punch.c

#define _GNU_SOURCE
#define _FILE_OFFSET_BITS 64

#include <unistd.h>
#include <linux/falloc.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <errno.h>

static void usage(int argc, char **argv)
{
	(void)argc;
	printf("Usage: %s <Path>\n", argv[0]);
	exit(EXIT_FAILURE);
}

int main(int argc, char **argv)
{
	int fd, ret;
	off_t i, blk;
	const int blk_size = 4096;
	struct stat file_stat;

	if (argc != 2)
		usage(argc, argv);

	fd = open(argv[1], O_RDWR);
	if (fd < 0) {
		perror("open");
		return EXIT_FAILURE;
	}

	ret = fstat(fd, &file_stat);
	if (ret < 0) {
		perror("stat");
		close(fd);
		return EXIT_FAILURE;
	}
	blk = (file_stat.st_size + blk_size - 1) / blk_size;
	for (i = 0; i < blk; i += 10) {
		printf("i: %llu\n", i);
		ret = fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, i * blk_size, blk_size * 6);
		if (ret < 0) {
			perror("fallcate");
			close(fd);
			return EXIT_FAILURE;
		}
	}

	fsync(fd);
	close(fd);
	return EXIT_SUCCESS;
}