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=-5.1 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 29310C2D0A8 for ; Mon, 28 Sep 2020 16:19:19 +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 A029A2065D for ; Mon, 28 Sep 2020 16:19:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bQj2vNht" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A029A2065D 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]:53450 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kMvrw-0003D3-PQ for qemu-devel@archiver.kernel.org; Mon, 28 Sep 2020 12:19:16 -0400 Received: from eggs.gnu.org ([209.51.188.92]:51428) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kMvqn-0001wD-6g for qemu-devel@nongnu.org; Mon, 28 Sep 2020 12:18:07 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:49661) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kMvqj-0006R6-1l for qemu-devel@nongnu.org; Mon, 28 Sep 2020 12:18:02 -0400 Dkim-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1601309879; 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=MJqs61XpTMU8IbiDJZRxuDfgRkI0vvURgaitP0ZLsQQ=; b=bQj2vNhtcLSJRXf9EaORWwGU2gc0pINfvKjvrtu7fvMgWnzuDU3BHeUP4kREWuzhyCqCWh bYHSJhEMlZFzqs8352YIlXJ0/ymgGy0i9dBHwGEcx838hHQZxGpUAjSN5I1y/yjxIJ0FdV 5lqoyji7A2EjALhrfNN6TZYskzZC8KE= 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-400-dWxVSEuUMP2EnjZ2kIH7kA-1; Mon, 28 Sep 2020 12:17:47 -0400 X-MC-Unique: dWxVSEuUMP2EnjZ2kIH7kA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A5517800683; Mon, 28 Sep 2020 16:17:46 +0000 (UTC) Received: from localhost (ovpn-112-51.ams2.redhat.com [10.36.112.51]) by smtp.corp.redhat.com (Postfix) with ESMTP id E6CCC1002C01; Mon, 28 Sep 2020 16:17:45 +0000 (UTC) Date: Mon, 28 Sep 2020 17:17:45 +0100 From: "Richard W.M. Jones" To: Eric Blake Subject: Re: [PATCH 2/3] nbd: Add new qemu:allocation-depth metacontext Message-ID: <20200928161745.GB30079@redhat.com> References: <20200925203249.155705-1-eblake@redhat.com> <20200925203249.155705-3-eblake@redhat.com> <20200926073308.GV3888@redhat.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=rjones@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=63.128.21.124; envelope-from=rjones@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/28 03:47:08 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.687, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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 , pkrempa@redhat.com, qemu-block@nongnu.org, Markus Armbruster , qemu-devel@nongnu.org, Max Reitz , vsementsov@virtuozzo.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Sep 28, 2020 at 09:33:22AM -0500, Eric Blake wrote: > On 9/26/20 2:33 AM, Richard W.M. Jones wrote: > >On Fri, Sep 25, 2020 at 03:32:48PM -0500, Eric Blake wrote: > >>+The second is related to exposing the source of various extents within > >>+the image, with a single context named: > >>+ > >>+ qemu:allocation-depth > >>+ > >>+In the allocation depth context, bits 0 and 1 form a tri-state value: > >>+ > >>+ bits 0-1 clear: NBD_STATE_DEPTH_UNALLOC, means the extent is unallocated > >>+ bit 0 set: NBD_STATE_DEPTH_LOCAL, the extent is allocated in this image > >>+ bit 1 set: NBD_STATE_DEPTH_BACKING, the extent is inherited from a > >>+ backing layer > > > >>From the cover description I imagined it would show the actual depth, ie: > > > > top -> backing -> backing -> backing > > depth: 1 2 3 .... (0 = unallocated) > > > >I wonder if that is possible? (Perhaps there's something I don't > >understand here.) > > The real reason I don't want to do a straight depth number is that > 'qemu-img map' combined with x-dirty-bitmap is still a very > convenient way to get at bits 0 and 1 (even if it requires > decoding). But if we plumb in a way for bdrv_get_status to return > depth counts (rather than reimplementing the depth count ourselves), > I would have no problem with returning a struct: > > bits 31-4: the depth of the chain > bits 3-2: reserved (to make reading hex values easier...) > bits 1-0: tri-state of unalloc, local, or backing > > where it would look like: > > 0x0000 -> unallocated > 0x0011 -> depth 1, local > 0x0022 -> depth 2, from the first backing layer > 0x0032 -> depth 3, from the second backing layer > 0x0042 ... This looks nice too. However I was only bikeshedding so if any of this is hard to do then don't worry too much. Would like to add support for this map to nbdinfo too :-) Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into KVM guests. http://libguestfs.org/virt-v2v