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bh=0m5lJuaoSCGNbF3I3vXvrsB1NZ7O+DJtEdGruxHpop0=; b=cw2O823Ff85zlkgi4LP+lulP4vyi+VBoRrwVmnvZHL5y4aIvSHhkIY/UNTPC6LNk+Lc8sS koiMv/zcQqfefXx047ar3eOyzUCQxUj2c+q/Wsz3x5NfoTDNigxrm3s+RnUsguygHYIGQC 6qIH9+BhTfY4HTjl/yA66dSgad+1Im0= 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-404-JHzpQuyCNSaZAVuPhd20zQ-1; Wed, 07 Jul 2021 11:11:01 -0400 X-MC-Unique: JHzpQuyCNSaZAVuPhd20zQ-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 66B9DA40C1; Wed, 7 Jul 2021 15:11:00 +0000 (UTC) Received: from redhat.com (ovpn-112-103.phx2.redhat.com [10.3.112.103]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B69EA84A01; Wed, 7 Jul 2021 15:10:59 +0000 (UTC) Date: Wed, 7 Jul 2021 10:10:57 -0500 From: Eric Blake To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH v3 2/2] qemu-img: Make unallocated part of backing chain obvious in map Message-ID: <20210707151057.n3vpooy4nb3diint@redhat.com> References: <20210701190655.2131223-1-eblake@redhat.com> <20210701190655.2131223-3-eblake@redhat.com> <481dc6cf-a353-b4a0-732c-b758f8750ff6@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: <481dc6cf-a353-b4a0-732c-b758f8750ff6@virtuozzo.com> User-Agent: NeoMutt/20210205-556-f84451-dirty X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 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: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.439, 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: kwolf@redhat.com, qemu-block@nongnu.org, Markus Armbruster , qemu-devel@nongnu.org, nsoffer@redhat.com, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Sat, Jul 03, 2021 at 10:25:28AM +0300, Vladimir Sementsov-Ogievskiy wrote: ... > > An obvious solution is to make 'qemu-img map --output=json' add an > > additional "present":false designation to any cluster lacking an > > allocation anywhere in the chain, without any change to the "depth" > > parameter to avoid breaking existing clients. The iotests have > > several examples where this distinction demonstrates the additional > > accuracy. > > > > Signed-off-by: Eric Blake > > +++ b/docs/tools/qemu-img.rst > > @@ -597,6 +597,9 @@ Command description: > > if false, the sectors are either unallocated or stored as optimized > > all-zero clusters); > > - whether the data is known to read as zero (boolean field ``zero``); > > + - whether the data is actually present (boolean field ``present``); > > + if false, rebasing the backing chain onto a deeper file would pick > > + up data from the deeper file; > > Preexisting, but rather strange style of documentation, when described option doesn't go first in the paragraph.. Yeah. I'll send a followup email with a rewording of those paragraphs for consideration. > > +++ b/qemu-img.c > > @@ -2980,8 +2980,9 @@ static int dump_map_entry(OutputFormat output_format, MapEntry *e, > > break; > > case OFORMAT_JSON: > > printf("{ \"start\": %"PRId64", \"length\": %"PRId64"," > > - " \"depth\": %"PRId64", \"zero\": %s, \"data\": %s", > > - e->start, e->length, e->depth, > > + " \"depth\": %"PRId64", \"present\": %s, \"zero\": %s," > > + "\"data\": %s", e->start, e->length, e->depth, > > + e->present ? "true" : "false", > > Didn't you want to put present at the end? Still, this shouldn't be significant. And it make sense to keep present, zero and data together. I wanted it before anything optional, which "offset" is, so it already can't be at the end. If I understood Nir correctly, it was more important to always be present (it's easy to write a parser that searches for terms in the same position, and tolerates a missing term from an older verseion, but harder to parse a term that might or might not be present). > > You missied a whitespace after '"zero": %s,', which is obvious from further test diff hunks. > > With it fixed: > Reviewed-by: Vladimir Sementsov-Ogievskiy Thanks for catching that. I've updated that, and will queue through my NBD tree. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org