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...
--
Damien Le Moal
Western Digital Research
