Re: [Qemu-devel] [PATCH] nbd/client: Relax handling of large NBD_CMD_BLOCK_STATUS reply

[Eric Blake]

On 05/04/2018 05:40 AM, Vladimir Sementsov-Ogievskiy wrote:
> 04.05.2018 01:26, Eric Blake wrote:
> > The NBD spec is proposing a relaxation of NBD_CMD_BLOCK_STATUS
> > where a server may have the final extent per context give a
> > length beyond the original request, if it can easily prove that
> > subsequent bytes have the same status, on the grounds that a
> > client can take advantage of this information for fewer block
> > status requests.  Since qemu 2.12 as a client always sends
> > NBD_CMD_FLAG_REQ_ONE, and rejects a server that sends extra
> > length, the upstream NBD spec will probably limit this behavior
> > to clients that don't request REQ_ONE semantics; but it doesn't
> > hurt to relax qemu to always be permissive of this server
> > behavior, even if it continues to use REQ_ONE.
> >
> > Signed-off-by: Eric Blake <address@hidden>
> > ---
> >   block/nbd-client.c | 10 +++++++---
> >   1 file changed, 7 insertions(+), 3 deletions(-)

> with s/==/=/
>
>
> Reviewed-by:  Vladimir Sementsov-Ogievskiy <address@hidden>

Thanks; queuing the fixed patch on my NBD tree.  Also, I think this 
deserves to go in a stable release, to minimize the chance that we choke 
on an incompatible server, so:

CC: address@hidden

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org