From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH v2 19/26] bounce: Refactor __blk_queue_bounce to not use bi_io_vec Date: Thu, 20 Sep 2012 17:25:55 -0700 Message-ID: <20120921002555.GV7264@google.com> References: <1347322957-25260-1-git-send-email-koverstreet@google.com> <1347322957-25260-20-git-send-email-koverstreet@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1347322957-25260-20-git-send-email-koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Kent Overstreet Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, neilb-l3A5Bk7waGM@public.gmane.org List-Id: linux-bcache@vger.kernel.org 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. Also, how was this tested? Thanks. -- tejun