From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.9]:39201 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751147AbcJ2P3f (ORCPT ); Sat, 29 Oct 2016 11:29:35 -0400 Date: Sat, 29 Oct 2016 08:29:33 -0700 From: Christoph Hellwig To: Ming Lei Cc: Jens Axboe , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, Christoph Hellwig , "Kirill A . Shutemov" , Mike Christie , Hannes Reinecke , Dan Williams , Toshi Kani , shli@kernel.org, linux-raid@vger.kernel.org Subject: Re: [PATCH 23/60] block: introduce flag QUEUE_FLAG_NO_MP Message-ID: <20161029152933.GA17241@infradead.org> References: <1477728600-12938-1-git-send-email-tom.leiming@gmail.com> <1477728600-12938-24-git-send-email-tom.leiming@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1477728600-12938-24-git-send-email-tom.leiming@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Sat, Oct 29, 2016 at 04:08:22PM +0800, Ming Lei wrote: > MD(especially raid1 and raid10) is a bit difficult to support > multipage bvec, so introduce this flag for not enabling multipage > bvec, then MD can still accept singlepage bvec only, and once > direct access to bvec table in MD and other fs/drivers are cleanuped, > the flag can be removed. BTRFS has the similar issue too. There is really no good reason for that. The RAID1 and 10 code really just needs some love to use the bio cloning infrastructure, bio iterators and generally recent bio apis. btrfs just needs a tiny little bit of help and I'll send patches soon. Having two different code path is just asking for trouble in the long run.