From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756736Ab2IUAcH (ORCPT ); Thu, 20 Sep 2012 20:32:07 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:33353 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756669Ab2IUA3U (ORCPT ); Thu, 20 Sep 2012 20:29:20 -0400 Date: Thu, 20 Sep 2012 17:29:16 -0700 From: Kent Overstreet To: Tejun Heo Cc: linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org, dm-devel@redhat.com, axboe@kernel.dk, neilb@suse.de Subject: Re: [PATCH v2 19/26] bounce: Refactor __blk_queue_bounce to not use bi_io_vec Message-ID: <20120921002916.GM5519@google.com> References: <1347322957-25260-1-git-send-email-koverstreet@google.com> <1347322957-25260-20-git-send-email-koverstreet@google.com> <20120921002555.GV7264@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120921002555.GV7264@google.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 20, 2012 at 05:25:55PM -0700, Tejun Heo wrote: > Hello, Kent. > > On Mon, Sep 10, 2012 at 05:22:30PM -0700, Kent Overstreet wrote: > > A bunch of what __blk_queue_bounce() was doing was problematic for the > > immutable bvec work; this cleans that up and the code is quite a bit > > smaller, too. > > > > The __bio_for_each_segment() in copy_to_high_bio_irq() was changed > > because that one's looping over the original bio, not the bounce bio - > > since the bounce code doesn't own that bio the __ version wasn't > > correct. > > I do like the new implementation. I think the function is broken > before and after tho. Allocating from fs_bio_set from block layer is > never safe and nothing seems to prevent multiple allocators compete in > the bounce page mempool. This will need a separate bioset and the > multiple mempool allocation would have to be put inside a mutex. Yeah, I should've at least made a note of that. I should really add "audit all uses of fs_bio_set" to my todo list. > Also, how was this tested? Changed queue_bounce_pfn() to return 0, forcing all io to be bounced.