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From: Eric Blake <eblake@redhat.com>
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Date: Tue, 29 May 2018 19:52:25 -0500
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Subject: Re: [Qemu-devel] [PATCH] nbd/client: Relax handling of large
 NBD_CMD_BLOCK_STATUS reply
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To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>, qemu-devel@nongnu.org
Cc: Paolo Bonzini <pbonzini@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Max Reitz <mreitz@redhat.com>, "open list:Network Block Dev..." <qemu-block@nongnu.org>

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.=C2=A0 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.
>=20
> Hi!
>=20
> 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

--=20
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org