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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DFC96FB5190 for ; Tue, 7 Apr 2026 05:19:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 345136B0088; Tue, 7 Apr 2026 01:19:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2A7036B0089; Tue, 7 Apr 2026 01:19:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 147F36B008A; Tue, 7 Apr 2026 01:19:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 0085B6B0088 for ; Tue, 7 Apr 2026 01:19:26 -0400 (EDT) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 859C41A0664 for ; Tue, 7 Apr 2026 05:19:26 +0000 (UTC) X-FDA: 84630606732.05.B31D056 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf21.hostedemail.com (Postfix) with ESMTP id E703D1C0009 for ; Tue, 7 Apr 2026 05:19:24 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=GoQvE2vM; dmarc=pass (policy=none) header.from=infradead.org; spf=none (imf21.hostedemail.com: domain of BATV+d54640da967e19434292+8262+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+d54640da967e19434292+8262+infradead.org+hch@bombadil.srs.infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1775539165; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=kYfX0e0sGJA1W1y/i1C2RTFkobNEnqp+InsvttluQ8Q=; b=RJ3fQQQZiBI0DWYCSAILwbkk2MIgXzG9xzjg2gJS33jzcNUu1NfzpnqA5olWDWL4ZrtqFP AYrkwVsN8wNp1Q3PaC5OO28DY4NVCtmamTqUU9G9L4u+NAyDSY02ROSrFKb3DeAuV4jUuS AgYhB0Ca6g7TG93FPnX5f2e/X/vT3NQ= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1775539165; a=rsa-sha256; cv=none; b=OTsPq9e5zg03U3laopr5eNlw1NaH5EA1z+R9XbjnJHL7MS7aXtm+0J2x9sHGe7IrCvmVDh i58Dauc5sE11G1FysqN715ukvXQaQgJ+zFy9vBzg0ZvmiLiNE4ocnIhzqvjp6CtAJOvyE8 gmZPrSuBUxgMUuLrnT6T5Qp4oBuzOAk= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=GoQvE2vM; dmarc=pass (policy=none) header.from=infradead.org; spf=none (imf21.hostedemail.com: domain of BATV+d54640da967e19434292+8262+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+d54640da967e19434292+8262+infradead.org+hch@bombadil.srs.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=kYfX0e0sGJA1W1y/i1C2RTFkobNEnqp+InsvttluQ8Q=; b=GoQvE2vM5lWJEyexT/Xn4xo36y Gy+icEYkiOc/xUgQBskvd6d1swvJCsZr2pKip8TOFGo5MO5q9koV92v4XQa0CPz8gQgsYxJ5Tkb+I qOAMmT9CNeMLjzInKOKN2JNkC8GEenLnMkFniRPLOsaEugnrRkjW5tDsU/m5V3Xj69sy5hEQB8lK3 FnQ7W+dbwh0AoPHPigt6T0ir468+a4g4XuEdV3upK+oJ67JMQgm38tN+BPL9q6itc87gyLcgxxoOb UE37IzYi+U0Qlp63i9gyssVJO/vs/WIOCuaI/4v/6hQxySnSqHLj/x4/+cGC/BY+09gibVg3J4NOF CDuAQLZA==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1w9yqK-00000005uGR-2fk7; Tue, 07 Apr 2026 05:19:16 +0000 Date: Mon, 6 Apr 2026 22:19:16 -0700 From: Christoph Hellwig To: Jeff Layton Cc: Christoph Hellwig , Alexander Viro , Christian Brauner , Jan Kara , "Matthew Wilcox (Oracle)" , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Mike Snitzer , Chuck Lever , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 2/4] mm: add atomic flush guard for IOCB_DONTCACHE writeback Message-ID: References: <20260401-dontcache-v1-0-1f5746fab47a@kernel.org> <20260401-dontcache-v1-2-1f5746fab47a@kernel.org> <629f21c6591903512eb2f3f3c4d6b14a9ac7b91a.camel@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Queue-Id: E703D1C0009 X-Stat-Signature: 1s6uhkmk3x3h3odijezg8eybx763qbc3 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1775539164-568258 X-HE-Meta: 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 NyZBYMqT 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 06, 2026 at 09:32:58AM -0400, Jeff Layton wrote: > > And that is called the writeback thread. So what we should do there > > is to make sure we queue up writeback on it for each dontcache write. > > Initially queuing up a wb_writeback_work for each range might be first > > approximation, although we should probably find a way to just increase > > a threshold if going down that road. > > > > Ok, I like that idea. I'll give that a shot and see how it does. I'll > note that there is no way to specify an inode or range (yet) in > wb_writeback_work(). > > Do you think it's sufficient to just call something like > wakeup_flusher_threads_bdi() after every RWF_DONTCACHE write, or should > I extend wb_writeback_work to allow for doing work on a range within a > single inode? I don't think we care about what exact data is written back as this is not an integrity operation. So just waking the flusher thread sounds like the right thing, but we might also need a way to communicate the higher writeback target.