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 BDD24CDB46E for ; Thu, 12 Oct 2023 15:07:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233039AbjJLPHQ (ORCPT ); Thu, 12 Oct 2023 11:07:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36768 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232712AbjJLPHP (ORCPT ); Thu, 12 Oct 2023 11:07:15 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23E9A90 for ; Thu, 12 Oct 2023 08:07:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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; bh=g75qOUtlM2UxdqGnT+sgTAeAKCMXu4QiHMG9BPg1AHk=; b=GNGwFoLwbecaUV4uMaDAYD47zw w4iD85V6MZebmNjcEBkaFTNx/+YeBfHVziWZfr5bwFG7Q6mEfvbqQ4a5BkLP/A9l5JnjzUPJWduhw Hh01WTOi/0BIT4aY82+DGHf5zrXfXF63cUr5Pz+uds6wA+CKKOcUoWzYngJU+OficW3gKa1WdVo6P CJiRHoPXgvhtT9nu74jWV/UP3JKkhErSE+D2nM2zKXx1Mgcvvh3HSgVHtJMmuOMQvKdRbOByIIJ1u kMePic1BQjtJ16+ZjJNZaz++N0bgh95PXY33c7Bt2kVXX92VvUrEtCYp4Ttr11ZG/8sYEIZfe0qGG OXg+DRZg==; Received: from hch by bombadil.infradead.org with local (Exim 4.96 #2 (Red Hat Linux)) id 1qqxHM-001FZr-18; Thu, 12 Oct 2023 15:07:12 +0000 Date: Thu, 12 Oct 2023 08:07:12 -0700 From: Christoph Hellwig To: "Darrick J. Wong" Cc: Christoph Hellwig , Catherine Hoang , linux-xfs@vger.kernel.org Subject: Re: [PATCH v3] xfs: allow read IO and FICLONE to run concurrently Message-ID: References: <20231012010845.64286-1-catherine.hoang@oracle.com> <20231012150231.GE21298@frogsfrogsfrogs> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231012150231.GE21298@frogsfrogsfrogs> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, Oct 12, 2023 at 08:02:31AM -0700, Darrick J. Wong wrote: > Catherine started with this, > https://lore.kernel.org/linux-xfs/8911B94D-DD29-4D6E-B5BC-32EAF1866245@oracle.com/ > > and the rest of us whittled it down to the single patch you see here. > Sections 1-2 are still relevant; S3 was the path not taken. I'd still take the core of that into the actual commit message. This part, maybe slightly rewored: "One of our VM cluster management products needs to snapshot KVM image files so that they can be restored in case of failure. Snapshotting is done by redirecting VM disk writes to a sidecar file and using reflink on the disk image, specifically the FICLONE ioctl as used by "cp --reflink". Reflink locks the source and destination files while it operates, which means that reads from the main vm disk image are blocked, causing the vm to stall. When an image file is heavily fragmented, the copy process could take several minutes. Some of the vm image files have 50-100 million extent records, and duplicating that much metadata locks the file for 30 minutes or more. Having activities suspended for such a long time in a cluster node could result in node eviction."