From: Fengguang Wu <fengguang.wu@intel.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
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
Date: Tue, 17 Apr 2012 10:14:24 +0800 [thread overview]
Message-ID: <20120417021424.GA9418@localhost> (raw)
In-Reply-To: <20120416155207.GB15437@redhat.com>
On Mon, Apr 16, 2012 at 11:52:07AM -0400, Vivek Goyal wrote:
> 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.
Yes indeed. I can confirm this with tracing. There are two main cases
- some filesystems do not have a real device for the bdi.
- add_disk() calls bdi_register_dev() with the devt, however this
information is not passed down for some reason.
device_create_vargs() will try to create a sysfs dev file if the
devt is not MKDEV(0,0).
Thanks,
Fengguang
next prev parent reply other threads:[~2012-04-17 2:19 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-03 18:36 [RFC] writeback and cgroup Tejun Heo
2012-04-04 14:51 ` Vivek Goyal
2012-04-04 15:36 ` [Lsf] " Steve French
2012-04-04 18:56 ` Tejun Heo
2012-04-04 19:19 ` Vivek Goyal
2012-04-25 8:47 ` Suresh Jayaraman
2012-04-04 18:49 ` Tejun Heo
2012-04-04 19:23 ` [Lsf] " Steve French
2012-04-14 12:15 ` Peter Zijlstra
2012-04-04 20:32 ` Vivek Goyal
2012-04-04 23:02 ` Tejun Heo
2012-04-05 16:38 ` Tejun Heo
2012-04-05 17:13 ` Vivek Goyal
2012-04-14 11:53 ` [Lsf] " Peter Zijlstra
2012-04-07 8:00 ` Jan Kara
2012-04-10 16:23 ` [Lsf] " Steve French
2012-04-10 18:16 ` Vivek Goyal
2012-04-10 18:06 ` Vivek Goyal
2012-04-10 21:05 ` Jan Kara
2012-04-10 21:20 ` Vivek Goyal
2012-04-10 22:24 ` Jan Kara
2012-04-11 15:40 ` Vivek Goyal
2012-04-11 15:45 ` Vivek Goyal
2012-04-11 17:05 ` Jan Kara
2012-04-11 17:23 ` Vivek Goyal
2012-04-11 19:44 ` Jan Kara
2012-04-17 21:48 ` Tejun Heo
2012-04-18 18:18 ` Vivek Goyal
2012-04-11 19:22 ` Jan Kara
2012-04-12 20:37 ` Vivek Goyal
2012-04-12 20:51 ` Tejun Heo
2012-04-14 14:36 ` Fengguang Wu
2012-04-16 14:57 ` Vivek Goyal
2012-04-24 11:33 ` Fengguang Wu
2012-04-24 14:56 ` Jan Kara
2012-04-24 15:58 ` Vivek Goyal
2012-04-25 2:42 ` Fengguang Wu
2012-04-25 3:16 ` Fengguang Wu
2012-04-25 9:01 ` Jan Kara
2012-04-25 12:05 ` Fengguang Wu
2012-04-15 11:37 ` [Lsf] " Peter Zijlstra
2012-04-17 22:01 ` Tejun Heo
2012-04-18 6:30 ` Jan Kara
2012-04-14 12:25 ` [Lsf] " Peter Zijlstra
2012-04-16 12:54 ` Vivek Goyal
2012-04-16 13:07 ` Fengguang Wu
2012-04-16 14:19 ` Fengguang Wu
2012-04-16 15:52 ` Vivek Goyal
2012-04-17 2:14 ` Fengguang Wu [this message]
2012-04-04 17:51 ` Fengguang Wu
2012-04-04 18:35 ` Vivek Goyal
2012-04-04 21:42 ` Fengguang Wu
2012-04-05 15:10 ` Vivek Goyal
2012-04-06 0:32 ` Fengguang Wu
2012-04-04 19:33 ` Tejun Heo
2012-04-04 20:18 ` Vivek Goyal
2012-04-05 16:31 ` Tejun Heo
2012-04-05 17:09 ` Vivek Goyal
2012-04-06 9:59 ` Fengguang Wu
2012-04-17 22:38 ` Tejun Heo
2012-04-19 14:23 ` Fengguang Wu
2012-04-19 18:31 ` Vivek Goyal
2012-04-20 12:45 ` Fengguang Wu
2012-04-20 19:29 ` Vivek Goyal
2012-04-20 21:33 ` Tejun Heo
2012-04-22 14:26 ` Fengguang Wu
2012-04-23 12:30 ` Vivek Goyal
2012-04-23 16:04 ` Tejun Heo
2012-04-19 20:26 ` Jan Kara
2012-04-20 13:34 ` Fengguang Wu
2012-04-20 19:08 ` Tejun Heo
2012-04-22 14:46 ` Fengguang Wu
2012-04-23 16:56 ` Tejun Heo
2012-04-24 7:58 ` Fengguang Wu
2012-04-25 15:47 ` Tejun Heo
2012-04-23 9:14 ` Jan Kara
2012-04-23 10:24 ` Fengguang Wu
2012-04-23 12:42 ` Jan Kara
2012-04-23 14:31 ` Fengguang Wu
2012-04-18 6:57 ` Jan Kara
2012-04-18 7:58 ` Fengguang Wu
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