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Date: Wed, 10 Mar 2010 09:38:35 -0800
Message-ID: <1786ab031003100938x19e7c054ieba6c34ebd939ad6@mail.gmail.com>
Subject: Re: [PATCH 1/2 V3] io-controller: Add a new interface "weight_device" 
	for IO-Controller
From: Chad Talbott <ctalbott@google.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Gui Jianfeng <guijianfeng@cn.fujitsu.com>,
       Nauman Rafique <nauman@google.com>, jens.axboe@oracle.com,
       linux-kernel@vger.kernel.org, Li Zefan <lizf@cn.fujitsu.com>
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On Wed, Mar 10, 2010 at 7:30 AM, Vivek Goyal <vgoyal@redhat.com> wrote:
> This still leaves the issue of reaching a gendisk object from request
> queue. Looking into it.

It looks like we have that pairing way back in blk_register_queue()
which takes a gendisk.  Is there any reason we don't hold onto the
gendisk there?  Eyeballing add_disk() and unlink_gendisk() seems to
confirm that gendisk lifetime spans request_queue.

Nauman and I were also wondering why blkio_group and blkio_policy_node
store a dev_t, rather than a direct pointer to gendisk.  dev_t seems
more like a userspace<->kernel interface than an inside-the-kernel
interface.

Chad