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 <[email protected]> >> --- >> 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
