Re: [PATCH 2/4] block: use the same failfast bits for bio and request

[Jens Axboe <jens.axboe@oracle.com>]

On Thu, Jul 09 2009, Jeff Garzik wrote:
> Christoph Hellwig wrote:
>> On Thu, Jul 09, 2009 at 09:45:24AM +0900, Tejun Heo wrote:
>>> What's more disturbing to me is the different between RQ and BIO
>>> flags.  __REQ_* are bit positions, REQ_* are masks while BIO_* are bit
>>> positions.  Sadly it seems it's already too late to change that.  I
>>> personally an not a big fan of simple accessors or flags defined as
>>> bit positions.  They seem to obscure things without much benefit.
>>
>> flags as bit positions generally only make sense if you use
>> test/set/clear_bit, otherwise they just confuse things.  And the
>> accessors are pretty annoying, especially in the block layer.  Trying to
>> find the places where a BIO flag has an actual effect is pretty painful
>> due to the mix of the different flags and the accessors.
>
> Indeed -- the accessors mean in practice that you always have at least  
> _two_ things to grep for, just to catch all accesses.  Block layer is  
> pretty bad about that style of usage :/

Yeah, I'm not too fond of it either, it does add to the confusion. I'll
sanitize it.

-- 
Jens Axboe