title: When is an AsynchronousFileChannel write "complete"?
body: <p>In Java, when one calls <code>AsynchronousFileChannel.write(...)</code> one receives a <code>Future</code>, which one can then wait on for completion via <code>Future.get()</code>.</p>
  
  <p>When that <code>get()</code> call returns, has the write been written to the disk, or just the page cache?</p>
  
  <p>If it matters, the specific platform I'm curious about is Linux &amp; ext4.</p>