#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <err.h>
#include <sys/stat.h>
#include <sys/mount.h>

int main(int argc, char *argv[])
{
	char *base_path = argv[1];
	char name[4096];
	int nr_mounts, i, sleep_ms = 0;

	if (argc < 3 || argc > 4)
		errx(1, "usage: %s base_path nr_mounts [sleep_ms]", argv[0]);

	nr_mounts = atoi(argv[2]);
	if (argc > 3)
		sleep_ms = atoi(argv[3]);

	fprintf(stderr, "Mounting...\n");
	if (mount("none", base_path, "tmpfs", 0, NULL) == -1)
		err(1, "mount/tmpfs");
	if (mount("none", base_path, NULL, MS_PRIVATE, NULL) == -1)
		err(1, "mount/MS_PRIVATE");
	for (i = 0; i < nr_mounts; i++) {
		sprintf(name, "%s/%d", base_path, i);
		if (mkdir(name, 0755) == -1)
			err(1, "mkdir");
		if (mount("none", name, "tmpfs", 0, NULL) == -1)
			err(1, "mount/tmpfs");
		if (mount("none", name, NULL, MS_PRIVATE, NULL) == -1)
			err(1, "mount/MS_PRIVATE");
		if (sleep_ms)
			usleep(sleep_ms * 1000);
	}
	fprintf(stderr, "Press ENTER\n");
	getchar();

	fprintf(stderr, "Unmounting...\n");
	if (umount2(base_path, MNT_DETACH) == -1)
		err(1, "umount");

	fprintf(stderr, "Done\n");

	return 0;
}