Re: [PATCH] null_blk: add simple write-zeroes support

[Chaitanya Kulkarni <chaitanyak@xxxxxxxxxx>]

On 2/26/24 04:20, Johannes Thumshirn wrote:
> On 26.02.24 08:15, Chaitanya Kulkarni wrote:
>> @@ -1684,8 +1689,13 @@ static void null_del_dev(struct nullb *nullb)
>>    	dev->nullb = NULL;
>>    }
>>    
>> -static void null_config_discard(struct nullb *nullb, struct queue_limits *lim)
>> +static void null_config_discard_write_zeroes(struct nullb *nullb,
>> +					     struct queue_limits *lim)
>>    {
>> +	/* REQ_OP_WRITE_ZEROES only supported in non memory backed mode */
>> +	if (!nullb->dev->memory_backed && nullb->dev->write_zeroes)
>> +		lim->max_write_zeroes_sectors = UINT_MAX >> 9;
>> +
>>    	if (nullb->dev->discard == false)
>>    		return;
> Please use SECTOR_SHIFT instead of the magic '9'.

In past I've been told explicitly to not use SECTOR_SHIFT.
That also follows existing code in the function where SECTOR_SHIFT is not
used [1].

Now I'm really confused :(.

-ck

[1]

static void null_config_discard(struct nullb *nullb, struct queue_limits 
*lim)
{
         if (nullb->dev->discard == false)
                 return;

         if (!nullb->dev->memory_backed) {
                 nullb->dev->discard = false;
                 pr_info("discard option is ignored without memory 
backing\n");
                 return;
         }

         if (nullb->dev->zoned) {
                 nullb->dev->discard = false;
                 pr_info("discard option is ignored in zoned mode\n");
                 return;
         }

         lim->max_hw_discard_sectors = UINT_MAX >> 9;
}