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=-5.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, USER_AGENT_MUTT 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 89643C43381 for ; Sun, 17 Feb 2019 18:18:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 55B50217FA for ; Sun, 17 Feb 2019 18:18:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550427485; bh=ofhN024YwaoNTAFTHoyltK1SRdq2uZUaid4C9hkBpNk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=aG695fQHGLD7SxNJmaNGYcIuldVIo3aqKdsknNGOIauyzwnPKli6U7Yyikub5dc2e fT4aTXIamLNo6v/3a9Ncph3f2Ank9jIBYIDjzlMkxpDDT8/w1ESHSvpyO6+zxJrer4 AM4esk95l2INL+e9AikaB/yi1UdAQQvUM/uEKyVg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726106AbfBQSSE (ORCPT ); Sun, 17 Feb 2019 13:18:04 -0500 Received: from mail.kernel.org ([198.145.29.99]:36108 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725771AbfBQSSE (ORCPT ); Sun, 17 Feb 2019 13:18:04 -0500 Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9E894217F5; Sun, 17 Feb 2019 18:18:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550427483; bh=ofhN024YwaoNTAFTHoyltK1SRdq2uZUaid4C9hkBpNk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=iKgLTbgoXPCTYJI4blpX0HSg/cHJ98Wzx4sqJy25m1ak5aap7oWbXpj6QamfpHM2R wrWOUYiJ1Gky+Y+W792ON0wYttWGqSTm4U+MLg5n/nRqfn8GUCRCRRpWVJGit3Ft94 nUVIyXHZWNj13RtnPLlcpaRrJq/8/4E0JiAsumAk= Date: Sun, 17 Feb 2019 13:18:02 -0500 From: Sasha Levin To: Linus Walleij Cc: Greg Kroah-Hartman , stable@vger.kernel.org, openwrt-devel@lists.openwrt.org, "David S . Miller" , Eric Dumazet , Liping Zhang , John Youn , =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= , James Hughes , Felix Fietkau , Boris Brezillon , Richard Weinberger Subject: Re: [PATCH 6/8 v3] ubifs: Use dirty_writeback_interval value for wbuf timer Message-ID: <20190217181802.GH10616@sasha-vm> References: <20190214132403.10687-1-linus.walleij@linaro.org> <20190214132403.10687-7-linus.walleij@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190214132403.10687-7-linus.walleij@linaro.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Feb 14, 2019 at 02:24:01PM +0100, Linus Walleij wrote: >From: Rafał Miłecki > >commit 1b7fc2c0069f3864a3dda15430b7aded31c0bfcc upstream. > >Right now wbuf timer has hardcoded timeouts and there is no place for >manual adjustments. Some projects / cases many need that though. Few >file systems allow doing that by respecting dirty_writeback_interval >that can be set using sysctl (dirty_writeback_centisecs). > >Lowering dirty_writeback_interval could be some way of dealing with user >space apps lacking proper fsyncs. This is definitely *not* a perfect >solution but we don't have ideal (user space) world. There were already >advanced discussions on this matter, mostly when ext4 was introduced and >it wasn't behaving as ext3. Anyway, the final decision was to add some >hacks to the ext4, as trying to fix whole user space or adding new API >was pointless. > >We can't (and shouldn't?) just follow ext4. We can't e.g. sync on close >as this would cause too many commits and flash wearing. On the other >hand we still should allow some trade-off between -o sync and default >wbuf timeout. Respecting dirty_writeback_interval should allow some sane >cutomizations if used warily. > >Signed-off-by: Rafał Miłecki >Reviewed-by: Boris Brezillon >Signed-off-by: Richard Weinberger >Signed-off-by: Linus Walleij This one looks like a new feature that will also require changes to userspace. Is there actual breakage this fixes? -- Thanks, Sasha