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 44216C433F5 for ; Mon, 9 May 2022 18:20:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240026AbiEISYl (ORCPT ); Mon, 9 May 2022 14:24:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59704 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240101AbiEISYl (ORCPT ); Mon, 9 May 2022 14:24:41 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 58C1C18384 for ; Mon, 9 May 2022 11:20:45 -0700 (PDT) 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 EC13E61632 for ; Mon, 9 May 2022 18:20:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4C9EFC385B5; Mon, 9 May 2022 18:20:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1652120444; bh=D6vW7fTicE9ZVgH0GExG6C3mvt7KkINx/UxH3xbvWbM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dq6eoSgHaR+psPdisf1nJFUG7iiGt2qNQBwAQMjEVRi+1pZIgkSFaFRqlMNirmymP Tvku7H+F1LRVOKw6F/pYjWL7SCpzDptVRzeAbivMAhn5UWdAjx5RVBZWi2I4IMOqTm VfVuG1HDNaCU4r9KMI2Lf6yL4GXpfh6/U4CKRwPUbfrmlw2t1l2VjEgqAcA12BmkT1 sH4WV/HAdVPKZ96ag6K6rjDoz47hQzea/iedIFJM7/84npAImp0y+4Aj6ZQb9ArbqZ 9/QD11fiTLg0WeuDS0M8U17TMfRXABlWUAMcmxFUDweKE9gEoyix2lMBWFAz7r5XC7 zq5glFOEgZf7w== Date: Mon, 9 May 2022 11:20:43 -0700 From: "Darrick J. Wong" To: Amir Goldstein Cc: Dave Chinner , linux-xfs Subject: Re: [QUESTION] Upgrade xfs filesystem to reflink support? Message-ID: <20220509182043.GW27195@magnolia> 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-xfs@vger.kernel.org [drop my oracle email from cc, outlook sux] On Mon, May 09, 2022 at 10:50:20AM +0300, Amir Goldstein wrote: > Hi Darrick and Dave, > > I might have asked this back when reflink was introduced, but cannot > find the question nor answer. > > Is there any a priori NACK or exceptional challenges w.r.t implementing > upgrade of xfs to reflink support? No, just lack of immediate user demand + time to develop and merge code + time to QA the whole mess to make sure it doesn't introduce any messes. > We have several customers with xfs formatted pre reflink that we would > like to consider > upgrading. > > Back in the time of reflink circa v4.9 there were few xfs features > that could be > upgraded, but nowadays, there are several features that could be upgraded. > > If I am not mistaken, the target audience for this upgrade would be > xfs formatted > with xfsprogs 4.17 (defaults). > I realize that journal size may have been smaller at that time (I need to check) > which may be a source of additional problems, Yes. We've found in practice that logsize < 100MB produce serious scalability problems and increase deadlock opportunities on such old kernels. The 64MB floor we just put in for xfsprogs 5.15 was a good enough downwards estimate assuming that most people will end up on 5.19+ kernels in the (very) long run. > but hopefully, some of your work > to do a diet for journal credits for reflink could perhaps mitigate > that issue(?). That work reduces the internal transaction size but leaves the existing minimum log size standards intact. > Shall I take a swing at it? It's already written: https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=upgrade-older-features I think the upcoming nrext64 xfsprogs patches took in the first patch in that series. Question: Now that mkfs has a min logsize of 64MB, should we refuse upgrades for any filesystem with logsize < 64MB? --D > Thanks, > Amir.