[dm-devel] [PATCH v2] blk-mq: enforce op-specific segment limits in blk_insert_cloned_request

[Uday Shankar]

On Wed, Feb 22, 2023 at 12:16:02PM -0700, Keith Busch wrote:
> On Wed, Feb 22, 2023 at 11:52:25AM -0700, Uday Shankar wrote:
> >  static inline unsigned int blk_rq_get_max_segments(struct request *rq)
> >  {
> > -	if (req_op(rq) == REQ_OP_DISCARD)
> > -		return queue_max_discard_segments(rq->q);
> > -	return queue_max_segments(rq->q);
> > +	return blk_queue_get_max_segments(rq->q, req_op(rq));
> >  }
> 
> I think you should just move this function to blk.h instead of
> introducing a new one.

I chose to add blk_queue_get_max_segments as a public function because
it parallels blk_queue_get_max_sectors. If you don't want two functions,
I could manually inline the (2) uses of blk_rq_get_max_segments(rq),
converting them to blk_queue_get_max_segments(rq->q, req_op(rq)).