RDMA/rtrs-clt: Use the right sg_cnt after ib_dma_map_sg

[ Upstream commit b66905e ]

When iommu is enabled, we hit warnings like this:
WARNING: at rtrs/rtrs.c:178 rtrs_iu_post_rdma_write_imm+0x9b/0x110

rtrs warn on one sge entry length is 0, which is unexpected.

The problem is ib_dma_map_sg augments the SGL into a 'dma mapped SGL'.
This process may change the number of entries and the lengths of each
entry.

Code that touches dma_address is iterating over the 'dma mapped SGL'
and must use dma_nents which returned from ib_dma_map_sg().
So pass the count return from ib_dma_map_sg.

Fixes: 6a98d71 ("RDMA/rtrs: client: main functionality")
Link: https://lore.kernel.org/r/20220818105355.110344-3-haris.iqbal@ionos.com
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Aleksei Marov <aleksei.marov@ionos.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/infiniband/ulp/rtrs/rtrs-clt.c

@@ -1004,7 +1004,8 @@ rtrs_clt_get_copy_req(struct rtrs_clt_path *alive_path,
 static int rtrs_post_rdma_write_sg(struct rtrs_clt_con *con,
 				   struct rtrs_clt_io_req *req,
 				   struct rtrs_rbuf *rbuf, bool fr_en,
-				   u32 size, u32 imm, struct ib_send_wr *wr,
+				   u32 count, u32 size, u32 imm,
+				   struct ib_send_wr *wr,
 				   struct ib_send_wr *tail)
 {
 	struct rtrs_clt_path *clt_path = to_clt_path(con->c.path);
@@ -1024,12 +1025,12 @@ static int rtrs_post_rdma_write_sg(struct rtrs_clt_con *con,
 		num_sge = 2;
 		ptail = tail;
 	} else {
-		for_each_sg(req->sglist, sg, req->sg_cnt, i) {
+		for_each_sg(req->sglist, sg, count, i) {
 			sge[i].addr   = sg_dma_address(sg);
 			sge[i].length = sg_dma_len(sg);
 			sge[i].lkey   = clt_path->s.dev->ib_pd->local_dma_lkey;
 		}
-		num_sge = 1 + req->sg_cnt;
+		num_sge = 1 + count;
 	}
 	sge[i].addr   = req->iu->dma_addr;
 	sge[i].length = size;
@@ -1142,7 +1143,7 @@ static int rtrs_clt_write_req(struct rtrs_clt_io_req *req)
 	 */
 	rtrs_clt_update_all_stats(req, WRITE);
 
-	ret = rtrs_post_rdma_write_sg(req->con, req, rbuf, fr_en,
+	ret = rtrs_post_rdma_write_sg(req->con, req, rbuf, fr_en, count,
 				      req->usr_len + sizeof(*msg),
 				      imm, wr, &inv_wr);
 	if (ret) {