From patchwork Tue May 17 09:15:39 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Denis V. Lunev" X-Patchwork-Id: 9110751 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 3E276BF29F for ; Tue, 17 May 2016 09:17:06 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id A1F5B202EC for ; Tue, 17 May 2016 09:17:05 +0000 (UTC) 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.kernel.org (Postfix) with ESMTPS id 89CB32022D for ; Tue, 17 May 2016 09:17:04 +0000 (UTC) Received: from localhost ([::1]:49427 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b2b7f-0008Cd-Mu for patchwork-qemu-devel@patchwork.kernel.org; Tue, 17 May 2016 05:17:03 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39550) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b2b6a-0005h3-74 for qemu-devel@nongnu.org; Tue, 17 May 2016 05:16:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b2b6U-0007LI-5t for qemu-devel@nongnu.org; Tue, 17 May 2016 05:15:55 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:9001 helo=relay.sw.ru) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b2b6T-0007Km-OL for qemu-devel@nongnu.org; Tue, 17 May 2016 05:15:50 -0400 Received: from irbis.sw.ru ([10.24.38.119]) by relay.sw.ru (8.13.4/8.13.4) with ESMTP id u4H9FhxI030135; Tue, 17 May 2016 12:15:46 +0300 (MSK) From: "Denis V. Lunev" To: qemu-devel@nongnu.org Date: Tue, 17 May 2016 12:15:39 +0300 Message-Id: <1463476543-3087-2-git-send-email-den@openvz.org> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1463476543-3087-1-git-send-email-den@openvz.org> References: <1463476543-3087-1-git-send-email-den@openvz.org> X-detected-operating-system: by eggs.gnu.org: OpenBSD 3.x X-Received-From: 195.214.232.25 Subject: [Qemu-devel] [PATCH 1/5] block: split write_zeroes always 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: Kevin Wolf , den@openvz.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP We should split requests even if they are less than write_zeroes_alignment. For example we can have the following request: offset 62k size 4k write_zeroes_alignment 64k The original code sent 1 request covering 2 qcow2 clusters, and resulted in both clusters being allocated. But by splitting the request, we can cater to the case where one of the two clusters can be zeroed as a whole, for only 1 cluster allocated after the operation. Signed-off-by: Denis V. Lunev CC: Eric Blake CC: Kevin Wolf --- block/io.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/block/io.c b/block/io.c index cd6d71a..6a24ea8 100644 --- a/block/io.c +++ b/block/io.c @@ -1172,13 +1172,13 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs, /* Align request. Block drivers can expect the "bulk" of the request * to be aligned. */ - if (bs->bl.write_zeroes_alignment - && num > bs->bl.write_zeroes_alignment) { + if (bs->bl.write_zeroes_alignment) { if (sector_num % bs->bl.write_zeroes_alignment != 0) { /* Make a small request up to the first aligned sector. */ num = bs->bl.write_zeroes_alignment; num -= sector_num % bs->bl.write_zeroes_alignment; - } else if ((sector_num + num) % bs->bl.write_zeroes_alignment != 0) { + } else if (num > bs->bl.write_zeroes_alignment && + (sector_num + num) % bs->bl.write_zeroes_alignment != 0) { /* Shorten the request to the last aligned sector. num cannot * underflow because num > bs->bl.write_zeroes_alignment. */