[PATCHv2 2/3] block: introduce rq_list_move

[Keith Busch]

On Wed, Dec 29, 2021 at 06:41:09PM +0100, Christoph Hellwig wrote:
> On Mon, Dec 27, 2021 at 08:41:37AM -0800, Keith Busch wrote:
> > +/**
> > + * rq_list_move() - move a struct request from one list to another
> > + * @src: The source list @rq is currently in
> > + * @dst: The destination list that @rq will be appended to
> > + * @rq: The request to move
> > + * @prv: The request preceding @rq in @src (NULL if @rq is the head)
> > + * @nxt: The request following @rq in @src (NULL if @rq is the tail)
> > + */
> > +static void inline rq_list_move(struct request **src, struct request **dst,
> > +				struct request *rq, struct request *prv,
> > +				struct request *nxt)
> > +{
> > +	if (prv)
> > +		prv->rq_next = nxt;
> > +	else
> > +		*src = nxt;
> > +	rq_list_add(dst, rq);
> > +}
> 
> Do we even need the nxt argument?  I think it should always be
> rq->rq_next?

Sure. I only used it here because the safe iterator already has rq_next.
It's not an optimization, so I'll remove it.