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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14FB5C64ED6 for ; Wed, 1 Mar 2023 17:00:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229624AbjCARAU (ORCPT ); Wed, 1 Mar 2023 12:00:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60136 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229900AbjCARAR (ORCPT ); Wed, 1 Mar 2023 12:00:17 -0500 Received: from mail-pl1-x62c.google.com (mail-pl1-x62c.google.com [IPv6:2607:f8b0:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E1DE410BD for ; Wed, 1 Mar 2023 09:00:13 -0800 (PST) Received: by mail-pl1-x62c.google.com with SMTP id a2so4240181plm.4 for ; Wed, 01 Mar 2023 09:00:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:subject:cc:to:from:message-id:date:from:to:cc:subject :date:message-id:reply-to; bh=ovbh2Ow5Lqvqr3WKhiVlyFb7KfbpfT0ZYOesBpWl4m0=; b=grUVyn7vzAz6c1+XejF+kJiBzdOK0iJNKed1S2cKdkfJCnVvMx5PYO3477OAh9GG1p Uo4hou31ELVeGMvd3+Cf71UAWMeqctc04MFqZFOZbaKpmmkgcT6u8ZFCz2jRqHxzcP0M M16hBzzWnP9PSVqm/0E0+SppJsdbKvhuExH/f9a4K0pLKg+VzgZ72gSpG4CYzieO8rdw jyXc2SOmYfTUqTQq1ffqygpKAhAjtw5K+krUESvTPagUilWbuNXBgIhyWWsnESUCQhof sO2yGRbKweMc9eLkuWzwsgf/Z3xeG92CeHVAR/Af0hQqtE1xEZjhpkvSrf5kOHdbpfzp +xMg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:subject:cc:to:from:message-id:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=ovbh2Ow5Lqvqr3WKhiVlyFb7KfbpfT0ZYOesBpWl4m0=; b=kym4wvB8mD4zkLGP/hWyAAwS/QTOrBaKqXkPqGXiyJdgfYBzSorhQMOhJ7QtnivhMz 2Lu0Tqyn3Ju2GfNZlmJBmZvJ14Z6amRI9SVB6pG2/PXgAREIR3P9g5Xbl2w9X1gUS3uD gmgUxlTOxLWlWFkW2hdRT0fHnBCTiTO1SZ+yFstI7+mj3jYxjGvxU7qnen8oNJJnsZQp NmtATe9wHJWKQtEjGO0GPqwux+ya9D++0e71genN1KnnAeI0R5bU6C8wz8R24LuTnsOz UKxPfA4N59PUyghuYHarfGcN51l4LTTv8bJ02m75Xob+16R/YAqUe7rcK15A0gnpyKyZ Ye/Q== X-Gm-Message-State: AO0yUKVChc6y1JImm2PfW3znFr54E6efzg5GDvMamJtzDRzr77lKiMH7 urdrFKIXxwI1FdqN3gh6JrU= X-Google-Smtp-Source: AK7set+2QlRkKoWmVdH6Tezjq9aeyQJTb4v8/cm93NNNaOJPD6EOXrRft986vyW+HvhURZQ4z6QbYw== X-Received: by 2002:a17:90b:4c4c:b0:233:e305:f617 with SMTP id np12-20020a17090b4c4c00b00233e305f617mr8188672pjb.32.1677690012757; Wed, 01 Mar 2023 09:00:12 -0800 (PST) Received: from rh-tp ([2406:7400:63:469f:eb50:3ffb:dc1b:2d55]) by smtp.gmail.com with ESMTPSA id s17-20020a639251000000b00502ecb91940sm7671585pgn.55.2023.03.01.09.00.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Mar 2023 09:00:12 -0800 (PST) Date: Wed, 01 Mar 2023 22:29:56 +0530 Message-Id: <87wn40mmpf.fsf@doe.com> From: Ritesh Harjani (IBM) To: Luis Chamberlain , lsf-pc@lists.linux-foundation.org, Christoph Hellwig , Matthew Wilcox , David Howells Cc: Luis Chamberlain , "kbus >> Keith Busch" , Pankaj Raghav , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: LSF/MM/BPF 2023 IOMAP conversion status update In-Reply-To: <20230129044645.3cb2ayyxwxvxzhah@garbanzo> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Luis Chamberlain writes: > One of the recurring themes that comes up at LSF is "iomap has little > to no documentation, it is hard to use". I've only recently taken a > little nose dive into it, and so I also can frankly admit to say I don't > grok it well either yet. However, the *general* motivation and value is clear: > avoiding the old ugly monster of struct buffer_head, and abstracting > the page cache for non network filesystems, and that is because for > network filesystems my understanding is that we have another side effort > for that. We could go a bit down memory lane on prior attempts to kill > the struct buffer_head evil demon from Linux, or why its evil, but I'm not > sure if recapping that is useful at this point in time, let me know, I could > do that if it helps if folks want to talk about this at LSF. For now I rather It would certainly help to hear on what are our plans of IOMAP_F_BUFFER_HEAD flag and it's related code. I know it is there for gfs2, but it would be good to know on what are our plans before we start converting all other filesystems to move to iomap? Do we advise on not to use this path for other filesystems? Do we plan to deprecate it in order to kill buffer heads in future? e.g. root> git grep "buffer_head" fs/iomap/ fs/iomap/buffered-io.c:#include Wanted more insights on this and our plans w.r.t other filesystem wanting to use it. So a short walk down the memory lane and our plans for future w.r.t IOMAP_F_BUFFER_HEAD would certainly help. Thanks -ritesh