Re: [PATCH] scsi: ufs: mark HPB support as BROKEN

Bart Van Assche
2021-10-27T13:16:24Z

On 10/26/21 10:27 PM, Christoph Hellwig wrote:
> On Tue, Oct 26, 2021 at 01:10:47PM -0700, Bart Van Assche wrote:
>> If blk_insert_cloned_request() is moved into the device mapper then I
>> think that blk_mq_request_issue_directly() will need to be exported.
>
> Which is even worse.
>
>> How
>> about the (totally untested) patch below for removing the
>> blk_insert_cloned_request() call from the UFS-HPB code?
>
> Which again doesn't fix anything. The problem is that it fans out one
> request into two on the same queue, not the specific interface used.

That patch fixes the reported issue, namely removing the additional accounting
caused by calling blk_insert_cloned_request(). Please explain why it is
considered wrong to fan out one request into two. That code could be reworked
such that the block layer is not involved as Adrian Hunter explained. However,
before someone spends time on making these changes I think that someone should
provide more information about why it is considered wrong to fan out one request
into two.

Thanks,

Bart.