On 10/13/19 6:03 PM, Damien Le Moal wrote:
> On 2019/10/09 7:40, Damien Le Moal wrote:
>> A BIO based request queue does not have a tag_set, which prevent testing
>> for the flag BLK_MQ_F_NO_SCHED indicating that the queue does not
>> require an elevator. This leads to an incorrect initialization of a
>> default elevator in some cases such as BIO based null_blk
>> (queue_mode == BIO) with zoned mode enabled as the default elevator in
>> this case is mq-deadline instead of "none".
>>
>> Fix this by testing for a NULL queue mq_ops field which indicates that
>> the queue is BIO based and should not have an elevator.
>>
>> Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@xxxxxxx>
>> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
>> ---
>> Changes from V1:
>> * Test if q->mq_ops is NULL to identify BIO based queues
>>
>> block/elevator.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/block/elevator.c b/block/elevator.c
>> index 5437059c9261..076ba7308e65 100644
>> --- a/block/elevator.c
>> +++ b/block/elevator.c
>> @@ -616,7 +616,8 @@ int elevator_switch_mq(struct request_queue *q,
>>
>> static inline bool elv_support_iosched(struct request_queue *q)
>> {
>> - if (q->tag_set && (q->tag_set->flags & BLK_MQ_F_NO_SCHED))
>> + if (!q->mq_ops ||
>> + (q->tag_set && (q->tag_set->flags & BLK_MQ_F_NO_SCHED)))
>> return false;
>> return true;
>> }
>>
>
> Jens,
>
> Ping ? This was not in your rc3 pull request...
Yeah that missed -rc3, I've queued it up for -rc4. Thanks!
--
Jens Axboe
