compat_hdio_ioctl: get rid of set_fs()

static int compat_hdio_ioctl(struct block_device *bdev, fmode_t mode,

		unsigned int cmd, unsigned long arg)

{

	mm_segment_t old_fs = get_fs();

	unsigned long kval;

	unsigned int __user *uvp;

	unsigned long *__user p;

	int error;

	set_fs(KERNEL_DS);

	p = compat_alloc_user_space(sizeof(unsigned long));

	error = __blkdev_driver_ioctl(bdev, mode,

				cmd, (unsigned long)(&kval));

	set_fs(old_fs);

				cmd, (unsigned long)p);

	if (error == 0) {

		uvp = compat_ptr(arg);

		if (put_user(kval, uvp))

		unsigned int __user *uvp = compat_ptr(arg);

		unsigned long v;

		if (get_user(v, p) || put_user(v, uvp))

			error = -EFAULT;

	}

	return error;