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=-0.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 77447C2BA19 for ; Wed, 15 Apr 2020 11:24:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3E81B20575 for ; Wed, 15 Apr 2020 11:24:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ClQLKHw9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2896921AbgDOLX4 (ORCPT ); Wed, 15 Apr 2020 07:23:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37938 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2896897AbgDOLWS (ORCPT ); Wed, 15 Apr 2020 07:22:18 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E4600C061A0C; Wed, 15 Apr 2020 04:22:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; 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=p5k96MLyrJ0Kc/9UM6Xw8FfLDEnTX/dVH39aK5qAXAA=; b=ClQLKHw92puBJhU2nimC3BH8wA 355osRMfVxhDQVssm7Zm9jE6v3E3dRGs+Oc5jFRy3/jQbyNAsfVORzBRmGEfW7/HIf4gbDH2d4DT2 gL3rNu+X2XBNBJ3NpW/Bx0FlYJMdgdadGJM/y2cHwCtDUUl9b+KcgcTHyz2DkqV52KYqOQaeHmfVH s2D+J2WiHScmuPaZ+HVg8gSTWAFyV0P0cKjdmyQFi/TapX8CRjBU8aFB/npLmiZAvjPQMvj6Rpgij Vy0bfVHN0vosqBiQDXjyzG7mDrHdrpJGmw7wYW8mNvb2TBTAiSuOkc9Tu/G2eouAmkldMad/NLN38 jgC7ixKA==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jOg7U-0004jU-L2; Wed, 15 Apr 2020 11:22:16 +0000 Date: Wed, 15 Apr 2020 04:22:16 -0700 From: Matthew Wilcox To: Andrew Morton Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, ocfs2-devel@oss.oracle.com, linux-xfs@vger.kernel.org, Christoph Hellwig , William Kucharski Subject: Re: [PATCH v11 05/25] mm: Add new readahead_control API Message-ID: <20200415112216.GC5820@bombadil.infradead.org> References: <20200414150233.24495-1-willy@infradead.org> <20200414150233.24495-6-willy@infradead.org> <20200414181705.bfc4c0087092051a9475141e@linux-foundation.org> <20200415021808.GA5820@bombadil.infradead.org> <20200414215616.f665d12f8549f52606784d1e@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200414215616.f665d12f8549f52606784d1e@linux-foundation.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 14, 2020 at 09:56:16PM -0700, Andrew Morton wrote: > On Tue, 14 Apr 2020 19:18:08 -0700 Matthew Wilcox wrote: > > Hmm. They don't seem that big to me. > > They're really big! v5.7-rc1: 11636 636 224 12496 30d0 fs/iomap/buffered-io.o readahead_v11: 11528 636 224 12388 3064 fs/iomap/buffered-io.o > > __readahead_batch is much bigger, but it's only used by btrfs and fuse, > > and it seemed unfair to make everybody pay the cost for a function only > > used by two filesystems. > > Do we expect more filesystems to use these in the future? I'm honestly not sure. I think it'd be nice to be able to fill a bvec from the page cache directly, but I haven't tried to write that function yet. If so, then it'd be appropriate to move that functionality into the core. > > > The code adds quite a few (inlined!) VM_BUG_ONs. Can we plan to remove > > > them at some stage? Such as, before Linus shouts at us :) > > > > I'd be happy to remove them. Various reviewers said things like "are you > > sure this can't happen?" > > Yeah, these things tend to live for ever. Please add a todo to remove > them after the code has matured? Sure! I'm touching this code some more in the large pages patch set, so I can get rid of it there.