Re: [PATCH v2 08/22] dma-mapping: Allow map_sg() ops to return negative error codes

[Christoph Hellwig]

> +int __dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int nents,
>  		enum dma_data_direction dir, unsigned long attrs);

I don't think it makes sense to expose this __dma_map_sg_attrs helper.
Just keep it static and move the sgtable helper to kernel/dma/mapping.c
as well.