#define _GNU_SOURCE 1
#include <stdio.h>
#include <errno.h>
#include <libaio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

char buf[1024*1024*100*4 + 4096];

int main (int argc, char *argv[])
{
	char *bufp = buf;
	struct iocb iocb;
	struct iocb *iocbs[] = { &iocb, NULL };
	io_context_t ctx = 0;
	int ret;
	int fd;
	int i;

	if (argc != 2) {
		printf("usage: %s <file to write to>\n", argv[0]);
		return 1;
	}

	printf("opening\n");
	fflush(stdout);
	fd = open(argv[1], O_RDWR | O_DIRECT);
	if (fd < 0) {
		perror("open");
		return 1;
	}

	if (((unsigned long)bufp) & 4095)
		bufp += 4096 - ((unsigned long)bufp & 4095);

	printf("init\n");
	fflush(stdout);
	for (i=0; i < (sizeof(buf) - 4096); i++)
		bufp[i] = (char)i;

	printf("post init\n");
	fflush(stdout);

	ret = io_setup(100, &ctx);
	if (ret) {
		printf("io_setup = %d (%s)\n", ret, strerror(ret));
		return 1;
	}

	io_prep_pwrite(&iocb, fd, bufp, sizeof(buf), 0);

	printf("about to submit!\n");
	fflush(stdout);
	ret = io_submit(ctx, 1, iocbs);
	printf("submit!\n");
	fflush(stdout);
	close(fd);
	printf("done close!\n");
	fflush(stdout);

	ret = io_destroy(ctx);
	if (ret) {
		printf("io_destroy = %d (%s)\n", ret, strerror(ret));
		return 1;
	}

	printf("okay!\n");

	return 0;
}