Tester for failing lseek(..., SEEK_HOLE) on ext4 with inline_data

seekhole_tester.c

#define _GNU_SOURCE
#include <stdlib.h>
#include <time.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>

int create_file (const char *fn) {
  return open(fn, O_CREAT|O_RDWR, 0644);
}

void append_file (int fd, size_t nb) {
  void *buf = malloc(nb);
  memset(buf, 42, nb);
  ssize_t nw = write(fd, buf, nb);
  free(buf);
}

void test_seek_hole (int fd) {
  off_t hole_start = lseek(fd, 0, SEEK_HOLE);
  if (hole_start < 0) {
    printf("seek_hole failed with errno %d\n", errno);
  } else {
    printf("seek_hole got %ld\n", (long)hole_start);
  }
}

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

  const char *fn = argv[1];

  puts("Synced single-write test...");
  for (int i = 0; i < 10; i++) {
    int fd = create_file(fn);
    append_file(fd, 192);
    fdatasync(fd);
    test_seek_hole(fd);
    close(fd);
    unlink(fn);
  }

  puts("Unsynced single-write test...");
  for (int i = 0; i < 10; i++) {
    int fd = create_file(fn);
    append_file(fd, 192);
    test_seek_hole(fd);
    close(fd);
    unlink(fn);
  }

  puts("Synced multiple-write test...");
  for (int i = 0; i < 10; i++) {
    int fd = create_file(fn);
    append_file(fd, 64);
    append_file(fd, 128);
    fdatasync(fd);
    test_seek_hole(fd);
    close(fd);
    unlink(fn);
  }

  puts("Unsynced multiple-write test...");
  for (int i = 0; i < 10; i++) {
    int fd = create_file(fn);
    append_file(fd, 64);
    append_file(fd, 128);
    test_seek_hole(fd);
    close(fd);
    unlink(fn);
  }

  puts("Unsynced multiple-write test with delays...");
  for (int i = 0; i < 10; i++) {
    puts("Create file, wait 5 secs...");
    int fd = create_file(fn);
    append_file(fd, 64);
    append_file(fd, 128);
    sleep(5);

    puts("Check...");
    test_seek_hole(fd);
    close(fd);

    puts("Delete...");
    unlink(fn);
  }

  return 0;
}