IB/iser: Have iSER data transaction object point to iSER conn

iSER uses a data transaction object (struct iser_dto) as part
of its IB data descriptors (struct iser_desc) management.
It also uses a hierarchy of connection structures pointing to
each other. A DTO may exist even after the iscsi_iser connection
pointed by it is destroyed (eg one that is bound to a post
receive buffer which was flushed by the IB HW). Hence DTOs need
point to the lowest connection, which is struct iser_conn.

Signed-off-by: Erez Zilber <erezz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.c b/drivers/infiniband/ulp/iser/iscsi_iser.c
index 2a14fe2..eb6f98d 100644
--- a/drivers/infiniband/ulp/iser/iscsi_iser.c
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.c
@@ -317,6 +317,8 @@
 	struct iscsi_iser_conn *iser_conn = conn->dd_data;
 
 	iscsi_conn_teardown(cls_conn);
+	if (iser_conn->ib_conn)
+		iser_conn->ib_conn->iser_conn = NULL;
 	kfree(iser_conn);
 }