From patchwork Thu Nov 9 13:59:11 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Tokarev X-Patchwork-Id: 1862102 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=patchwork.ozlabs.org) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4SR3px0SVsz1yRF for ; Fri, 10 Nov 2023 01:14:01 +1100 (AEDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1r15fy-0006RW-2t; Thu, 09 Nov 2023 09:06:30 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r15dC-0005k8-P5; Thu, 09 Nov 2023 09:03:44 -0500 Received: from isrv.corpit.ru ([86.62.121.231]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r15dA-0006xU-6r; Thu, 09 Nov 2023 09:03:37 -0500 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 6D06A31BE3; Thu, 9 Nov 2023 16:59:57 +0300 (MSK) Received: from tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with SMTP id 74DA23451A; Thu, 9 Nov 2023 16:59:49 +0300 (MSK) Received: (nullmailer pid 1462909 invoked by uid 1000); Thu, 09 Nov 2023 13:59:47 -0000 From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Andrey Drobyshev , "Denis V . Lunev" , Hanna Czenczek , Kevin Wolf , Michael Tokarev Subject: [Stable-7.2.7 43/62] qemu-img: rebase: stop when reaching EOF of old backing file Date: Thu, 9 Nov 2023 16:59:11 +0300 Message-Id: <20231109135933.1462615-43-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.2 In-Reply-To: References: MIME-Version: 1.0 Received-SPF: pass client-ip=86.62.121.231; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Andrey Drobyshev In case when we're rebasing within one backing chain, and when target image is larger than old backing file, bdrv_is_allocated_above() ends up setting *pnum = 0. As a result, target offset isn't getting incremented, and we get stuck in an infinite for loop. Let's detect this case and proceed further down the loop body, as the offsets beyond the old backing size need to be explicitly zeroed. Signed-off-by: Andrey Drobyshev Reviewed-by: Denis V. Lunev Reviewed-by: Hanna Czenczek Message-ID: <20230919165804.439110-2-andrey.drobyshev@virtuozzo.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf (cherry picked from commit 8b097fd6b06ec295faefd4f30f96f8709abc9605) Signed-off-by: Michael Tokarev diff --git a/qemu-img.c b/qemu-img.c index a9b3a8103c..2c32d9da4e 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -3753,6 +3753,8 @@ static int img_rebase(int argc, char **argv) } if (prefix_chain_bs) { + uint64_t bytes = n; + /* * If cluster wasn't changed since prefix_chain, we don't need * to take action @@ -3765,9 +3767,18 @@ static int img_rebase(int argc, char **argv) strerror(-ret)); goto out; } - if (!ret) { + if (!ret && n) { continue; } + if (!n) { + /* + * If we've reached EOF of the old backing, it means that + * offsets beyond the old backing size were read as zeroes. + * Now we will need to explicitly zero the cluster in + * order to preserve that state after the rebase. + */ + n = bytes; + } } /*