If you're waiting for I/O to complete, it helps if you actually have an I/O to begin with
We saw earlier the importance of waiting for I/O to complete before freeing the data structures associated with that I/O. On the other hand, before you start waiting, you have to make sure that you have something to wait for. A customer reported a hang in waiting for an I/O to cancel, and the I/O team was brought in to investigate. They looked...