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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 EF8E3C3A589 for ; Tue, 20 Aug 2019 13:05:36 +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 C3B6F22D6D for ; Tue, 20 Aug 2019 13:05:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C3B6F22D6D 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]:37294 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i03pP-0003Wc-Q6 for qemu-devel@archiver.kernel.org; Tue, 20 Aug 2019 09:05:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39942) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i03oh-0002e1-4H for qemu-devel@nongnu.org; Tue, 20 Aug 2019 09:04:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i03og-0000Eh-4N for qemu-devel@nongnu.org; Tue, 20 Aug 2019 09:04:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36240) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i03oZ-0000Bp-UC; Tue, 20 Aug 2019 09:04:44 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id E5C435F17E; Tue, 20 Aug 2019 13:04:42 +0000 (UTC) Received: from [10.3.116.234] (ovpn-116-234.phx2.redhat.com [10.3.116.234]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 604F03DA5; Tue, 20 Aug 2019 13:04:42 +0000 (UTC) To: Max Reitz , qemu-block@nongnu.org References: <20190819185602.4267-1-mreitz@redhat.com> <20190819185602.4267-13-mreitz@redhat.com> <272cbeba-2053-9aa6-7ceb-e1b3827de540@redhat.com> <39066a69-e319-c3ad-7b3b-2983bb248a25@redhat.com> From: Eric Blake Openpgp: preference=signencrypt Autocrypt: addr=eblake@redhat.com; keydata= xsBNBEvHyWwBCACw7DwsQIh0kAbUXyqhfiKAKOTVu6OiMGffw2w90Ggrp4bdVKmCaEXlrVLU xphBM8mb+wsFkU+pq9YR621WXo9REYVIl0FxKeQo9dyQBZ/XvmUMka4NOmHtFg74nvkpJFCD TUNzmqfcjdKhfFV0d7P/ixKQeZr2WP1xMcjmAQY5YvQ2lUoHP43m8TtpB1LkjyYBCodd+LkV GmCx2Bop1LSblbvbrOm2bKpZdBPjncRNob73eTpIXEutvEaHH72LzpzksfcKM+M18cyRH+nP sAd98xIbVjm3Jm4k4d5oQyE2HwOur+trk2EcxTgdp17QapuWPwMfhaNq3runaX7x34zhABEB AAHNHkVyaWMgQmxha2UgPGVibGFrZUByZWRoYXQuY29tPsLAegQTAQgAJAIbAwULCQgHAwUV CgkICwUWAgMBAAIeAQIXgAUCS8fL9QIZAQAKCRCnoWtKJSdDahBHCACbl/5FGkUqJ89GAjeX RjpAeJtdKhujir0iS4CMSIng7fCiGZ0fNJCpL5RpViSo03Q7l37ss+No+dJI8KtAp6ID+PMz wTJe5Egtv/KGUKSDvOLYJ9WIIbftEObekP+GBpWP2+KbpADsc7EsNd70sYxExD3liwVJYqLc Rw7so1PEIFp+Ni9A1DrBR5NaJBnno2PHzHPTS9nmZVYm/4I32qkLXOcdX0XElO8VPDoVobG6 gELf4v/vIImdmxLh/w5WctUpBhWWIfQDvSOW2VZDOihm7pzhQodr3QP/GDLfpK6wI7exeu3P pfPtqwa06s1pae3ad13mZGzkBdNKs1HEm8x6zsBNBEvHyWwBCADGkMFzFjmmyqAEn5D+Mt4P zPdO8NatsDw8Qit3Rmzu+kUygxyYbz52ZO40WUu7EgQ5kDTOeRPnTOd7awWDQcl1gGBXgrkR pAlQ0l0ReO57Q0eglFydLMi5bkwYhfY+TwDPMh3aOP5qBXkm4qIYSsxb8A+i00P72AqFb9Q7 3weG/flxSPApLYQE5qWGSXjOkXJv42NGS6o6gd4RmD6Ap5e8ACo1lSMPfTpGzXlt4aRkBfvb NCfNsQikLZzFYDLbQgKBA33BDeV6vNJ9Cj0SgEGOkYyed4I6AbU0kIy1hHAm1r6+sAnEdIKj cHi3xWH/UPrZW5flM8Kqo14OTDkI9EtlABEBAAHCwF8EGAEIAAkFAkvHyWwCGwwACgkQp6Fr SiUnQ2q03wgAmRFGDeXzc58NX0NrDijUu0zx3Lns/qZ9VrkSWbNZBFjpWKaeL1fdVeE4TDGm I5mRRIsStjQzc2R9b+2VBUhlAqY1nAiBDv0Qnt+9cLiuEICeUwlyl42YdwpmY0ELcy5+u6wz mK/jxrYOpzXKDwLq5k4X+hmGuSNWWAN3gHiJqmJZPkhFPUIozZUCeEc76pS/IUN72NfprZmF Dp6/QDjDFtfS39bHSWXKVZUbqaMPqlj/z6Ugk027/3GUjHHr8WkeL1ezWepYDY7WSoXwfoAL 2UXYsMAr/uUncSKlfjvArhsej0S4zbqim2ZY6S8aRWw94J3bSvJR+Nwbs34GPTD4Pg== Organization: Red Hat, Inc. Message-ID: <12094c23-597d-b6fc-a279-5609e29c31a9@redhat.com> Date: Tue, 20 Aug 2019 08:04:41 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <39066a69-e319-c3ad-7b3b-2983bb248a25@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="lS80dSunIXD6koqyXPwwDeTcVn1eZF9Z3" X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Tue, 20 Aug 2019 13:04:42 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v2 12/16] qcow2: Fix overly long snapshot tables 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 , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --lS80dSunIXD6koqyXPwwDeTcVn1eZF9Z3 Content-Type: multipart/mixed; boundary="3SnIbpC7KmS1mwNRdiiuJQp5TJtvdzwqi"; protected-headers="v1" From: Eric Blake To: Max Reitz , qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, Kevin Wolf Message-ID: <12094c23-597d-b6fc-a279-5609e29c31a9@redhat.com> Subject: Re: [PATCH v2 12/16] qcow2: Fix overly long snapshot tables References: <20190819185602.4267-1-mreitz@redhat.com> <20190819185602.4267-13-mreitz@redhat.com> <272cbeba-2053-9aa6-7ceb-e1b3827de540@redhat.com> <39066a69-e319-c3ad-7b3b-2983bb248a25@redhat.com> In-Reply-To: <39066a69-e319-c3ad-7b3b-2983bb248a25@redhat.com> --3SnIbpC7KmS1mwNRdiiuJQp5TJtvdzwqi Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 8/20/19 7:09 AM, Max Reitz wrote: > On 19.08.19 21:43, Eric Blake wrote: >> On 8/19/19 1:55 PM, Max Reitz wrote: >>> We currently refuse to open qcow2 images with overly long snapshot >>> tables. This patch makes qemu-img check -r all drop all offending >>> entries past what we deem acceptable. >>> >>> Signed-off-by: Max Reitz >>> --- >>> block/qcow2-snapshot.c | 88 +++++++++++++++++++++++++++++++++++++---= -- >>> 1 file changed, 78 insertions(+), 10 deletions(-) >> >> I know I was reluctant in v1, but you also managed to convince me that= >> it really takes a LOT of effort to get a table with that many entries.= >> And a user has to opt-in to 'qemu-img -r' (it may discard a snapshot >> they value, but that beats not being able to use the image under qemu = at >> all, and we don't erase it for plain 'qemu-img check'). So I'm okay >> with this going in. Maybe the commit message can state this sort of >> reasoning. >=20 > So maybe: >=20 > The user cannot choose which snapshots are removed. This is fine > because we have chosen the maximum snapshot table size to be so large > (64 MB) that it cannot be reasonably reached. If the snapshot table > exceeds this size, the image has probably been corrupted in some way; i= n > this case, it is most important to just make the image usable such that= > the user can copy off at least the active layer. > (Also note that the snapshots will be removed only with "-r all", so a > plain "check" or "check -r leaks" will not delete any data.) I like it. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org --3SnIbpC7KmS1mwNRdiiuJQp5TJtvdzwqi-- --lS80dSunIXD6koqyXPwwDeTcVn1eZF9Z3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAl1b7+kACgkQp6FrSiUn Q2ppRwf9H6pXDvz0CNBsTmqbR2ok+a7rZS1sbDPkmgyWkPuurMZpt8CE3BXSvYqM sqf7y+JMqk4KC124hMA60g4U0UmIfT1tfgThZCaRTL9GCku5VD2iWn4Qo6eT9g3h SlZdkrlXLZMBLGTtc6rGnMKdi9s6m4feKZpaluaZdHqd3+SUQ5+5PjEWP19y8kyL WFum4nax2fd/5VXr90oLQDDlLGMuy2bLj6W2NzmrLW7E8IJ/3Clmf0yU1fgNxa2N kYP9JZIgdbI2UdMBdN7UMYYWxjeTCuc8ThxioDa4POMWeS7zmDOofAvUBCDY1mqX 3aTlopBFcNAyfUpjyqgtPIUlvDkSJg== =JOXz -----END PGP SIGNATURE----- --lS80dSunIXD6koqyXPwwDeTcVn1eZF9Z3--