From patchwork Thu May 26 03:48:49 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 9136557 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9DCD5607D3 for ; Thu, 26 May 2016 03:52:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 93E43279E2 for ; Thu, 26 May 2016 03:52:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 88B92282BB; Thu, 26 May 2016 03:52:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id E2FD8279E2 for ; Thu, 26 May 2016 03:52:47 +0000 (UTC) Received: from localhost ([::1]:36264 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b5mLn-00052S-3j for patchwork-qemu-devel@patchwork.kernel.org; Wed, 25 May 2016 23:52:47 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43852) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b5mIH-00021F-R7 for qemu-devel@nongnu.org; Wed, 25 May 2016 23:49:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b5mIB-00043p-N0 for qemu-devel@nongnu.org; Wed, 25 May 2016 23:49:08 -0400 Received: from resqmta-po-02v.sys.comcast.net ([2001:558:fe16:19:96:114:154:161]:38395) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b5mIB-000430-Hw for qemu-devel@nongnu.org; Wed, 25 May 2016 23:49:03 -0400 Received: from resomta-po-18v.sys.comcast.net ([96.114.154.242]) by comcast with SMTP id 5mI3bB1RZGhQ05mIBbeEsR; Thu, 26 May 2016 03:49:03 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20140121; t=1464234543; bh=2hO/HeEGe3HFzbmwoxNAyEF551bJvZy70jNrwyvMuyM=; h=Received:Received:From:To:Subject:Date:Message-Id; b=XSsUvwwruNQCbj1QBoDwY1jRNkjUWDx6dvcTbcQv7L8WzbBsQvVzHbAay1UNcSDWx E4wk9hhTCoQuC0s7yr0L/cxDQfnJymlhHCwXnIkftQxgyH/mGgAk11VAGtM3TYh97n bGF1slva8HT85wFh5XhQM5ocC3jqmI7Egxs+UBdStZOyW6acv6XoibfesetdxCiEdm KNeRaWqfcHzb02aQ5rgzYt7L2jvY7BpDabjTDKcaNHWxGaVjA93h/XlQ2cGUrFgKRQ ELN30OobmDpKTBZKnUN0CiyiiU6efLytnl5FlQ1pRPoebZRAmNSa8SaSPae7okmWSW /cgMtVyTwVYHA== Received: from red.localdomain ([24.10.254.122]) by resomta-po-18v.sys.comcast.net with comcast id yrop1s00E2fD5rL01rp2li; Thu, 26 May 2016 03:49:03 +0000 From: Eric Blake To: qemu-devel@nongnu.org Date: Wed, 25 May 2016 21:48:49 -0600 Message-Id: <1464234529-13018-6-git-send-email-eblake@redhat.com> X-Mailer: git-send-email 2.5.5 In-Reply-To: <1464234529-13018-1-git-send-email-eblake@redhat.com> References: <1464234529-13018-1-git-send-email-eblake@redhat.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2001:558:fe16:19:96:114:154:161 Subject: [Qemu-devel] [PATCH v3 5/5] qcow2: Catch more unaligned write_zero into zero cluster X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, den@openvz.org, qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP is_zero_cluster() and is_zero_cluster_top_locked() are used only by qcow2_co_write_zeroes(). The former is too broad (we don't care if the sectors we are about to overwrite are non-zero, only that all other sectors in the cluster are zero), so it needs to be called up to twice but with smaller limits - rename it along with adding the neeeded parameter. The latter can be inlined for more compact code. The testsuite change shows that we now have a sparser top file when an unaligned write_zeroes overwrites the only portion of the backing file with data. Based on a patch proposal by Denis V. Lunev. CC: Denis V. Lunev Signed-off-by: Eric Blake Reviewed-by: Denis V. Lunev --- block/qcow2.c | 47 +++++++++++++++++++++++----------------------- tests/qemu-iotests/154.out | 8 ++++---- 2 files changed, 27 insertions(+), 28 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index 105fd5e..ecac399 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2406,26 +2406,19 @@ finish: } -static bool is_zero_cluster(BlockDriverState *bs, int64_t start) +static bool is_zero_sectors(BlockDriverState *bs, int64_t start, + uint32_t count) { - BDRVQcow2State *s = bs->opaque; int nr; BlockDriverState *file; - int64_t res = bdrv_get_block_status_above(bs, NULL, start, - s->cluster_sectors, &nr, &file); - return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == s->cluster_sectors; -} + int64_t res; -static bool is_zero_cluster_top_locked(BlockDriverState *bs, int64_t start) -{ - BDRVQcow2State *s = bs->opaque; - int nr = s->cluster_sectors; - uint64_t off; - int ret; - - ret = qcow2_get_cluster_offset(bs, start << BDRV_SECTOR_BITS, &nr, &off); - assert(nr == s->cluster_sectors); - return ret == QCOW2_CLUSTER_UNALLOCATED || ret == QCOW2_CLUSTER_ZERO; + if (!count) { + return true; + } + res = bdrv_get_block_status_above(bs, NULL, start, count, + &nr, &file); + return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == count; } static coroutine_fn int qcow2_co_write_zeroes(BlockDriverState *bs, @@ -2434,27 +2427,33 @@ static coroutine_fn int qcow2_co_write_zeroes(BlockDriverState *bs, int ret; BDRVQcow2State *s = bs->opaque; - int head = sector_num % s->cluster_sectors; - int tail = (sector_num + nb_sectors) % s->cluster_sectors; + uint32_t head = sector_num % s->cluster_sectors; + uint32_t tail = (sector_num + nb_sectors) % s->cluster_sectors; trace_qcow2_write_zeroes_start_req(qemu_coroutine_self(), sector_num, nb_sectors); - if (head != 0 || tail != 0) { + if (head || tail) { int64_t cl_start = sector_num - head; + uint64_t off; + int nr; assert(cl_start + s->cluster_sectors >= sector_num + nb_sectors); - sector_num = cl_start; - nb_sectors = s->cluster_sectors; - - if (!is_zero_cluster(bs, sector_num)) { + /* check whether remainder of cluster already reads as zero */ + if (!(is_zero_sectors(bs, cl_start, head) && + is_zero_sectors(bs, sector_num + nb_sectors, + -tail & (s->cluster_sectors - 1)))) { return -ENOTSUP; } qemu_co_mutex_lock(&s->lock); /* We can have new write after previous check */ - if (!is_zero_cluster_top_locked(bs, sector_num)) { + sector_num = cl_start; + nb_sectors = nr = s->cluster_sectors; + ret = qcow2_get_cluster_offset(bs, cl_start << BDRV_SECTOR_BITS, + &nr, &off); + if (ret != QCOW2_CLUSTER_UNALLOCATED && ret != QCOW2_CLUSTER_ZERO) { qemu_co_mutex_unlock(&s->lock); return -ENOTSUP; } diff --git a/tests/qemu-iotests/154.out b/tests/qemu-iotests/154.out index 531fd8c..da9eabd 100644 --- a/tests/qemu-iotests/154.out +++ b/tests/qemu-iotests/154.out @@ -102,13 +102,13 @@ wrote 2048/2048 bytes at offset 29696 read 4096/4096 bytes at offset 28672 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) [{ "start": 0, "length": 4096, "depth": 1, "zero": true, "data": false}, -{ "start": 4096, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 20480}, +{ "start": 4096, "length": 4096, "depth": 0, "zero": true, "data": false}, { "start": 8192, "length": 4096, "depth": 1, "zero": true, "data": false}, -{ "start": 12288, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 24576}, +{ "start": 12288, "length": 4096, "depth": 0, "zero": true, "data": false}, { "start": 16384, "length": 4096, "depth": 1, "zero": true, "data": false}, -{ "start": 20480, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 28672}, +{ "start": 20480, "length": 4096, "depth": 0, "zero": true, "data": false}, { "start": 24576, "length": 4096, "depth": 1, "zero": true, "data": false}, -{ "start": 28672, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 32768}, +{ "start": 28672, "length": 4096, "depth": 0, "zero": true, "data": false}, { "start": 32768, "length": 134184960, "depth": 1, "zero": true, "data": false}] == spanning two clusters, non-zero before request ==