From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: [PATCH 36/51] writeback: implement bdi_for_each_wb() Date: Wed, 1 Jul 2015 09:27:57 +0200 Message-ID: <20150701072757.GW7252@quack.suse.cz> References: <1432329245-5844-1-git-send-email-tj@kernel.org> <1432329245-5844-37-git-send-email-tj@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, jack-AlSwsSmVLrQ@public.gmane.org, hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, mhocko-AlSwsSmVLrQ@public.gmane.org, clm-b10kYP2dOMg@public.gmane.org, fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org, gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, khlebnikov-XoJtRXgx1JseBXzfvpsJ4g@public.gmane.org To: Tejun Heo Return-path: Content-Disposition: inline In-Reply-To: <1432329245-5844-37-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-fsdevel.vger.kernel.org On Fri 22-05-15 17:13:50, Tejun Heo wrote: > This will be used to implement bdi-wide operations which should be > distributed across all its cgroup bdi_writebacks. > > Signed-off-by: Tejun Heo > Cc: Jens Axboe > Cc: Jan Kara One comment below. > @@ -445,6 +500,14 @@ static inline void wb_blkcg_offline(struct blkcg *blkcg) > { > } > > +struct wb_iter { > + int next_id; > +}; > + > +#define bdi_for_each_wb(wb_cur, bdi, iter, start_blkcg_id) \ > + for ((iter)->next_id = (start_blkcg_id); \ > + ({ (wb_cur) = !(iter)->next_id++ ? &(bdi)->wb : NULL; }); ) > + This looks quite confusing. Won't it be easier to understand as: struct wb_iter { } __attribute__ ((unused)); #define bdi_for_each_wb(wb_cur, bdi, iter, start_blkcg_id) \ if (((wb_cur) = (!start_blkcg_id ? &(bdi)->wb : NULL))) Honza -- Jan Kara SUSE Labs, CR