Re: [PATCH v2 2/3] fat: make ctime and mtime identical explicitly

[OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>]

Chung-Chiang Cheng <shepjeng@gmail.com> writes:

> On Sun, Apr 10, 2022 at 11:43 PM OGAWA Hirofumi
> <hirofumi@mail.parknet.co.jp> wrote:
>>
>> Hm, this changes mtime includes ctime update. So, the question is, this
>> behavior is compatible with Windows's fatfs behavior? E.g. Windows
>> updates mtime on rename?
>>
>> If not same behavior with Windows, new behavior is new incompatible
>> behavior, and looks break fundamental purpose of this.
>>
>> I was thinking, we ignores ctime update (because fatfs doesn't have) and
>> always same with mtime. What behavior was actually compatible with
>> Windows?
>>
>
> If possible, to ignore ctime update may be a better choice that doesn't
> affect mtime. But we need an initial value for ctime when the inode is
> loaded.
>
> One possible option is to use mtime. Although ctime won't be updated
> anymore, when mtime is changed, ctime needs to take effect. Otherwise
> the next time the inode is loaded, ctime will be inconsistent. That is,
> ctime is still updated indirectly by mtime. It seems impossible to avoid
> updating ctime, or do we just show ctime a non-sense value?

I mean I also think the behavior what you said sounds like reasonable.
mtime change affect to ctime, but ctime change doesn't affect to mtime.

Thanks.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>