From mboxrd@z Thu Jan 1 00:00:00 1970 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=-12.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 2C81EC388F9 for ; Wed, 11 Nov 2020 05:17:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CCD1E20709 for ; Wed, 11 Nov 2020 05:17:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="buzQAx13" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726102AbgKKFR0 (ORCPT ); Wed, 11 Nov 2020 00:17:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58146 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726055AbgKKFRY (ORCPT ); Wed, 11 Nov 2020 00:17:24 -0500 Received: from mail-ej1-x643.google.com (mail-ej1-x643.google.com [IPv6:2a00:1450:4864:20::643]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6C474C0613D4; Tue, 10 Nov 2020 21:17:24 -0800 (PST) Received: by mail-ej1-x643.google.com with SMTP id f20so1040748ejz.4; Tue, 10 Nov 2020 21:17:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=W4oa2arKXpCRAolq9D2lGXxHhmUs0bsO+JdBDi0oVas=; b=buzQAx13RV4ZvT8vzuWft03dlaFWsa3Rd6LiKF6cHOoQPS6NWgOngBONvdZ4d0eLUV hC/xKc9rpZG0TEu/NuB1zbkYQSvjM6bzXbM2l6yjocs2GJd6zn4H1fRLKlwUoJtPk5QC dG+1Wu/3wmVfqg1WwtUdq3bSnloCZWlH81U1dcZdWCGvitQkND6TjQVe8i6nplTHNobO 4E4IxyyvckskewIatN0QJhPjOa5DTJOoaJRylSXtiKYUbk6cGb/2HSKbmXlXnI8KJ+EO Y8Mk3PAMLdk4KpbXISgtsYlsJlntbVelXJQ2r7alnLeZNIzFotwkvOuD77nnf1yuS4hK teFg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=W4oa2arKXpCRAolq9D2lGXxHhmUs0bsO+JdBDi0oVas=; b=fgR3N862VDyWUTfXI/DQ8fEd8x4iNSLP50SjGetjFcVvLANKHBEU9xiULRveUT67n9 Ec5ZFyo5DYCzRT9LWu8sBNUKqrH0DIe9vPh1MqcJlzCx/GnWbZZ/+jZbB24uAWDBGUDT zxp/nskQlEbSndo0zQS59P4iJlhmprfzChWQeDsNJ9KyCPK0fsNCLy2ioNkB+aklrsdD zSJZ96Zawm0mNdRITufc8SOLRd4krKPiauFnqRX9JKw9IOflNkjb0u+I0kt4fTs84Fdi rnc58TLvxSHQz20NoC94HlpbuoUYDt+xlZ0zKrTf9QR8vVrfJEDGHOv1uCa/1TC8jyU4 99AA== X-Gm-Message-State: AOAM532wiNPpAyCRBmbkp0Yxe0sLed9PJZfZCRHwvpiUYW4cVcPjIWMo wyagJj2OwzzEzY3Xp7A0mOMFodPFzhE= X-Google-Smtp-Source: ABdhPJxXNQihstkl7oxxs8OthEimIkqJbVWvYENvEA1AiBAtUJ+7d/QbEngohM8pmnQbv0gIP40ocQ== X-Received: by 2002:a17:906:6d83:: with SMTP id h3mr22986842ejt.481.1605071843221; Tue, 10 Nov 2020 21:17:23 -0800 (PST) Received: from lb01399.pb.local (p200300ca573cea52c98ae5b6a31510db.dip0.t-ipconnect.de. [2003:ca:573c:ea52:c98a:e5b6:a315:10db]) by smtp.gmail.com with ESMTPSA id g20sm363628ejz.88.2020.11.10.21.17.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Nov 2020 21:17:22 -0800 (PST) From: Pankaj Gupta To: song@kernel.org Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, pankaj.gupta.linux@gmail.com, Pankaj Gupta Subject: [PATCH 2/3] md: add comments in md_flush_request() Date: Wed, 11 Nov 2020 06:16:57 +0100 Message-Id: <20201111051658.18904-3-pankaj.gupta.linux@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20201111051658.18904-1-pankaj.gupta.linux@gmail.com> References: <20201111051658.18904-1-pankaj.gupta.linux@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org From: Pankaj Gupta Request coalescing logic is dependent on flush time update in other context. This patch adds comments to understand the code flow better. Signed-off-by: Pankaj Gupta --- drivers/md/md.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/md/md.c b/drivers/md/md.c index 167c80f98533..a330e61876e0 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -662,10 +662,14 @@ bool md_flush_request(struct mddev *mddev, struct bio *bio) { ktime_t req_start = ktime_get_boottime(); spin_lock_irq(&mddev->lock); + /* flush requests wait until ongoing flush completes, + * hence coalescing all the pending requests. + */ wait_event_lock_irq(mddev->sb_wait, !mddev->flush_bio || ktime_after(mddev->prev_flush_start, req_start), mddev->lock); + /* new request after previous flush is completed */ if (!ktime_after(mddev->prev_flush_start, req_start)) { WARN_ON(mddev->flush_bio); mddev->flush_bio = bio; -- 2.20.1