From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: [PATCH v2 19/26] bounce: Refactor __blk_queue_bounce to not use bi_io_vec Date: Thu, 20 Sep 2012 17:29:16 -0700 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> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20120921002555.GV7264@google.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Tejun Heo Cc: axboe@kernel.dk, linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org, dm-devel@redhat.com List-Id: linux-bcache@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.