scsi: scsi_dh_alua: Properly handle the ALUA transitioning state
The handling of the ALUA transitioning state is currently broken. When a target goes into this state, it is expected that the target is allowed to stay in this state for the implicit transition timeout without a path failure. The handler has this logic, but it gets skipped currently. When the target transitions, there is in-flight I/O from the initiator. The first of these responses from the target will be a unit attention letting the initiator know that the ALUA state has changed. The remaining in-flight I/Os, before the initiator finds out that the portal state has changed, will return not ready, ALUA state is transitioning. The portal state will change to SCSI_ACCESS_STATE_TRANSITIONING. This will lead to all new I/O immediately failing the path unexpectedly. The path failure happens in less than a second instead of the expected successes until the transition timer is exceeded. Allow I/Os to continue while the path is in the ALUA transitioning state. The handler already takes care of a target that stays in the transitioning state for too long by changing the state to ALUA state standby once the transition timeout is exceeded at which point the path will fail. Link: https://lore.kernel.org/r/CAHZQxy+4sTPz9+pY3=7VJH+CLUJsDct81KtnR2be8ycN5mhqTg@mail.gmail.com Reviewed-by:Hannes Reinecke <hare@suse.de> Acked-by: