linux-kernel - RE: [PATCH] exfat: use local UTC offset when EXFAT_TZ

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Date:   Fri, 1 Oct 2021 22:19:07 +0900
From:   "Sungjong Seo" <sj1557.seo@...sung.com>
To:     "'Namjae Jeon'" <linkinjeon@...nel.org>,
        "'Chung-Chiang Cheng'" <cccheng@...ology.com>
Cc:     <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <shepjeng@...il.com>, <sj1557.seo@...sung.com>
Subject: RE: [PATCH] exfat: use local UTC offset when EXFAT_TZ_VALID isn't
 set

Hello, Namjae,

I found an important difference between the code we first wrote and the code that has changed since our initial patch review. This difference seems to cause compatibility issues when reading saved timestamps without timezone. (In our initial patch review, there were concerns about possible compatibility issues.)
I think the code that reads timestamps without timezone should go back to the concept we wrote in the first place like reported patch.
It could be an answer of another timestamp issue.

Could you please let me know what you think?

Thanks.
> -----Original Message-----
> From: Namjae Jeon [mailto:linkinjeon@...nel.org]
> Sent: Friday, September 10, 2021 10:01 AM
> To: Chung-Chiang Cheng <cccheng@...ology.com>
> Cc: sj1557.seo@...sung.com; linux-fsdevel@...r.kernel.org; linux-
> kernel@...r.kernel.org; shepjeng@...il.com
> Subject: Re: [PATCH] exfat: use local UTC offset when EXFAT_TZ_VALID isn't
> set
> 
> 2021-09-09 15:55 GMT+09:00, Chung-Chiang Cheng <cccheng@...ology.com>:
> > EXFAT_TZ_VALID is corresponding to OffsetValid field in exfat
> > specification [1]. If this bit isn't set, timestamps should be treated
> > as having the same UTC offset as the current local time.
> >
> > This patch uses the existing mount option 'time_offset' as fat does.
> > If time_offset isn't set, local UTC offset in sys_tz will be used as
> > the default value.
> >
> > Link: [1]
> > https://protect2.fireeye.com/v1/url?k=cba4edf5-943fd4c8-cba566ba-0cc47
> > a31309a-e70aa065be678729&q=1&e=225feff2-841f-404c-9a2e-c12064b232d0&u=
> > https%3A%2F%2Fdocs.microsoft.com%2Fen-us%2Fwindows%2Fwin32%2Ffileio%2F
> > exfat-specification%2374102-offsetvalid-field
> > Signed-off-by: Chung-Chiang Cheng <cccheng@...ology.com>
> Please read this discussion:
>  https://patchwork.kernel.org/project/linux-
> fsdevel/patch/20200115082447.19520-10-namjae.jeon@...sung.com/
> 
> Thanks!