[PATCH-part-2 9/9] nvme: force sgls on user passthrough if possible

[Keith Busch]

On Wed, Sep 04, 2024 at 11:38:17AM -0700, Keith Busch wrote:
> @@ -146,6 +156,13 @@ static int nvme_map_user_request(struct request *req, u64 ubuffer,
>  	if (bdev) {
>  		bio_set_dev(bio, bdev);
>  		if (meta_buffer && meta_len) {
> +			if (nvme_ctrl_meta_sgl_supported(ctrl)) {
> +				nvme_req(req)->flags |= NVME_REQ_USE_META_SGLS;
> +			} else {
> +				dev_warn_once(ctrl->device,
> +					      "using unchecked meta buffer\n");
> +				add_taint(TAINT_USER, LOCKDEP_STILL_OK);
> +			}
>  			ret = bio_integrity_map_user(bio, meta_buffer, meta_len,
>  						     meta_seed);
>  			if (ret)

This actually needs to add this line on successful:

	req->nr_integrity_segments = bio_integrity(bio)->bip_vcnt;

But it think it would be even better to introce a request helper,
blk_integrity_map_user() that takes a struct instead of a bio so it can
handle updating the request state appropriately.