title: Does blockdev --flushbufs reliably sync to disk?
body: <p>I am using <code>blockdev --flushbufs /dev/mmcblk0p1</code> in one of our shell scripts.</p>
  
  <p>I have assumed that it has same effect as sync for raw block device access.</p>
  
  <p>I wonder whether it's safe to assume at the end of <code>blockdev --flushbufs</code> all delayed writes are completed for that device?</p>
  
  <p>(The man page mentions ioctls so I think it should be blocking?)</p>