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 11CBACCF9E4 for ; Tue, 5 Sep 2023 23:23:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232389AbjIEXXl (ORCPT ); Tue, 5 Sep 2023 19:23:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229861AbjIEXXk (ORCPT ); Tue, 5 Sep 2023 19:23:40 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87801B0 for ; Tue, 5 Sep 2023 16:23:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=QF0lefaut/7y5ErwShPnn4OJeHvxH9Dxkxy4uPBeatU=; b=nCZjt/AQYCacBPtIsf4wE7x+L7 so80nKJ4HeZCgNBv/7bQTM9AJZ6TPNE+UpMDtVYHKsdsg+EwLUh70lvsEgFvJ40FAfju06vAWRuDl l+kA1/kUWntAGklDmclGsTX8CLGAwRdZTH5S+pG9sZLd0q0/CwW7YZmDXchf+abOgoXPJH4qHlzo2 ZGVfdmpG3VFiwyVnjLtaCWlnLraoHJP93pq+R0EXUzell5Q1hyAfynAcEd51uBIIA5jo8nh1od2fx 1/F0k0BvFUlsVpxcLKIjFZK11o3BOxetSL1YzFLVSxfRA+9EcEkh6zzwryiVNUmU8voYAPg5Q+Gxf usxkZumg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qdfOE-00EVyZ-6p; Tue, 05 Sep 2023 23:23:22 +0000 Date: Wed, 6 Sep 2023 00:23:22 +0100 From: Matthew Wilcox To: Dave Chinner Cc: Christoph Hellwig , ksummit@lists.linux.dev, linux-fsdevel@vger.kernel.org Subject: Re: [MAINTAINERS/KERNEL SUMMIT] Trust and maintenance of file systems Message-ID: References: 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-fsdevel@vger.kernel.org On Wed, Sep 06, 2023 at 09:06:21AM +1000, Dave Chinner wrote: > > Part 2: unmaintained file systems > > > > A lot of our file system drivers are either de facto or formally > > unmaintained. If we want to move the kernel forward by finishing > > API transitions (new mount API, buffer_head removal for the I/O path, > > ->writepage removal, etc) these file systems need to change as well > > and need some kind of testing. The easiest way forward would be > > to remove everything that is not fully maintained, but that would > > remove a lot of useful features. > > Linus has explicitly NACKed that approach. > > https://lore.kernel.org/linux-fsdevel/CAHk-=wg7DSNsHY6tWc=WLeqDBYtXges_12fFk1c+-No+fZ0xYQ@mail.gmail.com/ > > Which is a problem, because historically we've taken code into > the kernel without requiring a maintainer, or the people who > maintained the code have moved on, yet we don't have a policy for > removing code that is slowly bit-rotting to uselessness. > > > E.g. the hfsplus driver is unmaintained despite collecting odd fixes. > > It collects odd fixes because it is really useful for interoperating > > with MacOS and it would be a pity to remove it. At the same time > > it is impossible to test changes to hfsplus sanely as there is no > > mkfs.hfsplus or fsck.hfsplus available for Linux. We used to have > > one that was ported from the open source Darwin code drops, and > > I managed to get xfstests to run on hfsplus with them, but this > > old version doesn't compile on any modern Linux distribution and > > new versions of the code aren't trivially portable to Linux. > > > > Do we have volunteers with old enough distros that we can list as > > testers for this code? Do we have any other way to proceed? > > > > If we don't, are we just going to untested API changes to these > > code bases, or keep the old APIs around forever? > > We do slowly remove device drivers and platforms as the hardware, > developers and users disappear. We do also just change driver APIs > in device drivers for hardware that no-one is actually able to test. > The assumption is that if it gets broken during API changes, > someone who needs it to work will fix it and send patches. > > That seems to be the historical model for removing unused/obsolete > code from the kernel, so why should we treat unmaintained/obsolete > filesystems any differently? i.e. Just change the API, mark it > CONFIG_BROKEN until someone comes along and starts fixing it... Umm. If I change ->write_begin and ->write_end to take a folio, convert only the filesystems I can test via Luis' kdevops and mark the rest as CONFIG_BROKEN, I can guarantee you that Linus will reject that pull request. I really feel we're between a rock and a hard place with our unmaintained filesystems. They have users who care passionately, but not the ability to maintain them.