From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7740C48BDF for ; Tue, 22 Jun 2021 15:39:27 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 84BDF61357 for ; Tue, 22 Jun 2021 15:39:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 84BDF61357 Authentication-Results: mail.kernel.org; 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]:60718 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lviUo-00071U-IS for qemu-devel@archiver.kernel.org; Tue, 22 Jun 2021 11:39:26 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:55256) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lviU3-0006Di-99 for qemu-devel@nongnu.org; Tue, 22 Jun 2021 11:38:39 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:22044) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lviU1-0007Fc-D6 for qemu-devel@nongnu.org; Tue, 22 Jun 2021 11:38:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624376315; 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: in-reply-to:in-reply-to:references:references; bh=2iKC9yl8vSkHFGCGsaH9IqEz1iSDxP7rVwKdckQoh9I=; b=gzB6c3RmU8WCKFnbvbvg4kHWzyW2otXwBM6Nj7MiGflAIe2HFxgAGzp+0U3Z8+QP4yTlSz SQZmt87BWYqWLeIlaNmDEMjGbN3w1JjBXzlgXG+lsefTLUzzbgvHfJKfwRqLuoksYRSOEF dP0CW6dqZ3rgITyU+c4ySyqMOk8swZU= 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-227-se_Y7ysONB6AVIPZn8IFWw-1; Tue, 22 Jun 2021 11:38:34 -0400 X-MC-Unique: se_Y7ysONB6AVIPZn8IFWw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4EFE81935790; Tue, 22 Jun 2021 15:38:33 +0000 (UTC) Received: from redhat.com (ovpn-114-58.ams2.redhat.com [10.36.114.58]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C0D3119C46; Tue, 22 Jun 2021 15:38:31 +0000 (UTC) Date: Tue, 22 Jun 2021 17:38:30 +0200 From: Kevin Wolf To: Eric Blake Subject: Re: [PATCH v2 2/1] qemu-img: Add "backing":true to unallocated map segments Message-ID: References: <20210611140157.1366738-1-eblake@redhat.com> <20210611190316.1424729-1-eblake@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210611190316.1424729-1-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.223, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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: vsementsov@virtuozzo.com, "open list:Block layer core" , Markus Armbruster , qemu-devel@nongnu.org, mreitz@redhat.com, nsoffer@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 11.06.2021 um 21:03 hat Eric Blake geschrieben: > To save the user from having to check 'qemu-img info --backing-chain' > or other followup command to determine which "depth":n goes beyond the > chain, add a boolean field "backing" that is set only for unallocated > portions of the disk. > > Signed-off-by: Eric Blake > --- > > Touches the same iotest output as 1/1. If we decide that switching to > "depth":n+1 is too risky, and that the mere addition of "backing":true > while keeping "depth":n is good enough, then we'd have just one patch, > instead of this double churn. Preferences? I think the additional flag is better because it's guaranteed to be backwards compatible, and because you don't need to know the number of layers to infer whether a cluster was allocated in the whole backing chain. And by exposing ALLOCATED we definitely give access to the whole information that exists in QEMU. However, to continue with the bike shedding: I won't insist on "allocated" even if that is what the flag is called internally and consistency is usually helpful, but "backing" is misleading, too, because intuitively it doesn't cover the top layer or standalone images without a backing file. How about something like "present"? Kevin