static blk_status_t nvme_pci_setup_sgls()

in host/pci.c [738:798]

• 49 lines of code
• 7 McCabe index (conditional complexity)

static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev,
		struct request *req, struct nvme_rw_command *cmd, int entries)
{
	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
	struct dma_pool *pool;
	struct nvme_sgl_desc *sg_list;
	struct scatterlist *sg = iod->sg;
	dma_addr_t sgl_dma;
	int i = 0;

	/* setting the transfer type as SGL */
	cmd->flags = NVME_CMD_SGL_METABUF;

	if (entries == 1) {
		nvme_pci_sgl_set_data(&cmd->dptr.sgl, sg);
		return BLK_STS_OK;
	}

	if (entries <= (256 / sizeof(struct nvme_sgl_desc))) {
		pool = dev->prp_small_pool;
		iod->npages = 0;
	} else {
		pool = dev->prp_page_pool;
		iod->npages = 1;
	}

	sg_list = dma_pool_alloc(pool, GFP_ATOMIC, &sgl_dma);
	if (!sg_list) {
		iod->npages = -1;
		return BLK_STS_RESOURCE;
	}

	nvme_pci_iod_list(req)[0] = sg_list;
	iod->first_dma = sgl_dma;

	nvme_pci_sgl_set_seg(&cmd->dptr.sgl, sgl_dma, entries);

	do {
		if (i == SGES_PER_PAGE) {
			struct nvme_sgl_desc *old_sg_desc = sg_list;
			struct nvme_sgl_desc *link = &old_sg_desc[i - 1];

			sg_list = dma_pool_alloc(pool, GFP_ATOMIC, &sgl_dma);
			if (!sg_list)
				goto free_sgls;

			i = 0;
			nvme_pci_iod_list(req)[iod->npages++] = sg_list;
			sg_list[i++] = *link;
			nvme_pci_sgl_set_seg(link, sgl_dma, entries);
		}

		nvme_pci_sgl_set_data(&sg_list[i++], sg);
		sg = sg_next(sg);
	} while (--entries > 0);

	return BLK_STS_OK;
free_sgls:
	nvme_free_sgls(dev, req);
	return BLK_STS_RESOURCE;
}