From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:39670 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S943145AbcJaSAf (ORCPT ); Mon, 31 Oct 2016 14:00:35 -0400 Date: Mon, 31 Oct 2016 11:58:29 -0600 From: Chris Mason To: Christoph Hellwig CC: Ming Lei , Jens Axboe , , , , "Kirill A . Shutemov" , Josef Bacik , David Sterba , "open list:BTRFS FILE SYSTEM" Subject: Re: [PATCH 26/60] btrfs: set NO_MP for request queues behind BTRFS Message-ID: <20161031175828.GB48277@clm-mbp.thefacebook.com> References: <1477728600-12938-1-git-send-email-tom.leiming@gmail.com> <1477728600-12938-27-git-send-email-tom.leiming@gmail.com> <20161031153644.GK30919@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed In-Reply-To: <20161031153644.GK30919@infradead.org> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Mon, Oct 31, 2016 at 08:36:44AM -0700, Christoph Hellwig wrote: >On Sat, Oct 29, 2016 at 04:08:25PM +0800, Ming Lei wrote: >> There are lots of direct access to .bi_vcnt & .bi_io_vec >> of bio, and it isn't ready to support multipage bvecs >> for BTRFS, so set NO_MP for these request queues. > >For one bio is an I/O submitter, it has absolutely no business changing >queue flags - if we need to stick to this limitation it simply needs >a version of bio_add_page that doesn't create multi-page bvecs. > >Second I don't think making it multipage bvec aware is all that hard, >and we should aim for doing the proper thing. Yeah, I'd rather make us less special. The direct access was a short term fix to adjust to the new bio interfaces, we should clean it up. -chris