From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752028Ab2DPQL3 (ORCPT ); Mon, 16 Apr 2012 12:11:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37222 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751454Ab2DPQL1 (ORCPT ); Mon, 16 Apr 2012 12:11:27 -0400 Date: Mon, 16 Apr 2012 11:52:07 -0400 From: Vivek Goyal To: Fengguang Wu Cc: Peter Zijlstra , ctalbott@google.com, rni@google.com, andrea@betterlinux.com, containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, lsf@lists.linux-foundation.org, linux-mm@kvack.org, jmoyer@redhat.com, lizefan@huawei.com, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org Subject: Re: [Lsf] [RFC] writeback and cgroup Message-ID: <20120416155207.GB15437@redhat.com> References: <20120404145134.GC12676@redhat.com> <20120407080027.GA2584@quack.suse.cz> <20120410180653.GJ21801@redhat.com> <20120410210505.GE4936@quack.suse.cz> <20120410212041.GP21801@redhat.com> <20120410222425.GF4936@quack.suse.cz> <20120411154005.GD16692@redhat.com> <1334406314.2528.90.camel@twins> <20120416125432.GB12776@redhat.com> <20120416130707.GA10532@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120416130707.GA10532@localhost> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 16, 2012 at 09:07:07PM +0800, Fengguang Wu wrote: [..] > Vivek, I noticed these lines in cfq code > > sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); > > Why not use bdi->dev->devt? The problem is that dev_name() will > return "btrfs-X" for btrfs rather than "major:minor". Isn't bdi->dev->devt 0? I see following code. add_disk() bdi_register_dev() bdi_register() device_create_vargs(MKDEV(0,0)) dev->devt = devt = MKDEV(0,0); So for normal block devices, I think bdi->dev->devt will be zero, that's why probably we don't use it. Thanks Vivek From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Goyal Subject: Re: [Lsf] [RFC] writeback and cgroup Date: Mon, 16 Apr 2012 11:52:07 -0400 Message-ID: <20120416155207.GB15437@redhat.com> References: <20120404145134.GC12676@redhat.com> <20120407080027.GA2584@quack.suse.cz> <20120410180653.GJ21801@redhat.com> <20120410210505.GE4936@quack.suse.cz> <20120410212041.GP21801@redhat.com> <20120410222425.GF4936@quack.suse.cz> <20120411154005.GD16692@redhat.com> <1334406314.2528.90.camel@twins> <20120416125432.GB12776@redhat.com> <20120416130707.GA10532@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Peter Zijlstra , ctalbott@google.com, rni@google.com, andrea@betterlinux.com, containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, lsf@lists.linux-foundation.org, linux-mm@kvack.org, jmoyer@redhat.com, lizefan@huawei.com, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org To: Fengguang Wu Return-path: Content-Disposition: inline In-Reply-To: <20120416130707.GA10532@localhost> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Mon, Apr 16, 2012 at 09:07:07PM +0800, Fengguang Wu wrote: [..] > Vivek, I noticed these lines in cfq code > > sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); > > Why not use bdi->dev->devt? The problem is that dev_name() will > return "btrfs-X" for btrfs rather than "major:minor". Isn't bdi->dev->devt 0? I see following code. add_disk() bdi_register_dev() bdi_register() device_create_vargs(MKDEV(0,0)) dev->devt = devt = MKDEV(0,0); So for normal block devices, I think bdi->dev->devt will be zero, that's why probably we don't use it. Thanks Vivek -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org