From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B21F83B8D75 for ; Wed, 10 Dec 2025 19:18:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765394306; cv=none; b=bm8FffcJcii+Aw2vkccSTErIubz+fyW6b47ztkYdaNkPdDWNHyRbY3yHm5hg6v3cJdZENYhMtTOGuiveYGnQGI/4fdcSVDH8pZQs8BvsbfO5/iwTvwt+CjdQvpTyCVH122jSP+lHr9YVAucW5T16qZDAGdANCiKBK34zBUbn5f0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765394306; c=relaxed/simple; bh=dODmr4Q3/tJkKW1aZw3c83xao+89PTFHSgBtXZWdcho=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=BsLn20OCpARTxKZ5eDSPgmmGOO7jhtyllcS9mrTtCJuZpV2/JH8FU9ifUIv+67gThUii3AdQNf+tYhsK06MlGoUykj5RzzrZSSjgtPlu6eSWWsv4gZeimumQY4fUHaj4WJ431avswH9z9rDcC9UtBb/HZiIxjBinnbpc7JRRXOI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=P4SJ4Mkr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="P4SJ4Mkr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2D9E6C4CEF1; Wed, 10 Dec 2025 19:18:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1765394306; bh=dODmr4Q3/tJkKW1aZw3c83xao+89PTFHSgBtXZWdcho=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=P4SJ4MkrcRF50KwC2W0UVIDuVpt088S7gleIfqOjhg8W0VPGTXq41+Fy1NQDRzfyy BnhkzxJpk6oVdM8RS8PxjTuRcye6KZsMaJeApFNp2rSkiJ9wVRLIXbv/6hRTMqQM68 Ex3iZspIa+UjPKIXRd3YPQI3UGeV0Aq2q69x5uEnEEHqxCJhQ8XJvT5LjdAO0VHu6o 2hODnvRlsuKvHwSFau4M7i1YwFh1sn80asxOznCQZWjZsvSNk/aGAWPJzdV+dklD53 FHV5kJX7gjsW3/0iq/MnQNsyKea8Y/CFJivcnEFOilLcIeDM6JFmBuP5WVh/o0o21l 6eahhPDc5j/RQ== Date: Wed, 10 Dec 2025 11:18:25 -0800 From: "Darrick J. Wong" To: Christoph Hellwig Cc: cem@kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH] xfs: validate that zoned RT devices are zone aligned Message-ID: <20251210191825.GD7725@frogsfrogsfrogs> References: <20251210142305.3660710-1-hch@lst.de> <20251210164859.GB7725@frogsfrogsfrogs> <20251210165438.GA9489@lst.de> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251210165438.GA9489@lst.de> On Wed, Dec 10, 2025 at 05:54:38PM +0100, Christoph Hellwig wrote: > On Wed, Dec 10, 2025 at 08:48:59AM -0800, Darrick J. Wong wrote: > > mkfs doesn't enforce that when you're creating a zoned filesystem on > > non-zoned storage: > ... > > (The mkfs enforcement does work if you have an actual zoned storage > > device since mkfs complains about changes in the zone sizes.) > > Ugg, and I thought only my horrible hacks caused that.. > > > > > > to avoid getting into trouble due to fuzzers or mkfs bugs. > > > > > > Fixes: 2167eaabe2fa ("xfs: define the zoned on-disk format") > > > Signed-off-by: Christoph Hellwig > > > > How many filesystems are there in the wild with rump rtgroups? > > I suspect very, very few as zoned mode on non-zoned devices is not a > widely advertised feature, and then you'd also need wiredly sized device > or manual override to get it. And then scrub would complain about it. > > Given that runt zoned rtgroups can exist in the wild, how hard would it > > be to fix zonegc? > > Very nasty. We can't ever GC into one. How nasty is it, exactly? AFAICT, * The zone targetting code (aka the zone we copy into) then has to know to avoid a runt endzone? * Thresholding gets weird because they don't apply right to the runt zone, which means the victim selection is also off. * The code that reserves zones for gc or other ENOSPC handling then has to ensure it never picks a runt zone to avoid corner case problems Any other reasons? Given that zoned is still experimental I think I'm ok with adding this restriction, but only after some more thorough understanding. :) Also does growfs need patching so that it doesn't create a runt zone? --D