[SCSI] IB/iser: Add Discovery support

To run discovery over iSER we need to advertize the CAP_TEXT_NEGO capability
towards user space. Also need to make sure the login RX buffer is posted when
SendTargets TEXT PDUs are sent. For that end, we use a setting of the
ISCSI_PARAM_DISCOVERY_SESS iscsi param as an indication that this is
discovery session.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index f757617..e399561 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -3170,6 +3170,7 @@
 {
 	struct iscsi_conn *conn = cls_conn->dd_data;
 	struct iscsi_session *session = conn->session;
+	int val;
 
 	switch(param) {
 	case ISCSI_PARAM_FAST_ABORT:
@@ -3264,6 +3265,10 @@
 	case ISCSI_PARAM_DISCOVERY_PARENT_TYPE:
 		return iscsi_switch_str_param(&session->discovery_parent_type,
 					      buf);
+	case ISCSI_PARAM_DISCOVERY_SESS:
+		sscanf(buf, "%d", &val);
+		session->discovery_sess = !!val;
+		break;
 	default:
 		return -ENOSYS;
 	}