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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 35229ECE58C for ; Fri, 11 Oct 2019 15:37:42 +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 0BBB0206A1 for ; Fri, 11 Oct 2019 15:37:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0BBB0206A1 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]:52298 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iIwz6-0002qX-Oh for qemu-devel@archiver.kernel.org; Fri, 11 Oct 2019 11:37:40 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57969) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iIwqg-0001vm-A3 for qemu-devel@nongnu.org; Fri, 11 Oct 2019 11:28:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iIwqf-0006hM-3r for qemu-devel@nongnu.org; Fri, 11 Oct 2019 11:28:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58454) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iIwqc-0006fc-NN; Fri, 11 Oct 2019 11:28:54 -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 F1CD199C42; Fri, 11 Oct 2019 15:28:53 +0000 (UTC) Received: from localhost (ovpn-116-40.ams2.redhat.com [10.36.116.40]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 883C6453B; Fri, 11 Oct 2019 15:28:53 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH v3 13/16] qcow2: Repair snapshot table with too many entries Date: Fri, 11 Oct 2019 17:28:11 +0200 Message-Id: <20191011152814.14791-14-mreitz@redhat.com> In-Reply-To: <20191011152814.14791-1-mreitz@redhat.com> References: <20191011152814.14791-1-mreitz@redhat.com> MIME-Version: 1.0 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 [10.5.110.38]); Fri, 11 Oct 2019 15:28:54 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 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, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The user cannot choose which snapshots are removed. This is fine because we have chosen the maximum snapshot table size to be so large (65536 entries) that it cannot be reasonably reached. If the snapshot table exceeds this size, the image has probably been corrupted in some way; in 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.) Signed-off-by: Max Reitz Reviewed-by: Eric Blake --- block/qcow2-snapshot.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index 366d9f574c..dac8a778e4 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -444,6 +444,14 @@ int coroutine_fn qcow2_check_read_snapshot_table(Blo= ckDriverState *bs, s->snapshots_offset =3D be64_to_cpu(snapshot_table_pointer.snapshots= _offset); s->nb_snapshots =3D be32_to_cpu(snapshot_table_pointer.nb_snapshots)= ; =20 + if (s->nb_snapshots > QCOW_MAX_SNAPSHOTS && (fix & BDRV_FIX_ERRORS))= { + fprintf(stderr, "Discarding %u overhanging snapshots\n", + s->nb_snapshots - QCOW_MAX_SNAPSHOTS); + + nb_clusters_reduced +=3D s->nb_snapshots - QCOW_MAX_SNAPSHOTS; + s->nb_snapshots =3D QCOW_MAX_SNAPSHOTS; + } + ret =3D qcow2_validate_table(bs, s->snapshots_offset, s->nb_snapshot= s, sizeof(QCowSnapshotHeader), sizeof(QCowSnapshotHeader) * QCOW_MAX_SNA= PSHOTS, @@ -452,6 +460,12 @@ int coroutine_fn qcow2_check_read_snapshot_table(Blo= ckDriverState *bs, result->check_errors++; error_reportf_err(local_err, "ERROR "); =20 + if (s->nb_snapshots > QCOW_MAX_SNAPSHOTS) { + fprintf(stderr, "You can force-remove all %u overhanging sna= pshots " + "with qemu-img check -r all\n", + s->nb_snapshots - QCOW_MAX_SNAPSHOTS); + } + /* We did not read the snapshot table, so invalidate this inform= ation */ s->snapshots_offset =3D 0; s->nb_snapshots =3D 0; --=20 2.21.0