#include <stdio.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

struct truncate_range {
	__u32 start_block;
	__u32 length;
};

#define EXT4_IOC_TRUNCATE_BLOCK_RANGE	_IOW('f', 18, struct truncate_range)

int main(int argc, char ** argv)
{
	struct truncate_range tr;
	int fd;
	if(argc != 4){
		printf("Usage: <filename> <startblock> <length>\n");
		return 0;
	}

	memset(&tr, 0, sizeof(struct truncate_range));
	tr.start_block = atoi(argv[2]);
	tr.length = atoi(argv[3]);

	fd = open(argv[1],O_RDWR ,0666);
	if(fd)
	{
		ioctl(fd, EXT4_IOC_TRUNCATE_BLOCK_RANGE, &tr);
		close(fd);
	}
	perror("Return:\n");
	return 0;
}