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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 23CA9C433E9 for ; Fri, 19 Feb 2021 16:19:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E0F6064EC0 for ; Fri, 19 Feb 2021 16:19:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229636AbhBSQTq (ORCPT ); Fri, 19 Feb 2021 11:19:46 -0500 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:37500 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S229765AbhBSQTp (ORCPT ); Fri, 19 Feb 2021 11:19:45 -0500 Received: from cwcc.thunk.org (pool-72-74-133-215.bstnma.fios.verizon.net [72.74.133.215]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 11JGIrWj012083 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 19 Feb 2021 11:18:54 -0500 Received: by cwcc.thunk.org (Postfix, from userid 15806) id 9670415C39E2; Fri, 19 Feb 2021 11:18:53 -0500 (EST) Date: Fri, 19 Feb 2021 11:18:53 -0500 From: "Theodore Ts'o" To: Alexey Lyashkov Cc: Lukas Czerner , Andreas Dilger , Artem Blagodarenko , linux-ext4 , Eric Sandeen Subject: Re: [PATCH v2] mmp: do not use O_DIRECT when working with regular file Message-ID: References: <20210212093719.162065-1-lczerner@redhat.com> <20210218095146.265302-1-lczerner@redhat.com> <99A17D19-8764-4027-8B1E-E7ADBE5E2CEE@gmail.com> <20210219105713.uu2mywenytfd2e5j@work> <20210219133459.vezgrlkjpmaizvb4@work> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org Alexey, It'd be helpful to me to understand _why_ this use case is important for your workloads. O_DIRECT support is rarely used as far as I know, and fs blocksize != page size is rare as well. The main use cases I know of fs blocksize != page size is on architectures (not terribly common) with 16k or 64k page sizes, that want to use 4k file system blocksizes for interoperability reasons. (And I suppose because mke2fs uses a 4k block size by default. Perhaps we should change this so that the default is that mke2fs will use a block size == page size, unless for some reason the page size is not one supported by ext4 (although I'm not aware of any architecture wanting page sizes > 64k), or the user explicitly specifies the block size using "mke2fs -b".) Are you trying to make O_DIRECT support in e2fsprogs a first class reason out of completeness concern? Or is this a use case which is important in production workloads that you are familiar with? Thanks, - Ted