Re: [PATCH 21/30] block: remove dead elevator code

Jens Axboe
2018-11-01T22:32:05Z

On 11/1/18 3:26 PM, Omar Sandoval wrote:
> On Wed, Oct 31, 2018 at 11:59:13AM -0600, Jens Axboe wrote:
>> This removes a bunch of core and elevator related code. On the core
>> front, we remove anything related to queue running, draining,
>> initialization, plugging, and congestions. We also kill anything
>> related to request allocation, merging, retrieval, and completion.
>>
>> Remove any checking for single queue IO schedulers, as they no
>> longer exist. This means we can also delete a bunch of code related
>> to request issue, adding, completion, etc - and all the SQ related
>> ops and helpers.
>>
>> Also kill the load_default_modules(), as all that did was provide
>> for a way to load the default single queue elevator.
>>
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>
> [snip]
>
>> -struct elevator_ops
>> -{
>> - elevator_merge_fn *elevator_merge_fn;
>> - elevator_merged_fn *elevator_merged_fn;
>> - elevator_merge_req_fn *elevator_merge_req_fn;
>> - elevator_allow_bio_merge_fn *elevator_allow_bio_merge_fn;
>> - elevator_allow_rq_merge_fn *elevator_allow_rq_merge_fn;
>> - elevator_bio_merged_fn *elevator_bio_merged_fn;
>> -
>> - elevator_dispatch_fn *elevator_dispatch_fn;
>> - elevator_add_req_fn *elevator_add_req_fn;
>> - elevator_activate_req_fn *elevator_activate_req_fn;
>> - elevator_deactivate_req_fn *elevator_deactivate_req_fn;
>> -
>> - elevator_completed_req_fn *elevator_completed_req_fn;
>> -
>> - elevator_request_list_fn *elevator_former_req_fn;
>> - elevator_request_list_fn *elevator_latter_req_fn;
>> -
>> - elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
>> - elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
>> -
>> - elevator_set_req_fn *elevator_set_req_fn;
>> - elevator_put_req_fn *elevator_put_req_fn;
>> -
>> - elevator_may_queue_fn *elevator_may_queue_fn;
>> -
>> - elevator_init_fn *elevator_init_fn;
>> - elevator_exit_fn *elevator_exit_fn;
>> - elevator_registered_fn *elevator_registered_fn;
>> -};
>> -
>> struct blk_mq_alloc_data;
>> struct blk_mq_hw_ctx;
>>
>> @@ -138,16 +70,15 @@ struct elevator_type
>>
>> /* fields provided by elevator implementation */
>> union {
>> - struct elevator_ops sq;
>> struct elevator_mq_ops mq;
>> } ops;
>> +
>
> Lol. Maybe we should get rid of this union in a followup? At least until
> we rewrite the block layer again.

Totally agree, wanted to do that in a followup patch, but just
haven't gotten around to it. I'll tack one on.

--
Jens Axboe