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 EC53B23BCE7 for ; Wed, 22 Oct 2025 16:05:33 +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=1761149134; cv=none; b=pCEcVebH8OMNowkL68PeOEgU1hHoHJAGUgunR7rDD1FmfYogiJegvNxp12OrrjI6sZtcBECING1IOpGnRn2YaC1TIjYoh1HZ3o3tmeezizC6OgWJp9JIdxjgOD/FlAxuGfaRkIi6NhtHUeN51txS4VvW8sGuQhxDWvZcWN9/xqU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761149134; c=relaxed/simple; bh=VTTzVCJzSCJNWtzD9mNKIxLN15XxZS+xWBBaaX6J2rY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=XSzt8f0Roo0Ra6u2wMbQ85YoyT3Rno1eqa14isJ/z+hT7+UunT83KyI3RQgdYGuVy+aN6d3LrZag29XSaBoEcOARyaiAThIddKhFzq7yY8k+5ez8DWcZ7drmVO9qrWtRIx2Uvw8XCPS4EfmDGF+Xvn8o2S46ehby40WZqLqu2Hc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tPxpM6bV; 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="tPxpM6bV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6BD0DC4CEE7; Wed, 22 Oct 2025 16:05:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761149133; bh=VTTzVCJzSCJNWtzD9mNKIxLN15XxZS+xWBBaaX6J2rY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tPxpM6bVkn6lQk7rcshGw1fsge1B9v9bhiioczzLShByCq/YpzDGeAXEPVhn+KjON oXJi20tk9slrtlXoeLzEimQ+aFj8HYV1gWVMQ0ZT4/x8Y//qWFbu9m2j5FcOKZE2ZQ TNWQC4Qvm24MFwgIUzQ289BXp3VZB6uZal4ZGlnqwksWPtHyGwJTSGpEOvfuAdDHRA wWUonxQfrpP1ysacxnU42uK9v54RqhImXSjElVPArvJUSIZMh4lXHFVIpuM/5+bkCI pEGcnmRgoKiDo1wsqKk0CHzdBDFe5tS7v6GE/X/bHPOpmKfnufWom5nfCsE9G5vo0d 7cFxoZZV8t7ug== Date: Wed, 22 Oct 2025 09:05:32 -0700 From: "Darrick J. Wong" To: Christoph Hellwig Cc: "Nirjhar Roy (IBM)" , linux-xfs@vger.kernel.org, ritesh.list@gmail.com, ojaswin@linux.ibm.com, bfoster@redhat.com, david@fromorbit.com, hsiangkao@linux.alibaba.com Subject: Re: [RFC V3 0/3] xfs: Add support to shrink multiple empty AGs Message-ID: <20251022160532.GM3356773@frogsfrogsfrogs> References: 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: On Wed, Oct 22, 2025 at 12:17:27AM -0700, Christoph Hellwig wrote: > On Mon, Oct 20, 2025 at 09:13:41PM +0530, Nirjhar Roy (IBM) wrote: > > This work is based on a previous RFC[1] by Gao Xiang and various ideas > > proposed by Dave Chinner in the RFC[1]. > > > > Currently the functionality of shrink is limited to shrinking the last > > AG partially but not beyond that. This patch extends the functionality > > to support shrinking beyond 1 AG. However the AGs that we will be remove > > have to empty in order to prevent any loss of data. > > > > The patch begins with the re-introduction of some of the data > > structures that were removed, some code refactoring and > > finally the patch that implements the multi AG shrink design. > > The final patch has all the details including the definition of the > > terminologies and the overall design. > > I'm still missing what the overall plan is here. For "normal" XFS > setups you'll always have inodes that we can't migrate. Do you plan > to use this with inode32 only? ...or resurrect xfs_reno? Data/attr extent migration might not be too hard if we can repurpose xfs_zonegc for relocations. I think moving inodes is going to be very very difficult because there's no way to atomically update all the parents. (Not to mention whatever happens when the inumber abruptly changes) > Also it would be nice to extent this > to rtgroups, as we are guaranteed to not have non-migratable metadata > there and things will actually just work. Seconded. --D