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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8FCEDCA9EC3 for ; Thu, 31 Oct 2019 04:55:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7185720862 for ; Thu, 31 Oct 2019 04:55:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726804AbfJaEzA (ORCPT ); Thu, 31 Oct 2019 00:55:00 -0400 Received: from mail.cn.fujitsu.com ([183.91.158.132]:27908 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725816AbfJaEzA (ORCPT ); Thu, 31 Oct 2019 00:55:00 -0400 X-IronPort-AV: E=Sophos;i="5.68,250,1569254400"; d="scan'208";a="77722261" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 31 Oct 2019 12:54:57 +0800 Received: from G08CNEXCHPEKD01.g08.fujitsu.local (unknown [10.167.33.80]) by cn.fujitsu.com (Postfix) with ESMTP id 7B345486A852; Thu, 31 Oct 2019 12:46:58 +0800 (CST) Received: from [10.167.225.140] (10.167.225.140) by G08CNEXCHPEKD01.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server (TLS) id 14.3.439.0; Thu, 31 Oct 2019 12:55:08 +0800 Subject: Re: [RFC PATCH v2 0/7] xfs: reflink & dedupe for fsdax (read/write path). To: Goldwyn Rodrigues CC: , , , , , , , , References: <20191030041358.14450-1-ruansy.fnst@cn.fujitsu.com> <20191030114818.emvmgfgqadiqintw@fiona> From: Shiyang Ruan Message-ID: <2737c6f6-5cca-2b92-edff-fb9227ccc6d1@cn.fujitsu.com> Date: Thu, 31 Oct 2019 12:54:54 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20191030114818.emvmgfgqadiqintw@fiona> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.167.225.140] X-yoursite-MailScanner-ID: 7B345486A852.A9538 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: ruansy.fnst@cn.fujitsu.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/30/19 7:48 PM, Goldwyn Rodrigues wrote: > On 12:13 30/10, Shiyang Ruan wrote: >> This patchset aims to take care of this issue to make reflink and dedupe >> work correctly (actually in read/write path, there still has some problems, >> such as the page->mapping and page->index issue, in mmap path) in XFS under >> fsdax mode. > > Have you managed to solve the problem of multi-mapped pages? I don't > think we can include this until we solve that problem. This is the > problem I faced when I was doing the btrfs dax support. That problem still exists, didn't be solved in this patchset. But I am also looking into it. As you know, it's a bit difficult. Since the iomap for cow is merged in for-next tree, I think it's time to update this in order to get some comments. > > Suppose there is an extent shared with multiple files. You map data for > both files. Which inode should page->mapping->host (precisely > page->mapping) point to? As Dave pointed out, this needs to be fixed at > the mm level, and will not only benefit dax with CoW but other > areas such as overlayfs and possibly containers. Yes, I will try to figure out a solution. > -- Thanks, Shiyang Ruan.