On Wed, 2012-04-25 at 09:45 +0100, Christoph Hellwig wrote:
> > - case BLKIF_OP_WRITE_BARRIER:
> > + case BLKIF_OP_FLUSH_DISKCACHE:
> > if (!ioreq->req.nr_segments) {
> > ioreq->presync = 1;
> > return 0;
> > }
> > - ioreq->presync = ioreq->postsync = 1;
> > + ioreq->postsync = 1;
> > /* fall through */
>
> It might be worth documenting the semantics of BLKIF_OP_FLUSH_DISKCACHE
> in a comment here. I haven't found any spec for the xen_disk protocol,
The blkif spec was recently much improved, you can find it at
http://xenbits.xen.org/docs/unstable/hypercall/include,public,io,blkif.h.html
TBH I'm not sure it actually answers your questions wrt
BLKIF_OP_FLUSH_DISKCACHE, if not please let us know and we can see about
improving it.
Ian
