Re: [PATCH 4/4] io_uring: mark opcodes that always need io-wq punt

Jens Axboe
2023-04-24T15:24:37Z

On 4/24/23 1:30?AM, Ming Lei wrote:
> On Thu, Apr 20, 2023 at 12:31:35PM -0600, Jens Axboe wrote:
>> Add an opdef bit for them, and set it for the opcodes where we always
>> need io-wq punt. With that done, exclude them from the file_can_poll()
>> check in terms of whether or not we need to punt them if any of the
>> NO_OFFLOAD flags are set.
>>
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>> ---
>> io_uring/io_uring.c | 2 +-
>> io_uring/opdef.c | 22 ++++++++++++++++++++--
>> io_uring/opdef.h | 2 ++
>> 3 files changed, 23 insertions(+), 3 deletions(-)
>>
>> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
>> index fee3e461e149..420cfd35ebc6 100644
>> --- a/io_uring/io_uring.c
>> +++ b/io_uring/io_uring.c
>> @@ -1948,7 +1948,7 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
>> return -EBADF;
>>
>> if (issue_flags & IO_URING_F_NO_OFFLOAD &&
>> - (!req->file || !file_can_poll(req->file)))
>> + (!req->file || !file_can_poll(req->file) || def->always_iowq))
>> issue_flags &= ~IO_URING_F_NONBLOCK;
>
> I guess the check should be !def->always_iowq?

How so? Nobody that takes pollable files should/is setting
->always_iowq. If we can poll the file, we should not force inline
submission. Basically the ones setting ->always_iowq always do -EAGAIN
returns if nonblock == true.

--
Jens Axboe