[PATCH v6 09/12] nvme-rdma: use ib_dma_map_sgtable_attrs()

[Mykola Marzhan]

ib_dma_map_sg() folds every mapping error into a zero return, losing
the DMA layer's error code.  Switch both scatterlist mappings to
ib_dma_map_sgtable_attrs(), which preserves it for the next patch to
act on.  No behavior change: failures are still reported as -EIO.

A local sg_table is needed: dma_map_sgtable() maps orig_nents
entries, and the embedded table's orig_nents is the allocated count,
not the count blk_rq_map_sg() produced.  rdma_rw_ctx_init() does the
same.

Assisted-by: Claude:claude-fable-5
Cc: stable@xxxxxxxxxxxxxxx # v7.1
Signed-off-by: Mykola Marzhan <mykola@xxxxxxxxxxx>
Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
---
 drivers/nvme/host/rdma.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 6909e3542794..63830334c73e 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -1469,6 +1469,7 @@ static int nvme_rdma_dma_map_req(struct ib_device *ibdev, struct request *rq,
 		int *count, int *pi_count)
 {
 	struct nvme_rdma_request *req = blk_mq_rq_to_pdu(rq);
+	struct sg_table sgt;
 	int ret;
 
 	req->data_sgl.sg_table.sgl = (struct scatterlist *)(req + 1);
@@ -1480,12 +1481,16 @@ static int nvme_rdma_dma_map_req(struct ib_device *ibdev, struct request *rq,
 
 	req->data_sgl.nents = blk_rq_map_sg(rq, req->data_sgl.sg_table.sgl);
 
-	*count = ib_dma_map_sg(ibdev, req->data_sgl.sg_table.sgl,
-			       req->data_sgl.nents, rq_dma_dir(rq));
-	if (unlikely(*count <= 0)) {
+	sgt = (struct sg_table) {
+		.sgl		= req->data_sgl.sg_table.sgl,
+		.orig_nents	= req->data_sgl.nents,
+	};
+	ret = ib_dma_map_sgtable_attrs(ibdev, &sgt, rq_dma_dir(rq), 0);
+	if (unlikely(ret)) {
 		ret = -EIO;
 		goto out_free_table;
 	}
+	*count = sgt.nents;
 
 	if (blk_integrity_rq(rq)) {
 		req->metadata_sgl->sg_table.sgl =
@@ -1501,14 +1506,16 @@ static int nvme_rdma_dma_map_req(struct ib_device *ibdev, struct request *rq,
 
 		req->metadata_sgl->nents = blk_rq_map_integrity_sg(rq,
 				req->metadata_sgl->sg_table.sgl);
-		*pi_count = ib_dma_map_sg(ibdev,
-					  req->metadata_sgl->sg_table.sgl,
-					  req->metadata_sgl->nents,
-					  rq_dma_dir(rq));
-		if (unlikely(*pi_count <= 0)) {
+		sgt = (struct sg_table) {
+			.sgl		= req->metadata_sgl->sg_table.sgl,
+			.orig_nents	= req->metadata_sgl->nents,
+		};
+		ret = ib_dma_map_sgtable_attrs(ibdev, &sgt, rq_dma_dir(rq), 0);
+		if (unlikely(ret)) {
 			ret = -EIO;
 			goto out_free_pi_table;
 		}
+		*pi_count = sgt.nents;
 	}
 
 	return 0;
-- 
2.52.0