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

[Jeff Garzik <jeff@garzik.org>]

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 :/

	Jeff