Re: [PATCH RESEND block#for-2.6.36] block_dev: always serialize exclusive open attempts

From: Jens Axboe
Date: Thu Aug 05 2010 - 05:02:57 EST

On 2010-08-04 17:59, Tejun Heo wrote:
> bd_prepare_to_claim() incorrectly allowed multiple attempts for
> exclusive open to progress in parallel if the attempting holders are
> identical. This triggered BUG_ON() as reported in the following bug.
> __bd_abort_claiming() is used to finish claiming blocks and doesn't
> work if multiple openers are inside a claiming block. Allowing
> multiple parallel open attempts to continue doesn't gain anything as
> those are serialized down in the call chain anyway. Fix it by always
> allowing only single open attempt in a claiming block.
> This problem can easily be reproduced by adding a delay after
> bd_prepare_to_claim() and attempting to mount two partitions of a
> disk.
> stable: only applicable to v2.6.35
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Reported-by: Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxx

Thanks Tejun, applied.

Jens Axboe

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