Re: [PATCH v5 10/10] io_uring: add support for IORING_OP_MKNODAT

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

On 6/23/21 7:26 AM, Dmitry Kadashev wrote:
> On Tue, Jun 22, 2021 at 6:52 PM Pavel Begunkov <asml.silence@gmail.com> wrote:
>>
>> On 6/3/21 6:18 AM, Dmitry Kadashev wrote:
>>> IORING_OP_MKNODAT behaves like mknodat(2) and takes the same flags and
>>> arguments.
>>>
>>> Suggested-by: Christian Brauner <christian.brauner@ubuntu.com>
>>> Link: https://lore.kernel.org/io-uring/20210514145259.wtl4xcsp52woi6ab@wittgenstein/
>>> Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
>>> ---
>>>  fs/internal.h                 |  2 ++
>>>  fs/io_uring.c                 | 56 +++++++++++++++++++++++++++++++++++
>>>  fs/namei.c                    |  2 +-
>>>  include/uapi/linux/io_uring.h |  2 ++
>>>  4 files changed, 61 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/fs/internal.h b/fs/internal.h
>>> index 15a7d210cc67..c6fb9974006f 100644
>>
>> [...]
>>
>>>  static bool io_disarm_next(struct io_kiocb *req);
>>> @@ -3687,6 +3697,44 @@ static int io_linkat(struct io_kiocb *req, int issue_flags)
>>>       io_req_complete(req, ret);
>>>       return 0;
>>>  }
>>> +static int io_mknodat_prep(struct io_kiocb *req,
>>> +                         const struct io_uring_sqe *sqe)
>>> +{
>>> +     struct io_mknod *mkn = &req->mknod;
>>> +     const char __user *fname;
>>> +
>>> +     if (unlikely(req->flags & REQ_F_FIXED_FILE))
>>> +             return -EBADF;
>>
>> IOPOLL won't support it, and the check is missing.
>> Probably for other opcodes as well.
>>
>> if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
>>         return -EINVAL;
> 
> This change is based on some other similar opcodes (unlinkat, renameat) that
> were added a while ago. Those lack the check as well. I guess I'll just prepare
> a patch that adds the checks to all of them. Thanks, Pavel.
> 
> Jens, separately it's my understanding that you do not want the MKNODAT opcode
> at all, should I drop this from the subsequent series?

I guess that comment was to my note that the patch with it
doesn't compile, but as it should be already fixed up...

-- 
Pavel Begunkov