dma_map_bvec
dma_addr = dma_map_bvec(dev, bv, DMA_FROM_DEVICE, 0);
iod->first_dma = dma_map_bvec(anv->dev, bv, rq_dma_dir(req), 0);
dma_addr = dma_map_bvec(nvmeq->dev->dev, &bv, rq_dma_dir(req), 0);
iod->meta_dma = dma_map_bvec(nvmeq->dev->dev, &bv, rq_dma_dir(req), 0);