RDMA/hns: Fix return value in hns_roce_map_mr_sg

As described in the ib_map_mr_sg function comment, it returns the number
of sg elements that were mapped to the memory region. However,
hns_roce_map_mr_sg returns the number of pages required for mapping the
DMA area. Fix it.

Fixes: 9b2cf76c ("RDMA/hns: Optimize PBL buffer allocation process")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Link: https://lore.kernel.org/r/20240411033851.2884771-1-shaozhengchao@huawei.comReviewed-by: Junxian Huang <huangjunxian6@hisilicon.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/hw/hns/hns_roce_mr.c

@@ -441,18 +441,18 @@ int hns_roce_map_mr_sg(struct ib_mr *ibmr, struct scatterlist *sg, int sg_nents,
 	struct ib_device *ibdev = &hr_dev->ib_dev;
 	struct hns_roce_mr *mr = to_hr_mr(ibmr);
 	struct hns_roce_mtr *mtr = &mr->pbl_mtr;
-	int ret = 0;
+	int ret, sg_num = 0;
 
 	mr->npages = 0;
 	mr->page_list = kvcalloc(mr->pbl_mtr.hem_cfg.buf_pg_count,
 				 sizeof(dma_addr_t), GFP_KERNEL);
 	if (!mr->page_list)
-		return ret;
+		return sg_num;
 
-	ret = ib_sg_to_pages(ibmr, sg, sg_nents, sg_offset, hns_roce_set_page);
-	if (ret < 1) {
+	sg_num = ib_sg_to_pages(ibmr, sg, sg_nents, sg_offset, hns_roce_set_page);
+	if (sg_num < 1) {
 		ibdev_err(ibdev, "failed to store sg pages %u %u, cnt = %d.\n",
-			  mr->npages, mr->pbl_mtr.hem_cfg.buf_pg_count, ret);
+			  mr->npages, mr->pbl_mtr.hem_cfg.buf_pg_count, sg_num);
 		goto err_page_list;
 	}
 
@@ -463,17 +463,16 @@ int hns_roce_map_mr_sg(struct ib_mr *ibmr, struct scatterlist *sg, int sg_nents,
 	ret = hns_roce_mtr_map(hr_dev, mtr, mr->page_list, mr->npages);
 	if (ret) {
 		ibdev_err(ibdev, "failed to map sg mtr, ret = %d.\n", ret);
-		ret = 0;
+		sg_num = 0;
 	} else {
 		mr->pbl_mtr.hem_cfg.buf_pg_shift = (u32)ilog2(ibmr->page_size);
-		ret = mr->npages;
 	}
 
 err_page_list:
 	kvfree(mr->page_list);
 	mr->page_list = NULL;
 
-	return ret;
+	return sg_num;
 }
 
 static void hns_roce_mw_free(struct hns_roce_dev *hr_dev,