On 11/4/21 11:30 AM, Christoph Hellwig wrote:
> On Thu, Nov 04, 2021 at 05:41:35AM -0600, Jens Axboe wrote:
>>>> if (!submit_bio_checks(bio) || !blk_crypto_bio_prep(&bio))
>>>> - goto queue_exit;
>>>> + return;
>>>
>>> This is broken, we really ant the submit checks under freeze
>>> protection to make sure the parameters can't be changed underneath
>>> us.
>>
>> Which parameters are you worried about in submit_bio_checks()? I don't
>> immediately see anything that would make me worry about it.
>
> Mostly checks if certain operations are supported or not, as
> revalidation could clear those.
>
>>> This looks weird, as blk_try_enter_queue is already called by
>>> bio_queue_enter.
>>
>> It's just for avoiding a pointless call into bio_queue_enter(), which
>> isn't needed it blk_try_enter_queue() is successful. The latter is short
>> and small and can be inlined, while bio_queue_enter() is a lot bigger.
>
> If this is so impotant let's operated with an inlined bio_queue_enter
> that calls out of line into slow path instead of open coding it
> like this.
Sure, I can do that instead.
>>>> } else {
>>>> struct blk_mq_alloc_data data = {
>>>> .q = q,
>>>> @@ -2528,6 +2534,11 @@ void blk_mq_submit_bio(struct bio *bio)
>>>> .cmd_flags = bio->bi_opf,
>>>> };
>>>>
>>>> + if (unlikely(!blk_mq_queue_enter(q, bio)))
>>>> + return;
>>>> +
>>>> + rq_qos_throttle(q, bio);
>>>> +
>>>
>>> At some point the code in this !cached branch really needs to move
>>> into a helper..
>>
>> Like in the next patch?
>
> No, I mean the !cached case which is a lot more convoluted.
Yeah, a helper there might be appropriate. I'll write it up.
--
Jens Axboe
