[Sheepdog] [QEMU PATCH] sheepdog: add cache flush support

[MORITA Kazutaka]

At Wed, 16 Nov 2011 03:12:39 -0500,
Christoph Hellwig wrote:
> 
> On Wed, Nov 16, 2011 at 02:07:07PM +0900, MORITA Kazutaka wrote:
> > At Tue, 15 Nov 2011 17:06:52 -0500,
> > Christoph Hellwig wrote:
> > > 
> > > This patch implement support for writeback-style cache in the sheepdog
> > > protocol.  The SD_OP_FLUSH_VDI command will flush all data for the
> > > referenced VDI to stable storage.
> > > 
> > > XXX: we'll need to figure out if the sheep server actually support this
> > > command somehow.
> > 
> > If we increment SD_PROTO_VER, the sheep daemon should return
> > SD_RES_VER_MISMATCH error when opening the VDI.
> 
> And then revert to trying the old protocol revision if it fails?  Sounds
> like that would be worth a try.

Or perhaps it might be better not to support the old protocol in the
qemu block driver?  It will make the code complicated.

Thanks,

Kazutaka