From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 BD51C2C81 for ; Fri, 22 Oct 2021 05:36:48 +0000 (UTC) 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> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: 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 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.