From patchwork Tue May 23 16:24:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Drobyshev X-Patchwork-Id: 13252618 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id D2C57C7EE26 for ; Tue, 23 May 2023 16:26:07 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1q1Up0-0005LI-Cs; Tue, 23 May 2023 12:25:14 -0400 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 1q1Uou-0005JY-QY; Tue, 23 May 2023 12:25:10 -0400 Received: from relay.virtuozzo.com ([130.117.225.111]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q1Uos-00076p-MR; Tue, 23 May 2023 12:25:08 -0400 Received: from dev005.ch-qa.vzint.dev ([172.29.1.10]) by relay.virtuozzo.com with esmtp (Exim 4.96) (envelope-from ) id 1q1UnN-00DnIw-1X; Tue, 23 May 2023 18:24:48 +0200 To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, kwolf@redhat.com, shmuel.eiderman@oracle.com, andrey.drobyshev@virtuozzo.com, den@virtuozzo.com Subject: [PATCH 1/2] qemu-img: rebase: stop when reaching EOF of old backing file Date: Tue, 23 May 2023 19:24:57 +0300 Message-Id: <20230523162458.704266-2-andrey.drobyshev@virtuozzo.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20230523162458.704266-1-andrey.drobyshev@virtuozzo.com> References: <20230523162458.704266-1-andrey.drobyshev@virtuozzo.com> MIME-Version: 1.0 Received-SPF: pass client-ip=130.117.225.111; envelope-from=andrey.drobyshev@virtuozzo.com; helo=relay.virtuozzo.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, 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: , Reply-to: Andrey Drobyshev X-Patchwork-Original-From: Andrey Drobyshev via From: Andrey Drobyshev Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org 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 break the loop, as there's no more data to be read and merged from the old backing. Signed-off-by: Andrey Drobyshev --- qemu-img.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/qemu-img.c b/qemu-img.c index 27f48051b0..55b6ce407c 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -3813,6 +3813,13 @@ static int img_rebase(int argc, char **argv) strerror(-ret)); goto out; } + if (!n) { + /* + * We've reached EOF of the old backing, therefore there's + * no more mergeable data. + */ + break; + } if (!ret) { continue; }