[PATCH 6/8] nvme: fix queue freeze vs limits lock order

[Nilay Shroff]

On 1/7/25 1:52 PM, Christoph Hellwig wrote:
> On Tue, Jan 07, 2025 at 12:28:29PM +0530, Nilay Shroff wrote:
>>> -	blk_mq_freeze_queue(ns->disk->queue);
>>>  	lim = queue_limits_start_update(ns->disk->queue);
>>>  	nvme_set_ctrl_limits(ns->ctrl, &lim);
>>> +
>>> +	blk_mq_freeze_queue(ns->disk->queue);
>>>  	ret = queue_limits_commit_update(ns->disk->queue, &lim);
>>>  	set_disk_ro(ns->disk, nvme_ns_is_readonly(ns, info));
>>>  	blk_mq_unfreeze_queue(ns->disk->queue);
>>
>> I think we should freeze queue before nvme_set_ctrl_limits(). 
> 
> Why?
>
The nvme_set_ctrl_limits() sets certain queue limits which are 
also used during IO processing. For instance, ->max_segment_size
is used while submitting bio.
Also, if we look at the code before your patch, nvme_set_ctrl_limits()
is called when the queue is freezed.

Thanks,
--Nilay