On 10/9/19 6:39 AM, 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 <[email protected]> > Signed-off-by: Damien Le Moal <[email protected]> > --- > 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; > } >
Looks good to me. Reviewed-by: Bob Liu <[email protected]>
