From nobody Tue Feb 10 11:15:31 2026 Delivered-To: importer@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+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1763777936813106.01605743698599; Fri, 21 Nov 2025 18:18:56 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vMd6B-00046u-Tl; Fri, 21 Nov 2025 21:11:40 -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 1vMcsv-0007fj-Qe; Fri, 21 Nov 2025 20:57:57 -0500 Received: from isrv.corpit.ru ([212.248.84.144]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vMcrX-0007RP-TZ; Fri, 21 Nov 2025 20:57:54 -0500 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 0DEB016CA78; Fri, 21 Nov 2025 21:44:28 +0300 (MSK) Received: from think4mjt.tls.msk.ru (mjtthink.wg.tls.msk.ru [192.168.177.146]) by tsrv.corpit.ru (Postfix) with ESMTP id BFFA5321CB4; Fri, 21 Nov 2025 21:44:36 +0300 (MSK) From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Vincent Vanlaer , Vladimir Sementsov-Ogievskiy , Michael Tokarev Subject: [Stable-10.0.7 61/81] block: allow commit to unmap zero blocks Date: Fri, 21 Nov 2025 21:44:00 +0300 Message-ID: <20251121184424.1137669-61-mjt@tls.msk.ru> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: 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+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=212.248.84.144; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru 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, T_SPF_HELO_TEMPERROR=0.01, T_SPF_TEMPERROR=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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1763777939244018900 Content-Type: text/plain; charset="utf-8" From: Vincent Vanlaer Non-active block commits do not discard blocks only containing zeros, causing images to lose sparseness after the commit. This commit fixes that by writing zero blocks using blk_co_pwrite_zeroes rather than writing them out as any other arbitrary data. Signed-off-by: Vincent Vanlaer Reviewed-by: Vladimir Sementsov-Ogievskiy Message-Id: <20241026163010.2865002-5-libvirt-e6954efa@volkihar.be> Signed-off-by: Vladimir Sementsov-Ogievskiy (cherry picked from commit 6f3199f99600fe75f32f78574e507f347de80854) Signed-off-by: Michael Tokarev diff --git a/block/commit.c b/block/commit.c index 5c6596a52e..7cc8c0f0df 100644 --- a/block/commit.c +++ b/block/commit.c @@ -150,19 +150,39 @@ static int commit_iteration(CommitBlockJob *s, int64_= t offset, } =20 if (ret & BDRV_BLOCK_ALLOCATED) { - assert(bytes < SIZE_MAX); + if (ret & BDRV_BLOCK_ZERO) { + /* + * If the top (sub)clusters are smaller than the base + * (sub)clusters, this will not unmap unless the underlying de= vice + * does some tracking of these requests. Ideally, we would find + * the maximal extent of the zero clusters. + */ + ret =3D blk_co_pwrite_zeroes(s->base, offset, bytes, + BDRV_REQ_MAY_UNMAP); + if (ret < 0) { + error_in_source =3D false; + goto fail; + } + } else { + assert(bytes < SIZE_MAX); =20 - ret =3D blk_co_pread(s->top, offset, bytes, buf, 0); - if (ret < 0) { - goto fail; - } + ret =3D blk_co_pread(s->top, offset, bytes, buf, 0); + if (ret < 0) { + goto fail; + } =20 - ret =3D blk_co_pwrite(s->base, offset, bytes, buf, 0); - if (ret < 0) { - error_in_source =3D false; - goto fail; + ret =3D blk_co_pwrite(s->base, offset, bytes, buf, 0); + if (ret < 0) { + error_in_source =3D false; + goto fail; + } } =20 + /* + * Whether zeroes actually end up on disk depends on the details of + * the underlying driver. Therefore, this might rate limit more th= an + * is necessary. + */ block_job_ratelimit_processed_bytes(&s->common, bytes); } =20 --=20 2.47.3