[PATCH 3/8] nvme-pci: refactor nvme_pci_use_sgls

[Christoph Hellwig]

On Mon, Jun 23, 2025 at 09:27:30AM -0600, Keith Busch wrote:
> > -	if (nvme_pci_use_sgls(dev, req, iod->sgt.nents))
> > +	if (use_sgl == SGL_FORCED ||
> > +	    (use_sgl == SGL_SUPPORTED &&
> > +	     (!sgl_threshold || nvme_pci_avg_seg_size(req) >= sgl_threshold)))
> >  		ret = nvme_pci_setup_sgls(nvmeq, req, &cmnd->rw);
> 
> We historically interpreted sgl_threshold set to 0 to mean disable SGL
> usage, maybe because the controller is broken or something. It might be
> okay to have 0 mean to not consider segment sizes, but I just wanted to
> point out this is a different interpretation of the user parameter.

This is still a leftover from the threshold mess in the first version.
I'll fix it for the next one.