linux-kernel - Re: [PATCH v10 09/14] exfat: add misc operations

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Message-ID: <CAK8P3a28NRp+SGr44=DTYqL0+ZqtamHwn+WYNTxVRJOJ3HtLSg@mail.gmail.com>
Date:   Fri, 17 Jan 2020 11:13:39 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Namjae Jeon <namjae.jeon@...sung.com>
Cc:     Namjae Jeon <linkinjeon@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linux FS-devel Mailing List <linux-fsdevel@...r.kernel.org>,
        gregkh <gregkh@...uxfoundation.org>,
        Pali Rohár <pali.rohar@...il.com>,
        Valdis Kletnieks <valdis.kletnieks@...edu>,
        Christoph Hellwig <hch@....de>, sj1557.seo@...sung.com
Subject: Re: [PATCH v10 09/14] exfat: add misc operations

On Fri, Jan 17, 2020 at 3:59 AM Namjae Jeon <namjae.jeon@...sung.com> wrote:
>
>
> > This is what I think the timezone mount option should be used
> > for: if we don't know what the timezone was for the on-disk timestamp, use
> > the one provided by the user. However, if none was specified, it should be
> > either sys_tz or UTC (i.e. no conversion). I would prefer the use of UTC
> > here given the problems with sys_tz, but sys_tz would be more consistent
> > with how fs/fat works.
> Hi Arnd,
>
> Could you please review this change ?

Looks all good to me now.

      Arnd

> /* Convert a EXFAT time/date pair to a UNIX date (seconds since 1 1 70). */
> void exfat_get_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts,
>                 __le16 time, __le16 date, u8 tz)
> {
>         u16 t = le16_to_cpu(time);
>         u16 d = le16_to_cpu(date);
>
>         ts->tv_sec = mktime64(1980 + (d >> 9), d >> 5 & 0x000F, d & 0x001F,
>                               t >> 11, (t >> 5) & 0x003F, (t & 0x001F) << 1);
>         ts->tv_nsec = 0;
>
>         if (tz & EXFAT_TZ_VALID)
>                 /* Adjust timezone to UTC0. */
>                 exfat_adjust_tz(ts, tz & ~EXFAT_TZ_VALID);
>         else
>                 /* Convert from local time to UTC using time_offset. */
>                 ts->tv_sec -= sbi->options.time_offset * SECS_PER_MIN;
> }
>
> /* Convert linear UNIX date to a EXFAT time/date pair. */
> void exfat_set_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts,
>                 __le16 *time, __le16 *date, u8 *tz)
> {
>         struct tm tm;
>         u16 t, d;
>
>         time64_to_tm(ts->tv_sec, 0, &tm);
>         t = (tm.tm_hour << 11) | (tm.tm_min << 5) | (tm.tm_sec >> 1);
>         d = ((tm.tm_year - 80) <<  9) | ((tm.tm_mon + 1) << 5) | tm.tm_mday;
>
>         *time = cpu_to_le16(t);
>         *date = cpu_to_le16(d);
>
>         /*
>          * Record 00h value for OffsetFromUtc field and 1 value for OffsetValid
>          * to indicate that local time and UTC are the same.
>          */
>         *tz = EXFAT_TZ_VALID;
> }
>
> Thanks!
>