[PATCH] xfs: prevent deadlock in xfs_qm_shake()

[Felix Blyakher]

On May 29, 2009, at 2:25 PM, Christoph Hellwig wrote:

> On Fri, May 29, 2009 at 01:10:31PM -0500, Felix Blyakher wrote:
>> It's possible to recurse into filesystem from the memory
>> allocation, which deadlocks in xfs_qm_shake(). Add check
>> for __GFP_FS, and bailout if it is not set.
>>
>> Signed-off-by: Felix Blyakher <felixb at sgi.com>
>> Signed-off-by: Hedi Berriche <hedi at sgi.com>
>> ---
>> fs/xfs/linux-2.6/kmem.h |    2 +-
>> 1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/fs/xfs/linux-2.6/kmem.h b/fs/xfs/linux-2.6/kmem.h
>> index af6843c..d8d2321 100644
>> --- a/fs/xfs/linux-2.6/kmem.h
>> +++ b/fs/xfs/linux-2.6/kmem.h
>> @@ -103,7 +103,7 @@ extern void *kmem_zone_zalloc(kmem_zone_t *,  
>> unsigned int __nocast);
>> static inline int
>> kmem_shake_allow(gfp_t gfp_mask)
>> {
>> -	return (gfp_mask & __GFP_WAIT) != 0;
>> +	return ((gfp_mask & __GFP_WAIT && gfp_mask & __GFP_FS) != 0;
>
> Looks good to me.  But this could be written simpler as:
>
> 	return ((gfp_mask & (__GFP_WAIT|__GFP_FS)) != 0;

Yeah, sure. Weird it didn't occur to me :)

Thanks,
Felix