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 0700
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
];
163 opts
->mode
= DEBUGFS_DEFAULT_MODE
;
165 while ((p
= strsep(&data
, ",")) != NULL
) {
169 token
= match_token(p
, tokens
, args
);
172 if (match_int(&args
[0], &option
))
174 uid
= make_kuid(current_user_ns(), option
);
180 if (match_octal(&args
[0], &option
))
182 gid
= make_kgid(current_user_ns(), option
);
188 if (match_octal(&args
[0], &option
))
190 opts
->mode
= option
& S_IALLUGO
;
193 * We might like to report bad mount options here;
194 * but traditionally debugfs has ignored all mount options
202 static int debugfs_apply_options(struct super_block
*sb
)
204 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
205 struct inode
*inode
= sb
->s_root
->d_inode
;
206 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
208 inode
->i_mode
&= ~S_IALLUGO
;
209 inode
->i_mode
|= opts
->mode
;
211 inode
->i_uid
= opts
->uid
;
212 inode
->i_gid
= opts
->gid
;
217 static int debugfs_remount(struct super_block
*sb
, int *flags
, char *data
)
220 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
222 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
226 debugfs_apply_options(sb
);
232 static int debugfs_show_options(struct seq_file
*m
, struct dentry
*root
)
234 struct debugfs_fs_info
*fsi
= root
->d_sb
->s_fs_info
;
235 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
237 if (!uid_eq(opts
->uid
, GLOBAL_ROOT_UID
))
238 seq_printf(m
, ",uid=%u",
239 from_kuid_munged(&init_user_ns
, opts
->uid
));
240 if (!gid_eq(opts
->gid
, GLOBAL_ROOT_GID
))
241 seq_printf(m
, ",gid=%u",
242 from_kgid_munged(&init_user_ns
, opts
->gid
));
243 if (opts
->mode
!= DEBUGFS_DEFAULT_MODE
)
244 seq_printf(m
, ",mode=%o", opts
->mode
);
249 static const struct super_operations debugfs_super_operations
= {
250 .statfs
= simple_statfs
,
251 .remount_fs
= debugfs_remount
,
252 .show_options
= debugfs_show_options
,
255 static int debug_fill_super(struct super_block
*sb
, void *data
, int silent
)
257 static struct tree_descr debug_files
[] = {{""}};
258 struct debugfs_fs_info
*fsi
;
261 save_mount_options(sb
, data
);
263 fsi
= kzalloc(sizeof(struct debugfs_fs_info
), GFP_KERNEL
);
270 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
274 err
= simple_fill_super(sb
, DEBUGFS_MAGIC
, debug_files
);
278 sb
->s_op
= &debugfs_super_operations
;
280 debugfs_apply_options(sb
);
286 sb
->s_fs_info
= NULL
;
290 static struct dentry
*debug_mount(struct file_system_type
*fs_type
,
291 int flags
, const char *dev_name
,
294 return mount_single(fs_type
, flags
, data
, debug_fill_super
);
297 static struct file_system_type debug_fs_type
= {
298 .owner
= THIS_MODULE
,
300 .mount
= debug_mount
,
301 .kill_sb
= kill_litter_super
,
304 static struct dentry
*__create_file(const char *name
, umode_t mode
,
305 struct dentry
*parent
, void *data
,
306 const struct file_operations
*fops
)
308 struct dentry
*dentry
= NULL
;
311 pr_debug("debugfs: creating file '%s'\n",name
);
313 error
= simple_pin_fs(&debug_fs_type
, &debugfs_mount
,
314 &debugfs_mount_count
);
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
324 parent
= debugfs_mount
->mnt_root
;
327 mutex_lock(&parent
->d_inode
->i_mutex
);
328 dentry
= lookup_one_len(name
, parent
, strlen(name
));
329 if (!IS_ERR(dentry
)) {
330 switch (mode
& S_IFMT
) {
332 error
= debugfs_mkdir(parent
->d_inode
, dentry
, mode
);
336 error
= debugfs_link(parent
->d_inode
, dentry
, mode
,
340 error
= debugfs_create(parent
->d_inode
, dentry
, mode
,
346 error
= PTR_ERR(dentry
);
347 mutex_unlock(&parent
->d_inode
->i_mutex
);
351 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
358 * debugfs_create_file - create a file in the debugfs filesystem
359 * @name: a pointer to a string containing the name of the file to create.
360 * @mode: the permission that the file should have.
361 * @parent: a pointer to the parent dentry for this file. This should be a
362 * directory dentry if set. If this paramater is NULL, then the
363 * file will be created in the root of the debugfs filesystem.
364 * @data: a pointer to something that the caller will want to get to later
365 * on. The inode.i_private pointer will point to this value on
367 * @fops: a pointer to a struct file_operations that should be used for
370 * This is the basic "create a file" function for debugfs. It allows for a
371 * wide range of flexibility in creating a file, or a directory (if you want
372 * to create a directory, the debugfs_create_dir() function is
373 * recommended to be used instead.)
375 * This function will return a pointer to a dentry if it succeeds. This
376 * pointer must be passed to the debugfs_remove() function when the file is
377 * to be removed (no automatic cleanup happens if your module is unloaded,
378 * you are responsible here.) If an error occurs, %NULL will be returned.
380 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
383 struct dentry
*debugfs_create_file(const char *name
, umode_t mode
,
384 struct dentry
*parent
, void *data
,
385 const struct file_operations
*fops
)
387 switch (mode
& S_IFMT
) {
395 return __create_file(name
, mode
, parent
, data
, fops
);
397 EXPORT_SYMBOL_GPL(debugfs_create_file
);
400 * debugfs_create_dir - create a directory in the debugfs filesystem
401 * @name: a pointer to a string containing the name of the directory to
403 * @parent: a pointer to the parent dentry for this file. This should be a
404 * directory dentry if set. If this paramater is NULL, then the
405 * directory will be created in the root of the debugfs filesystem.
407 * This function creates a directory in debugfs with the given name.
409 * This function will return a pointer to a dentry if it succeeds. This
410 * pointer must be passed to the debugfs_remove() function when the file is
411 * to be removed (no automatic cleanup happens if your module is unloaded,
412 * you are responsible here.) If an error occurs, %NULL will be returned.
414 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
417 struct dentry
*debugfs_create_dir(const char *name
, struct dentry
*parent
)
419 return __create_file(name
, S_IFDIR
| S_IRWXU
| S_IRUGO
| S_IXUGO
,
422 EXPORT_SYMBOL_GPL(debugfs_create_dir
);
425 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
426 * @name: a pointer to a string containing the name of the symbolic link to
428 * @parent: a pointer to the parent dentry for this symbolic link. This
429 * should be a directory dentry if set. If this paramater is NULL,
430 * then the symbolic link will be created in the root of the debugfs
432 * @target: a pointer to a string containing the path to the target of the
435 * This function creates a symbolic link with the given name in debugfs that
436 * links to the given target path.
438 * This function will return a pointer to a dentry if it succeeds. This
439 * pointer must be passed to the debugfs_remove() function when the symbolic
440 * link is to be removed (no automatic cleanup happens if your module is
441 * unloaded, you are responsible here.) If an error occurs, %NULL will be
444 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
447 struct dentry
*debugfs_create_symlink(const char *name
, struct dentry
*parent
,
450 struct dentry
*result
;
453 link
= kstrdup(target
, GFP_KERNEL
);
457 result
= __create_file(name
, S_IFLNK
| S_IRWXUGO
, parent
, link
, NULL
);
462 EXPORT_SYMBOL_GPL(debugfs_create_symlink
);
464 static int __debugfs_remove(struct dentry
*dentry
, struct dentry
*parent
)
468 if (debugfs_positive(dentry
)) {
469 if (dentry
->d_inode
) {
471 switch (dentry
->d_inode
->i_mode
& S_IFMT
) {
473 ret
= simple_rmdir(parent
->d_inode
, dentry
);
476 kfree(dentry
->d_inode
->i_private
);
479 simple_unlink(parent
->d_inode
, dentry
);
491 * debugfs_remove - removes a file or directory from the debugfs filesystem
492 * @dentry: a pointer to a the dentry of the file or directory to be
495 * This function removes a file or directory in debugfs that was previously
496 * created with a call to another debugfs function (like
497 * debugfs_create_file() or variants thereof.)
499 * This function is required to be called in order for the file to be
500 * removed, no automatic cleanup of files will happen when a module is
501 * removed, you are responsible here.
503 void debugfs_remove(struct dentry
*dentry
)
505 struct dentry
*parent
;
508 if (IS_ERR_OR_NULL(dentry
))
511 parent
= dentry
->d_parent
;
512 if (!parent
|| !parent
->d_inode
)
515 mutex_lock(&parent
->d_inode
->i_mutex
);
516 ret
= __debugfs_remove(dentry
, parent
);
517 mutex_unlock(&parent
->d_inode
->i_mutex
);
519 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
521 EXPORT_SYMBOL_GPL(debugfs_remove
);
524 * debugfs_remove_recursive - recursively removes a directory
525 * @dentry: a pointer to a the dentry of the directory to be removed.
527 * This function recursively removes a directory tree in debugfs that
528 * was previously created with a call to another debugfs function
529 * (like debugfs_create_file() or variants thereof.)
531 * This function is required to be called in order for the file to be
532 * removed, no automatic cleanup of files will happen when a module is
533 * removed, you are responsible here.
535 void debugfs_remove_recursive(struct dentry
*dentry
)
537 struct dentry
*child
;
538 struct dentry
*parent
;
540 if (IS_ERR_OR_NULL(dentry
))
543 parent
= dentry
->d_parent
;
544 if (!parent
|| !parent
->d_inode
)
548 mutex_lock(&parent
->d_inode
->i_mutex
);
552 * When all dentries under "parent" has been removed,
553 * walk up the tree until we reach our starting point.
555 if (list_empty(&parent
->d_subdirs
)) {
556 mutex_unlock(&parent
->d_inode
->i_mutex
);
557 if (parent
== dentry
)
559 parent
= parent
->d_parent
;
560 mutex_lock(&parent
->d_inode
->i_mutex
);
562 child
= list_entry(parent
->d_subdirs
.next
, struct dentry
,
567 * If "child" isn't empty, walk down the tree and
568 * remove all its descendants first.
570 if (!list_empty(&child
->d_subdirs
)) {
571 mutex_unlock(&parent
->d_inode
->i_mutex
);
573 mutex_lock(&parent
->d_inode
->i_mutex
);
576 __debugfs_remove(child
, parent
);
577 if (parent
->d_subdirs
.next
== &child
->d_u
.d_child
) {
579 * Try the next sibling.
581 if (child
->d_u
.d_child
.next
!= &parent
->d_subdirs
) {
582 child
= list_entry(child
->d_u
.d_child
.next
,
589 * Avoid infinite loop if we fail to remove
592 mutex_unlock(&parent
->d_inode
->i_mutex
);
595 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
598 parent
= dentry
->d_parent
;
599 mutex_lock(&parent
->d_inode
->i_mutex
);
600 __debugfs_remove(dentry
, parent
);
601 mutex_unlock(&parent
->d_inode
->i_mutex
);
602 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
604 EXPORT_SYMBOL_GPL(debugfs_remove_recursive
);
607 * debugfs_rename - rename a file/directory in the debugfs filesystem
608 * @old_dir: a pointer to the parent dentry for the renamed object. This
609 * should be a directory dentry.
610 * @old_dentry: dentry of an object to be renamed.
611 * @new_dir: a pointer to the parent dentry where the object should be
612 * moved. This should be a directory dentry.
613 * @new_name: a pointer to a string containing the target name.
615 * This function renames a file/directory in debugfs. The target must not
616 * exist for rename to succeed.
618 * This function will return a pointer to old_dentry (which is updated to
619 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
622 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
625 struct dentry
*debugfs_rename(struct dentry
*old_dir
, struct dentry
*old_dentry
,
626 struct dentry
*new_dir
, const char *new_name
)
629 struct dentry
*dentry
= NULL
, *trap
;
630 const char *old_name
;
632 trap
= lock_rename(new_dir
, old_dir
);
633 /* Source or destination directories don't exist? */
634 if (!old_dir
->d_inode
|| !new_dir
->d_inode
)
636 /* Source does not exist, cyclic rename, or mountpoint? */
637 if (!old_dentry
->d_inode
|| old_dentry
== trap
||
638 d_mountpoint(old_dentry
))
640 dentry
= lookup_one_len(new_name
, new_dir
, strlen(new_name
));
641 /* Lookup failed, cyclic rename or target exists? */
642 if (IS_ERR(dentry
) || dentry
== trap
|| dentry
->d_inode
)
645 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
647 error
= simple_rename(old_dir
->d_inode
, old_dentry
, new_dir
->d_inode
,
650 fsnotify_oldname_free(old_name
);
653 d_move(old_dentry
, dentry
);
654 fsnotify_move(old_dir
->d_inode
, new_dir
->d_inode
, old_name
,
655 S_ISDIR(old_dentry
->d_inode
->i_mode
),
657 fsnotify_oldname_free(old_name
);
658 unlock_rename(new_dir
, old_dir
);
662 if (dentry
&& !IS_ERR(dentry
))
664 unlock_rename(new_dir
, old_dir
);
667 EXPORT_SYMBOL_GPL(debugfs_rename
);
670 * debugfs_initialized - Tells whether debugfs has been registered
672 bool debugfs_initialized(void)
674 return debugfs_registered
;
676 EXPORT_SYMBOL_GPL(debugfs_initialized
);
679 static struct kobject
*debug_kobj
;
681 static int __init
debugfs_init(void)
685 debug_kobj
= kobject_create_and_add("debug", kernel_kobj
);
689 retval
= register_filesystem(&debug_fs_type
);
691 kobject_put(debug_kobj
);
693 debugfs_registered
= true;
697 core_initcall(debugfs_init
);