Re: [Qemu-devel] [PATCH] nbd/server: introduce NBD_CMD_CACHE

[Vladimir Sementsov-Ogievskiy]

18.04.2018 19:37, Eric Blake wrote:
> On 04/13/2018 09:31 AM, Vladimir Sementsov-Ogievskiy wrote:
> > Handle nbd CACHE command. Just do read, without sending read data back.
> > Cache mechanism should be done by exported node driver chain.
> >
> > Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> > ---
> >   include/block/nbd.h |  3 ++-
> >   nbd/server.c        | 10 ++++++----
> >   2 files changed, 8 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/block/nbd.h b/include/block/nbd.h
> > index fcdcd54502..b4793d0a29 100644
> > --- a/include/block/nbd.h
> > +++ b/include/block/nbd.h
> > @@ -135,6 +135,7 @@ typedef struct NBDExtent {
> >   #define NBD_FLAG_SEND_TRIM         (1 << 5) /* Send TRIM (discard) */
> >   #define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */
> >   #define NBD_FLAG_SEND_DF           (1 << 7) /* Send DF (Do not Fragment) */
> > +#define NBD_FLAG_SEND_CACHE        (1 << 8) /* Send CACHE (prefetch) */
> Hmm, this flag is not documented in the upstream NBD protocol yet; are
> we sure it matches the xNBD implementation?  We'll want at least a
> documentation patch proposed for the NBD list before taking this.

The discussion already on list:
https://lists.debian.org/nbd/2018/03/msg00040.html

--
Best regards,
Vladimir