block_dev: switch to fixed_size_llseek()

static loff_t block_llseek(struct file *file, loff_t offset, int whence)

{

	struct inode *bd_inode = file->f_mapping->host;

	loff_t size;

	loff_t retval;

	mutex_lock(&bd_inode->i_mutex);

	size = i_size_read(bd_inode);

	retval = -EINVAL;

	switch (whence) {

		case SEEK_END:

			offset += size;

			break;

		case SEEK_CUR:

			offset += file->f_pos;

		case SEEK_SET:

			break;

		default:

			goto out;

	}

	if (offset >= 0 && offset <= size) {

		if (offset != file->f_pos) {

			file->f_pos = offset;

		}

		retval = offset;

	}

out:

	retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));

	mutex_unlock(&bd_inode->i_mutex);

	return retval;

}