target: Handle GET_EVENT_STATUS_NOTIFICATION passthrough

The SCSI MMC GET_EVENT_STATUS_NOTIFICATION command can be used to find
out about media change, among other things.  This patch adds it to the
command sequencer so that PSCSI CD-ROM passthrough works with modern
Linux guests that issue this command.

Tested-by: Cong Meng <mengcong@cn.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_transport.c

@@ -3143,6 +3143,10 @@ static int transport_generic_cmd_sequencer(
 			cmd->sam_task_attr = MSG_HEAD_TAG;
 		cmd->se_cmd_flags |= SCF_SCSI_CONTROL_SG_IO_CDB;
 		break;
+	case GET_EVENT_STATUS_NOTIFICATION:
+		size = (cdb[7] << 8) | cdb[8];
+		cmd->se_cmd_flags |= SCF_SCSI_CONTROL_SG_IO_CDB;
+		break;
 	default:
 		pr_warn("TARGET_CORE[%s]: Unsupported SCSI Opcode"
 			" 0x%02x, sending CHECK_CONDITION.\n",