fs.access throws permission error while checking W_OK on writable dir

* **Version**: `v10.16.0` (also happening on `v12.6.0`) * **Platform**: `18.6.0 Darwin Kernel Version 18.6.0` (also happening on `4.15.0-54-generic Ubuntu`) * **Subsystem**: `fs` I'm experiencing a rather unexpected behaviour when trying `fs.access` on a directory that's also an NFS shared mount point. The check for `fs.constants.W_OK` throws `Error: EACCES: permission denied, access '/mnt/test/nfs'` even though the directory is writable and permissions seem to be correct for the user running the `node` script process. Below is a reproduction of what I'm seeing. ```js const os = require('os'); const path = require('path'); const fs = require('fs'); // Path to the mount directory const MOUNT_PATH = '/mnt/test/nfs'; const filePath = path.join(MOUNT_PATH, 'foo.txt'); // Write a file fs.writeFileSync(filePath, 'Hello world!'); // Passes OK // Read a file const contents = fs.readFileSync(filePath); // Passes OK console.log(contents.toString('utf-8')); // 'Hello World!' // Get stats os.userInfo(); /* { uid: 431, gid: 433, username: 'test', homedir: '/home/test', shell: '/sbin/nologin' } */ fs.stat(MOUNT_PATH, console.log); /* > null Stats { dev: 52, mode: 16895, <- '0777' octal nlink: 1, uid: 431, <- Correct uid gid: 433, <- Correct gid rdev: 0, blksize: 4096, ino: 263, size: 184, blocks: 0, atimeMs: 1562948571578.2288, mtimeMs: 1562897414354.1873, ctimeMs: 1562897414354.1873, birthtimeMs: 0, atime: 2019-07-12T16:22:51.578Z, mtime: 2019-07-12T02:10:14.354Z, ctime: 2019-07-12T02:10:14.354Z, birthtime: 1970-01-01T00:00:00.000Z } */ // Test permissions fs.access(MOUNT_PATH, fs.constants.R_OK, console.error); // Passes OK fs.access(MOUNT_PATH, fs.constants.W_OK, console.error); /* [Error: EACCES: permission denied, access '/mnt/test/nfs'] { errno: -13, code: 'EACCES', syscall: 'access', path: '/mnt/test/nfs' */ ``` This **does not happen on any other directory outside the NFS share**. I stumbled upon the exception when…