Re: [PATCH] io_uring: make OP_CLOSE consistent direct open

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

On 9/24/21 9:06 PM, Jens Axboe wrote:
> On 9/24/21 1:57 PM, Jens Axboe wrote:
>> On 9/24/21 1:04 PM, Pavel Begunkov wrote:
>>> From recently open/accept are now able to manipulate fixed file table,
>>> but it's inconsistent that close can't. Close the gap, keep API same as
>>> with open/accept, i.e. via sqe->file_slot.
>>
>> I really think we should do this for 5.15 to make the API a bit more
>> sane from the user point of view, folks definitely expect being able
>> to use IORING_OP_CLOSE with a fixed file that they got with IORING_OP_OPEN,
>> for example.
>>
>> How about this small tweak, basically making it follow the same rules
>> as other commands that do fixed files:
>>
>> 1) Require IOSQE_FIXED_FILE to be set for a direct close. sqe->file_index
>>    will be the descriptor to close in that case. If sqe->fd is set, we
>>    -EINVAL the request.
>>
>> 2) If IOSQE_FIXED_FILE isn't set, it's a normal close. As before, if
>>    sqe->file_index is set and IOSQE_FIXED_FILE isn't, then we -EINVAL
>>    the request.
>>
>> Basically this incremental on top of yours.
> 
> Hmm, we don't require that for open or accept. Why not? Seems a bit
> counter intuitive. But maybe it's better we do this one as-is, and then

Accept takes a fd as an argument and so IOSQE_FIXED_FILE already applies
to it and can't be used as described. Close is just made consistent with
the rest.


> do a followup patch that solidifies the fact that IOSQE_FIXED_FILE
> should be set for direct open/accept/close.
> 

-- 
Pavel Begunkov