[PATCH 2/5] iov_iter: introduce type for preregistered dma tags

[Al Viro]

On Tue, Jul 26, 2022 at 10:38:11AM -0700, Keith Busch wrote:

> +void iov_iter_dma_tag(struct iov_iter *i, unsigned int direction,
> +			void *dma_tag, unsigned int dma_offset,
> +			unsigned long nr_segs, size_t count)
> +{
> +	WARN_ON(direction & ~(READ | WRITE));
> +	*i = (struct iov_iter){
> +		.iter_type = ITER_DMA_TAG,
> +		.data_source = direction,
> +		.nr_segs = nr_segs,

Could you can that cargo-culting?  Just what the hell is nr_segs
here?