From: Dan Williams Subject: Re: [PATCH v2 5/5] dax: handle media errors in dax_do_io Date: Fri, 15 Apr 2016 11:17:39 -0700 Message-ID: References: <1459303190-20072-1-git-send-email-vishal.l.verma@intel.com> <1459303190-20072-6-git-send-email-vishal.l.verma@intel.com> <1460739288.3012.3.camel@intel.com> <1460741821.3012.11.camel@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: "Verma, Vishal L" , "hch@infradead.org" , "jack@suse.cz" , "axboe@fb.com" , "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" , "viro@zeniv.linux.org.uk" , "linux-fsdevel@vger.kernel.org" , "akpm@linux-foundation.org" , "linux-ext4@vger.kernel.org" , "Wilcox, Matthew R" To: Jeff Moyer Return-path: In-Reply-To: Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org On Fri, Apr 15, 2016 at 11:06 AM, Jeff Moyer wrote: > Dan Williams writes: > >>>> There's a lot of special casing here, so you might consider adding >>>> comments. >>> >>> Correct - maybe we should reconsider wrapper-izing this? :) >> >> Another option is just to skip dax_do_io() and this special casing >> fallback entirely if errors are present. I.e. only attempt dax_do_io >> when: IS_DAX() && gendisk->bb && bb->count == 0. > > So, if there's an error anywhere on the device, penalize all I/O (not > just writes, and not just on sectors that are bad)? I'm not sure that's > a great plan, either. > If errors are rare how much are we actually losing in practice? Moreover, we're going to do the full badblocks lookup anyway when we call ->direct_access(). If we had that information earlier we can avoid this fallback dance. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org