On 11/2/22 1:09 AM, Christoph Hellwig wrote:
> On Wed, Nov 02, 2022 at 07:05:35AM +0900, Damien Le Moal wrote:
>>>> + if (!op_is_write(rq->cmd_flags) && (rq->cmd_flags & REQ_FUA)) {
>>>> + blk_mq_end_request(rq, BLK_STS_NOTSUPP);
>>>
>>> How could this even happen? If we want a debug check, I think it
>>> should be in submit_bio and a WARN_ON_ONCE.
>>
>> I have not found any code that issues a FUA read. So I do not think this
>> can happen at all currently. The check is about making sure that it
>> *never* happens.
>>
>> I thought of having the check higher up in the submit path but I wanted to
>> avoid adding yet another check in the very hot path. But if you are OK
>> with that, I will move it.
>
> I'd do something like this:
This looks fine, but if we're never expecting this to happen, I do think
it should just go into libata instead as that's the only user that
cares about it. Yes, that'll lose the backtrace for who submitted it
potentially, but you can debug it pretty easily at that point if you
run into it.
--
Jens Axboe
