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/*
* file.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.
*
*/
/* uncomment to get debug messages from the debug filesystem, ah the irony. */
/* #define DEBUG */
#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/magic.h>
static struct vfsmount *debugfs_mount;
static int debugfs_mount_count;
static bool debugfs_registered;
static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev)
{
struct inode *inode = new_inode(sb);
if (inode) {
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 = &debugfs_file_operations;
break;
case S_IFLNK:
inode->i_op = &debugfs_link_operations;
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,
int mode, dev_t dev)
{
struct inode *inode;
int error = -EPERM;
if (dentry->d_inode)
return -EEXIST;
inode = debugfs_get_inode(dir->i_sb, mode, dev);
if (inode) {
d_instantiate(dentry, inode);
dget(dentry);
error = 0;
}
return error;
}
static int debugfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
int res;
mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
res = debugfs_mknod(dir, dentry, mode, 0);
if (!res) {
inc_nlink(dir);
fsnotify_mkdir(dir, dentry);
}
return res;
}
static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode)
{
mode = (mode & S_IALLUGO) | S_IFLNK;
return debugfs_mknod(dir, dentry, mode, 0);
}
static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode)
{
int res;
mode = (mode & S_IALLUGO) | S_IFREG;
res = debugfs_mknod(dir, dentry, mode, 0);
if (!res)
fsnotify_create(dir, dentry);
return res;
}
static inline int debugfs_positive(struct dentry *dentry)
{
return dentry->d_inode && !d_unhashed(dentry);
}
static int debug_fill_super(struct super_block *sb, void *data, int silent)
{
static struct tree_descr debug_files[] = {{""}};
return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
}
static int debug_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data, struct vfsmount *mnt)
{
return get_sb_single(fs_type, flags, data, debug_fill_super, mnt);
}
static struct file_system_type debug_fs_type = {
.owner = THIS_MODULE,
.name = "debugfs",
.get_sb = debug_get_sb,
.kill_sb = kill_litter_super,
};
static int debugfs_create_by_name(const char *name, mode_t mode,
struct dentry *parent,
struct dentry **dentry)
{
int error = 0;
/* 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) {
if (debugfs_mount && debugfs_mount->mnt_sb) {
parent = debugfs_mount->mnt_sb->s_root;
}
}
if (!parent) {
pr_debug("debugfs: Ah! can not find a parent!\n");
return -EFAULT;
}
*dentry = NULL;
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);
break;
default:
error = debugfs_create(parent->d_inode, *dentry, mode);
break;
}
dput(*dentry);
} else
error = PTR_ERR(*dentry);
mutex_unlock(&parent->d_inode->i_mutex);
return error;
}
/**
* 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.
* @parent: 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, mode_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;
error = debugfs_create_by_name(name, mode, parent, &dentry);
if (error) {
dentry = NULL;
simple_release_fs(&debugfs_mount, &debugfs_mount_count);
goto exit;
}
if (dentry->d_inode) {
if (data)
dentry->d_inode->i_private = data;
if (fops)
dentry->d_inode->i_fop = fops;
}
exit:
return dentry;
}
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.
* @parent: 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 direc
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