From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH stable] block: discard bdi_unregister() in favour of bdi_destroy() Date: Thu, 30 Apr 2015 10:35:03 +0200 Message-ID: <20150430083503.GU5029@twins.programming.kicks-ass.net> References: <20150414171537.GH25394@azat> <20150423160551.45345f96@notabene.brown> <20150427141222.5dac22f1@notabene.brown> <20150429072530.39d38b00@notabene.brown> <20150429133512.GA4436@lst.de> <20150429160258.GK17717@twins.programming.kicks-ass.net> <20150430103233.75227693@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20150430103233.75227693@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: Jens Axboe , Christoph Hellwig , Mike Snitzer , Azat Khuzhin , "Kernel.org-Linux-RAID" , Guoqing Jiang , Tejun Heo , Jan Kara , lkml , device-mapper development List-Id: linux-raid.ids On Thu, Apr 30, 2015 at 10:32:33AM +1000, NeilBrown wrote: > > bdi_unregister() now contains very little functionality. > > It contains a "WARN_ON" if bdi->dev is NULL. This warning is of no > real consequence as bdi->dev isn't needed by anything else in the function, > and it triggers if > blk_cleanup_queue() -> bdi_destroy() > is called before bdi_unregister, which a subsequent patch will make happen. > So this isn't wanted. > > It also calls bdi_set_min_ratio(). This needs to be called after > writes through the bdi have all been flushed, and before the bdi is destroyed. > Calling it early is better than calling it late as it frees up a global > resource. > > Calling it immediately after bdi_wb_shutdown() in bdi_destroy() > perfectly fits these requirements. > > So bdi_unregister can be discarded with the important content moved to > bdi_destroy, as can the > writeback_bdi_unregister > event which is already not used. > > This is tagged for 'stable' as it is a pre-requisite for a subsequent > patch which moves calls to blk_cleanup_queue() before calls to > del_gendisk(). The commit identified as 'Fixes' removed a lot of > other functionality from bdi_unregister(), and made a change which > necessitated moving the blk_cleanup_queue() calls. > > Reported-by: Mike Snitzer > Cc: Christoph Hellwig > Cc: Peter Zijlstra > Cc: stable@vger.kernel.org (v4.0) > Fixes: c4db59d31e39ea067c32163ac961e9c80198fd37 Fixes: c4db59d31e39 ("fs: don't reassign dirty inodes to default_backing_dev_info") > Signed-off-by: NeilBrown Acked-by: Peter Zijlstra (Intel)