Re: [PATCH] io_uring/rsrc: fix incorrect assignment of iter->nr_segs in io_import_fixed

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

On 6/19/24 16:47, Chenliang Li wrote:
> 
> 在 2024/6/19 22:27, Pavel Begunkov 写道:
>> On 6/19/24 07:38, Chenliang Li wrote:
>>> In io_import_fixed when advancing the iter within the first bvec, the
>>> iter->nr_segs is set to bvec->bv_len. nr_segs should be the number of
>>> bvecs, plus we don't need to adjust it here, so just remove it.
>>
>> Good catch, quite old. It's our luck that bvec iteration
>> honours the length and doesn't step outside of the first entry.
>>
>>> Fixes: b000ae0ec2d7 ("io_uring/rsrc: optimise single entry advance")
>>> Signed-off-by: Chenliang Li <cliang01.li@samsung.com>
>>> ---
>>>   io_uring/rsrc.c | 1 -
>>>   1 file changed, 1 deletion(-)
>>>
>>> diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
>>> index 60c00144471a..a860516bf448 100644
>>> --- a/io_uring/rsrc.c
>>> +++ b/io_uring/rsrc.c
>>> @@ -1049,7 +1049,6 @@ int io_import_fixed(int ddir, struct iov_iter *iter,
>>>                * branch doesn't expect non PAGE_SIZE'd chunks.
>>>                */
>>>               iter->bvec = bvec;
>>> -            iter->nr_segs = bvec->bv_len;
>>
>> iter->nr_segs = 1, please
> Why 1? There could be multiple bvecs.

You're right

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>

-- 
Pavel Begunkov