[HACK] fs/super.c: sync ro remount after blocking writers

[Andrew Ruder]

On Fri, Feb 28, 2014 at 10:25:24AM +0100, Richard Weinberger wrote:
> Is it possible to create such a test case?  I don't know whether it is
> possible to trigger the issue on a regular filesystem.  But as hch
> noted, it would be nice to have. :)

I've given this some thought after initially receiving the email and it
would not be easily recreated.  As best as I can tell, the test case
would be something along the line of:

1. # Start up a filesystem writer
2. mount -o remount,ro /testfilesystem
3. # Immediately mark block device as read only
4. # Reboot, show that the filesystem is dirty next time around.

Step 3 I'm not sure how to do, Step 4 makes for the world's most painful
test case.  The thread from Leon Pollak is probably the easiest way to
recreate these issues (remount,ro followed by a hardware-enabled
read-only) and I'm just not sure it belongs in a test case.

- Andy