Jan Kara <jack@xxxxxxx> writes:
> So far FAT either offsets time stamps by sys_tz.minuteswest or leaves them
> as they are (when tz=UTC mount option is used). However in some cases it
> is useful if one can specify time stamp offset on his own (e.g. when time
> zone of the camera connected is different from time zone of the computer,
> or when HW clock is in UTC and thus sys_tz.minuteswest == 0).
>
> So provide a mount option time_offset= which allows user to specify offset in
> minutes that should be applied to time stamps on the filesystem.
Acked-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
> Documentation/filesystems/vfat.txt | 9 +++++++++
> fs/fat/fat.h | 3 ++-
> fs/fat/inode.c | 25 ++++++++++++++++++++-----
> fs/fat/misc.c | 9 ++++++---
> 4 files changed, 37 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt
> index de1e6c4..d230dd9 100644
> --- a/Documentation/filesystems/vfat.txt
> +++ b/Documentation/filesystems/vfat.txt
> @@ -111,6 +111,15 @@ tz=UTC -- Interpret timestamps as UTC rather than local time.
> useful when mounting devices (like digital cameras)
> that are set to UTC in order to avoid the pitfalls of
> local time.
> +time_offset=minutes
> + -- Set offset for conversion of timestamps from local time
> + used by FAT to UTC. I.e. <minutes> minutes will be subtracted
> + from each timestamp to convert it to UTC used internally by
> + Linux. This is useful when time zone set in sys_tz is
> + not the time zone used by the filesystem. Note that this
> + option still does not provide correct time stamps in all
> + cases in presence of DST - time stamps in a different DST
> + setting will be off by one hour.
>
> showexec -- If set, the execute permission bits of the file will be
> allowed only if the extension part of the name is .EXE,
> diff --git a/fs/fat/fat.h b/fs/fat/fat.h
> index 623f36f..12701a5 100644
> --- a/fs/fat/fat.h
> +++ b/fs/fat/fat.h
> @@ -29,6 +29,7 @@ struct fat_mount_options {
> unsigned short fs_fmask;
> unsigned short fs_dmask;
> unsigned short codepage; /* Codepage for shortname conversions */
> + int time_offset; /* Offset of timestamps from UTC (in minutes) */
> char *iocharset; /* Charset used for filename input/display */
> unsigned short shortname; /* flags for shortname display/create rule */
> unsigned char name_check; /* r = relaxed, n = normal, s = strict */
> @@ -45,7 +46,7 @@ struct fat_mount_options {
> flush:1, /* write things quickly */
> nocase:1, /* Does this need case conversion? 0=need case conversion*/
> usefree:1, /* Use free_clusters for FAT32 */
> - tz_utc:1, /* Filesystem timestamps are in UTC */
> + tz_set:1, /* Filesystem timestamps' offset set */
> rodir:1, /* allow ATTR_RO for directory */
> discard:1, /* Issue discard requests on deletions */
> nfs:1; /* Do extra work needed for NFS export */
> diff --git a/fs/fat/inode.c b/fs/fat/inode.c
> index 5bafaad..e3ef664 100644
> --- a/fs/fat/inode.c
> +++ b/fs/fat/inode.c
> @@ -777,8 +777,12 @@ static int fat_show_options(struct seq_file *m, struct dentry *root)
> }
> if (opts->flush)
> seq_puts(m, ",flush");
> - if (opts->tz_utc)
> - seq_puts(m, ",tz=UTC");
> + if (opts->tz_set) {
> + if (opts->time_offset)
> + seq_printf(m, ",time_offset=%d", opts->time_offset);
> + else
> + seq_puts(m, ",tz=UTC");
> + }
> if (opts->errors == FAT_ERRORS_CONT)
> seq_puts(m, ",errors=continue");
> else if (opts->errors == FAT_ERRORS_PANIC)
> @@ -800,7 +804,8 @@ enum {
> Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
> Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
> Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
> - Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_err,
> + Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
> + Opt_err,
> };
>
> static const match_table_t fat_tokens = {
> @@ -825,6 +830,7 @@ static const match_table_t fat_tokens = {
> {Opt_immutable, "sys_immutable"},
> {Opt_flush, "flush"},
> {Opt_tz_utc, "tz=UTC"},
> + {Opt_time_offset, "time_offset=%d"},
> {Opt_err_cont, "errors=continue"},
> {Opt_err_panic, "errors=panic"},
> {Opt_err_ro, "errors=remount-ro"},
> @@ -909,7 +915,7 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat,
> opts->utf8 = opts->unicode_xlate = 0;
> opts->numtail = 1;
> opts->usefree = opts->nocase = 0;
> - opts->tz_utc = 0;
> + opts->tz_set = 0;
> opts->nfs = 0;
> opts->errors = FAT_ERRORS_RO;
> *debug = 0;
> @@ -1005,8 +1011,17 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat,
> case Opt_flush:
> opts->flush = 1;
> break;
> + case Opt_time_offset:
> + if (match_int(&args[0], &option))
> + return 0;
> + if (option < -12 * 60 || option > 12 * 60)
> + return 0;
> + opts->tz_set = 1;
> + opts->time_offset = option;
> + break;
> case Opt_tz_utc:
> - opts->tz_utc = 1;
> + opts->tz_set = 1;
> + opts->time_offset = 0;
> break;
> case Opt_err_cont:
> opts->errors = FAT_ERRORS_CONT;
> diff --git a/fs/fat/misc.c b/fs/fat/misc.c
> index 6d93360..5eb600d 100644
> --- a/fs/fat/misc.c
> +++ b/fs/fat/misc.c
> @@ -212,8 +212,10 @@ void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,
> + days_in_year[month] + day
> + DAYS_DELTA) * SECS_PER_DAY;
>
> - if (!sbi->options.tz_utc)
> + if (!sbi->options.tz_set)
> second += sys_tz.tz_minuteswest * SECS_PER_MIN;
> + else
> + second -= sbi->options.time_offset * SECS_PER_MIN;
>
> if (time_cs) {
> ts->tv_sec = second + (time_cs / 100);
> @@ -229,8 +231,9 @@ void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts,
> __le16 *time, __le16 *date, u8 *time_cs)
> {
> struct tm tm;
> - time_to_tm(ts->tv_sec, sbi->options.tz_utc ? 0 :
> - -sys_tz.tz_minuteswest * 60, &tm);
> + time_to_tm(ts->tv_sec,
> + (sbi->options.tz_set ? sbi->options.time_offset :
> + -sys_tz.tz_minuteswest) * SECS_PER_MIN, &tm);
>
> /* FAT can only support year between 1980 to 2107 */
> if (tm.tm_year < 1980 - 1900) {
--
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
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