From nobody Mon May 12 13:58:10 2025 Delivered-To: importer2@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer2=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=nongnu.org ARC-Seal: i=1; a=rsa-sha256; t=1695142817; cv=none; d=zohomail.com; s=zohoarc; b=FGBMrFdP1XhKRFf2pWNRZfQnDe0Ao52lyFCxXre/rmaD9qmIrA6aJ00u/U7vZYKM4QPdgRj82P9kxoc4pgT8siSFwjwzv97BBylLi3d9fMzeBaCIE/3xP0kwEs5qDTExcjb206FXP7kxjTFJr3l3gWHcUBqaqG5KLIXE/g6s9/I= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1695142817; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:Reply-To:References:Sender:Subject:To; bh=jY4pafEDv7pLVgxPmZpFOAs+FDZKZeE3uI4uyAX+VHA=; b=RyuUy9BixuM8wAOG1cRuasQwzbWjBpW3toaP/frjYowT7O+KHW6IAPx4/QSaTmvutWGE1jQd5eTQVLvmiRiEIQ1D6Z5qf2vfEfp9UFKP+weQOtOFhH2OZfS3Q9i5a8ljfxSnLCxazLvoPMTGKmCz/JNq5l5XsHgxZcQBAGluW7k= ARC-Authentication-Results: i=1; mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer2=patchew.org@nongnu.org; dmarc=pass header.from= (p=none dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1695142817668122.80458292710193; Tue, 19 Sep 2023 10:00:17 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qie3H-0003iw-OF; Tue, 19 Sep 2023 12:58:19 -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 1qie3B-0003eH-CY; Tue, 19 Sep 2023 12:58:13 -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 1qie37-0002Mb-Ev; Tue, 19 Sep 2023 12:58:13 -0400 Received: from [130.117.225.1] (helo=dev005.ch-qa.vzint.dev) by relay.virtuozzo.com with esmtp (Exim 4.96) (envelope-from ) id 1qidzZ-00DUte-2m; Tue, 19 Sep 2023 18:57:54 +0200 To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, hreitz@redhat.com, kwolf@redhat.com, eblake@redhat.com, andrey.drobyshev@virtuozzo.com, den@virtuozzo.com Subject: [PATCH v3 1/8] qemu-img: rebase: stop when reaching EOF of old backing file Date: Tue, 19 Sep 2023 19:57:57 +0300 Message-Id: <20230919165804.439110-2-andrey.drobyshev@virtuozzo.com> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20230919165804.439110-1-andrey.drobyshev@virtuozzo.com> References: <20230919165804.439110-1-andrey.drobyshev@virtuozzo.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer2=patchew.org@nongnu.org; helo=lists.gnu.org; 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 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 From: Andrey Drobyshev via Errors-To: qemu-devel-bounces+importer2=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer2=patchew.org@nongnu.org X-ZM-MESSAGEID: 1695142818565100001 Content-Type: text/plain; charset="utf-8" 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 =3D 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 --- qemu-img.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/qemu-img.c b/qemu-img.c index a48edb7101..50660ba920 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -3805,6 +3805,8 @@ static int img_rebase(int argc, char **argv) } =20 if (prefix_chain_bs) { + uint64_t bytes =3D n; + /* * If cluster wasn't changed since prefix_chain, we don't = need * to take action @@ -3817,9 +3819,18 @@ 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 t= hat + * offsets beyond the old backing size were read as ze= roes. + * Now we will need to explicitly zero the cluster in + * order to preserve that state after the rebase. + */ + n =3D bytes; + } } =20 /* --=20 2.39.3