Re: [PATCH v3 1/2] bio: limit bio max size

From: Damien Le Moal
Date: Wed Jan 27 2021 - 02:00:53 EST


On 2021/01/27 9:36, Changheun Lee wrote:
>>> +
>>> /**
>>> * bio_reset - reinitialize a bio
>>> * @bio: bio to reset
>>> @@ -877,7 +892,7 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page,
>>> struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
>>>
>>> if (page_is_mergeable(bv, page, len, off, same_page)) {
>>> - if (bio->bi_iter.bi_size > UINT_MAX - len) {
>>> + if (bio->bi_iter.bi_size > bio_max_size(bio) - len) {
>>> *same_page = false;
>>> return false;
>>> }
>>> diff --git a/include/linux/bio.h b/include/linux/bio.h
>>> index 1edda614f7ce..cdb134ca7bf5 100644
>>> --- a/include/linux/bio.h
>>> +++ b/include/linux/bio.h
>>> @@ -100,6 +100,8 @@ static inline void *bio_data(struct bio *bio)
>>> return NULL;
>>> }
>>>
>>> +extern unsigned int bio_max_size(struct bio *);
>>
>> No need for extern.
>
> It's just for compile warning in my test environment.
> I'll remove it too. But I think compile warning could be in the other
> .c file which includes bio.h. Is it OK?

Hmmm... not having extern should not generate a compilation warning. There are
tons of functions declared without extern in header files in the kernel. What
compiler are you using ?


--
Damien Le Moal
Western Digital Research