Re: [PATCH 10/10] null_blk: Support configuring the maximum segment size

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

On 10/21/22 08:34, Bart Van Assche wrote:
> On 10/20/22 16:13, Damien Le Moal wrote:
>> On 10/20/22 07:23, Bart Van Assche wrote:
>>> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
>>> index 1f154f92f4c2..bc811ab52c4a 100644
>>> --- a/drivers/block/null_blk/main.c
>>> +++ b/drivers/block/null_blk/main.c
>>> @@ -157,6 +157,10 @@ static int g_max_sectors;
>>>   module_param_named(max_sectors, g_max_sectors, int, 0444);
>>>   MODULE_PARM_DESC(max_sectors, "Maximum size of a command (in 512B sectors)");
>>>   
>>> +static unsigned int g_max_segment_size = 1UL << 31;
>>
>> Nit: UINT_MAX ?
> 
> Hi Damien,
> 
> That would be a valid alternative. I will consider changing the value 
> into UINT_MAX.
> 
>>> @@ -2088,6 +2100,7 @@ static int null_add_dev(struct nullb_device *dev)
>>>   	nullb->q->queuedata = nullb;
>>>   	blk_queue_flag_set(QUEUE_FLAG_NONROT, nullb->q);
>>>   	blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, nullb->q);
>>> +	blk_queue_flag_set(QUEUE_FLAG_SUB_PAGE_SEGMENTS, nullb->q);
>>
>> Where is this defined ? I do not see this flag defined anywhere in Linus
>> tree nor in Jens for-next...
> 
> That flag has been defined in patch 05/10 of this series.
> 
> In case you would like to take a look, the code I used to test this 
> series is available here: 
> https://github.com/bvanassche/blktests/commits/master

Please always send full patch series. Hard to review a patch without the
context for it :)

> 
> Thanks,
> 
> Bart.

-- 
Damien Le Moal
Western Digital Research