CIFS_ECHO_OP
add_credits(server, &credits, CIFS_ECHO_OP);
server, CIFS_NON_BLOCKING | CIFS_ECHO_OP, NULL);
case CIFS_ECHO_OP:
add_credits(server, &credits, CIFS_ECHO_OP);
server, CIFS_ECHO_OP, NULL);
if (*credits <= 0 && optype == CIFS_ECHO_OP)