#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/fs.h>
#include <errno.h>
#include <string.h>
#include <linux/loop.h>

int main(int argc, char *argv[])
{
    if (argc != 2) {
        fprintf(stderr, "Usage: %s [dev path]\n", argv[0]);
        return 1;
    }

    const char *dev = argv[1];
    struct loop_info64 info;
    memset(&info, 0, sizeof(info));

    int fd = open(dev, O_RDWR | O_EXCL);
    if (fd < 0) {
        fprintf(stderr, "Failed to open %s exclusively: %s\n",
                dev, strerror(errno));
        return 1;
    }

    if (ioctl(fd, LOOP_SET_STATUS64, &info) == -1) {
        perror("ioctl error");
        close(fd);
        return 1;
    }

    close(fd);
    return 0;
}