iser: Accept arbitrary sg lists mapping if the device supports it

If the device support arbitrary sg list mapping (device cap
IB_DEVICE_SG_GAPS_REG set) we allocate the memory regions with
IB_MR_TYPE_SG_GAPS and allow the block layer to pass us
gaps by skip setting the queue virt_boundary.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/iser/iscsi_iser.c

@@ -969,7 +969,16 @@ static umode_t iser_attr_is_visible(int param_type, int param)
 
 static int iscsi_iser_slave_alloc(struct scsi_device *sdev)
 {
-	blk_queue_virt_boundary(sdev->request_queue, ~MASK_4K);
+	struct iscsi_session *session;
+	struct iser_conn *iser_conn;
+	struct ib_device *ib_dev;
+
+	session = starget_to_session(scsi_target(sdev))->dd_data;
+	iser_conn = session->leadconn->dd_data;
+	ib_dev = iser_conn->ib_conn.device->ib_device;
+
+	if (!(ib_dev->attrs.device_cap_flags & IB_DEVICE_SG_GAPS_REG))
+		blk_queue_virt_boundary(sdev->request_queue, ~MASK_4K);
 
 	return 0;
 }