Introduce support for enhanced I/O error handling.
A device state is added to track 3 possible states of the device:
Normal - the device is operating normally and is fully operational
Limbo - the device is in a reset/recovery scenario and its operational
status is paused
Failed/terminating - the device has either failed to be reset/recovered
or is being terminated (removed); it is no longer
operational
All operations are allowed when the device is operating normally. When the
device transitions to limbo state, I/O must be paused. To help accomplish
this, a wait queue is introduced where existing and new threads can wait
until the device is no longer in limbo. When coming out of limbo, threads
need to check the state and error out gracefully when encountering the
failed state. When the device transitions to the failed/terminating state,
normal operations are no longer allowed. Only specially designated
operations related to graceful cleanup are permitted.
Signed-off-by: Matthew R. Ochs
Signed-off-by: Manoj N. Kumar
Reviewed-by: Daniel Axtens
Reviewed-by: Michael Neuling
Reviewed-by: Wen Xiong
Reviewed-by: Brian King
Signed-off-by: James Bottomley
