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
;
63 /* directory inodes start off with i_nlink == 2
73 static int debugfs_mknod(struct dentry
*dentry
,
74 umode_t mode
, void *data
,
75 const struct file_operations
*fops
)
79 inode
= debugfs_get_inode(dentry
->d_sb
, mode
, 0, data
, fops
);
82 d_instantiate(dentry
, inode
);
87 static int debugfs_mkdir(struct dentry
*dentry
, umode_t mode
)
89 struct inode
*dir
= dentry
->d_parent
->d_inode
;
92 mode
= (mode
& (S_IRWXUGO
| S_ISVTX
)) | S_IFDIR
;
93 res
= debugfs_mknod(dentry
, mode
, NULL
, NULL
);
96 fsnotify_mkdir(dir
, dentry
);
101 static int debugfs_create(struct dentry
*dentry
, umode_t mode
,
102 void *data
, const struct file_operations
*fops
)
104 struct inode
*dir
= dentry
->d_parent
->d_inode
;
107 mode
= (mode
& S_IALLUGO
) | S_IFREG
;
108 res
= debugfs_mknod(dentry
, mode
, data
, fops
);
110 fsnotify_create(dir
, dentry
);
114 static inline int debugfs_positive(struct dentry
*dentry
)
116 return dentry
->d_inode
&& !d_unhashed(dentry
);
119 struct debugfs_mount_opts
{
132 static const match_table_t tokens
= {
135 {Opt_mode
, "mode=%o"},
139 struct debugfs_fs_info
{
140 struct debugfs_mount_opts mount_opts
;
143 static int debugfs_parse_options(char *data
, struct debugfs_mount_opts
*opts
)
145 substring_t args
[MAX_OPT_ARGS
];
152 opts
->mode
= DEBUGFS_DEFAULT_MODE
;
154 while ((p
= strsep(&data
, ",")) != NULL
) {
158 token
= match_token(p
, tokens
, args
);
161 if (match_int(&args
[0], &option
))
163 uid
= make_kuid(current_user_ns(), option
);
169 if (match_int(&args
[0], &option
))
171 gid
= make_kgid(current_user_ns(), option
);
177 if (match_octal(&args
[0], &option
))
179 opts
->mode
= option
& S_IALLUGO
;
182 * We might like to report bad mount options here;
183 * but traditionally debugfs has ignored all mount options
191 static int debugfs_apply_options(struct super_block
*sb
)
193 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
194 struct inode
*inode
= sb
->s_root
->d_inode
;
195 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
197 inode
->i_mode
&= ~S_IALLUGO
;
198 inode
->i_mode
|= opts
->mode
;
200 inode
->i_uid
= opts
->uid
;
201 inode
->i_gid
= opts
->gid
;
206 static int debugfs_remount(struct super_block
*sb
, int *flags
, char *data
)
209 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
212 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
216 debugfs_apply_options(sb
);
222 static int debugfs_show_options(struct seq_file
*m
, struct dentry
*root
)
224 struct debugfs_fs_info
*fsi
= root
->d_sb
->s_fs_info
;
225 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
227 if (!uid_eq(opts
->uid
, GLOBAL_ROOT_UID
))
228 seq_printf(m
, ",uid=%u",
229 from_kuid_munged(&init_user_ns
, opts
->uid
));
230 if (!gid_eq(opts
->gid
, GLOBAL_ROOT_GID
))
231 seq_printf(m
, ",gid=%u",
232 from_kgid_munged(&init_user_ns
, 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
,
293 MODULE_ALIAS_FS("debugfs");
295 static struct dentry
*start_creating(const char *name
, struct dentry
*parent
)
297 struct dentry
*dentry
;
300 pr_debug("debugfs: creating file '%s'\n",name
);
302 error
= simple_pin_fs(&debug_fs_type
, &debugfs_mount
,
303 &debugfs_mount_count
);
305 return ERR_PTR(error
);
307 /* If the parent is not specified, we create it in the root.
308 * We need the root dentry to do this, which is in the super
309 * block. A pointer to that is in the struct vfsmount that we
313 parent
= debugfs_mount
->mnt_root
;
315 mutex_lock(&parent
->d_inode
->i_mutex
);
316 dentry
= lookup_one_len(name
, parent
, strlen(name
));
317 if (!IS_ERR(dentry
) && dentry
->d_inode
) {
319 dentry
= ERR_PTR(-EEXIST
);
322 mutex_unlock(&parent
->d_inode
->i_mutex
);
326 static struct dentry
*end_creating(struct dentry
*dentry
, int error
)
328 mutex_unlock(&dentry
->d_parent
->d_inode
->i_mutex
);
333 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
339 * debugfs_create_file - create a file in the debugfs filesystem
340 * @name: a pointer to a string containing the name of the file to create.
341 * @mode: the permission that the file should have.
342 * @parent: a pointer to the parent dentry for this file. This should be a
343 * directory dentry if set. If this parameter is NULL, then the
344 * file will be created in the root of the debugfs filesystem.
345 * @data: a pointer to something that the caller will want to get to later
346 * on. The inode.i_private pointer will point to this value on
348 * @fops: a pointer to a struct file_operations that should be used for
351 * This is the basic "create a file" function for debugfs. It allows for a
352 * wide range of flexibility in creating a file, or a directory (if you want
353 * to create a directory, the debugfs_create_dir() function is
354 * recommended to be used instead.)
356 * This function will return a pointer to a dentry if it succeeds. This
357 * pointer must be passed to the debugfs_remove() function when the file is
358 * to be removed (no automatic cleanup happens if your module is unloaded,
359 * you are responsible here.) If an error occurs, %NULL will be returned.
361 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
364 struct dentry
*debugfs_create_file(const char *name
, umode_t mode
,
365 struct dentry
*parent
, void *data
,
366 const struct file_operations
*fops
)
368 struct dentry
*dentry
;
371 if (!(mode
& S_IFMT
))
373 BUG_ON(!S_ISREG(mode
));
374 dentry
= start_creating(name
, parent
);
379 error
= debugfs_create(dentry
, mode
, data
, fops
);
380 return end_creating(dentry
, error
);
382 EXPORT_SYMBOL_GPL(debugfs_create_file
);
385 * debugfs_create_dir - create a directory in the debugfs filesystem
386 * @name: a pointer to a string containing the name of the directory to
388 * @parent: a pointer to the parent dentry for this file. This should be a
389 * directory dentry if set. If this parameter is NULL, then the
390 * directory will be created in the root of the debugfs filesystem.
392 * This function creates a directory in debugfs with the given name.
394 * This function will return a pointer to a dentry if it succeeds. This
395 * pointer must be passed to the debugfs_remove() function when the file is
396 * to be removed (no automatic cleanup happens if your module is unloaded,
397 * you are responsible here.) If an error occurs, %NULL will be returned.
399 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
402 struct dentry
*debugfs_create_dir(const char *name
, struct dentry
*parent
)
404 struct dentry
*dentry
= start_creating(name
, parent
);
410 error
= debugfs_mkdir(dentry
, S_IFDIR
| S_IRWXU
| S_IRUGO
| S_IXUGO
);
411 return end_creating(dentry
, error
);
413 EXPORT_SYMBOL_GPL(debugfs_create_dir
);
416 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
417 * @name: a pointer to a string containing the name of the symbolic link to
419 * @parent: a pointer to the parent dentry for this symbolic link. This
420 * should be a directory dentry if set. If this parameter is NULL,
421 * then the symbolic link will be created in the root of the debugfs
423 * @target: a pointer to a string containing the path to the target of the
426 * This function creates a symbolic link with the given name in debugfs that
427 * links to the given target path.
429 * This function will return a pointer to a dentry if it succeeds. This
430 * pointer must be passed to the debugfs_remove() function when the symbolic
431 * link is to be removed (no automatic cleanup happens if your module is
432 * unloaded, you are responsible here.) If an error occurs, %NULL will be
435 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
438 struct dentry
*debugfs_create_symlink(const char *name
, struct dentry
*parent
,
441 struct dentry
*dentry
;
445 link
= kstrdup(target
, GFP_KERNEL
);
449 dentry
= start_creating(name
, parent
);
451 if (IS_ERR(dentry
)) {
456 error
= debugfs_mknod(dentry
, S_IFLNK
| S_IRWXUGO
, link
, NULL
);
460 return end_creating(dentry
, error
);
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
, *parent
;
539 if (IS_ERR_OR_NULL(dentry
))
542 parent
= dentry
->d_parent
;
543 if (!parent
|| !parent
->d_inode
)
548 mutex_lock(&parent
->d_inode
->i_mutex
);
551 * The parent->d_subdirs is protected by the d_lock. Outside that
552 * lock, the child can be unlinked and set to be freed which can
553 * use the d_u.d_child as the rcu head and corrupt this list.
555 spin_lock(&parent
->d_lock
);
556 list_for_each_entry(child
, &parent
->d_subdirs
, d_child
) {
557 if (!debugfs_positive(child
))
560 /* perhaps simple_empty(child) makes more sense */
561 if (!list_empty(&child
->d_subdirs
)) {
562 spin_unlock(&parent
->d_lock
);
563 mutex_unlock(&parent
->d_inode
->i_mutex
);
568 spin_unlock(&parent
->d_lock
);
570 if (!__debugfs_remove(child
, parent
))
571 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
574 * The parent->d_lock protects agaist child from unlinking
575 * from d_subdirs. When releasing the parent->d_lock we can
576 * no longer trust that the next pointer is valid.
577 * Restart the loop. We'll skip this one with the
578 * debugfs_positive() check.
582 spin_unlock(&parent
->d_lock
);
584 mutex_unlock(&parent
->d_inode
->i_mutex
);
586 parent
= parent
->d_parent
;
587 mutex_lock(&parent
->d_inode
->i_mutex
);
593 if (!__debugfs_remove(child
, parent
))
594 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
595 mutex_unlock(&parent
->d_inode
->i_mutex
);
597 EXPORT_SYMBOL_GPL(debugfs_remove_recursive
);
600 * debugfs_rename - rename a file/directory in the debugfs filesystem
601 * @old_dir: a pointer to the parent dentry for the renamed object. This
602 * should be a directory dentry.
603 * @old_dentry: dentry of an object to be renamed.
604 * @new_dir: a pointer to the parent dentry where the object should be
605 * moved. This should be a directory dentry.
606 * @new_name: a pointer to a string containing the target name.
608 * This function renames a file/directory in debugfs. The target must not
609 * exist for rename to succeed.
611 * This function will return a pointer to old_dentry (which is updated to
612 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
615 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
618 struct dentry
*debugfs_rename(struct dentry
*old_dir
, struct dentry
*old_dentry
,
619 struct dentry
*new_dir
, const char *new_name
)
622 struct dentry
*dentry
= NULL
, *trap
;
623 const char *old_name
;
625 trap
= lock_rename(new_dir
, old_dir
);
626 /* Source or destination directories don't exist? */
627 if (!old_dir
->d_inode
|| !new_dir
->d_inode
)
629 /* Source does not exist, cyclic rename, or mountpoint? */
630 if (!old_dentry
->d_inode
|| old_dentry
== trap
||
631 d_mountpoint(old_dentry
))
633 dentry
= lookup_one_len(new_name
, new_dir
, strlen(new_name
));
634 /* Lookup failed, cyclic rename or target exists? */
635 if (IS_ERR(dentry
) || dentry
== trap
|| dentry
->d_inode
)
638 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
640 error
= simple_rename(old_dir
->d_inode
, old_dentry
, new_dir
->d_inode
,
643 fsnotify_oldname_free(old_name
);
646 d_move(old_dentry
, dentry
);
647 fsnotify_move(old_dir
->d_inode
, new_dir
->d_inode
, old_name
,
648 S_ISDIR(old_dentry
->d_inode
->i_mode
),
650 fsnotify_oldname_free(old_name
);
651 unlock_rename(new_dir
, old_dir
);
655 if (dentry
&& !IS_ERR(dentry
))
657 unlock_rename(new_dir
, old_dir
);
660 EXPORT_SYMBOL_GPL(debugfs_rename
);
663 * debugfs_initialized - Tells whether debugfs has been registered
665 bool debugfs_initialized(void)
667 return debugfs_registered
;
669 EXPORT_SYMBOL_GPL(debugfs_initialized
);
672 static struct kobject
*debug_kobj
;
674 static int __init
debugfs_init(void)
678 debug_kobj
= kobject_create_and_add("debug", kernel_kobj
);
682 retval
= register_filesystem(&debug_fs_type
);
684 kobject_put(debug_kobj
);
686 debugfs_registered
= true;
690 core_initcall(debugfs_init
);