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spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:34132 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1krkDU-0004ju-O7 for qemu-devel@archiver.kernel.org; Tue, 22 Dec 2020 11:08:52 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:44602) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1krkCE-0003d8-Fo for qemu-devel@nongnu.org; Tue, 22 Dec 2020 11:07:37 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:49673) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1krkCC-0000aM-4b for qemu-devel@nongnu.org; Tue, 22 Dec 2020 11:07:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608653251; 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=tr0RF5mNK3Z7XmBCMZCf7xz6qy3jLZC7WGPVXd2VIdU=; b=S9kQx+Y3NMFMRL2HxX9iS3+YLg9NQxftJi155lgjB+5qzR72Q27cT/Lgo1B4oGvEJ2nnJx 6ytOkAEW41TruyMetwyIxQezg+W8y6bgMq+NfceIR8pEW0oU26os59HGDk1l9bHFutgZ1M 50vinS5s5YCEmQGzzmMFSjfQalCRYlc= 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-234-V_3a2XQnNzebM20Bz_sraQ-1; Tue, 22 Dec 2020 11:07:27 -0500 X-MC-Unique: V_3a2XQnNzebM20Bz_sraQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CB0E8800D53; Tue, 22 Dec 2020 16:07:25 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-113-243.ams2.redhat.com [10.36.113.243]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7E1D5779CD; Tue, 22 Dec 2020 16:07:20 +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> From: Max Reitz Message-ID: Date: Tue, 22 Dec 2020 17:07:18 +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: <20201216061703.70908-11-vsementsov@virtuozzo.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 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=63.128.21.124; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -45 X-Spam_score: -4.6 X-Spam_bar: ---- X-Spam_report: (-4.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-2.521, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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 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)? Or do you consider the change to patch 9 sufficient to make at least the case work for which backing-file was purportedly introduced, i.e. FD passing? (Patch 9’s new version will just take the format of the base post-streaming, which would be most likely a correct guess when using FD passing.) (I.e., now with patch 9 being more liberal in guessing, perhaps you decided to no longer make backing-fmt mandatory after all.) Max