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 0602BC3DA7A for ; Thu, 5 Jan 2023 17:42:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234892AbjAERmg (ORCPT ); Thu, 5 Jan 2023 12:42:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52812 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235053AbjAERmV (ORCPT ); Thu, 5 Jan 2023 12:42:21 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87E663DBEC for ; Thu, 5 Jan 2023 09:42:14 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1599B61BB0 for ; Thu, 5 Jan 2023 17:42:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4EEBEC433D2; Thu, 5 Jan 2023 17:42:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672940533; bh=a61KkIePdXlYGDag8VaLi1SSd+gN9exN7x8rEnDhhZA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eXjGS9OtwvQcP9O3OIa0l9g8LrBaQy+nYS688Qah1j7pLXN16gaaJ5SNSaLuG3syy l8ZggK2srDEWdrLV9puJtd9h649v2AVocniXs5RRQbHe/o5Shba8P3HVj8eB6QjnXm bPzOs9FknSzvjjPwyjOR7Zwcy0ftiyRRyxOirgzhF0A72AYK3JQs7COrcpxZVKFFTo 0M9WlKIWkfb1pchUktEo3RNrRsPDPZVa26vCrw/ArMR4H3JRT52Bawu/ijZJ/M1MxE KKTUL41pp3e5LKQY1tlgDrgKIpDkb1HbgBAT8y2gUvCNI4l041WVLO4rHGZCLfEeB3 UMTD3DgWYXpFA== Received: by pali.im (Postfix) id 5A6DAAC9; Thu, 5 Jan 2023 18:42:10 +0100 (CET) Date: Thu, 5 Jan 2023 18:42:10 +0100 From: Pali =?utf-8?B?Um9ow6Fy?= To: Jens Axboe Cc: Linus Torvalds , Christoph Hellwig , Greg Kroah-Hartman , Linux Kernel Mailing List Subject: Re: Linux 6.2-rc1 Message-ID: <20230105174210.jbjoqelllcrd57q6@pali> References: <20230104190115.ceglfefco475ev6c@pali> <20230104205640.o2uy2jk4v6yfm4w3@pali> <90eb90da-2679-cac0-979d-6ba0cc8ccbb8@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <90eb90da-2679-cac0-979d-6ba0cc8ccbb8@kernel.dk> User-Agent: NeoMutt/20180716 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 04 January 2023 14:43:16 Jens Axboe wrote: > On 1/4/23 2:32?PM, Linus Torvalds wrote: > >> But here it is CD-RW media in read-write mode with kernel udf > >> filesystem driver without any userspace involved (after proper > >> formatting). > > > > ... but I'm not sure about direct writeable mount support. > > > > That may indeed be an area that only pktcdvd ended up doing. I've > > never used it myself, even historically. > > > > Let's bring in more people. Because they may not have thought about > > some RW UDF case. > > We did think about it, since that's the only reason for pktcdvd to > exist. Basically what the driver does is ensure that any write is 32K in > size, which is the size which can be written to media. It'll gather data > as needed to make that happen. Thats it. Outside of that, it's just some > setup and closing code. > > This obviously would be better to handle in userspace, all of it. Back > when I wrote this driver, we didn't have a lot of the fancier stuff we > have today. It could be done via ublk, for example, or something like > that. > > The surprising bit here is: > > 1) Someone is still using this driver, and > 2) It actually works! Yes, there are still users and userspace tools (cdrwtool / pktsetup) are still receiving either small patches or issue reports. I think that it was two years ago when cdrwtool received big fixups to support formatting CD-RW discs on new CD/DVD drives. > While I'd love to nudge folks in other directions for this use case, and > I strongly think that we should, it also doesn't seem fair to just yank > it while folks are using it... But I'd like to VERY strongly encourage > folks to come up with a new solution for this use case. It really isn't > a solution that belongs in the kernel today. Linus in previous email wrote that he did "make SCSI commands generic" work in past so direct usage of /dev/cdrom device works for CD-R burning and read-only mounting. So could not be (for example sr.c) driver extended to directly do pktcdvd's work? So when somebody opens /dev/cdrom device in O_RDWR mode and CD-RW medium is present then it would behave like pktcdvd device... To have /dev/cdrom generic also for CD-RW write access. > > The removal seems to revert cleanly, although it does require > > reverting a few subsequent commits too (that removed code that only > > pktcdvd used): > > > > git revert db1c7d779767 85d6ce58e493 f40eb99897af > > > > where we have > > > > db1c7d779767 block: bio_copy_data_iter > > 85d6ce58e493 block: remove devnode callback from struct > > block_device_operations > > f40eb99897af pktcdvd: remove driver. > > I'll queue this up - and unless I hear valid complaints to why we should > not just reinstate the driver for now, it'll go out with the next pull > request. > > -- > Jens Axboe >