/*
* Copyright (c) International Business Machines Corp., 2006
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Author: Artem Bityutskiy (Битюцкий Артём)
*/
/*
* This file includes implementation of UBI character device operations.
*
* There are two kinds of character devices in UBI: UBI character devices and
* UBI volume character devices. UBI character devices allow users to
* manipulate whole volumes: create, remove, and re-size them. Volume character
* devices provide volume I/O capabilities.
*
* Major and minor numbers are assigned dynamically to both UBI and volume
* character devices.
*
* Well, there is the third kind of character devices - the UBI control
* character device, which allows to manipulate by UBI devices - create and
* delete them. In other words, it is used for attaching and detaching MTD
* devices.
*/
#include <linux/module.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/ioctl.h>
#include <linux/capability.h>
#include <linux/uaccess.h>
#include <linux/compat.h>
#include <linux/math64.h>
#include <mtd/ubi-user.h>
#include "ubi.h"
/**
* get_exclusive - get exclusive access to an UBI volume.
* @desc: volume descriptor
*
* This function changes UBI volume open mode to "exclusive". Returns previous
* mode value (positive integer) in case of success and a negative error code
* in case of failure.
*/
static int get_exclusive(struct ubi_volume_desc *desc)
{
int users, err;
struct ubi_volume *vol = desc->vol;
spin_lock(&vol->ubi->volumes_lock);
users = vol->readers + vol->writers + vol->exclusive;
ubi_assert(users > 0);
if (users > 1) {
ubi_err("%d users for volume %d", users, vol->vol_id);
err = -EBUSY;
} else {
vol->readers = vol->writers = 0;
vol->exclusive = 1;
err = desc->mode;
desc->mode = UBI_EXCLUSIVE;
}
spin_unlock(&vol->ubi->volumes_lock);
return err;
}
/**
* revoke_exclusive - revoke exclusive mode.
* @desc: volume descriptor
* @mode: new mode to switch to
*/
static void revoke_exclusive(struct ubi_volume_desc *desc, int mode)
{
struct ubi_volume *vol = desc->vol;
spin_lock(&vol->ubi->volumes_lock);
ubi_assert(vol->readers == 0 && vol->writers == 0);
ubi_assert(vol->exclusive == 1 && desc->mode == UBI_EXCLUSIVE);
vol->exclusive = 0;
if (mode == UBI_READONLY)
vol->readers = 1;
else if (mode == UBI_READWRITE)
vol->writers = 1;
else
vol->exclusive = 1;
spin_unlock(&vol->ubi->volumes_lock);
desc->mode = mode;
}
static int vol_cdev_open(struct inode *inode, struct file *file)
{
struct ubi_volume_desc *desc;
int vol_id = iminor(inode) - 1, mode, ubi_num;
ubi_num = ubi_major2num(imajor(inode));
if (ubi_num < 0)
return ubi_num;
if (file->f_mode & FMODE_WRITE)
mode = UBI_READWRITE;
else
mode = UBI_READONLY;
dbg_gen("open device %d, volume %d, mode %d",
ubi_num, vol_id, mode);
desc = ubi_open_volume(ubi_num, vol_id, mode);
if (IS_ERR(desc))
return PTR_ERR(desc);
file->private_data = desc;
return 0;
}
static int vol_cdev_release(struct inode *inode, struct file *file)
{
struct ubi_volume_desc *desc = file->private_data;
struct ubi_volume *vol = desc->vol;
dbg_gen("release device %d, volume %d, mode %d",
vol->ubi-