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Subject[PATCH 2/2] fs/fat: Use common localtime/gmtime in fat_time_unix2fat()
It is not necessary to write custom code for convert calendar time
to broken-down time.
localtime()/gmtime() is more generic to do that.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
---
fs/fat/misc.c | 62
++++++++++++++++++--------------------------------------
1 files changed, 20 insertions(+), 42 deletions(-)
diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index a6c2047..d9b6552 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -9,6 +9,7 @@
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/buffer_head.h>
+#include <linux/time.h>
#include "fat.h"

/*
@@ -155,10 +156,6 @@ extern struct timezone sys_tz;
#define SECS_PER_MIN 60
#define SECS_PER_HOUR (60 * 60)
#define SECS_PER_DAY (SECS_PER_HOUR * 24)
-#define UNIX_SECS_1980 315532800L
-#if BITS_PER_LONG == 64
-#define UNIX_SECS_2108 4354819200L
-#endif
/* days between 1.1.70 and 1.1.80 (2 leap days) */
#define DAYS_DELTA (365 * 10 + 2)
/* 120 (2100 - 1980) isn't leap year */
@@ -211,58 +208,40 @@ void fat_time_fat2unix(struct msdos_sb_info *sbi,
struct timespec *ts,
void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts,
__le16 *time, __le16 *date, u8 *time_cs)
{
- time_t second = ts->tv_sec;
- time_t day, leap_day, month, year;
-
- if (!sbi->options.tz_utc)
- second -= sys_tz.tz_minuteswest * SECS_PER_MIN;
+ unsigned int year, mon, mday, hour, min, sec;
+ if (sbi->options.tz_utc) {
+ gmtime(ts->tv_sec,
+ &year, &mon, &mday, &hour, &min, &sec, NULL, NULL);
+ } else {
+ localtime(ts->tv_sec,
+ &year, &mon, &mday, &hour, &min, &sec, NULL, NULL);
+ }

- /* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
- if (second < UNIX_SECS_1980) {
+ /* FAT can only support year between 1980 to 2107 */
+ if (year < 1980 - 1900) {
*time = 0;
*date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
if (time_cs)
*time_cs = 0;
return;
}
-#if BITS_PER_LONG == 64
- if (second >= UNIX_SECS_2108) {
+ if (year > 2107 - 1900) {
*time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
*date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
if (time_cs)
*time_cs = 199;
return;
}
-#endif

- day = second / SECS_PER_DAY - DAYS_DELTA;
- year = day / 365;
- leap_day = (year + 3) / 4;
- if (year > YEAR_2100) /* 2100 isn't leap year */
- leap_day--;
- if (year * 365 + leap_day > day)
- year--;
- leap_day = (year + 3) / 4;
- if (year > YEAR_2100) /* 2100 isn't leap year */
- leap_day--;
- day -= year * 365 + leap_day;
+ /* from 1900 -> from 1980 */
+ year -= 80;
+ /* 0~11 -> 1~12 */
+ mon++;
+ /* 0~59 -> 0~29(2sec counts) */
+ sec >>= 1;

- if (IS_LEAP_YEAR(year) && day == days_in_year[3]) {
- month = 2;
- } else {
- if (IS_LEAP_YEAR(year) && day > days_in_year[3])
- day--;
- for (month = 1; month < 12; month++) {
- if (days_in_year[month + 1] > day)
- break;
- }
- }
- day -= days_in_year[month];
-
- *time = cpu_to_le16(((second / SECS_PER_HOUR) % 24) << 11
- | ((second / SECS_PER_MIN) % 60) << 5
- | (second % SECS_PER_MIN) >> 1);
- *date = cpu_to_le16((year << 9) | (month << 5) | (day + 1));
+ *time = cpu_to_le16(hour << 11 | min << 5 | sec);
+ *date = cpu_to_le16(year << 9 | mon << 5 | mday);
if (time_cs)
*time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
}
@@ -283,4 +262,3 @@ int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
}
return err;
}
-
--
1.5.5.3



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