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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 2C096C433DB for ; Tue, 30 Mar 2021 16:02:00 +0000 (UTC) Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CA27260241 for ; Tue, 30 Mar 2021 16:01:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CA27260241 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=mit.edu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linux-f2fs-devel-bounces@lists.sourceforge.net Received: from [127.0.0.1] (helo=sfs-ml-1.v29.lw.sourceforge.com) by sfs-ml-1.v29.lw.sourceforge.com with esmtp (Exim 4.90_1) (envelope-from ) id 1lRGoY-00082D-Tq; Tue, 30 Mar 2021 16:01:58 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lRGoG-0007zr-Td for linux-f2fs-devel@lists.sourceforge.net; Tue, 30 Mar 2021 16:01:40 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; 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:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=EdzCFCLMvvg0RnoP86wisrN9O1agsv+ZeQ7KKgGHrn0=; b=XsCw20Xlb7RzGUdbAkHl1rMEOI 7pc11PHC+ZfsiFrD6zxN5MGS+vRy4sR3BIZ78ulaB0BFFOy60qa3TXthl1EbwMeYJI6/GJg3SiJ4C LHdx/93aYOk0xWIaErd/a1XWW6y0MgBcn98Gp1AOlOBSdOCIdmL0hsPoSeFDdHUPbsko=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; 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:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=EdzCFCLMvvg0RnoP86wisrN9O1agsv+ZeQ7KKgGHrn0=; b=XbCjAu88TKoNASB0gMN2jRwt6S 1inqpFR9JLTnoFRj4zPF0yAdPGApF02RyBajLv0FV4OcwbdbFTkEJesirvkdE2xjxDEfkfMHavnv6 p6DbkGyhoGIUkazd9D5v02W7agVHFwM1HdTX4EN2leXRg67aSjPwtfY64WcFb8TBPPoQ=; Received: from outgoing-auth-1.mit.edu ([18.9.28.11] helo=outgoing.mit.edu) by sfi-mx-2.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92.3) id 1lRGo7-00076B-PZ for linux-f2fs-devel@lists.sourceforge.net; Tue, 30 Mar 2021 16:01:40 +0000 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 12UG0nHa013090 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 30 Mar 2021 12:00:49 -0400 Received: by cwcc.thunk.org (Postfix, from userid 15806) id 32C5415C39CD; Tue, 30 Mar 2021 12:00:49 -0400 (EDT) Date: Tue, 30 Mar 2021 12:00:49 -0400 From: "Theodore Ts'o" To: Eric Biggers Message-ID: References: <20210329204240.359184-1-shreeya.patel@collabora.com> <20210329204240.359184-5-shreeya.patel@collabora.com> <87v999pequ.fsf@collabora.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Headers-End: 1lRGo7-00076B-PZ Subject: Re: [f2fs-dev] [PATCH v5 4/4] fs: unicode: Add utf8 module and a unicode layer X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kernel@collabora.com, drosen@google.com, Gabriel Krisman Bertazi , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, adilger.kernel@dilger.ca, linux-fsdevel@vger.kernel.org, jaegeuk@kernel.org, andre.almeida@collabora.com, linux-ext4@vger.kernel.org, Shreeya Patel Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Mon, Mar 29, 2021 at 10:47:52PM -0700, Eric Biggers wrote: > > Isn't this a user problem? If the modules required to boot are on the > > filesystem itself, you are in trouble. But, if that is the case, your > > rootfs is case-insensitive and you gotta have utf8 as built-in or have > > it in an early userspace. > > We could make it the user's problem, but that seems rather unfriendly. > Especially because the utf8 module would be needed if the filesystem has the > casefold feature at all, regardless of whether any casefolded directories are > needed at boot time or not. (Unless there is a plan to change that?) I guess I'm not that worried, since the vast majority of desktop distribution are using initial ramdisks these days. And if someone did build a monolithic kernel that couldn't mount the root file system, they would figure that out pretty quickly. The biggest problem they would have with trying to enable encryption or casefolding on the root file system is that if they are using Grub, older versions of Grub would see an unknown incompat feature, and immediately have heartburn, and refuse to touch whatever file system /boot is located on. If the distribution has /boot as a stand-alone partition, that won't be a problem, but if you have a single file system which includes the location of kernels and initrds' are located, the moment you try set the encryption or casefold on the file system, you're immediately hosed --- and if you do this on a laptop while you are on an airplane, without thinking things through, and without access to a rescue USB thumb drive, life can get... interesting. (Why, yes, I'm speaking from direct experience; why do you ask? :-) So in comparison to making such a mistake, building a kernel that was missing casefold, and needing to fall back to an older kernel is not really that bad of a user experience. You just have to fall back the distro kernel, which most kernel developers who are dogfooding bleeding kernels are probably smart enough keep one around. We *could* teach ext4 to support mounting file systems that have casefold, without having the unicode module loaded, which would make things a bit better, but I'm not sure it's worth the effort. We could even make the argument that letting the system boot, and then having access to some directories return ENOTSUPP would actually be a more confusing user experience than a simple hard failure when we try mounting the file system. Cheers, - Ted _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel