- 根目录:
- fs
- debugfs
- inode.c
/*
* inode.c - part of debugfs, a tiny little debug file system
*
* Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
* Copyright (C) 2004 IBM Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* debugfs is for people to use instead of /proc or /sys.
* See Documentation/DocBook/kernel-api for more details.
*
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/kobject.h>
#include <linux/namei.h>
#include <linux/debugfs.h>
#include <linux/fsnotify.h>
#include <linux/string.h>
#include <linux/seq_file.h>
#include <linux/parser.h>
#include <linux/magic.h>
#include <linux/slab.h>
#define DEBUGFS_DEFAULT_MODE 0700
static struct vfsmount *debugfs_mount;
static int debugfs_mount_count;
static bool debugfs_registered;
static struct inode *debugfs_get_inode(struct super_block *sb, umode_t mode, dev_t dev,
void *data, const struct file_operations *fops)
{
struct inode *inode = new_inode(sb);
if (inode) {
inode->i_ino = get_next_ino();
inode->i_mode = mode;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
switch (mode & S_IFMT) {
default:
init_special_inode(inode, mode, dev);
break;
case S_IFREG:
inode->i_fop = fops ? fops : &debugfs_file_operations;
inode->i_private = data;
break;
case S_IFLNK:
inode->i_op = &debugfs_link_operations;
inode->i_private = data;
break;
case S_IFDIR:
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
/* directory inodes start off with i_nlink == 2
* (for "." entry) */
inc_nlink(inode);
break;
}
}
return inode;
}
/* SMP-safe */
static int debugfs_mknod(struct inode *dir, struct dentry *dentry,
umode_t mode, dev_t dev, void *data,
const struct file_operations *fops)
{
struct inode *inode;
int error = -EPERM;
if (dentry->d_inode)
return -EEXIST;
inode = debugfs_get_inode(dir->i_sb, mode, dev, data, fops);
if (inode) {
d_instantiate(dentry, inode);
dget(dentry);
error = 0;
}
return error;
}
static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
int res;
mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
res = debugfs_mknod(dir, dentry, mode, 0, NULL, NULL);
if (!res) {
inc_nlink(dir);
fsnotify_mkdir(dir, dentry);
}
return res;
}
static int debugfs_link(struct inode *dir, struct dentry *dentry, umode_t mode,
void *data)
{
mode = (mode & S_IALLUGO) | S_IFLNK;
return debugfs_mknod(dir, dentry, mode, 0, data, NULL);
}
static int debugfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
void *data, const struct file_operations *fops)
{
int res;
mode = (mode & S_IALLUGO) | S_IFREG;
res = debugfs_mknod(dir, dentry, mode, 0, data, fops);
if (!res)
fsnotify_create(dir, dentry);
return res;
}
static inline int debugfs_positive(struct dentry *dentry)
{
return dentry->d_inode && !d_unhashed(dentry);
}
struct debugfs_mount_opts {
kuid_t uid;
kgid_t gid;
umode_t mode;
};
enum {
Opt_uid,
Opt_gid,
Opt_mode,
Opt_err
};
static const match_table_t tokens = {
{Opt_uid, "uid=%u"},
{Opt_gid, "gid=%u"},
{Opt_mode, "mode=%o"},
{Opt_err, NULL}
};
struct debugfs_fs_info {
struct debugfs_mount_opts mount_opts;
};
static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts)
{
substring_t args[MAX_OPT_ARGS];
int option;
int token;
kuid_t uid;
kgid_t gid;
char *p;
opts->mode = DEBUGFS_DEFAULT_MODE;
while ((p = strsep(&data, ",")) != NULL) {
if (!*p)
continue;
token = match_token(p, tokens, args);
switch (token) {
case Opt_uid:
if (match_int(&args[0], &option))
return -EINVAL;
uid = make_kuid(current_user_ns(), option);
if (!uid_valid(uid))
return -EINVAL;
opts->uid = uid;
break;
case Opt_gid:
if (match_int(&args[0], &option))
return -EINVAL;
gid = make_kgid(current_user_ns(), option);
if (!gid_valid(gid))
return -EINVAL;
opts->gid = gid;
break;
case Opt_mode:
if (match_octal(&args[0], &option))
return -EINVAL;
opts->mode = option & S_IALLUGO;
break;
/*
* We might like to report bad mount options here;
* but traditionally debugfs has ignored all mount options
*/
}
}
return 0;
}
static int debugfs_apply_options(struct super_block *sb)
{
struct debugfs_fs_info *fsi = sb->s_fs_info;
struct inode *inode = sb->s_root->d_inode;
struct debugfs_mount_opts *opts = &fsi->mount_opts;
inode->i_mode &= ~S_IALLUGO;
inode->i_mode |= opts->mode;
inode->i_uid = opts->uid;
inode->i_gid = opts->gid;
return 0;
}
static int debugfs_remount(struct super_block *sb, int *flags, char *data)
{
int err;
struct debugfs_fs_info *fsi = sb->s_fs_info;
err = debugfs_parse_options(data, &fsi->mount_opts);
if (err)
goto fail;
debugfs_apply_options(sb);
fail:
return err;
}
static int debugfs_show_options(struct seq_file *m, struct dentry *root)
{
struct debugfs_fs_info *fsi = root->d_sb->s_fs_info;
struct debugfs_mount_opts *opts = &fsi->mount_opts;
if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
seq_printf(m, ",uid=%u",
from_kuid_munged(&init_user_ns, opts->uid));
if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
seq_printf(m, ",gid=%u",
from_kgid_munged(&init_user_ns, opts->gid));
if (opts->mode != DEBUGFS_DEFAULT_MODE)
seq_printf(m, ",mode=%o", opts->mode);
return 0;
}
static const struct super_operations debugfs_super_operations = {
.statfs = simple_statfs,
.remount_fs = debugfs_remount,
.show_options = debugfs_show_options,
};
static int debug_fill_super(struct super_block *sb, void *data, int silent)
{
static struct tree_descr debug_files[] = {{""}};
struct debugfs_fs_info *fsi;
int err;
save_mount_options(sb, data);
fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL);
sb->s_fs_info = fsi;
if (!fsi) {
err = -ENOMEM;
goto fail;
}
err = debugfs_parse_options(data, &fsi->mount_opts);
if (err)
goto fail;
err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
if (err)
goto fail;
sb->s_op = &debugfs_super_operations;
debugfs_apply_options(sb);
return 0;
fail:
kfree(fsi);
sb->s_fs_info = NULL;
return err;
}
static struct dentry *debug_mount(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data)
{
return mount_single(fs_type, flags, data, debug_fill_super);
}
static struct file_system_type debug_fs_type = {
.owner = THIS_MODULE,
.name = "debugfs",
.mount = debug_mount,
.kill_sb = kill_litter_super,
};
MODULE_ALIAS_FS("debugfs");
static struct dentry *__create_file(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops)
{
struct dentry *dentry = NULL;
int error;
pr_debug("debugfs: creating file '%s'\n",name);
error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
&debugfs_mount_count);
if (error)
goto exit;
/* If the parent is not specified, we create it in the root.
* We need the root dentry to do this, which is in the super
* block. A pointer to that is in the struct vfsmount that we
* have around.
*/
if (!parent)
parent = debugfs_mount->mnt_root;
mutex_lock(&parent->d_inode->i_mutex);
dentry = lookup_one_len(name, parent, strlen(name));
if (!IS_ERR(dentry)) {
switch (mode & S_IFMT) {
case S_IFDIR:
error = debugfs_mkdir(parent->d_inode, dentry, mode);
break;
case S_IFLNK:
error = debugfs_link(parent->d_inode, dentry, mode,
data);
break;
default:
error = debugfs_create(parent->d_inode, dentry, mode,
data, fops);
break;
}
dput(dentry);
} else
error = PTR_ERR(dentry);
mutex_unlock(&parent->d_inode->i_mutex);
if (error) {
dentry = NULL;
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
}
exit:
return dentry;
}
/**
* debugfs_create_file - create a file in the debugfs filesystem
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have.
* : a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this paramater is NULL, then the
* file will be created in the root of the debugfs filesystem.
* @data: a pointer to something that the caller will want to get to later
* on. The inode.i_private pointer will point to this value on
* the open() call.
* @fops: a pointer to a struct file_operations that should be used for
* this file.
*
* This is the basic "create a file" function for debugfs. It allows for a
* wide range of flexibility in creating a file, or a directory (if you want
* to create a directory, the debugfs_create_dir() function is
* recommended to be used instead.)
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *debugfs_create_file(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops)
{
switch (mode & S_IFMT) {
case S_IFREG:
case 0:
break;
default:
BUG();
}
return __create_file(name, mode, parent, data, fops);
}
EXPORT_SYMBOL_GPL(debugfs_create_file);
/**
* debugfs_create_dir - create a directory in the debugfs filesystem
* @name: a pointer to a string containing the name of the directory to
* create.
* : a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this paramater is NULL, then the
* directory will be created in the root of the debugfs filesystem.
*
* This function creates a directory in debugfs with the given name.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
{
return __create_file(name, S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
parent, NULL, NULL);
}
EXPORT_SYMBOL_GPL(debugfs_create_dir);
/**
* debugfs_create_symlink- create a symbolic link in the debugfs filesystem
* @name: a pointer to a string containing the name of the symbolic link to
* create.
* : a pointer to the parent dentry for this symbolic link. This
* should be a directory dentry if set. If this paramater is NULL,
* then the symbolic link will be created in the root of the debugfs
* filesystem.
* @target: a pointer to a string containing the path to the target of the
* symbolic link.
*
* This function creates a symbolic link with the given name in debugfs that
* links to the given target path.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the symbolic
* link is to be removed (no automatic cleanup happens if your module is
* unloaded, you are responsible here.) If an error occurs, %NULL will be
* returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
const char *target)
{
struct dentry *result;
char *link;
link = kstrdup(target, GFP_KERNEL);
if (!link)
return NULL;
result = __create_file(name, S_IFLNK | S_IRWXUGO, parent, link, NULL);
if (!result)
kfree(link);
return result;
}
EXPORT_SYMBOL_GPL(debugfs_create_symlink);
static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
{
int ret = 0;
if (debugfs_positive(dentry)) {
if (dentry->d_inode) {
dget(dentry);
switch (dentry->d_inode->i_mode & S_IFMT) {
case S_IFDIR:
ret = simple_rmdir(parent->d_inode, dentry);
break;
case S_IFLNK:
kfree(dentry->d_inode->i_private);
/* fall through */
default:
simple_unlink(parent->d_inode, dentry);
break;
}
if (!ret)
d_delete(dentry);
dput(dentry);
}
}
return ret;
}
/**
* debugfs_remove - removes a file or directory from the debugfs filesystem
* @dentry: a pointer to a the dentry of the file or directory to be
* removed.
*
* This function removes a file or directory in debugfs that was previously
* created with a call to another debugfs function (like
* debugfs_create_file() or variants thereof.)
*
* This function is required to be called in order for the file to be
* removed, no automatic cleanup of files will happen when a module is
* removed, you are responsible here.
*/
void debugfs_remove(struct dentry *dentry)
{
struct dentry *parent;
int ret;
if (IS_ERR_OR_NULL(dentry))
return;
parent = dentry->d_parent;
if (!parent || !parent->d_inode)
return;
mutex_lock(&parent->d_inode->i_mutex);
ret = __debugfs_remove(dentry, parent);
mutex_unlock(&parent->d_inode->i_mutex);
if (!ret)
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
}
EXPORT_SYMBOL_GPL(debugfs_remove);
/**
* debugfs_remove_recursive - recursively removes a directory
* @dentry: a pointer to a the dentry of the directory to be removed.
*
* This function recursively removes a directory tree in debugfs that
* was previously created with a call to another debugfs function
* (like debugfs_create_file() or variants thereof.)
*
* This function is required to be called in order for the file to be
* removed, no automatic cleanup of files will happen when a module is
* removed, you are responsible here.
*/
void debugfs_remove_recursive(struct dentry *dentry)
{
struct dentry *child, *next, *parent;
if (IS_ERR_OR_NULL(dentry))
return;
parent = dentry->d_parent;
if (!parent || !parent->d_inode)
return;
parent = dentry;
down:
mutex_lock(&parent->d_inode->i_mutex);
list_for_each_entry_safe(child, next, &parent->d_subdirs, d_u.d_child) {
if (!debugfs_positive(child))
continue;
/* perhaps simple_empty(child) makes more sense */
if (!list_empty(&child->d_subdirs)) {
mutex_unlock(&parent->d_inode->i_mutex);
parent = child;
goto down;
}
up:
if (!__debugfs_remove(child, parent))
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
}
mutex_unlock(&parent->d_inode->i_mutex);
child = parent;
parent = parent->d_parent;
mutex_lock(&parent->d_inode->i_mutex);
if (child != dentry) {
next = list_next_entry(child, d_u.d_child);
goto up;
}
if (!__debugfs_remove(child, parent))
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
mutex_unlock(&parent->d_inode->i_mutex);
}
EXPORT_SYMBOL_GPL(debugfs_remove_recursive);
/**
* debugfs_rename - rename a file/directory in the debugfs filesystem
* @old_dir: a pointer to the parent dentry for the renamed object. This
* should be a directory dentry.
* @old_dentry: dentry of an object to be renamed.
* @new_dir: a pointer to the parent dentry where the object should be
* moved. This should be a directory dentry.
* @new_name: a pointer to a string containing the target name.
*
* This function renames a file/directory in debugfs. The target must not
* exist for rename to succeed.
*
* This function will return a pointer to old_dentry (which is updated to
* reflect renaming) if it succeeds. If an error occurs, %NULL will be
* returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
struct dentry *new_dir, const char *new_name)
{
int error;
struct dentry *dentry = NULL, *trap;
const char *old_name;
trap = lock_rename(new_dir, old_dir);
/* Source or destination directories don't exist? */
if (!old_dir->d_inode || !new_dir->d_inode)
goto exit;
/* Source does not exist, cyclic rename, or mountpoint? */
if (!old_dentry->d_inode || old_dentry == trap ||
d_mountpoint(old_dentry))
goto exit;
dentry = lookup_one_len(new_name, new_dir, strlen(new_name));
/* Lookup failed, cyclic rename or target exists? */
if (IS_ERR(dentry) || dentry == trap || dentry->d_inode)
goto exit;
old_name = fsnotify_oldname_init(old_dentry->d_name.name);
error = simple_rename(old_dir->d_inode, old_dentry, new_dir->d_inode,
dentry);
if (error) {
fsnotify_oldname_free(old_name);
goto exit;
}
d_move(old_dentry, dentry);
fsnotify_move(old_dir->d_inode, new_dir->d_inode, old_name,
S_ISDIR(old_dentry->d_inode->i_mode),
NULL, old_dentry);
fsnotify_oldname_free(old_name);
unlock_rename(new_dir, old_dir);
dput(dentry);
return old_dentry;
exit:
if (dentry && !IS_ERR(dentry))
dput(dentry);
unlock_rename(new_dir, old_dir);
return NULL;
}
EXPORT_SYMBOL_GPL(debugfs_rename);
/**
* debugfs_initialized - Tells whether debugfs has been registered
*/
bool debugfs_initialized(void)
{
return debugfs_registered;
}
EXPORT_SYMBOL_GPL(debugfs_initialized);
static struct kobject *debug_kobj;
static int __init debugfs_init(void)
{
int retval;
debug_kobj = kobject_create_and_add("debug", kernel_kobj);
if (!debug_kobj)
return -EINVAL;
retval = register_filesystem(&debug_fs_type);
if (retval)
kobject_put(debug_kobj);
else
debugfs_registered = true;
return retval;
}
core_initcall(debugfs_init);