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[130.117.225.111]) by mx.google.com with ESMTPS id ffacd0b85a97d-482fbab3389si3920968f8f.6.2026.08.28.10.03.49 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Aug 2026 10:03:49 -0700 (PDT) Received-SPF: pass (google.com: domain of khorenko@virtuozzo.com designates 130.117.225.111 as permitted sender) client-ip=130.117.225.111; Authentication-Results: mx.google.com; dkim=pass header.i=@virtuozzo.com header.s=relay header.b=Yj9hhOt2; spf=pass (google.com: domain of khorenko@virtuozzo.com designates 130.117.225.111 as permitted sender) smtp.mailfrom=khorenko@virtuozzo.com; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=virtuozzo.com DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=Subject:From:Message-Id:Date:Content-Type: MIME-Version; bh=0zU1fgHpfgZMJKJMuF5xlfcTFYT7dguZjuMTCTju9TY=; b=Yj9hhOt2Kv+e 87iCQBwxx7sJep339zjbUi0uwW/6wJ/NzuTQapxIYbWA/c+ZDuNqeWLDo0pAtdZH7VxsaNr3XnUs4 LO+/xLJW6FJuNphrRvI0YEs1gTLffvWtb0HcM3lXZd/+KEgWfDF3U2PuAo1CfcJw/3Nzpjz3PLZeT O9CXsSQ4MVwvJToIinWOhGFgdaiszG0VfIamJ4FdOMdfB6T/M+9uBKCgtOp2xTAks1Mm/xf8wdA1W vPgjHD2tQsvUdO0NjTG7O85pzBJzF7JQX6TyJtHpNHdJ9FJEJSXXYeDloYAqgzILvXQPyk6YzboF0 2tMKPVurbqxuTcg2/VXsJA==; Received: from ch-demo-asa.virtuozzo.com ([130.117.225.8] helo=f0.sw.ru) by relay.virtuozzo.com with esmtps (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1wzzxH-008dtj-0j; Fri, 28 Aug 2026 19:03:45 +0200 Received: from f0.sw.ru (localhost [127.0.0.1]) by f0.sw.ru (8.18.1/8.18.1/Debian-2) with ESMTP id 67SH3mZU1063939; Fri, 28 Aug 2026 19:03:48 +0200 Received: (from kostja@localhost) by f0.sw.ru (8.18.1/8.18.1/Submit) id 67SH3lus1063931; Fri, 28 Aug 2026 19:03:47 +0200 Date: Fri, 28 Aug 2026 19:03:47 +0200 Message-Id: <202608281703.67SH3lus1063931@f0.sw.ru> X-Authentication-Warning: f0.sw.ru: kostja set sender to khorenko@virtuozzo.com using -f From: Konstantin Khorenko To: Andrey Zhadchenko In-Reply-to: <20260827160619.303398-12-andrey.zhadchenko@virtuozzo.com> X-OZ-Fwd: true Cc: OpenVZ devel Subject: Re: [Devel] [PATCH RHEL10 COMMIT] drivers/md/dm-qcow2: respect zeroes during merge X-BeenThere: devel@openvz.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: OpenVZ development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: devel-bounces@openvz.org Errors-To: devel-bounces@openvz.org The commit is pushed to "branch-rh10-6.12.0-211.39.1.16.x.vz10-ovz" and will appear at git@bitbucket.org:openvz/vzkernel.git after rh10-6.12.0-211.39.1.16.11.vz10 ------> commit 21c4cf6aff361f9183ed73540de82c24294c7995 Author: Andrey Zhadchenko Date: Thu Aug 27 19:06:19 2026 +0300 drivers/md/dm-qcow2: respect zeroes during merge The merge machinery used to skip unallocated clusters, therefore breaking all clusters with zero bits and non-zero backing. Technically this bug was present even before discard changes, as qcow2 image could have 'reads as zero' bits before being inserted into dm-qcow2. Properly commit all zero clusters (albeit with data for now). https://virtuozzo.atlassian.net/browse/VSTOR-138288 Feature: dm-qcow2: block device over QCOW2 files driver Signed-off-by: Andrey Zhadchenko Reviewed-by: Pavel Tikhomirov Reviewed-by: Vasileios Almpanis Reviewed-by: Konstantin Khorenko --- drivers/md/dm-qcow2-map.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm-qcow2-map.c b/drivers/md/dm-qcow2-map.c index 53cb11242bf0d..78ee7cf5e8817 100644 --- a/drivers/md/dm-qcow2-map.c +++ b/drivers/md/dm-qcow2-map.c @@ -2744,6 +2744,13 @@ static void requeue_if_ok(struct qcow2_target *tgt, struct qio *unused, qcow2_dispatch_qios(qio->qcow2, qio, NULL); } +static bool clu_zeroes_present(struct qcow2 *qcow2, struct qcow2_map *map) +{ + if (qcow2->ext_l2) + return (map->ext_l2 >> 32) != 0; + return map->all_zeroes; +} + static int prepare_backward_merge(struct qcow2 *qcow2, struct qio **qio, struct qcow2_map *map, bool write) { @@ -2761,7 +2768,7 @@ static int prepare_backward_merge(struct qcow2 *qcow2, struct qio **qio, } } - if (!map->data_clu_alloced) { + if (!map->data_clu_alloced && !clu_zeroes_present(qcow2, map)) { /* Strange COW at L1, except the merge from RO image */ WARN_ON_ONCE(map->clu_is_cow && qio_may_modify_image(qcow2, *qio)); if (fake_merge_qio(*qio)) { @@ -2808,7 +2815,7 @@ static int prepare_backward_merge(struct qcow2 *qcow2, struct qio **qio, goto endio; } - if (!map->clu_is_cow) { + if (!map->clu_is_cow && map->data_clu_alloced) { /* Forced set these to unuse them after discard */ (*qio)->ext->unuse_clu_pos = map->data_clu_pos; (*qio)->ext->unuse_clu_end = map->data_clu_pos + qcow2->clu_size; _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel