[dm-devel] [PATCH RFC] block: blktrace framework cleanup

[Chaitanya Kulkarni]

On 6/23/20 11:48 PM, Christoph Hellwig wrote:
> 
> 
> On Tue, Jun 23, 2020 at 08:27:52PM -0700, Chaitanya Kulkarni wrote:
>> There are many places where trace API accepts the struct request_queue*
>> parameter which can be derived from other function parameters.
>>
>> This patch removes the struct request queue parameter from the
>> blktrace framework and adjusts the tracepoints definition and usage
>> along with the tracing API itself.
> 
> Good idea, and I had a half-ready patch for this already as well.
> 
Well, I sent out the reply to your suggestion didn't get any response so 
I decided to send a patch, if you want we can merge it I'll keep you as 
an author for the right reasons.
> One issue, and two extra requests below:
> 
> 
>>   	if (bio->bi_disk && bio_flagged(bio, BIO_TRACE_COMPLETION)) {
>> -		trace_block_bio_complete(bio->bi_disk->queue, bio);
>> +		trace_block_bio_complete(bio);
> 
> This one can also be called for a different queue than
> bio->bi_disk->queue, so for this one particular tracepoint we'll need
> to keep the request_queue argument.
> 
Yes, we should.
>> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
>> index fdcc2c1dd178..a3cade16ef80 100644
>> --- a/block/blk-mq-sched.c
>> +++ b/block/blk-mq-sched.c
>> @@ -409,7 +409,7 @@ EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge);
>>   
>>   void blk_mq_sched_request_inserted(struct request *rq)
>>   {
>> -	trace_block_rq_insert(rq->q, rq);
>> +	trace_block_rq_insert(rq);
>>   }
>>   EXPORT_SYMBOL_GPL(blk_mq_sched_request_inserted);
> 
> As a follow on patch we should also remove this function.
> 
Okay will make it is a 2nd patch.
>>   	}
>>   
>>   	spin_lock(&ctx->lock);
>> @@ -2111,7 +2111,7 @@ blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
>>   		goto queue_exit;
>>   	}
>>   
>> -	trace_block_getrq(q, bio, bio->bi_opf);
>> +	trace_block_getrq(bio, bio->bi_opf);
> 
> The second argument can be removed as well.  Maybe as another patch.
Okay I'll make it in a 3rd patch.
>