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 7B560C433FE for ; Wed, 23 Mar 2022 05:46:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241887AbiCWFr4 (ORCPT ); Wed, 23 Mar 2022 01:47:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58876 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241886AbiCWFrz (ORCPT ); Wed, 23 Mar 2022 01:47:55 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1022B710C8; Tue, 22 Mar 2022 22:46:23 -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=7ZAsD6U+OpZrl9q+vvF5BO0Ld/peFEuasZX9wg8w/7c=; b=nlGt60I9cy8CABM8dFM997RIev lf+Vu/g9DqcVUJgBuwjYjHU9jOV3QQCh4gomYHEWmUbee1hju7Vb6RO0DEA9S5CmbmQe/zXKweFXn 8EVK7EgUoutyRvQb8bI9IhY1/UZJtuu/qqg9kSmpHJ1YGuAsMtO/ZauNT7m3eiq2M7Urm1DDCQ6cy u9yF+0Tbj77cKFKrTYwHSOfN80W+1eYN9ITP5OdtfmjQfHxk1qXo0WX7STlhFRN4cS2UgCMWDrFen cyC6TLzVbiAgxvrwxolPd8ULMLpgLYxqVhw8SAFfUge+NFNrjR50q2wFlEV6DOACqQ0c/5lF0epQv 0VigWM/g==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nWtok-00CoLR-Fp; Wed, 23 Mar 2022 05:45:58 +0000 Date: Tue, 22 Mar 2022 22:45:58 -0700 From: Christoph Hellwig To: Jane Chu Cc: Christoph Hellwig , "david@fromorbit.com" , "djwong@kernel.org" , "dan.j.williams@intel.com" , "vishal.l.verma@intel.com" , "dave.jiang@intel.com" , "agk@redhat.com" , "snitzer@redhat.com" , "dm-devel@redhat.com" , "ira.weiny@intel.com" , "willy@infradead.org" , "vgoyal@redhat.com" , "linux-fsdevel@vger.kernel.org" , "nvdimm@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "linux-xfs@vger.kernel.org" Subject: Re: [PATCH v6 4/6] dax: add DAX_RECOVERY flag and .recovery_write dev_pgmap_ops Message-ID: References: <20220319062833.3136528-1-jane.chu@oracle.com> <20220319062833.3136528-5-jane.chu@oracle.com> <3dabd58b-70f2-12af-419f-a7dfc07fbb1c@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3dabd58b-70f2-12af-419f-a7dfc07fbb1c@oracle.com> 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-fsdevel@vger.kernel.org On Tue, Mar 22, 2022 at 11:05:09PM +0000, Jane Chu wrote: > > This DAX_RECOVERY doesn't actually seem to be used anywhere here or > > in the subsequent patches. Did I miss something? > > dax_iomap_iter() uses the flag in the same patch, > + if ((map_len == -EIO) && (iov_iter_rw(iter) == WRITE)) { > + flags |= DAX_RECOVERY; > + map_len = dax_direct_access(dax_dev, pgoff, nrpg, > + flags, &kaddr, NULL); Yes, it passes it on to dax_direct_access, and dax_direct_access passes it onto ->direct_access. But nothing in this series actually checks for it as far as I can tell. > >> Also introduce a new dev_pagemap_ops .recovery_write function. > >> The function is applicable to FSDAX device only. The device > >> page backend driver provides .recovery_write function if the > >> device has underlying mechanism to clear the uncorrectable > >> errors on the fly. > > > > Why is this not in struct dax_operations? > > Per Dan's comments to the v5 series, adding .recovery_write to > dax_operations causes a number of trivial dm targets changes. > Dan suggested that adding .recovery_write to pagemap_ops could > cut short the logistics of figuring out whether the driver backing > up a page is indeed capable of clearing poison. Please see > https://lkml.org/lkml/2022/2/4/31 But at least in this series there is 1:1 association between the pgmap and the dax_device so that scheme won't work. It would have to lookup the pgmap based on the return physical address from dax_direct_access. Which sounds more complicated than just adding the (annoying) boilerplate code to DM. > include/linux/memremap.h doesn't know struct iov_iter which is defined > in include/linux/uio.h, would you prefer to adding include/linux/uio.h > to include/linux/memremap.h ? As it is not derefences just adding a struct iov_iter; line to memremap.h below the includes should be all that is needed.