Message-ID: <49E440D9.4020803@kernel.org>
Date: Tue, 14 Apr 2009 16:52:57 +0900
From: Tejun Heo <tj@kernel.org>
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To: Daniel Collins <solemnwarning@solemnwarning.no-ip.org>
CC: linux-kernel@vger.kernel.org
Subject: Re: 2.6.28 /proc/diskstats
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Daniel Collins wrote:
> Hi
> 
> Since 2.6.28, fd0 isn't visible in /proc/diskstats from boot, only after
> access/mount. It is visible in /sys/block/ from boot, so there are no
> issues detecting it. This may also affect other devices such as hda but
> I haven't tested this yet, my test system and QEMU both only have
> ram0-ram15 from boot. I have tested 2.6.30-rc1 and found the same
> behavior. Is this a bug or a deliberate change?

Hmm... the reason why fd device is skipped before the first open is
because diskstats_show() skips zero sized devices and open is when the
floppy driver sets the capacity.  I think the original code also
skipped zero sized device.  It could be that the original code
triggered revalidation while the current one doesn't.  I'll dig
deeper.

Thanks.

-- 
tejun
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