From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Sender: Tejun Heo Date: Fri, 31 Aug 2018 17:29:00 -0700 From: Tejun Heo To: Dennis Zhou Cc: Jens Axboe , Johannes Weiner , Josef Bacik , kernel-team@fb.com, linux-block@vger.kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 12/15] blkcg: cleanup and make blk_get_rl use blkg_lookup_create Message-ID: <20180901002900.GJ1488037@devbig004.ftw2.facebook.com> References: <20180831015356.69796-1-dennisszhou@gmail.com> <20180831015356.69796-13-dennisszhou@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180831015356.69796-13-dennisszhou@gmail.com> List-ID: On Thu, Aug 30, 2018 at 09:53:53PM -0400, Dennis Zhou wrote: > From: "Dennis Zhou (Facebook)" > > blk_get_rl is responsible for identifying which request_list a request > should be allocated to. Try get logic was added earlier, but > semantically the logic was not changed. > > This patch makes better use of the bio already having a reference to the > blkg in the hot path. The cold path uses a better fallback of > blkg_lookup_create rather than just blkg_lookup and then falling back to > the q->root_rl. If lookup_create fails with anything but -ENODEV, it > falls back to q->root_rl. > > A clarifying comment is added to explain why q->root_rl is used rather > than the root blkg's rl. > > Signed-off-by: Dennis Zhou Acked-by: Tejun Heo We're replicating that retry busy loop a lot. It'd be really great to factor that out and document what it's doing. Thanks. -- tejun