#define _GNU_SOURCE

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

#define FILE_COUNT 100
#define FILE_SIZE 4194304

#define STRING "0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789"

#define BTRFS_IOCTL_MAGIC 0x94
#define BTRFS_IOC_SYNC         _IO(BTRFS_IOCTL_MAGIC, 8)

int main(int argc, char *argv[]) {
    char *imgname = argv[1]; 
    char *tempname;
    int fd[FILE_COUNT]; 
    int ilen, i;

    ilen = strlen(imgname);
    tempname = malloc(ilen + 8);

    for(i=0; i < FILE_COUNT; i++) {
	snprintf(tempname, ilen + 8, "%s.%i", imgname, i);
    	fd[i] = open(tempname, O_CREAT|O_RDWR);
    }
	
    i=0;
    while(1) {
        int start = rand() % FILE_SIZE;
        int file = rand() % FILE_COUNT;

        putc('.', stderr);

        lseek(fd[file], start, SEEK_SET);
        write(fd[file], STRING, 100);
        sync_file_range(fd[file], start, 100, 0x2);

        usleep(25000);

        i++;
        if (i == 100) {
            i=0;
            ioctl(fd[file], BTRFS_IOC_SYNC);
        }
    }
}