On 12/21/18 4:20 AM, Christoph Hellwig wrote:
> On Tue, Dec 18, 2018 at 08:42:10AM -0700, Jens Axboe wrote:
>> For the upcoming async polled IO, we can't sleep allocating requests.
>> If we do, then we introduce a deadlock where the submitter already
>> has async polled IO in-flight, but can't wait for them to complete
>> since polled requests must be active found and reaped.
>
> So two comments here. First I think after the next -rc1 we really
> need to rename REQ_HIPRI to REQ_POLLED. Unlike the iocb hipri flag
> which is an advice to treat this I/O as urgent REQ_POLLED is a hard
> charaterisation and having the hipri name is badly misnamed for that.
Agree, it doesn't make a lot of sense to not call it _POLLED.
> Second I retract my suggestion to add this _ASYNC variant, as it seems
> to cause more confusion than it helps. I think instead we want
> a helper like this:
>
> static void bio_set_polled(struct bio *bio, struct kiocb *kiocb)
> {
> bio->bi_opf |= REQ_POLLED;
> if (!is_sync_kiocb(kiocb)
> bio->bi_opf |= REQ_NOWAIT;
> }
>
> maybe plus comments to better indicate the intentional and consolidate
> the is_sync check.
I'm fine with that, I'll do the cleanup.
--
Jens Axboe
