| !parent
->d_inode
)
538 mutex_lock(&parent
->d_inode
->i_mutex
);
542 * When all dentries under "parent" has been removed,
543 * walk up the tree until we reach our starting point.
545 if (list_empty(&parent
->d_subdirs
)) {
546 mutex_unlock(&parent
->d_inode
->i_mutex
);
547 if (parent
== dentry
)
549 parent
= parent
->d_parent
;
550 mutex_lock(&parent
->d_inode
->i_mutex
);
552 child
= list_entry(parent
->d_subdirs
.next
, struct dentry
,
557 * If "child" isn't empty, walk down the tree and
558 * remove all its descendants first.
560 if (!list_empty(&child
->d_subdirs
)) {
561 mutex_unlock(&parent
->d_inode
->i_mutex
);
563 mutex_lock(&parent
->d_inode
->i_mutex
);
566 __debugfs_remove(child
, parent
);
567 if (parent
->d_subdirs
.next
== &child
->d_u
.d_child
) {
569 * Try the next sibling.
571 if (child
->d_u
.d_child
.next
!= &parent
->d_subdirs
) {
572 child
= list_entry(child
->d_u
.d_child
.next
,
579 * Avoid infinite loop if we fail to remove
582 mutex_unlock(&parent
->d_inode
->i_mutex
);
585 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
588 parent
= dentry
->d_parent
;
589 mutex_lock(&parent
->d_inode
->i_mutex
);
590 __debugfs_remove(dentry
, parent
);
591 mutex_unlock(&parent
->d_inode
->i_mutex
);
592 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
594 EXPORT_SYMBOL_GPL(debugfs_remove_recursive
);
597 * debugfs_rename - rename a file/directory in the debugfs filesystem
598 * @old_dir: a pointer to the parent dentry for the renamed object. This
599 * should be a directory dentry.
600 * @old_dentry: dentry of an object to be renamed.
601 * @new_dir: a pointer to the parent dentry where the object should be
602 * moved. This should be a directory dentry.
603 * @new_name: a pointer to a string containing the target name.
605 * This function renames a file/directory in debugfs. The target must not
606 * exist for rename to succeed.
608 * This function will return a pointer to old_dentry (which is updated to
609 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
612 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
615 struct dentry
*debugfs_rename(struct dentry
*old_dir
, struct dentry
*old_dentry
,
616 struct dentry
*new_dir
, const char *new_name
)
619 struct dentry
*dentry
= NULL
, *trap
;
620 const char *old_name
;
622 trap
= lock_rename(new_dir
, old_dir
);
623 /* Source or destination directories don't exist? */
624 if (!old_dir
->d_inode
|| !new_dir
->d_inode
)
626 /* Source does not exist, cyclic rename, or mountpoint? */
627 if (!old_dentry
->d_inode
|| old_dentry
== trap
||
628 d_mountpoint(old_dentry
))
630 dentry
= lookup_one_len(new_name
, new_dir
, strlen(new_name
));
631 /* Lookup failed, cyclic rename or target exists? */
632 if (IS_ERR(dentry
) || dentry
== trap
|| dentry
->d_inode
)
635 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
637 error
= simple_rename(old_dir
->d_inode
, old_dentry
, new_dir
->d_inode
,
640 fsnotify_oldname_free(old_name
);
643 d_move(old_dentry
, dentry
);
644 fsnotify_move(old_dir
->d_inode
, new_dir
->d_inode
, old_name
,
645 S_ISDIR(old_dentry
->d_inode
->i_mode
),
647 fsnotify_oldname_free(old_name
);
648 unlock_rename(new_dir
, old_dir
);
652 if (dentry
&& !IS_ERR(dentry
))
654 unlock_rename(new_dir
, old_dir
);
657 EXPORT_SYMBOL_GPL(debugfs_rename
);
660 * debugfs_initialized - Tells whether debugfs has been registered
662 bool debugfs_initialized(void)
664 return debugfs_registered
;
666 EXPORT_SYMBOL_GPL(debugfs_initialized
);
669 static struct kobject
*debug_kobj
;
671 static int __init
debugfs_init(void)
675 debug_kobj
= kobject_create_and_add("debug", kernel_kobj
);
679 retval
= register_filesystem(&debug_fs_type
);
681 kobject_put(debug_kobj
);
683 debugfs_registered
= true;
687 core_initcall(debugfs_init
);