[dm-devel] split scsi passthrough fields out of struct request V2

[Jens Axboe]

On 01/26/2017 04:50 PM, Jens Axboe wrote:
> On 01/26/2017 04:47 PM, Bart Van Assche wrote:
>> On Thu, 2017-01-26 at 16:26 -0700, Jens Axboe wrote:
>>> What device is stuck? Is it running with an mq scheduler attached, or
>>> with "none"?
>>>
>>> Would also be great to see the output of /sys/block/*/mq/*/tags and
>>> sched_tags so we can see if they have anything pending.
>>>
>>> From a quick look at the below, it looks like a request leak. Bisection
>>> would most likely be very helpful.
>>
>> Hello Jens,
>>
>> This happens with and without scheduler attached. The most recent test I ran
>> was with the deadline scheduler configured as default scheduler for all blk-mq
>> devices (CONFIG_DEFAULT_SQ_IOSCHED="mq-deadline" and
>> CONFIG_DEFAULT_MQ_IOSCHED="mq-deadline"). The block devices that hang are
>> /dev/dm-0 and /dev/dm-1. The tags and sched_tags data is as follows:
>>
>> # (cd /sys/class/block && grep -aH '' dm*/mq/*/tags)
>> dm-0/mq/0/tags:nr_tags=2048, reserved_tags=0, bits_per_word=64
>> dm-0/mq/0/tags:nr_free=1795, nr_reserved=0
>> dm-0/mq/0/tags:active_queues=0
>> dm-1/mq/0/tags:nr_tags=2048, reserved_tags=0, bits_per_word=64
>> dm-1/mq/0/tags:nr_free=2047, nr_reserved=0
>> dm-1/mq/0/tags:active_queues=0
>> # (cd /sys/class/block && grep -aH '' dm*/mq/*/sched_tags)
>> dm-0/mq/0/sched_tags:nr_tags=256, reserved_tags=0, bits_per_word=64
>> dm-0/mq/0/sched_tags:nr_free=0, nr_reserved=0
>> dm-0/mq/0/sched_tags:active_queues=0
>> dm-1/mq/0/sched_tags:nr_tags=256, reserved_tags=0, bits_per_word=64
>> dm-1/mq/0/sched_tags:nr_free=254, nr_reserved=0
>> dm-1/mq/0/sched_tags:active_queues=0
> 
> Clearly we are missing some requests. How do I setup dm similarly to
> you?
> 
> Does it reproduce without Christoph's patchset?

I have dm-mpath running using blk_mq and with mq-deadline on both dm and
the lower level device, and it seems to be running just fine here.
Note, this is without Christoph's patchset, I'll try that next once
xfstest finishes.

-- 
Jens Axboe