cdev.c

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		count -= len;
		*offp += len;
		buf += len;
		len = count > tbuf_size ? tbuf_size : count;
	}

	vfree(tbuf);
	return err ? err : count_save - count;
}

#else
#define vol_cdev_direct_write(file, buf, count, offp) -EPERM
#endif /* CONFIG_MTD_UBI_DEBUG_USERSPACE_IO */

static ssize_t vol_cdev_write(struct file *file, const char __user *buf,
			      size_t count, loff_t *offp)
{
	int err = 0;
	struct ubi_volume_desc *desc = file->private_data;
	struct ubi_volume *vol = desc->vol;
	struct ubi_device *ubi = vol->ubi;

	if (!vol->updating)
		return vol_cdev_direct_write(file, buf, count, offp);

	err = ubi_more_update_data(ubi, vol->vol_id, buf, count);
	if (err < 0) {
		ubi_err("cannot write %zd bytes of update data", count);
		return err;
	}

	if (err) {
		/*
		 * Update is finished, @err contains number of actually written
		 * bytes now.
		 */
		count = err;

		err = ubi_check_volume(ubi, vol->vol_id);
		if (err < 0)
			return err;

		if (err) {
			ubi_warn("volume %d on UBI device %d is corrupted",
				 vol->vol_id, ubi->ubi_num);
			vol->corrupted = 1;
		}
		vol->checked = 1;
		ubi_gluebi_updated(vol);
		revoke_exclusive(desc, UBI_READWRITE);
	}

	*offp += count;
	return count;
}

static int vol_cdev_ioctl(struct inode *inode, struct file *file,
			  unsigned int cmd, unsigned long arg)
{
	int err = 0;
	struct ubi_volume_desc *desc = file->private_data;
	struct ubi_volume *vol = desc->vol;
	struct ubi_device *ubi = vol->ubi;
	void __user *argp = (void __user *)arg;

	switch (cmd) {
	/* Volume update command */
	case UBI_IOCVOLUP:
	{
		int64_t bytes, rsvd_bytes;

		if (!capable(CAP_SYS_RESOURCE)) {
			err = -EPERM;
			break;
		}

		err = copy_from_user(&bytes, argp, sizeof(int64_t));
		if (err) {
			err = -EFAULT;
			break;
		}

		if (desc->mode == UBI_READONLY) {
			err = -EROFS;
			break;
		}

		rsvd_bytes = vol->reserved_pebs * (ubi->leb_size-vol->data_pad);
		if (bytes < 0 || bytes > rsvd_bytes) {
			err = -EINVAL;
			break;
		}

		err = get_exclusive(desc);
		if (err < 0)
			break;

		err = ubi_start_update(ubi, vol->vol_id, bytes);
		if (bytes == 0)
			revoke_exclusive(desc, UBI_READWRITE);

		file->f_pos = 0;
		break;
	}

#ifdef CONFIG_MTD_UBI_DEBUG_USERSPACE_IO
	/* Logical eraseblock erasure command */
	case UBI_IOCEBER:
	{
		int32_t lnum;

		err = get_user(lnum, (__user int32_t *)argp);
		if (err) {
			err = -EFAULT;
			break;
		}

		if (desc->mode == UBI_READONLY) {
			err = -EROFS;
			break;
		}

		if (lnum < 0 || lnum >= vol->reserved_pebs) {
			err = -EINVAL;
			break;
		}

		if (vol->vol_type != UBI_DYNAMIC_VOLUME) {
			err = -EROFS;
			break;
		}

		dbg_msg("erase LEB %d:%d", vol->vol_id, lnum);
		err = ubi_eba_unmap_leb(ubi, vol->vol_id, lnum);
		if (err)
			break;

		err = ubi_wl_flush(ubi);
		break;
	}
#endif

	default:
		err = -ENOTTY;
		break;
	}

	return err;
}

/**
 * verify_mkvol_req - verify volume creation request.
 * @ubi: UBI device description object
 * @req: the request to check
 *
 * This function zero if the request is correct, and %-EINVAL if not.
 */
static int verify_mkvol_req(const struct ubi_device *ubi,
			    const struct ubi_mkvol_req *req)
{
	int n, err = -EINVAL;

	if (req->bytes < 0 || req->alignment < 0 || req->vol_type < 0 ||
	    req->name_len < 0)
		goto bad;

	if ((req->vol_id < 0 || req->vol_id >= ubi->vtbl_slots) &&
	    req->vol_id != UBI_VOL_NUM_AUTO)
		goto bad;

	if (req->alignment == 0)
		goto bad;

	if (req->bytes == 0)
		goto bad;

	if (req->vol_type != UBI_DYNAMIC_VOLUME &&
	    req->vol_type != UBI_STATIC_VOLUME)
		goto bad;

	if (req->alignment > ubi->leb_size)
		goto bad;

	n = req->alignment % ubi->min_io_size;
	if (req->alignment != 1 && n)
		goto bad;

	if (req->name_len > UBI_VOL_NAME_MAX) {
		err = -ENAMETOOLONG;
		goto bad;
	}

	return 0;

bad:
	dbg_err("bad volume creation request");
	ubi_dbg_dump_mkvol_req(req);
	return err;
}

/**
 * verify_rsvol_req - verify volume re-size request.
 * @ubi: UBI device description object
 * @req: the request to check
 *
 * This function returns zero if the request is correct, and %-EINVAL if not.
 */
static int verify_rsvol_req(const struct ubi_device *ubi,
			    const struct ubi_rsvol_req *req)
{
	if (req->bytes <= 0)
		return -EINVAL;

	if (req->vol_id < 0 || req->vol_id >= ubi->vtbl_slots)
		return -EINVAL;

	return 0;
}

static int ubi_cdev_ioctl(struct inode *inode, struct file *file,
			  unsigned int cmd, unsigned long arg)
{
	int err = 0;
	struct ubi_device *ubi;
	struct ubi_volume_desc *desc;
	void __user *argp = (void __user *)arg;

	if (!capable(CAP_SYS_RESOURCE))
		return -EPERM;

	ubi = major_to_device(imajor(inode));
	if (IS_ERR(ubi))
		return PTR_ERR(ubi);

	switch (cmd) {
	/* Create volume command */
	case UBI_IOCMKVOL:
	{
		struct ubi_mkvol_req req;

		dbg_msg("create volume");
		err = copy_from_user(&req, argp,
				       sizeof(struct ubi_mkvol_req));
		if (err) {
			err = -EFAULT;
			break;
		}

		err = verify_mkvol_req(ubi, &req);
		if (err)
			break;

		req.name[req.name_len] = '\0';

		err = ubi_create_volume(ubi, &req);
		if (err)
			break;

		err = put_user(req.vol_id, (__user int32_t *)argp);
		if (err)
			err = -EFAULT;

		break;
	}

	/* Remove volume command */
	case UBI_IOCRMVOL:
	{
		int vol_id;

		dbg_msg("remove volume");
		err = get_user(vol_id, (__user int32_t *)argp);
		if (err) {
			err = -EFAULT;
			break;
		}

		desc = ubi_open_volume(ubi->ubi_num, vol_id, UBI_EXCLUSIVE);
		if (IS_ERR(desc)) {
			err = PTR_ERR(desc);
			break;
		}

		err = ubi_remove_volume(desc);
		if (err)
			ubi_close_volume(desc);

		break;
	}

	/* Re-size volume command */
	case UBI_IOCRSVOL:
	{
		int pebs;
		uint64_t tmp;
		struct ubi_rsvol_req req;

		dbg_msg("re-size volume");
		err = copy_from_user(&req, argp,
				       sizeof(struct ubi_rsvol_req));
		if (err) {
			err = -EFAULT;
			break;
		}

		err = verify_rsvol_req(ubi, &req);
		if (err)
			break;

		desc = ubi_open_volume(ubi->ubi_num, req.vol_id, UBI_EXCLUSIVE);
		if (IS_ERR(desc)) {
			err = PTR_ERR(desc);
			break;
		}

		tmp = req.bytes;
		pebs = !!do_div(tmp, desc->vol->usable_leb_size);
		pebs += tmp;

		err = ubi_resize_volume(desc, pebs);
		ubi_close_volume(desc);
		break;
	}

	default:
		err = -ENOTTY;
		break;
	}

	return err;
}

/* UBI character device operations */
struct file_operations ubi_cdev_operations = {
	.owner = THIS_MODULE,
	.ioctl = ubi_cdev_ioctl,
	.llseek = no_llseek,
};

/* UBI volume character device operations */
struct file_operations ubi_vol_cdev_operations = {
	.owner   = THIS_MODULE,
	.open    = vol_cdev_open,
	.release = vol_cdev_release,
	.llseek  = vol_cdev_llseek,
	.read    = vol_cdev_read,
	.write   = vol_cdev_write,
	.ioctl   = vol_cdev_ioctl,
};