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=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 8CE99C47094 for ; Thu, 10 Jun 2021 14:06:22 +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 35826613BC for ; Thu, 10 Jun 2021 14:06:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 35826613BC 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]:51076 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lrLK9-00036S-DC for qemu-devel@archiver.kernel.org; Thu, 10 Jun 2021 10:06:21 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54060) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lrLI9-0000Zj-Il for qemu-devel@nongnu.org; Thu, 10 Jun 2021 10:04:17 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:47611) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lrLI4-0006rL-3M for qemu-devel@nongnu.org; Thu, 10 Jun 2021 10:04:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623333850; 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=jsT63Ix6jEnXnT+1jAmW+4KyGK5RwpN6nVbid4d/AOY=; b=d7U6edf755/rwJfxzTn9F550UY+pJJpZxpf+wf3fH2sRmvTNaFm8Ptr8Bubmi6r0gEOAqp Ri9Y/oMNTiA/lCq+1knNuoZvhQzD4lcN1B1zrzWFeHqS95UEQI0wfH4MlhhpXc464dZg2C BKDTjn/z8+HjZjjtelNr+WBBn1yf2bA= 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-42-hQnjt5NgMMSkWbb7Mbg07Q-1; Thu, 10 Jun 2021 10:04:07 -0400 X-MC-Unique: hQnjt5NgMMSkWbb7Mbg07Q-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 7397A18D6A2F; Thu, 10 Jun 2021 14:04:06 +0000 (UTC) Received: from redhat.com (ovpn-113-53.phx2.redhat.com [10.3.113.53]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7305E19D7C; Thu, 10 Jun 2021 14:04:02 +0000 (UTC) Date: Thu, 10 Jun 2021 09:04:00 -0500 From: Eric Blake To: Nir Soffer Subject: Re: [PATCH 2/2] nbd: Add new qemu:joint-allocation metadata context Message-ID: <20210610140400.s5bprikdunfkc5uh@redhat.com> References: <20210609180118.1003774-1-eblake@redhat.com> <20210609180118.1003774-3-eblake@redhat.com> MIME-Version: 1.0 In-Reply-To: User-Agent: NeoMutt/20210205 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@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=170.10.133.124; envelope-from=eblake@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=-0.199, 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: Kevin Wolf , Vladimir Sementsov-Ogievskiy , qemu-block , QEMU Developers , Markus Armbruster , Max Reitz , libguestfs@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Jun 10, 2021 at 04:16:27PM +0300, Nir Soffer wrote: > On Thu, Jun 10, 2021 at 2:52 AM Nir Soffer wrote: > > > > On Wed, Jun 9, 2021 at 9:01 PM Eric Blake wrote: > > I posted a work in progress patch implementing support for > qemu:joint-allocaition > in oVirt: > https://gerrit.ovirt.org/c/ovirt-imageio/+/115197 > > The most important part is the nbd client: > https://gerrit.ovirt.org/c/ovirt-imageio/+/115197/1/daemon/ovirt_imageio/_internal/nbd.py > > With this our tests pass with qemu-nbd build with Eric patch: > https://gerrit.ovirt.org/c/ovirt-imageio/+/115197/1/daemon/test/client_test.py Note that you _don't_ have to use qemu:joint-allocation; you could get the same information by using the already-existing qemu:allocation-depth. But your patch DOES make it obvious that it was a lot simpler to use a single context (the bulk of your tweak is trying an additional NBD_OPT_SET_META_CONTEXT), than it would be to handle parallel contexts (where you would have to tweak your NBD_CMD_BLOCK_STATUS handler to cross-correlate information). > > We may need to use qemu:joint-allocation only for qcow2 images, and > base:allocation > for raw images, because allocation depth reporting is not correct for > raw images. Since Allocation depth (aka how deep in the backing chain is data allocated) IS correct for raw images (the raw image IS the source of all data); it is just not useful. > we control the qemu-nbd in both cases this should not be an issue. But > it would be > better if allocation depth would work for any kind of image, and we always use > qemu:joint-allocation. Maybe the thing to do is improve the documentation and try to avoid ambiguous terminalogy; in qemu:allocation-depth, a return of depth 0 should be called "absent", not "unallocated". And in libnbd, a base:allocation of 0 should be "data" or "normal", not "allocated". But I don't see how qemu will ever advertise an allocation depth of 0 for a raw image, because raw images have no backing chain to defer to. If you are trying to recreate a sparse raw image, then you really do want to pay attention to NBD_STATE_HOLE and NBD_STATE_ZERO, as those are more accurate pictures of the properties of extents within the raw file. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org