On 12/05/2016 08:10 AM, Jens Axboe wrote:
> On 12/05/2016 06:07 AM, Christoph Hellwig wrote:
>> On Fri, Dec 02, 2016 at 08:15:17PM -0700, Jens Axboe wrote:
>>> Use MQ variants for MQ, legacy ones for legacy.
>>>
>>> Signed-off-by: Jens Axboe <axboe@xxxxxx>
>>> ---
>>> block/blk-core.c | 5 ++++-
>>> block/blk-exec.c | 10 ++++++++--
>>> block/blk-flush.c | 14 ++++++++++----
>>> block/elevator.c | 5 ++++-
>>> 4 files changed, 26 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/block/blk-core.c b/block/blk-core.c
>>> index 0e23589ab3bf..3591f5419509 100644
>>> --- a/block/blk-core.c
>>> +++ b/block/blk-core.c
>>> @@ -340,7 +340,10 @@ void __blk_run_queue(struct request_queue *q)
>>> if (unlikely(blk_queue_stopped(q)))
>>> return;
>>>
>>> - __blk_run_queue_uncond(q);
>>> + if (WARN_ON_ONCE(q->mq_ops))
>>> + blk_mq_run_hw_queues(q, true);
>>> + else
>>
>> This looks odd with the WARN_ON..
>
> It's just a debug thing, should go away.
>
>>> +++ b/block/blk-exec.c
>>> @@ -80,8 +80,14 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
>>> }
>>>
>>> __elv_add_request(q, rq, where);
>>> - __blk_run_queue(q);
>>> - spin_unlock_irq(q->queue_lock);
>>> +
>>> + if (q->mq_ops) {
>>> + spin_unlock_irq(q->queue_lock);
>>> + blk_mq_run_hw_queues(q, false);
>>> + } else {
>>> + __blk_run_queue(q);
>>> + spin_unlock_irq(q->queue_lock);
>>> + }
>>
>> We already branch out to the blk-mq path earlier in the function.
>
> Ah good point, this is a subset of an earlier branch that also checks
> q->elevator.
Actually, I take that back - if q->mq_ops && q->elevator, we still get
here, and we should run the queue with the MQ variant. The code was
correct as-is.
--
Jens Axboe
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