Re: [PATCH] io_uring: don't mark S_ISBLK async work as unbounded

[Pavel Begunkov <asml.silence@gmail.com>]

On 02/04/2021 09:52, Hao Xu wrote:
> 在 2021/4/1 下午10:57, Jens Axboe 写道:
>> S_ISBLK is marked as unbounded work for async preparation, because it
>> doesn't match S_ISREG. That is incorrect, as any read/write to a block
>> device is also a bounded operation. Fix it up and ensure that S_ISBLK
>> isn't marked unbounded.
>>
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>
> Hi Jens, I saw a (un)bounded work is for a (un)bounded worker to
> execute. What is the difference between bounded and unbounded?

Unbounded works are not bounded in execution time, i.e. they may take
forever to complete. E.g. recv depends on the other end to send something,
that not necessarily will ever happen.


> 
> Thanks,
> Hao
>> ---
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index 6d7a1b69712b..a16b7df934d1 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -1213,7 +1213,7 @@ static void io_prep_async_work(struct io_kiocb *req)
>>       if (req->flags & REQ_F_ISREG) {
>>           if (def->hash_reg_file || (ctx->flags & IORING_SETUP_IOPOLL))
>>               io_wq_hash_work(&req->work, file_inode(req->file));
>> -    } else {
>> +    } else if (!req->file || !S_ISBLK(file_inode(req->file)->i_mode)) {
>>           if (def->unbound_nonreg_file)
>>               req->work.flags |= IO_WQ_WORK_UNBOUND;
>>       }
>>
> 

-- 
Pavel Begunkov