- 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)
{
struct inode *inode = new_inode(sb);
if (inode) {
inode->i_ino = get_next_ino();
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
}
return inode;
}
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 = d_inode(sb->s_root);
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;
sync_filesystem(sb);
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 void debugfs_evict_inode(struct inode *inode)
{
truncate_inode_pages_final(&inode->i_data);
clear_inode(inode);
if (S_ISLNK(inode->i_mode))
kfree(inode->i_link);
}
static const struct super_operations debugfs_super_operations = {
.statfs = simple_statfs,
.remount_fs = debugfs_remount,
.show_options = debugfs_show_options,
.evict_inode = debugfs_evict_inode,
};
static struct vfsmount *debugfs_automount(struct path *path)
{
struct vfsmount *(*f)(void *);
f = (struct vfsmount *(*)(void *))path->dentry->d_fsdata;
return f(d_inode(path->dentry)->i_private);
}
static const struct dentry_operations debugfs_dops = {
.d_delete = always_delete_dentry,
.d_automount = debugfs_automount,
};
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;
sb->s_d_op = &debugfs_dops;
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 *start_creating(const char *name, struct dentry *parent)
{
struct dentry *dentry;
int error;
pr_debug("debugfs: creating file '%s'\n",name);
if (IS_ERR(parent))
return parent;
error = simple_pin_fs(&debug_fs_type, &debugfs_mount,
&debugfs_mount_count);
if (error)
return ERR_PTR(error);
/* 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(&d_inode(parent)->i_mutex);
dentry = lookup_one_len(name, parent, strlen(name));
if (!IS_ERR(dentry) && d_really_is_positive(dentry)) {
dput(dentry);
dentry = ERR_PTR(-EEXIST);
}
if (IS_ERR(dentry)) {
mutex_unlock(&d_inode(parent)->i_mutex);
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
}
return dentry;
}
static struct dentry *failed_creating(struct dentry *dentry)
{
mutex_unlock(&d_inode(dentry->d_parent)->i_mutex);
dput(dentry);
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
return NULL;
}
static struct dentry *end_creating(struct dentry *dentry)
{
mutex_unlock(&d_inode(dentry->d_parent)->i_mutex);
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 parameter 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)
{
struct dentry *dentry;
struct inode *inode;
if (!(mode & S_IFMT))
mode |= S_IFREG;
BUG_ON(!S_ISREG(mode));
dentry = start_creating(name, parent);
if (IS_ERR(dentry))
return NULL;
inode = debugfs_get_inode(dentry->d_sb);
if (unlikely(!inode))
return failed_creating(dentry);
inode->i_mode = mode;
inode->i_fop = fops ? fops : &debugfs_file_operations;
inode->i_private = data;
d_instantiate(dentry, inode);
fsnotify_create(d_inode(dentry->d_parent), dentry);
return end_creating(dentry);
}
EXPORT_SYMBOL_GPL(debugfs_create_file);
/**
* debugfs_create_file_size - 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 parameter 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.
* @file_size: initial file size
*
* 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_size(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops,
loff_t file_size)
{
struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
if (de)
d_inode(de)->i_size = file_size;
return de;
}
EXPORT_SYMBOL_GPL(debugfs_create_file_size);
/**
* 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 parameter 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)
{
struct dentry *dentry = start_creating(name, parent);
struct inode *inode;
if (IS_ERR(dentry))
return NULL;
inode = debugfs_get_inode(dentry->d_sb);
if (unlikely(!inode))
return failed_creating(dentry);
inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
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);
d_instantiate(dentry, inode);
inc_nlink(d_inode(dentry->d_parent));
fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
return end_creating(dentry);
}
EXPORT_SYMBOL_GPL(debugfs_create_dir);
/**
* debugfs_create_automount - create automount point in the debugfs filesystem
* @name: a pointer to a string containing the name of the file to create.
* : a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is NULL, then the
* file will be created in the root of the debugfs filesystem.
* @f: function to be called when pathname resolution steps on that one.
* @data: opaque argument to pass to f().
*
* @f should return what ->d_automount() would.
*/
struct dentry *debugfs_create_automount(const char *name,
struct dentry *parent,
struct vfsmount *(*f)(void *),
void *data)
{
struct dentry *dentry = start_creating(name, parent);
struct inode *inode;
if (IS_ERR(dentry))
return NULL;
inode = debugfs_get_inode(dentry->d_sb);
if (unlikely(!inode))
return failed_creating(dentry);
inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
inode->i_flags |= S_AUTOMOUNT;
inode->i_private = data;
dentry->d_fsdata = (void *)f;
d_instantiate(dentry, inode);
return end_creating(dentry);
}
EXPORT_SYMBOL(debugfs_create_automount);
/**
* 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 parameter 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 *dentry;
struct inode *inode;
char *link = kstrdup(target, GFP_KERNEL);
if (!link)
return NULL;
dentry = start_creating(name, parent);
if (IS_ERR(dentry)) {
kfree(link);
return NULL;
}
inode = debugfs_get_inode(dentry->d_sb);
if (unlikely(!inode)) {
kfree(link);
return failed_creating(dentry);
}
inode->i_mode = S_IFLNK | S_IRWXUGO;
inode->i_op = &simple_symlink_inode_operations;
inode->i_link = link;
d_instantiate(dentry, inode);
return end_creating(dentry);
}
EXPORT_SYMBOL_GPL(debugfs_create_symlink);
static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
{
int ret = 0;
if (simple_positive(dentry)) {
dget(dentry);
if (d_is_dir(dentry))
ret = simple_rmdir(d_inode(parent), dentry);
else
simple_unlink(d_inode(parent), dentry);
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. If this parameter is NULL or an error value, nothing
* will be done.
*
* 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 || d_really_is_negative(parent))
return;
mutex_lock(&d_inode(parent)->i_mutex);
ret = __debugfs_remove(dentry, parent);
mutex_unlock(&d_inode(parent)->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. If this
* parameter is NULL or an error value, nothing will be done.
*
* 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, *parent;
if (IS_ERR_OR_NULL(dentry))
return;
parent = dentry->d_parent;
if (!parent || d_really_is_negative(parent))
return;
parent = dentry;
down:
mutex_lock(&d_inode(parent)->i_mutex);
loop:
/*
* The parent->d_subdirs is protected by the d_lock. Outside that
* lock, the child can be unlinked and set to be freed which can
* use the d_u.d_child as the rcu head and corrupt this list.
*/
spin_lock(&parent->d_lock);
list_for_each_entry(child, &parent->d_subdirs, d_child) {
if (!simple_positive(child))
continue;
/* perhaps simple_empty(child) makes more sense */
if (!list_empty(&child->d_subdirs)) {
spin_unlock(&parent->d_lock);
mutex_unlock(&d_inode(parent)->i_mutex);
parent = child;
goto down;
}
spin_unlock(&parent->d_lock);
if (!__debugfs_remove(child, parent))
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
/*
* The parent->d_lock protects agaist child from unlinking
* from d_subdirs. When releasing the parent->d_lock we can
* no longer trust that the next pointer is valid.
* Restart the loop. We'll skip this one with the
* simple_positive() check.
*/
goto loop;
}
spin_unlock(&parent->d_lock);
mutex_unlock(&d_inode(parent)->i_mutex);
child = parent;
parent = parent->d_parent;
mutex_lock(&d_inode(parent)->i_mutex);
if (child != dentry)
/* go up */
goto loop;
if (!__debugfs_remove(child, parent))
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
mutex_unlock(&d_inode(parent)->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 (d_really_is_negative(old_dir) || d_really_is_negative(new_dir))
goto exit;
/* Source does not exist, cyclic rename, or mountpoint? */
if (d_really_is_negative(old_dentry) || 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 || d_really_is_positive(dentry))
goto exit;
old_name = fsnotify_oldname_init(old_dentry->d_name.name);
error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
dentry);
if (error) {
fsnotify_oldname_free(old_name);
goto exit;
}
d_move(old_dentry, dentry);
fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name,
d_is_dir(old_dentry),
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 int __init debugfs_init(void)
{
int retval;
retval = sysfs_create_mount_point(kernel_kobj, "debug");
if (retval)
return retval;
retval = register_filesystem(&debug_fs_type);
if (retval)
sysfs_remove_mount_point(kernel_kobj, "debug");
else
debugfs_registered = true;
return retval;
}
core_initcall(debugfs_init);