Re: [PATCH V2] block: ignore RWF_HIPRI hint for sync dio

Ming Lei
2022-05-02T16:02:03Z

On Wed, Apr 20, 2022 at 10:31:10PM +0800, Ming Lei wrote:
> So far bio is marked as REQ_POLLED if RWF_HIPRI/IOCB_HIPRI is passed
> from userspace sync io interface, then block layer tries to poll until
> the bio is completed. But the current implementation calls
> blk_io_schedule() if bio_poll() returns 0, and this way causes io hang or
> timeout easily.
>
> But looks no one reports this kind of issue, which should have been
> triggered in normal io poll sanity test or blktests block/007 as
> observed by Changhui, that means it is very likely that no one uses it
> or no one cares it.
>
> Also after io_uring is invented, io poll for sync dio becomes legacy
> interface.
>
> So ignore RWF_HIPRI hint for sync dio.
>
> CC: linux-mm@kvack.org
> Cc: linux-xfs@vger.kernel.org
> Reported-by: Changhui Zhong <czhong@redhat.com>
> Suggested-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> V2:
> - avoid to break io_uring async polling as pointed by Chritoph

Hello Jens,

Can you take this patch if you are fine?

Thanks,
Ming