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dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:43224 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kdXOr-0004Bw-KQ for qemu-devel@archiver.kernel.org; Fri, 13 Nov 2020 06:37:53 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:51338) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kdXO9-0003Fn-P8 for qemu-devel@nongnu.org; Fri, 13 Nov 2020 06:37:09 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:54870) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kdXO4-00084V-3o for qemu-devel@nongnu.org; Fri, 13 Nov 2020 06:37:09 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605267422; 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=HsWH8Y79r50fdzH7z2ps7QNRmRndghvZyHj+h7f2MEw=; b=GWE1INgaPwuESxlAduJiyXCsOX+ai5juO3DIU6LP7g6sL0e88iiHZWGQu/Fibisp4h6bRZ 5BKSvIMEY5RX1mVOsTvQ8L4sqDCUoAaGFzBh0QMa785CIpfy8j2fEfkpSmnwRv46C5BjZ7 yXRwGuWEywsc5YqfzR+DjIyVh4el/tk= 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-148-WL_1bXDCMwK4HYdeXzohKA-1; Fri, 13 Nov 2020 06:37:01 -0500 X-MC-Unique: WL_1bXDCMwK4HYdeXzohKA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2C965185A0FC; Fri, 13 Nov 2020 11:37:00 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-114-96.ams2.redhat.com [10.36.114.96]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9708160BE2; Fri, 13 Nov 2020 11:36:58 +0000 (UTC) Subject: Re: [PATCH v3 1/2] quorum: Implement bdrv_co_block_status() To: Alberto Garcia , qemu-devel@nongnu.org References: <6b6256192945e7cacb9b0a9bf2b0db086d7f52e3.1605111801.git.berto@igalia.com> From: Max Reitz Message-ID: <6045ed83-ffa6-b5e8-e604-ce2140aef7ea@redhat.com> Date: Fri, 13 Nov 2020 12:36:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <6b6256192945e7cacb9b0a9bf2b0db086d7f52e3.1605111801.git.berto@igalia.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=mreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/11/12 16:09:27 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=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: Kevin Wolf , Tao Xu , qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 11.11.20 17:53, Alberto Garcia wrote: > The quorum driver does not implement bdrv_co_block_status() and > because of that it always reports to contain data even if all its > children are known to be empty. > > One consequence of this is that if we for example create a quorum with > a size of 10GB and we mirror it to a new image the operation will > write 10GB of actual zeroes to the destination image wasting a lot of > time and disk space. > > Since a quorum has an arbitrary number of children of potentially > different formats there is no way to report all possible allocation > status flags in a way that makes sense, so this implementation only > reports when a given region is known to contain zeroes > (BDRV_BLOCK_ZERO) or not (BDRV_BLOCK_DATA). > > If all children agree that a region contains zeroes then we can return > BDRV_BLOCK_ZERO using the smallest size reported by the children > (because all agree that a region of at least that size contains > zeroes). > > If at least one child disagrees we have to return BDRV_BLOCK_DATA. > In this case we use the largest of the sizes reported by the children > that didn't return BDRV_BLOCK_ZERO (because we know that there won't > be an agreement for at least that size). > > Signed-off-by: Alberto Garcia > Tested-by: Tao Xu > --- > block/quorum.c | 52 +++++++++++++ > tests/qemu-iotests/312 | 148 +++++++++++++++++++++++++++++++++++++ > tests/qemu-iotests/312.out | 67 +++++++++++++++++ > tests/qemu-iotests/group | 1 + > 4 files changed, 268 insertions(+) > create mode 100755 tests/qemu-iotests/312 > create mode 100644 tests/qemu-iotests/312.out Reviewed-by: Max Reitz