From patchwork Mon May 25 18:08:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alberto Garcia X-Patchwork-Id: 281927 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47F93C433E1 for ; Mon, 25 May 2020 18:22:48 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 1DE94207FB for ; Mon, 25 May 2020 18:22:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="M/poncsa" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1DE94207FB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=igalia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:34558 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jdHkN-0008NM-8S for qemu-devel@archiver.kernel.org; Mon, 25 May 2020 14:22:47 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45224) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jdHXr-0003va-TO; Mon, 25 May 2020 14:09:51 -0400 Received: from fanzine.igalia.com ([178.60.130.6]:51103) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jdHXp-0007qC-UM; Mon, 25 May 2020 14:09:51 -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:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From; bh=kaPNNW3QBgq2po7mlaGmxNCYnAPeNNVUXPsq1YJk0BM=; b=M/poncsataf8Co4IGxwpDYabgb45x0ddR57nG0N84D6ehQYfbgjTj40ugH3Joq9jDT95oD5hBjKezcMyrXe3OifAKga543JacSBm60GKrN2UtioTYo1LHhNy3s18u9v8T6U/+uy3HCyJRd5ZhPuPg7pafO6wEI4qywco/XzLI/5bACOnsr29wogjxXpCiTpoGucgmPVdwVsYJufqq+yb4dTW+ITqKmt0shPZkQdujoj/hstN3BRpEdw2WuHMcv5cgT67Xing9alAzMYVUfgs7SkuZ/lzCGSGYzoQEKEE6eFXkgDaYpc/Fis3mTmnkZwCg7QFE5ffr5BjTgTxChNJdg==; 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 1jdHXP-00088a-Ii; Mon, 25 May 2020 20:09:23 +0200 Received: from berto by perseus.local with local (Exim 4.92) (envelope-from ) id 1jdHXA-0002Ne-BM; Mon, 25 May 2020 20:09:08 +0200 From: Alberto Garcia To: qemu-devel@nongnu.org Subject: [PATCH v7 27/32] qcow2: Add subcluster support to handle_alloc_space() Date: Mon, 25 May 2020 20:08:52 +0200 Message-Id: <14b60dde8fe7863ae580e3f9d88e5755db28a108.1590429901.git.berto@igalia.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: References: 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 = 2020/05/25 14:09:23 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_PASS=-0.001, URIBL_BLOCKED=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 , Vladimir Sementsov-Ogievskiy , Alberto Garcia , qemu-block@nongnu.org, Derek Su , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The bdrv_co_pwrite_zeroes() call here fills complete clusters with zeroes, but it can happen that some subclusters are not part of the write request or the copy-on-write. This patch makes sure that only the affected subclusters are overwritten. A potential improvement would be to also fill with zeroes the other subclusters if we can guarantee that we are not overwriting existing data. However this would waste more disk space, so we should first evaluate if it's really worth doing. Signed-off-by: Alberto Garcia Reviewed-by: Max Reitz Reviewed-by: Vladimir Sementsov-Ogievskiy --- block/qcow2.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index 8126ad8fa0..430b4e423a 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2411,6 +2411,9 @@ static int handle_alloc_space(BlockDriverState *bs, QCowL2Meta *l2meta) for (m = l2meta; m != NULL; m = m->next) { int ret; + uint64_t start_offset = m->alloc_offset + m->cow_start.offset; + unsigned nb_bytes = m->cow_end.offset + m->cow_end.nb_bytes - + m->cow_start.offset; if (!m->cow_start.nb_bytes && !m->cow_end.nb_bytes) { continue; @@ -2425,16 +2428,14 @@ static int handle_alloc_space(BlockDriverState *bs, QCowL2Meta *l2meta) * efficiently zero out the whole clusters */ - ret = qcow2_pre_write_overlap_check(bs, 0, m->alloc_offset, - m->nb_clusters * s->cluster_size, + ret = qcow2_pre_write_overlap_check(bs, 0, start_offset, nb_bytes, true); if (ret < 0) { return ret; } BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_SPACE); - ret = bdrv_co_pwrite_zeroes(s->data_file, m->alloc_offset, - m->nb_clusters * s->cluster_size, + ret = bdrv_co_pwrite_zeroes(s->data_file, start_offset, nb_bytes, BDRV_REQ_NO_FALLBACK); if (ret < 0) { if (ret != -ENOTSUP && ret != -EAGAIN) {