1 files changed, 25 insertions, 8 deletions

diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c
index c4eb62b32a32..bec912547fb8 100644
--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -1010,6 +1010,23 @@ skip_fsfstatus:
                 send_ct->handler(send_ct->handler_data);
 }
 
+static void zfcp_fsf_setup_ct_els_unchained(struct qdio_buffer_element *sbale,
+                                            struct scatterlist *sg_req,
+                                            struct scatterlist *sg_resp)
+{
+        sbale[0].flags |= SBAL_FLAGS0_TYPE_WRITE_READ;
+        sbale[2].addr   = sg_virt(sg_req);
+        sbale[2].length = sg_req->length;
+        sbale[3].addr   = sg_virt(sg_resp);
+        sbale[3].length = sg_resp->length;
+        sbale[3].flags |= SBAL_FLAGS_LAST_ENTRY;
+}
+
+static int zfcp_fsf_one_sbal(struct scatterlist *sg)
+{
+        return sg_is_last(sg) && sg->length <= PAGE_SIZE;
+}
+
 static int zfcp_fsf_setup_ct_els_sbals(struct zfcp_fsf_req *req,
                                        struct scatterlist *sg_req,
                                        struct scatterlist *sg_resp,
@@ -1020,16 +1037,16 @@ static int zfcp_fsf_setup_ct_els_sbals(struct zfcp_fsf_req *req,
         int bytes;
 
         if (!(feat & FSF_FEATURE_ELS_CT_CHAINED_SBALS)) {
-                if (sg_req->length > PAGE_SIZE || sg_resp->length > PAGE_SIZE ||
-                    !sg_is_last(sg_req) || !sg_is_last(sg_resp))
+                if (!zfcp_fsf_one_sbal(sg_req) || !zfcp_fsf_one_sbal(sg_resp))
                         return -EOPNOTSUPP;
 
-                sbale[0].flags |= SBAL_FLAGS0_TYPE_WRITE_READ;
-                sbale[2].addr   = sg_virt(sg_req);
-                sbale[2].length = sg_req->length;
-                sbale[3].addr   = sg_virt(sg_resp);
-                sbale[3].length = sg_resp->length;
-                sbale[3].flags |= SBAL_FLAGS_LAST_ENTRY;
+                zfcp_fsf_setup_ct_els_unchained(sbale, sg_req, sg_resp);
+                return 0;
+        }
+
+        /* use single, unchained SBAL if it can hold the request */
+        if (zfcp_fsf_one_sbal(sg_req) && zfcp_fsf_one_sbal(sg_resp)) {
+                zfcp_fsf_setup_ct_els_unchained(sbale, sg_req, sg_resp);
                 return 0;
         }