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spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:56396 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kwlr1-0003Te-HP for qemu-devel@archiver.kernel.org; Tue, 05 Jan 2021 07:54:27 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:57254) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kwlol-0001S4-BV for qemu-devel@nongnu.org; Tue, 05 Jan 2021 07:52:07 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:41075) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kwloj-00053o-L2 for qemu-devel@nongnu.org; Tue, 05 Jan 2021 07:52:07 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1609851125; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nizhV6y2Te2uQs2B0KqdeSBngp1K7NSERI32b3e3Cbs=; b=DR+MccppXZOvgTEoQrd87RP+z0qH8mne/2MW/hQepSjzZ+HBruRbeU79ziYg9y+Sug61+f BDVFXBqkJvGHBBVS7HTOLtMSWX3G+TGWaC4jXSuoomUQt1fo9NE8fzribgatWwrwgClpb5 W9Ox6mV8mZiKZs1vMIhj3qTykcpKlm4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-377-vtPl9N03ORyzjrUOeAHnqw-1; Tue, 05 Jan 2021 07:52:01 -0500 X-MC-Unique: vtPl9N03ORyzjrUOeAHnqw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DCF35801817; Tue, 5 Jan 2021 12:51:59 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-113-1.ams2.redhat.com [10.36.113.1]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 69FF25C1C2; Tue, 5 Jan 2021 12:51:54 +0000 (UTC) Subject: Re: [PATCH v15 10/13] qapi: block-stream: add "bottom" argument To: Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org References: <20201216061703.70908-1-vsementsov@virtuozzo.com> <20201216061703.70908-11-vsementsov@virtuozzo.com> <4039f38e-e519-fe51-45c8-ce761587961b@virtuozzo.com> From: Max Reitz Message-ID: Date: Tue, 5 Jan 2021 13:51:53 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <4039f38e-e519-fe51-45c8-ce761587961b@virtuozzo.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -32 X-Spam_score: -3.3 X-Spam_bar: --- X-Spam_report: (-3.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.252, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.249, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fam@euphon.net, kwolf@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com, stefanha@redhat.com, den@openvz.org, andrey.shinkevich@virtuozzo.com, jsnow@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 22.12.20 19:00, Vladimir Sementsov-Ogievskiy wrote: > 22.12.2020 19:07, Max Reitz wrote: >> On 16.12.20 07:17, Vladimir Sementsov-Ogievskiy wrote: >>> The code already don't freeze base node and we try to make it prepared >>> for the situation when base node is changed during the operation. In >>> other words, block-stream doesn't own base node. >>> >>> Let's introduce a new interface which should replace the current one, >>> which will in better relations with the code. Specifying bottom node >>> instead of base, and requiring it to be non-filter gives us the >>> following benefits: >>> >>>   - drop difference between above_base and base_overlay, which will be >>>     renamed to just bottom, when old interface dropped >>> >>>   - clean way to work with parallel streams/commits on the same backing >>>     chain, which otherwise become a problem when we introduce a filter >>>     for stream job >>> >>>   - cleaner interface. Nobody will surprised the fact that base node may >>>     disappear during block-stream, when there is no word about "base" in >>>     the interface. >>> >>> Signed-off-by: Vladimir Sementsov-Ogievskiy >>> --- >>>   qapi/block-core.json           | 12 ++++--- >>>   include/block/block_int.h      |  1 + >>>   block/monitor/block-hmp-cmds.c |  3 +- >>>   block/stream.c                 | 50 +++++++++++++++++++--------- >>>   blockdev.c                     | 59 ++++++++++++++++++++++++++++------ >>>   5 files changed, 94 insertions(+), 31 deletions(-) >>> >>> diff --git a/qapi/block-core.json b/qapi/block-core.json >>> index b8094a5ec7..cb0066fd5c 100644 >>> --- a/qapi/block-core.json >>> +++ b/qapi/block-core.json >>> @@ -2517,10 +2517,14 @@ >>>   # @device: the device or node name of the top image >>>   # >>>   # @base: the common backing file name. >>> -#        It cannot be set if @base-node is also set. >>> +#        It cannot be set if @base-node or @bottom is also set. >>>   # >>>   # @base-node: the node name of the backing file. >>> -#             It cannot be set if @base is also set. (Since 2.8) >>> +#             It cannot be set if @base or @bottom is also set. >>> (Since 2.8) >>> +# >>> +# @bottom: the last node in the chain that should be streamed into >>> +#          top. It cannot be set if @base or @base-node is also set. >>> +#          It cannot be filter node. (Since 6.0) >> >> As far as I can make out, one of the results of our discussion on v14 >> was that when using backing-file + bottom, we want to require the user >> to specify backing-fmt as well.  Now, backing-fmt isn’t present yet. >> Doesn’t that mean we have to make bottom + backing-file an error until >> we have backing-fmt (like it was in v14)? > > See my answer on 09. I just have some doubts around backing-fmt and > decided to keep it as is. > > I don't think that we really need backing-fmt. We shouldn't have > use-cases when backing-fmt is set to something another than final base > node. Therefore, using format_name of final base node is a correct thing > to do. So, I don't see the reason now for introducing new option. Yup, yup, all good. Reviewed-by: Max Reitz