From patchwork Wed Jun 10 09:46:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alberto Garcia X-Patchwork-Id: 1306695 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: 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=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=igalia.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=igalia.com header.i=@igalia.com header.a=rsa-sha256 header.s=20170329 header.b=axKaANN3; dkim-atps=neutral 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 ozlabs.org (Postfix) with ESMTPS id 49hhzq4y0qz9sRh for ; Wed, 10 Jun 2020 19:49:59 +1000 (AEST) Received: from localhost ([::1]:38162 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jixMr-00013r-ET for incoming@patchwork.ozlabs.org; Wed, 10 Jun 2020 05:49:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51752) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jixJj-0006E6-U7; Wed, 10 Jun 2020 05:46:43 -0400 Received: from fanzine.igalia.com ([178.60.130.6]:45515) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jixJi-0002No-1M; Wed, 10 Jun 2020 05:46:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:Message-Id:Date:Subject:Cc:To:From; bh=P9vZ11NKkCaDVcMicVXwC8MMjREiPzHVeLAEkepras8=; b=axKaANN3z+kuCKmUC7tbvnkL8B1pI0/1ks0XogrMvkg9dVTOQ8fEvxTuUSs6W/ZSBNE+Pw7H4uPyuDNPOb7lPcCkGJ+25Kb4fSYCfvXKG0IE5taJRkpCfPCyU8TpmtLZ74Y2iBcRNGhFkGSLZU+engpmewFeIJ9Scgl5fqbG5tStBOildqrWHiZVIx0d3MUaDC+QdF8eGPMRLO9Y3vs2JC1sLV54lbhJ5o0lGdRMumHALKodDqmIav98lfRugcy35zOdWBHvUQKr2SG7Cxw9U3rNvzyc7crZ2vcbpQR7CRTEixvIIxpDn7+BxmlwV0o8Y6obTORU8IuA2odSO4GK6Q==; Received: from [81.0.38.199] (helo=perseus.local) by fanzine.igalia.com with esmtpsa (Cipher TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim) id 1jixJL-000379-2w; Wed, 10 Jun 2020 11:46:19 +0200 Received: from berto by perseus.local with local (Exim 4.92) (envelope-from ) id 1jixJ7-00013p-PK; Wed, 10 Jun 2020 11:46:05 +0200 From: Alberto Garcia To: qemu-devel@nongnu.org Subject: [PATCH] qcow2: Fix preallocation on images with unaligned sizes Date: Wed, 10 Jun 2020 11:46:00 +0200 Message-Id: <20200610094600.4029-1-berto@igalia.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Received-SPF: pass client-ip=178.60.130.6; envelope-from=berto@igalia.com; helo=fanzine.igalia.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/10 05:46:19 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x (no timestamps) [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Alberto Garcia , qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" When resizing an image with qcow2_co_truncate() using the falloc or full preallocation modes the code assumes that both the old and new sizes are cluster-aligned. There are two problems with this: 1) The calculation of how many clusters are involved does not always get the right result. Example: creating a 60KB image and resizing it (with preallocation=full) to 80KB won't allocate the second cluster. 2) No copy-on-write is performed, so in the previous example if there is a backing file then the first 60KB of the first cluster won't be filled with data from the backing file. This patch fixes both issues. Signed-off-by: Alberto Garcia Reviewed-by: Eric Blake --- block/qcow2.c | 17 ++++++++++++++--- tests/qemu-iotests/125 | 21 +++++++++++++++++++++ tests/qemu-iotests/125.out | 9 +++++++++ 3 files changed, 44 insertions(+), 3 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index 0cd2e6757e..e20590c3b7 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -4239,8 +4239,8 @@ static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset, old_file_size = ROUND_UP(old_file_size, s->cluster_size); } - nb_new_data_clusters = DIV_ROUND_UP(offset - old_length, - s->cluster_size); + nb_new_data_clusters = (ROUND_UP(offset, s->cluster_size) - + start_of_cluster(s, old_length)) >> s->cluster_bits; /* This is an overestimation; we will not actually allocate space for * these in the file but just make sure the new refcount structures are @@ -4317,10 +4317,21 @@ static int coroutine_fn qcow2_co_truncate(BlockDriverState *bs, int64_t offset, int64_t nb_clusters = MIN( nb_new_data_clusters, s->l2_slice_size - offset_to_l2_slice_index(s, guest_offset)); - QCowL2Meta allocation = { + unsigned cow_start_length = offset_into_cluster(s, guest_offset); + QCowL2Meta allocation; + guest_offset = start_of_cluster(s, guest_offset); + allocation = (QCowL2Meta) { .offset = guest_offset, .alloc_offset = host_offset, .nb_clusters = nb_clusters, + .cow_start = { + .offset = 0, + .nb_bytes = cow_start_length, + }, + .cow_end = { + .offset = nb_clusters << s->cluster_bits, + .nb_bytes = 0, + }, }; qemu_co_queue_init(&allocation.dependent_requests); diff --git a/tests/qemu-iotests/125 b/tests/qemu-iotests/125 index d510984045..5c249b4b23 100755 --- a/tests/qemu-iotests/125 +++ b/tests/qemu-iotests/125 @@ -164,6 +164,27 @@ for GROWTH_SIZE in 16 48 80; do done done +# Test image resizing using preallocation and unaligned offsets +$QEMU_IMG create -f raw "$TEST_IMG.base" 128k | _filter_img_create +$QEMU_IO -c 'write -q -P 1 0 128k' -f raw "$TEST_IMG.base" +for orig_size in 31k 33k; do + echo "--- Resizing image from $orig_size to 96k ---" + _make_test_img -F raw -b "$TEST_IMG.base" -o cluster_size=64k "$orig_size" + $QEMU_IMG resize -f "$IMGFMT" --preallocation=full "$TEST_IMG" 96k + # The first part of the image should contain data from the backing file + $QEMU_IO -c "read -q -P 1 0 ${orig_size}" "$TEST_IMG" + # The resized part of the image should contain zeroes + $QEMU_IO -c "read -q -P 0 ${orig_size} 63k" "$TEST_IMG" + # The resized image should have 7 clusters: + # header, L1 table, L2 table, refcount table, refcount block, 2 data clusters + expected_file_length=$((65536 * 7)) + file_length=$(stat -c '%s' "$TEST_IMG_FILE") + if [ "$file_length" != "$expected_file_length" ]; then + echo "ERROR: file length $file_length (expected $expected_file_length)" + fi + echo +done + # success, all done echo '*** done' rm -f $seq.full diff --git a/tests/qemu-iotests/125.out b/tests/qemu-iotests/125.out index 596905f533..7f76f7af20 100644 --- a/tests/qemu-iotests/125.out +++ b/tests/qemu-iotests/125.out @@ -767,4 +767,13 @@ wrote 2048000/2048000 bytes at offset 0 wrote 81920/81920 bytes at offset 2048000 80 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) +Formatting 'TEST_DIR/t.IMGFMT.base', fmt=raw size=131072 +--- Resizing image from 31k to 96k --- +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=31744 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw +Image resized. + +--- Resizing image from 33k to 96k --- +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33792 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw +Image resized. + *** done