linux-kernel - Re: [PATCH 1/2] cdrom: always check_disk

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Date:	Fri, 29 Apr 2011 12:27:18 +0530
From:	Amit Shah <amit.shah@...hat.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	Jens Axboe <axboe@...nel.dk>, David Zeuthen <zeuthen@...il.com>,
	Martin Pitt <martin.pitt@...ntu.com>,
	Kay Sievers <kay.sievers@...y.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] cdrom: always check_disk_change() on open

On (Wed) 06 Apr 2011 [05:20:09], Tejun Heo wrote:
> cdrom_open() called check_disk_change() after the rest of open path
> succeeded which leads to the following bizarre behavior.
> 
> * After media change, if the device opened without O_NONBLOCK,
>   open_for_data() naturally fails with -ENOMEDIA and
>   check_disk_change() is never called.  The media is known to be gone
>   and the open failure makes it obvious to the userland but device
>   invalidation never happens.
> 
> * But if the device is opened with O_NONBLOCK, all the checks are
>   bypassed and cdrom_open() doesn't notice that the media is not there
>   and check_disk_change() is called and invalidation happens.
> 
> There's nothing to be gained by avoiding calling check_disk_change()
> on open failure.  Common cases end up calling check_disk_change()
> anyway.  All we get is inconsistent behavior.
> 
> Fix it by moving check_disk_change() invocation to the top of
> cdrom_open() so that it always gets called regardless of how the rest
> of open proceeds.
> 
> Signed-off-by: Tejun Heo <tj@...nel.org>
> Reported-by: Amit Shah <amit.shah@...hat.com>
> Tested-by: Amit Shah <amit.shah@...hat.com>

Ping?

Also, please mark this for stable-2.6.38.

Thanks,

		Amit
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