Re: [PATCH V4 15/24] block: unifying elevator change

[Nilay Shroff <nilay@linux.ibm.com>]

On 4/30/25 10:05 AM, Ming Lei wrote:
> Elevator change is one well-define behavior:
> 
> - tear down current elevator if it exists
> 
> - setup new elevator
> 
> It is supposed to cover any case for changing elevator by single
> internal API, typically the following cases:
> 
> - setup default elevator in add_disk()
> 
> - switch to none in del_disk()
> 
> - reset elevator in blk_mq_update_nr_hw_queues()
> 
> - switch elevator in sysfs `store` elevator attribute
> 
> This patch uses elevator_change() to cover all above cases:
> 
> - every elevator switch is serialized with each other: add_disk/del_disk/
> store elevator is serialized already, blk_mq_update_nr_hw_queues() uses
> srcu for syncing with the other three cases
> 
> - for both add_disk()/del_disk(), queue freeze works at atomic mode
> or has been froze, so the freeze in elevator_change() won't add extra
> delay
> 
> - `struct elev_change_ctx` instance holds any info for changing elevator
> 
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>

Looks good to me:
Reviewed-by : Nilay Shroff <nilay@linux.ibm.com>