From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932380AbbEWQls (ORCPT ); Sat, 23 May 2015 12:41:48 -0400 Received: from mail-ie0-f178.google.com ([209.85.223.178]:36816 "EHLO mail-ie0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758000AbbEWQlq (ORCPT ); Sat, 23 May 2015 12:41:46 -0400 MIME-Version: 1.0 In-Reply-To: <20150523141209.GA19414@lst.de> References: <20150512042629.11521.70356.stgit@dwillia2-desk3.amr.corp.intel.com> <20150512043001.11521.3526.stgit@dwillia2-desk3.amr.corp.intel.com> <1431542149.31415.10.camel@intel.com> <20150523141209.GA19414@lst.de> Date: Sat, 23 May 2015 09:41:45 -0700 X-Google-Sender-Auth: bP_Bf9-JTtE28jbKrZyaFmbCkOQ Message-ID: Subject: Re: [PATCH v3 06/11] scatterlist: support "page-less" (__pfn_t only) entries From: Dan Williams To: "hch@lst.de" Cc: "axboe@kernel.dk" , "linux-arch@vger.kernel.org" , "riel@redhat.com" , "linux-nvdimm@lists.01.org" , "linux-fsdevel@vger.kernel.org" , "david@fromorbit.com" , "linux-kernel@vger.kernel.org" , "mingo@kernel.org" , "axboe@fb.com" , "dmaengine@vger.kernel.org" , "mgorman@suse.de" , "j.glisse@gmail.com" , "akpm@linux-foundation.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 23, 2015 at 7:12 AM, hch@lst.de wrote: > On Wed, May 13, 2015 at 06:35:55PM +0000, Williams, Dan J wrote: >> Jens, I'm wondering if you want to take this series(.) as patches or >> prepare a git branch to pull? > > Honestly I don't think it should go anyway. It makes a big mess of > a structure without providing a real user for it. Given how we are > using the bio_vec for in-kernel page based I/O these days it seems > like a very dangerous idea. There's nothing dangerous about the __pfn_t conversion of the block layer in the !CONFIG_DEV_PFN case a __pfn_t based bio_vec is bit-for-bit identical to a struct page based bio_vec. However, you're right, I can't make the same claim about a scatterlist before and after the change. Hmm, we're missing a pfn-only block I/O user and we're missing the second half of the implementation that provides __pfn_t_to_page() for persistent memory. I'm looking to have a solution __pfn_t_to_page() shortly, maybe that will allow the scatterlist changes to be skipped... we'll see.