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

[Eric Blake <eblake@redhat.com>]

On 05/29/2018 10:34 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.
> 
> Hi!
> 
> Patch is applied, are you going to make a patch for NBD spec?

Yes, thanks for the reminder (lots going on lately).

https://lists.debian.org/nbd/2018/05/msg00042.html

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