NBD_CMD_REQUEUED
clear_bit(NBD_CMD_REQUEUED, &cmd->flags);
if (!test_and_set_bit(NBD_CMD_REQUEUED, &cmd->flags))
set_bit(NBD_CMD_REQUEUED, &cmd->flags);
WARN_ON_ONCE(test_bit(NBD_CMD_REQUEUED, &cmd->flags));
if (test_bit(NBD_CMD_REQUEUED, &cmd->flags)) {