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>
30 #include <linux/srcu.h>
34 #define DEBUGFS_DEFAULT_MODE 0700
36 DEFINE_SRCU(debugfs_srcu
);
38 static struct vfsmount
*debugfs_mount
;
39 static int debugfs_mount_count
;
40 static bool debugfs_registered
;
42 static struct inode
*debugfs_get_inode(struct super_block
*sb
)
44 struct inode
*inode
= new_inode(sb
);
46 inode
->i_ino
= get_next_ino();
47 inode
->i_atime
= inode
->i_mtime
=
48 inode
->i_ctime
= current_fs_time(sb
);
53 struct debugfs_mount_opts
{
66 static const match_table_t tokens
= {
69 {Opt_mode
, "mode=%o"},
73 struct debugfs_fs_info
{
74 struct debugfs_mount_opts mount_opts
;
77 static int debugfs_parse_options(char *data
, struct debugfs_mount_opts
*opts
)
79 substring_t args
[MAX_OPT_ARGS
];
86 opts
->mode
= DEBUGFS_DEFAULT_MODE
;
88 while ((p
= strsep(&data
, ",")) != NULL
) {
92 token
= match_token(p
, tokens
, args
);
95 if (match_int(&args
[0], &option
))
97 uid
= make_kuid(current_user_ns(), option
);
103 if (match_int(&args
[0], &option
))
105 gid
= make_kgid(current_user_ns(), option
);
111 if (match_octal(&args
[0], &option
))
113 opts
->mode
= option
& S_IALLUGO
;
116 * We might like to report bad mount options here;
117 * but traditionally debugfs has ignored all mount options
125 static int debugfs_apply_options(struct super_block
*sb
)
127 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
128 struct inode
*inode
= d_inode(sb
->s_root
);
129 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
131 inode
->i_mode
&= ~S_IALLUGO
;
132 inode
->i_mode
|= opts
->mode
;
134 inode
->i_uid
= opts
->uid
;
135 inode
->i_gid
= opts
->gid
;
140 static int debugfs_remount(struct super_block
*sb
, int *flags
, char *data
)
143 struct debugfs_fs_info
*fsi
= sb
->s_fs_info
;
146 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
150 debugfs_apply_options(sb
);
156 static int debugfs_show_options(struct seq_file
*m
, struct dentry
*root
)
158 struct debugfs_fs_info
*fsi
= root
->d_sb
->s_fs_info
;
159 struct debugfs_mount_opts
*opts
= &fsi
->mount_opts
;
161 if (!uid_eq(opts
->uid
, GLOBAL_ROOT_UID
))
162 seq_printf(m
, ",uid=%u",
163 from_kuid_munged(&init_user_ns
, opts
->uid
));
164 if (!gid_eq(opts
->gid
, GLOBAL_ROOT_GID
))
165 seq_printf(m
, ",gid=%u",
166 from_kgid_munged(&init_user_ns
, opts
->gid
));
167 if (opts
->mode
!= DEBUGFS_DEFAULT_MODE
)
168 seq_printf(m
, ",mode=%o", opts
->mode
);
173 static void debugfs_evict_inode(struct inode
*inode
)
175 truncate_inode_pages_final(&inode
->i_data
);
177 if (S_ISLNK(inode
->i_mode
))
178 kfree(inode
->i_link
);
181 static const struct super_operations debugfs_super_operations
= {
182 .statfs
= simple_statfs
,
183 .remount_fs
= debugfs_remount
,
184 .show_options
= debugfs_show_options
,
185 .evict_inode
= debugfs_evict_inode
,
188 static struct vfsmount
*debugfs_automount(struct path
*path
)
190 struct vfsmount
*(*f
)(void *);
191 f
= (struct vfsmount
*(*)(void *))path
->dentry
->d_fsdata
;
192 return f(d_inode(path
->dentry
)->i_private
);
195 static const struct dentry_operations debugfs_dops
= {
196 .d_delete
= always_delete_dentry
,
197 .d_automount
= debugfs_automount
,
200 static int debug_fill_super(struct super_block
*sb
, void *data
, int silent
)
202 static struct tree_descr debug_files
[] = {{""}};
203 struct debugfs_fs_info
*fsi
;
206 save_mount_options(sb
, data
);
208 fsi
= kzalloc(sizeof(struct debugfs_fs_info
), GFP_KERNEL
);
215 err
= debugfs_parse_options(data
, &fsi
->mount_opts
);
219 err
= simple_fill_super(sb
, DEBUGFS_MAGIC
, debug_files
);
223 sb
->s_op
= &debugfs_super_operations
;
224 sb
->s_d_op
= &debugfs_dops
;
226 debugfs_apply_options(sb
);
232 sb
->s_fs_info
= NULL
;
236 static struct dentry
*debug_mount(struct file_system_type
*fs_type
,
237 int flags
, const char *dev_name
,
240 return mount_single(fs_type
, flags
, data
, debug_fill_super
);
243 static struct file_system_type debug_fs_type
= {
244 .owner
= THIS_MODULE
,
246 .mount
= debug_mount
,
247 .kill_sb
= kill_litter_super
,
249 MODULE_ALIAS_FS("debugfs");
251 static struct dentry
*start_creating(const char *name
, struct dentry
*parent
)
253 struct dentry
*dentry
;
256 pr_debug("debugfs: creating file '%s'\n",name
);
261 error
= simple_pin_fs(&debug_fs_type
, &debugfs_mount
,
262 &debugfs_mount_count
);
264 return ERR_PTR(error
);
266 /* If the parent is not specified, we create it in the root.
267 * We need the root dentry to do this, which is in the super
268 * block. A pointer to that is in the struct vfsmount that we
272 parent
= debugfs_mount
->mnt_root
;
274 inode_lock(d_inode(parent
));
275 dentry
= lookup_one_len(name
, parent
, strlen(name
));
276 if (!IS_ERR(dentry
) && d_really_is_positive(dentry
)) {
278 dentry
= ERR_PTR(-EEXIST
);
281 if (IS_ERR(dentry
)) {
282 inode_unlock(d_inode(parent
));
283 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
289 static struct dentry
*failed_creating(struct dentry
*dentry
)
291 inode_unlock(d_inode(dentry
->d_parent
));
293 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
297 static struct dentry
*end_creating(struct dentry
*dentry
)
299 inode_unlock(d_inode(dentry
->d_parent
));
303 static struct dentry
*__debugfs_create_file(const char *name
, umode_t mode
,
304 struct dentry
*parent
, void *data
,
305 const struct file_operations
*proxy_fops
,
306 const struct file_operations
*real_fops
)
308 struct dentry
*dentry
;
311 if (!(mode
& S_IFMT
))
313 BUG_ON(!S_ISREG(mode
));
314 dentry
= start_creating(name
, parent
);
319 inode
= debugfs_get_inode(dentry
->d_sb
);
320 if (unlikely(!inode
))
321 return failed_creating(dentry
);
323 inode
->i_mode
= mode
;
324 inode
->i_private
= data
;
326 inode
->i_fop
= proxy_fops
;
327 dentry
->d_fsdata
= (void *)real_fops
;
329 d_instantiate(dentry
, inode
);
330 fsnotify_create(d_inode(dentry
->d_parent
), dentry
);
331 return end_creating(dentry
);
335 * debugfs_create_file - create a file in the debugfs filesystem
336 * @name: a pointer to a string containing the name of the file to create.
337 * @mode: the permission that the file should have.
338 * @parent: a pointer to the parent dentry for this file. This should be a
339 * directory dentry if set. If this parameter is NULL, then the
340 * file will be created in the root of the debugfs filesystem.
341 * @data: a pointer to something that the caller will want to get to later
342 * on. The inode.i_private pointer will point to this value on
344 * @fops: a pointer to a struct file_operations that should be used for
347 * This is the basic "create a file" function for debugfs. It allows for a
348 * wide range of flexibility in creating a file, or a directory (if you want
349 * to create a directory, the debugfs_create_dir() function is
350 * recommended to be used instead.)
352 * This function will return a pointer to a dentry if it succeeds. This
353 * pointer must be passed to the debugfs_remove() function when the file is
354 * to be removed (no automatic cleanup happens if your module is unloaded,
355 * you are responsible here.) If an error occurs, %NULL will be returned.
357 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
360 struct dentry
*debugfs_create_file(const char *name
, umode_t mode
,
361 struct dentry
*parent
, void *data
,
362 const struct file_operations
*fops
)
365 return __debugfs_create_file(name
, mode
, parent
, data
,
366 fops
? &debugfs_full_proxy_file_operations
:
367 &debugfs_noop_file_operations
,
370 EXPORT_SYMBOL_GPL(debugfs_create_file
);
372 struct dentry
*debugfs_create_file_unsafe(const char *name
, umode_t mode
,
373 struct dentry
*parent
, void *data
,
374 const struct file_operations
*fops
)
377 return __debugfs_create_file(name
, mode
, parent
, data
,
378 fops
? &debugfs_open_proxy_file_operations
:
379 &debugfs_noop_file_operations
,
384 * debugfs_create_file_size - create a file in the debugfs filesystem
385 * @name: a pointer to a string containing the name of the file to create.
386 * @mode: the permission that the file should have.
387 * @parent: a pointer to the parent dentry for this file. This should be a
388 * directory dentry if set. If this parameter is NULL, then the
389 * file will be created in the root of the debugfs filesystem.
390 * @data: a pointer to something that the caller will want to get to later
391 * on. The inode.i_private pointer will point to this value on
393 * @fops: a pointer to a struct file_operations that should be used for
395 * @file_size: initial file size
397 * This is the basic "create a file" function for debugfs. It allows for a
398 * wide range of flexibility in creating a file, or a directory (if you want
399 * to create a directory, the debugfs_create_dir() function is
400 * recommended to be used instead.)
402 * This function will return a pointer to a dentry if it succeeds. This
403 * pointer must be passed to the debugfs_remove() function when the file is
404 * to be removed (no automatic cleanup happens if your module is unloaded,
405 * you are responsible here.) If an error occurs, %NULL will be returned.
407 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
410 struct dentry
*debugfs_create_file_size(const char *name
, umode_t mode
,
411 struct dentry
*parent
, void *data
,
412 const struct file_operations
*fops
,
415 struct dentry
*de
= debugfs_create_file(name
, mode
, parent
, data
, fops
);
418 d_inode(de
)->i_size
= file_size
;
421 EXPORT_SYMBOL_GPL(debugfs_create_file_size
);
424 * debugfs_create_dir - create a directory in the debugfs filesystem
425 * @name: a pointer to a string containing the name of the directory to
427 * @parent: a pointer to the parent dentry for this file. This should be a
428 * directory dentry if set. If this parameter is NULL, then the
429 * directory will be created in the root of the debugfs filesystem.
431 * This function creates a directory in debugfs with the given name.
433 * This function will return a pointer to a dentry if it succeeds. This
434 * pointer must be passed to the debugfs_remove() function when the file is
435 * to be removed (no automatic cleanup happens if your module is unloaded,
436 * you are responsible here.) If an error occurs, %NULL will be returned.
438 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
441 struct dentry
*debugfs_create_dir(const char *name
, struct dentry
*parent
)
443 struct dentry
*dentry
= start_creating(name
, parent
);
449 inode
= debugfs_get_inode(dentry
->d_sb
);
450 if (unlikely(!inode
))
451 return failed_creating(dentry
);
453 inode
->i_mode
= S_IFDIR
| S_IRWXU
| S_IRUGO
| S_IXUGO
;
454 inode
->i_op
= &simple_dir_inode_operations
;
455 inode
->i_fop
= &simple_dir_operations
;
457 /* directory inodes start off with i_nlink == 2 (for "." entry) */
459 d_instantiate(dentry
, inode
);
460 inc_nlink(d_inode(dentry
->d_parent
));
461 fsnotify_mkdir(d_inode(dentry
->d_parent
), dentry
);
462 return end_creating(dentry
);
464 EXPORT_SYMBOL_GPL(debugfs_create_dir
);
467 * debugfs_create_automount - create automount point in the debugfs filesystem
468 * @name: a pointer to a string containing the name of the file to create.
469 * @parent: a pointer to the parent dentry for this file. This should be a
470 * directory dentry if set. If this parameter is NULL, then the
471 * file will be created in the root of the debugfs filesystem.
472 * @f: function to be called when pathname resolution steps on that one.
473 * @data: opaque argument to pass to f().
475 * @f should return what ->d_automount() would.
477 struct dentry
*debugfs_create_automount(const char *name
,
478 struct dentry
*parent
,
479 struct vfsmount
*(*f
)(void *),
482 struct dentry
*dentry
= start_creating(name
, parent
);
488 inode
= debugfs_get_inode(dentry
->d_sb
);
489 if (unlikely(!inode
))
490 return failed_creating(dentry
);
492 inode
->i_mode
= S_IFDIR
| S_IRWXU
| S_IRUGO
| S_IXUGO
;
493 inode
->i_flags
|= S_AUTOMOUNT
;
494 inode
->i_private
= data
;
495 dentry
->d_fsdata
= (void *)f
;
496 /* directory inodes start off with i_nlink == 2 (for "." entry) */
498 d_instantiate(dentry
, inode
);
499 inc_nlink(d_inode(dentry
->d_parent
));
500 fsnotify_mkdir(d_inode(dentry
->d_parent
), dentry
);
501 return end_creating(dentry
);
503 EXPORT_SYMBOL(debugfs_create_automount
);
506 * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
507 * @name: a pointer to a string containing the name of the symbolic link to
509 * @parent: a pointer to the parent dentry for this symbolic link. This
510 * should be a directory dentry if set. If this parameter is NULL,
511 * then the symbolic link will be created in the root of the debugfs
513 * @target: a pointer to a string containing the path to the target of the
516 * This function creates a symbolic link with the given name in debugfs that
517 * links to the given target path.
519 * This function will return a pointer to a dentry if it succeeds. This
520 * pointer must be passed to the debugfs_remove() function when the symbolic
521 * link is to be removed (no automatic cleanup happens if your module is
522 * unloaded, you are responsible here.) If an error occurs, %NULL will be
525 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
528 struct dentry
*debugfs_create_symlink(const char *name
, struct dentry
*parent
,
531 struct dentry
*dentry
;
533 char *link
= kstrdup(target
, GFP_KERNEL
);
537 dentry
= start_creating(name
, parent
);
538 if (IS_ERR(dentry
)) {
543 inode
= debugfs_get_inode(dentry
->d_sb
);
544 if (unlikely(!inode
)) {
546 return failed_creating(dentry
);
548 inode
->i_mode
= S_IFLNK
| S_IRWXUGO
;
549 inode
->i_op
= &simple_symlink_inode_operations
;
550 inode
->i_link
= link
;
551 d_instantiate(dentry
, inode
);
552 return end_creating(dentry
);
554 EXPORT_SYMBOL_GPL(debugfs_create_symlink
);
556 static int __debugfs_remove(struct dentry
*dentry
, struct dentry
*parent
)
560 if (simple_positive(dentry
)) {
562 if (d_is_dir(dentry
))
563 ret
= simple_rmdir(d_inode(parent
), dentry
);
565 simple_unlink(d_inode(parent
), dentry
);
574 * debugfs_remove - removes a file or directory from the debugfs filesystem
575 * @dentry: a pointer to a the dentry of the file or directory to be
576 * removed. If this parameter is NULL or an error value, nothing
579 * This function removes a file or directory in debugfs that was previously
580 * created with a call to another debugfs function (like
581 * debugfs_create_file() or variants thereof.)
583 * This function is required to be called in order for the file to be
584 * removed, no automatic cleanup of files will happen when a module is
585 * removed, you are responsible here.
587 void debugfs_remove(struct dentry
*dentry
)
589 struct dentry
*parent
;
592 if (IS_ERR_OR_NULL(dentry
))
595 parent
= dentry
->d_parent
;
596 if (!parent
|| d_really_is_negative(parent
))
599 inode_lock(d_inode(parent
));
600 ret
= __debugfs_remove(dentry
, parent
);
601 inode_unlock(d_inode(parent
));
603 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
605 synchronize_srcu(&debugfs_srcu
);
607 EXPORT_SYMBOL_GPL(debugfs_remove
);
610 * debugfs_remove_recursive - recursively removes a directory
611 * @dentry: a pointer to a the dentry of the directory to be removed. If this
612 * parameter is NULL or an error value, nothing will be done.
614 * This function recursively removes a directory tree in debugfs that
615 * was previously created with a call to another debugfs function
616 * (like debugfs_create_file() or variants thereof.)
618 * This function is required to be called in order for the file to be
619 * removed, no automatic cleanup of files will happen when a module is
620 * removed, you are responsible here.
622 void debugfs_remove_recursive(struct dentry
*dentry
)
624 struct dentry
*child
, *parent
;
626 if (IS_ERR_OR_NULL(dentry
))
629 parent
= dentry
->d_parent
;
630 if (!parent
|| d_really_is_negative(parent
))
635 inode_lock(d_inode(parent
));
638 * The parent->d_subdirs is protected by the d_lock. Outside that
639 * lock, the child can be unlinked and set to be freed which can
640 * use the d_u.d_child as the rcu head and corrupt this list.
642 spin_lock(&parent
->d_lock
);
643 list_for_each_entry(child
, &parent
->d_subdirs
, d_child
) {
644 if (!simple_positive(child
))
647 /* perhaps simple_empty(child) makes more sense */
648 if (!list_empty(&child
->d_subdirs
)) {
649 spin_unlock(&parent
->d_lock
);
650 inode_unlock(d_inode(parent
));
655 spin_unlock(&parent
->d_lock
);
657 if (!__debugfs_remove(child
, parent
))
658 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
661 * The parent->d_lock protects agaist child from unlinking
662 * from d_subdirs. When releasing the parent->d_lock we can
663 * no longer trust that the next pointer is valid.
664 * Restart the loop. We'll skip this one with the
665 * simple_positive() check.
669 spin_unlock(&parent
->d_lock
);
671 inode_unlock(d_inode(parent
));
673 parent
= parent
->d_parent
;
674 inode_lock(d_inode(parent
));
680 if (!__debugfs_remove(child
, parent
))
681 simple_release_fs(&debugfs_mount
, &debugfs_mount_count
);
682 inode_unlock(d_inode(parent
));
684 synchronize_srcu(&debugfs_srcu
);
686 EXPORT_SYMBOL_GPL(debugfs_remove_recursive
);
689 * debugfs_rename - rename a file/directory in the debugfs filesystem
690 * @old_dir: a pointer to the parent dentry for the renamed object. This
691 * should be a directory dentry.
692 * @old_dentry: dentry of an object to be renamed.
693 * @new_dir: a pointer to the parent dentry where the object should be
694 * moved. This should be a directory dentry.
695 * @new_name: a pointer to a string containing the target name.
697 * This function renames a file/directory in debugfs. The target must not
698 * exist for rename to succeed.
700 * This function will return a pointer to old_dentry (which is updated to
701 * reflect renaming) if it succeeds. If an error occurs, %NULL will be
704 * If debugfs is not enabled in the kernel, the value -%ENODEV will be
707 struct dentry
*debugfs_rename(struct dentry
*old_dir
, struct dentry
*old_dentry
,
708 struct dentry
*new_dir
, const char *new_name
)
711 struct dentry
*dentry
= NULL
, *trap
;
712 const char *old_name
;
714 trap
= lock_rename(new_dir
, old_dir
);
715 /* Source or destination directories don't exist? */
716 if (d_really_is_negative(old_dir
) || d_really_is_negative(new_dir
))
718 /* Source does not exist, cyclic rename, or mountpoint? */
719 if (d_really_is_negative(old_dentry
) || old_dentry
== trap
||
720 d_mountpoint(old_dentry
))
722 dentry
= lookup_one_len(new_name
, new_dir
, strlen(new_name
));
723 /* Lookup failed, cyclic rename or target exists? */
724 if (IS_ERR(dentry
) || dentry
== trap
|| d_really_is_positive(dentry
))
727 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
729 error
= simple_rename(d_inode(old_dir
), old_dentry
, d_inode(new_dir
),
732 fsnotify_oldname_free(old_name
);
735 d_move(old_dentry
, dentry
);
736 fsnotify_move(d_inode(old_dir
), d_inode(new_dir
), old_name
,
737 d_is_dir(old_dentry
),
739 fsnotify_oldname_free(old_name
);
740 unlock_rename(new_dir
, old_dir
);
744 if (dentry
&& !IS_ERR(dentry
))
746 unlock_rename(new_dir
, old_dir
);
749 EXPORT_SYMBOL_GPL(debugfs_rename
);
752 * debugfs_initialized - Tells whether debugfs has been registered
754 bool debugfs_initialized(void)
756 return debugfs_registered
;
758 EXPORT_SYMBOL_GPL(debugfs_initialized
);
760 static int __init
debugfs_init(void)
764 retval
= sysfs_create_mount_point(kernel_kobj
, "debug");
768 retval
= register_filesystem(&debug_fs_type
);
770 sysfs_remove_mount_point(kernel_kobj
, "debug");
772 debugfs_registered
= true;
776 core_initcall(debugfs_init
);