static int strict_blocks_to_sectors(const char *buf, sector_t *sectors)
{
	unsigned long long blocks;
	sector_t new;

	if (kstrtoull(buf, 10, &blocks) < 0)
		return -EINVAL;

	if (blocks & 1ULL << (8 * sizeof(blocks) - 1))
		return -EINVAL; /* sector conversion overflow */

	new = blocks * 2;
	if (new != blocks * 2)
		return -EINVAL; /* unsigned long long to sector_t overflow */

	*sectors = new;
	return 0;
}

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