[dm-devel] [PATCH] block: add a bi_error field to struct bio

[Jens Axboe]

On 07/24/2015 04:49 AM, Christoph Hellwig wrote:
> On Wed, Jul 22, 2015 at 03:59:46PM -0600, Jens Axboe wrote:
>> One possible solution would be to shrink bi_flags to an unsigned int, no
>> problems fitting that in. Then we could stuff bi_error in that (new) hole,
>> and we would end up having the same size again.
>
> As long as we use set/test/clear_bt on bi_flags that won't work unfortunately.

Right, I don't think we need to do that though. If you look at the flags 
usage, it's all over the map. Some use test/set_bit, some set it just by 
OR'ing the mask. There's no reason we can't make this work without 
relying on set/test_bit, and then shrink it to an unsigned int.

-- 
Jens Axboe