Comment 1 for bug 1654288

Appended is a small program to reproduce the issue:

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

/*
 * Demonstrate file creation bug on NFS v4 and linux kernel 4.4+
 *
 * mktemp() is used on purpose.
 */
int
main(int argc, char *argv[])
{
 const char *name = argv[1];
 char tmp[] = "./tmpXXXXXXXXXX";
 struct stat buf;
 mode_t expected;
 int fd, i, n = 40;

 umask(S_IWGRP | S_IWOTH);
 expected = 0666 & ~(S_IWGRP | S_IWOTH);
 if (argv[1] == NULL)
  name = mktemp(tmp);
 for (i = 0; i < n; i++) {
  fd = open(name, O_RDWR|O_CREAT|O_EXCL, 0666);
  if (fd < 0)
   err(1, "open %s", name);
  memset(&buf, 0, sizeof(buf));
  if (stat(name, &buf) < 0)
   err(1, "stat %s", name);
  if ((buf.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != expected)
   printf("%s: %o\n", name,
       (int)buf.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO));
  else
   printf("%s: ok\n", name);
  unlink(name);
 }
 exit(0);
}