From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: [PATCH v5 12/12] block: Only clone bio vecs that are in use Date: Mon, 13 Aug 2012 14:46:54 -0700 Message-ID: <20120813214654.GD9541@google.com> References: <1344290921-25154-1-git-send-email-koverstreet@google.com> <1344290921-25154-13-git-send-email-koverstreet@google.com> <20120809173700.GB6644@dhcp-172-17-108-109.mtv.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120809173700.GB6644@dhcp-172-17-108-109.mtv.corp.google.com> Sender: linux-kernel-owner@vger.kernel.org To: Tejun Heo Cc: linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org, dm-devel@redhat.com, axboe@kernel.dk, agk@redhat.com, neilb@suse.de, drbd-dev@lists.linbit.com, vgoyal@redhat.com, mpatocka@redhat.com, sage@newdream.net, yehuda@hq.newdream.net List-Id: dm-devel.ids On Thu, Aug 09, 2012 at 10:37:00AM -0700, Tejun Heo wrote: > Hello, > > On Mon, Aug 06, 2012 at 03:08:41PM -0700, Kent Overstreet wrote: > > bcache creates large bios internally, and then splits them according to > > the device requirements before it sends them down. If a lower level > > device tries to clone the bio, and the original bio had more than > > BIO_MAX_PAGES, the clone will fail unecessarily. > > > > We can fix this by only cloning the bio vecs that are actually in use. > > How was this tested? This code has been in the bcache tree for months, and I added it to fix a real bug (think I saw it with bcache on top of dm) - and since then it's been tested in probably just about all the relevant configurations, certainly both dm and md.