Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754028AbcDYIbU (ORCPT ); Mon, 25 Apr 2016 04:31:20 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:42934 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753860AbcDYIbS (ORCPT ); Mon, 25 Apr 2016 04:31:18 -0400 Date: Mon, 25 Apr 2016 01:31:14 -0700 From: "hch@infradead.org" To: "Verma, Vishal L" Cc: "hch@infradead.org" , "jmoyer@redhat.com" , "axboe@fb.com" , "jack@suse.cz" , "linux-nvdimm@ml01.01.org" , "david@fromorbit.com" , "linux-kernel@vger.kernel.org" , "xfs@oss.sgi.com" , "linux-block@vger.kernel.org" , "linux-mm@kvack.org" , "Wilcox, Matthew R" , "linux-fsdevel@vger.kernel.org" , "akpm@linux-foundation.org" , "linux-ext4@vger.kernel.org" , "viro@zeniv.linux.org.uk" Subject: Re: [PATCH v2 5/5] dax: handle media errors in dax_do_io Message-ID: <20160425083114.GA27556@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1461434916.3695.7.camel@intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 743 Lines: 14 On Sat, Apr 23, 2016 at 06:08:37PM +0000, Verma, Vishal L wrote: > direct_IO might fail with -EINVAL due to misalignment, or -ENOMEM due > to some allocation failing, and I thought we should return the original > -EIO in such cases so that the application doesn't lose the information > that the bad block is actually causing the error. EINVAL is a concern here. Not due to the right error reported, but because it means your current scheme is fundamentally broken - we need to support I/O at any alignment for DAX I/O, and not fail due to alignbment concernes for a highly specific degraded case. I think this whole series need to go back to the drawing board as I don't think it can actually rely on using direct I/O as the EIO fallback.