[PATCH v6 12/12] nvme-rdma: factor out the scatterlist DMA mapping helper
From: Mykola Marzhan <hidden>
Date: 2026-07-26 11:33:03
Also in:
linux-block, linux-nvme, linux-pci, linux-rdma, lkml, stable
Subsystem:
nvm express driver, the rest · Maintainers:
Keith Busch, Jens Axboe, Christoph Hellwig, Sagi Grimberg, Linus Torvalds
The data and the metadata mapping do the same thing: describe the segments blk_rq_map_sg() produced in a local sg_table -- the embedded one's orig_nents is the allocated size, not the valid-segment count -- map that, and hand back the DMA-mapped count. Fold both into a helper. No functional change. Suggested-by: Logan Gunthorpe <logang@deltatee.com> Assisted-by: Claude:claude-fable-5 Signed-off-by: Mykola Marzhan <redacted> --- drivers/nvme/host/rdma.c | 42 +++++++++++++++++++++++++++------------- 1 file changed, 29 insertions(+), 13 deletions(-)
diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 2f50509a7a61..525e5aea65a1 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c@@ -1465,11 +1465,33 @@ static int nvme_rdma_map_sg_pi(struct nvme_rdma_queue *queue, return -EINVAL; } +/* + * Map the segments blk_rq_map_sg() produced. They are described by a local + * sg_table because the embedded one's orig_nents is the allocated size, not + * the number of valid segments; rdma_rw_ctx_init() does the same. + */ +static int nvme_rdma_dma_map_sgl(struct ib_device *ibdev, + struct scatterlist *sgl, int nents, + enum dma_data_direction dir, int *count) +{ + struct sg_table sgt = { + .sgl = sgl, + .orig_nents = nents, + }; + int ret; + + ret = ib_dma_map_sgtable_attrs(ibdev, &sgt, dir, 0); + if (unlikely(ret)) + return ret; + + *count = sgt.nents; + return 0; +} + 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);
@@ -1481,14 +1503,10 @@ 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); - 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); + ret = nvme_rdma_dma_map_sgl(ibdev, req->data_sgl.sg_table.sgl, + req->data_sgl.nents, rq_dma_dir(rq), count); if (unlikely(ret)) goto out_free_table; - *count = sgt.nents; if (blk_integrity_rq(rq)) { req->metadata_sgl->sg_table.sgl =
@@ -1504,14 +1522,12 @@ 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); - 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); + ret = nvme_rdma_dma_map_sgl(ibdev, + req->metadata_sgl->sg_table.sgl, + req->metadata_sgl->nents, + rq_dma_dir(rq), pi_count); if (unlikely(ret)) goto out_free_pi_table; - *pi_count = sgt.nents; } return 0;
--
2.52.0