[dm-devel] [PATCH 1/9] QUEUE_FLAG_NOWAIT to indicate device supports nowait

[Goldwyn Rodrigues]

On 08/10/2017 09:14 AM, Jens Axboe wrote:
> On 08/10/2017 05:38 AM, Goldwyn Rodrigues wrote:
>>
>>
>> On 08/09/2017 09:18 PM, Jens Axboe wrote:
>>> On 08/08/2017 02:36 PM, Jens Axboe wrote:
>>>> On 08/08/2017 02:32 PM, Shaohua Li wrote:
>>>>>> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
>>>>>> index 25f6a0cb27d3..fae021ebec1b 100644
>>>>>> --- a/include/linux/blkdev.h
>>>>>> +++ b/include/linux/blkdev.h
>>>>>> @@ -633,6 +633,7 @@ struct request_queue {
>>>>>>  #define QUEUE_FLAG_REGISTERED  29	/* queue has been registered to a disk */
>>>>>>  #define QUEUE_FLAG_SCSI_PASSTHROUGH 30	/* queue supports SCSI commands */
>>>>>>  #define QUEUE_FLAG_QUIESCED    31	/* queue has been quiesced */
>>>>>> +#define QUEUE_FLAG_NOWAIT      32	/* stack device driver supports REQ_NOWAIT */
>>>>
>>>> Does this work on 32-bit, where sizeof(unsigned long) == 32?
>>>
>>> I didn't get an answer to this one.
>>>
>>
>> Oh, I assumed the question is rhetorical.
>> No, it will not work on 32-bit. I was planning to change the field
>> queue_flags to u64. Is that okay?
> 
> No, besides that would not work with set/test_bit() and friends. Grab
> a free bit instead.
> 

Which bit is free? I don't see any gaps in QUEUE_FLAG_*, and I am not
sure if any one is unused.

-- 
Goldwyn