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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A233C433EF for ; Fri, 22 Oct 2021 05:36:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F0806101C for ; Fri, 22 Oct 2021 05:36:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231616AbhJVFjG (ORCPT ); Fri, 22 Oct 2021 01:39:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230193AbhJVFjE (ORCPT ); Fri, 22 Oct 2021 01:39:04 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0178FC061764; Thu, 21 Oct 2021 22:36:48 -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=+YDMPVpxVm8p9MUlUXzErZxvxROH6gniSaBDcG7u9TY=; b=HeJKI/GV+Bphar28aSxvNfHN7F PLzh2q5WkuWMqVzrxjqAwTTPxYsEElxMc9Pn1mbMhzYkNtzB5c0RXFEXR8Fi5DaRlyo9x0F2RYbxM qeCZS+ZThU9uOKaedUc1UT1ZsvdTPQLDWj3YEXIg1dVlcKr6PjPFlhSLlydBXd5iFQgsKmj6GyOKt 3AEA3Gwqc3oZ6ugPu97G4Nv22shMJOEnMMXUuaTH2rCt6TIIlAnl+oRmsvZBq3mcZnKMqgwR3rV6X Wj3/HI6mE8nEOKYDinJj9O4k7rQHMzEzzMsthVsIQyDhDEpDmoNdf+GWPgV0upMGxg79BAsY5HlgI jdGaySvg==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mdnEI-009lYf-Qe; Fri, 22 Oct 2021 05:36:34 +0000 Date: Thu, 21 Oct 2021 22:36:34 -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: [dm-devel] [PATCH 0/6] dax poison recovery with RWF_RECOVERY_DATA flag Message-ID: References: <20211021001059.438843-1-jane.chu@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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-kernel@vger.kernel.org On Fri, Oct 22, 2021 at 01:37:28AM +0000, Jane Chu wrote: > On 10/21/2021 4:31 AM, Christoph Hellwig wrote: > > Looking over the series I have serious doubts that overloading the > > slow path clear poison operation over the fast path read/write > > path is such a great idea. > > > > Understood, sounds like a concern on principle. But it seems to me > that the task of recovery overlaps with the normal write operation > on the write part. Without overloading some write operation for > 'recovery', I guess we'll need to come up with a new userland > command coupled with a new dax API ->clear_poison and propagate the > new API support to each dm targets that support dax which, again, > is an idea that sounds too bulky if I recall Dan's earlier rejection > correctly. When I wrote the above I mostly thought about the in-kernel API, that is use a separate method. But reading your mail and thinking about this a bit more I'm actually less and less sure that overloading pwritev2 and preadv2 with this at the syscall level makes sense either. read/write are our I/O fast path. We really should not overload the core of the VFS with error recovery for a broken hardware interface.