However io_kiocb is less
constrained, and could be used as a context to hold such a space.
Even if it is undesired to have io_kiocb be passed to uring_cmd(), it
can still hold a driver specific space paired with a helper to obtain it
(i.e. something like io_uring_cmd_to_driver_ctx(ioucmd) ). Then if the
space is pre-allocated it is only a small memory copy for a stable copy
that would allow a saner failover design.
I am thinking along the same lines, but it's not about few bytes of
space rather we need 80 (72 to be precise). Will think more, but
these 72 bytes really stand tall in front of my optimism.
You don't have to populate this space on every I/O, you can just
populate it when there is no usable path and when you failover a
request...
