nvme-pci: fix error unwind in nvme_map_data

Properly unwind step by step using refactored helpers from nvme_unmap_data
to avoid a potential double dma_unmap on a mapping failure.

Fixes: 7fe07d1 ("nvme-pci: merge nvme_free_iod into nvme_unmap_data")
Reported-by: Marc Orr <marcorr@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Marc Orr <marcorr@google.com>

drivers/nvme/host/pci.c

@@ -683,7 +683,7 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev,
 			__le64 *old_prp_list = prp_list;
 			prp_list = dma_pool_alloc(pool, GFP_ATOMIC, &prp_dma);
 			if (!prp_list)
-				return BLK_STS_RESOURCE;
+				goto free_prps;
 			list[iod->npages++] = prp_list;
 			prp_list[0] = old_prp_list[i - 1];
 			old_prp_list[i - 1] = cpu_to_le64(prp_dma);
@@ -703,14 +703,14 @@ static blk_status_t nvme_pci_setup_prps(struct nvme_dev *dev,
 		dma_addr = sg_dma_address(sg);
 		dma_len = sg_dma_len(sg);
 	}
-
 done:
 	cmnd->dptr.prp1 = cpu_to_le64(sg_dma_address(iod->sg));
 	cmnd->dptr.prp2 = cpu_to_le64(iod->first_dma);
-
 	return BLK_STS_OK;
-
- bad_sgl:
+free_prps:
+	nvme_free_prps(dev, req);
+	return BLK_STS_RESOURCE;
+bad_sgl:
 	WARN(DO_ONCE(nvme_print_sgl, iod->sg, iod->nents),
 			"Invalid SGL for payload:%d nents:%d\n",
 			blk_rq_payload_bytes(req), iod->nents);
@@ -782,7 +782,7 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev,
 
 			sg_list = dma_pool_alloc(pool, GFP_ATOMIC, &sgl_dma);
 			if (!sg_list)
-				return BLK_STS_RESOURCE;
+				goto free_sgls;
 
 			i = 0;
 			nvme_pci_iod_list(req)[iod->npages++] = sg_list;
@@ -795,6 +795,9 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev,
 	} while (--entries > 0);
 
 	return BLK_STS_OK;
+free_sgls:
+	nvme_free_sgls(dev, req);
+	return BLK_STS_RESOURCE;
 }
 
 static blk_status_t nvme_setup_prp_simple(struct nvme_dev *dev,
@@ -863,7 +866,7 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
 	sg_init_table(iod->sg, blk_rq_nr_phys_segments(req));
 	iod->nents = blk_rq_map_sg(req->q, req, iod->sg);
 	if (!iod->nents)
-		goto out;
+		goto out_free_sg;
 
 	if (is_pci_p2pdma_page(sg_page(iod->sg)))
 		nr_mapped = pci_p2pdma_map_sg_attrs(dev->dev, iod->sg,
@@ -872,16 +875,21 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
 		nr_mapped = dma_map_sg_attrs(dev->dev, iod->sg, iod->nents,
 					     rq_dma_dir(req), DMA_ATTR_NO_WARN);
 	if (!nr_mapped)
-		goto out;
+		goto out_free_sg;
 
 	iod->use_sgl = nvme_pci_use_sgls(dev, req);
 	if (iod->use_sgl)
 		ret = nvme_pci_setup_sgls(dev, req, &cmnd->rw, nr_mapped);
 	else
 		ret = nvme_pci_setup_prps(dev, req, &cmnd->rw);
-out:
 	if (ret != BLK_STS_OK)
-		nvme_unmap_data(dev, req);
+		goto out_unmap_sg;
+	return BLK_STS_OK;
+
+out_unmap_sg:
+	nvme_unmap_sg(dev, req);
+out_free_sg:
+	mempool_free(iod->sg, dev->iod_mempool);
 	return ret;
 }