Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752702AbcDZPBr (ORCPT ); Tue, 26 Apr 2016 11:01:47 -0400 Received: from mail.kernel.org ([198.145.29.136]:48178 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752675AbcDZPBo (ORCPT ); Tue, 26 Apr 2016 11:01:44 -0400 Message-ID: <1461682892.26226.23.camel@kernel.org> Subject: Re: [PATCH v2 5/5] dax: handle media errors in dax_do_io From: Vishal Verma To: "hch@infradead.org" , "Verma, Vishal L" Cc: "Wilcox, Matthew R" , "linux-kernel@vger.kernel.org" , "linux-block@vger.kernel.org" , "xfs@oss.sgi.com" , "linux-nvdimm@ml01.01.org" , "jmoyer@redhat.com" , "linux-mm@kvack.org" , "viro@zeniv.linux.org.uk" , "axboe@fb.com" , "akpm@linux-foundation.org" , "linux-fsdevel@vger.kernel.org" , "linux-ext4@vger.kernel.org" , "david@fromorbit.com" , "jack@suse.cz" Date: Tue, 26 Apr 2016 09:01:32 -0600 In-Reply-To: <20160426083332.GB364@infradead.org> References: <1459303190-20072-1-git-send-email-vishal.l.verma@intel.com> <1459303190-20072-6-git-send-email-vishal.l.verma@intel.com> <20160420205923.GA24797@infradead.org> <1461434916.3695.7.camel@intel.com> <20160425083114.GA27556@infradead.org> <1461604476.3106.12.camel@intel.com> <20160426083332.GB364@infradead.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.18.5.2 (3.18.5.2-1.fc23) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1269 Lines: 35 On Tue, 2016-04-26 at 01:33 -0700, hch@infradead.org wrote: > On Mon, Apr 25, 2016 at 05:14:36PM +0000, Verma, Vishal L wrote: > > > > - Application hits EIO doing dax_IO or load/store io > > > > - It checks badblocks and discovers it's files have lost data > > > > - It write()s those sectors (possibly converted to file offsets > > using > > fiemap) > > ?? ?? * This triggers the fallback path, but if the application is > > doing > > this level of recovery, it will know the sector is bad, and write > > the > > entire sector > This sounds like a mess. > > > > > I think if we want to keep allowing arbitrary alignments for the > > dax_do_io path, we'd need: > > 1. To represent badblocks at a finer granularity (likely cache > > lines) > > 2. To allow the driver to do IO to a *block device* at sub-sector > > granularity > It's not a block device if it supports DAX.  It's byte addressable > memory masquerading as a block device. Yes but we made that decision a while back with pmem :) Are you saying it should stop being a block device anymore? > -- > To unsubscribe from this list: send the line "unsubscribe linux- > block" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at  http://vger.kernel.org/majordomo-info.html