Re: JFYI: ext4 bug triggerable by kvm

Christoph Hellwig
2010-08-17T14:46:52Z

On Tue, Aug 17, 2010 at 09:44:49AM -0500, Anthony Liguori wrote:
> I think the real issue is we're mixing host configuration with guest
> visible state.

The last time I proposed to decouple the two you and Avi were heavily
opposed to it..

> With O_SYNC, we're causing cache=writethrough to do writethrough
> through two layers of the storage heirarchy. I don't think that's
> necessary or desirable though.

It's absolutely nessecary if we tell the guest that we do not have
a volatile write cache. Which is the only good reason to use
data=writethrough anyway - except for dealing with old guests that
can't handle volatile writecache it's an absolutely stupid mode of
operation.