On 10/25/2017 11:32 AM, Omar Sandoval wrote:
> On Wed, Oct 25, 2017 at 12:04:46PM -0600, Jens Axboe wrote:
>> Since we now lookup elevator types with the appropriate multiqueue
>> capability, allow schedulers to register with an alias alongside
>> the real name. This is in preparation for allowing 'mq-deadline'
>> to register an alias of 'deadline' as well.
>>
>> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
>> ---
>> block/elevator.c | 22 ++++++++++++++++------
>> include/linux/elevator.h | 1 +
>> 2 files changed, 17 insertions(+), 6 deletions(-)
>>
>> diff --git a/block/elevator.c b/block/elevator.c
>> index b70e69f795db..dc0432e12ecf 100644
>> --- a/block/elevator.c
>> +++ b/block/elevator.c
>> @@ -83,6 +83,16 @@ bool elv_bio_merge_ok(struct request *rq, struct bio *bio)
>> }
>> EXPORT_SYMBOL(elv_bio_merge_ok);
>>
>> +static bool elevator_match(const struct elevator_type *e, const char *name)
>> +{
>> + if (!strcmp(e->elevator_name, name))
>> + return true;
>> + if (e->elevator_alias && !strcmp(e->elevator_alias, name))
>> + return true;
>> +
>> + return false;
>> +}
>> +
>> /*
>> * Return scheduler with name 'name' and with matching 'mq capability
>> */
>> @@ -91,7 +101,7 @@ static struct elevator_type *elevator_find(const char *name, bool mq)
>> struct elevator_type *e;
>>
>> list_for_each_entry(e, &elv_list, list) {
>> - if (!strcmp(e->elevator_name, name) && !(mq ^ e->uses_mq))
>> + if (elevator_match(e, name) && !(mq ^ e->uses_mq))
>> return e;
>> }
>>
>> @@ -922,9 +932,9 @@ int elv_register(struct elevator_type *e)
>> spin_unlock(&elv_list_lock);
>>
>> /* print pretty message */
>> - if (!strcmp(e->elevator_name, chosen_elevator) ||
>> + if (elevator_match(e, chosen_elevator) ||
>> (!*chosen_elevator &&
>> - !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED)))
>> + elevator_match(e, CONFIG_DEFAULT_IOSCHED)))
>> def = " (default)";
>>
>> printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name,
>> @@ -1077,8 +1087,7 @@ static int __elevator_change(struct request_queue *q, const char *name)
>> if (!e)
>> return -EINVAL;
>>
>> - if (q->elevator &&
>> - !strcmp(elevator_name, q->elevator->type->elevator_name)) {
>> + if (q->elevator && elevator_match(q->elevator->type, elevator_name)) {
>> elevator_put(e);
>> return 0;
>> }
>> @@ -1126,7 +1135,8 @@ ssize_t elv_iosched_show(struct request_queue *q, char *name)
>>
>> spin_lock(&elv_list_lock);
>> list_for_each_entry(__e, &elv_list, list) {
>> - if (elv && !strcmp(elv->elevator_name, __e->elevator_name)) {
>> + if (elv && elevator_match(elv, __e->elevator_name) &&
>> + !(__e->uses_mq ^ (q->mq_ops != NULL))) {
>
> Same thing here, (__e->uses_mq == (q->mq_ops != NULL)). Still confusing
> but less so.
I'll just add a
bool uses_mq = q->mq_ops != NULL;
to make it clearer.
--
Jens Axboe
