diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index 91ad9be..a191e79 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -135,65 +135,131 @@
 
 extern struct timezone sys_tz;
 
+/*
+ * The epoch of FAT timestamp is 1980.
+ *     :  bits :     value
+ * date:  0 -  4: day	(1 -  31)
+ * date:  5 -  8: month	(1 -  12)
+ * date:  9 - 15: year	(0 - 127) from 1980
+ * time:  0 -  4: sec	(0 -  29) 2sec counts
+ * time:  5 - 10: min	(0 -  59)
+ * time: 11 - 15: hour	(0 -  23)
+ */
+#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 */
+#define YEAR_2100	120
+#define IS_LEAP_YEAR(y)	(!((y) & 3) && (y) != YEAR_2100)
+
 /* Linear day numbers of the respective 1sts in non-leap years. */
-static int day_n[] = {
-   /* Jan  Feb  Mar  Apr   May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
-	0,  31,  59,  90,  120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0, 0
+static time_t days_in_year[] = {
+	/* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
+	0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
 };
 
-/* Convert a MS-DOS time/date pair to a UNIX date (seconds since 1 1 70). */
-int date_dos2unix(unsigned short time, unsigned short date, int tz_utc)
+/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
+void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,
+		       __le16 __time, __le16 __date, u8 time_cs)
 {
-	int month, year, secs;
+	u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
+	time_t second, day, leap_day, month, year;
 
-	/*
-	 * first subtract and mask after that... Otherwise, if
-	 * date == 0, bad things happen
-	 */
-	month = ((date >> 5) - 1) & 15;
-	year = date >> 9;
-	secs = (time & 31)*2+60*((time >> 5) & 63)+(time >> 11)*3600+86400*
-	    ((date & 31)-1+day_n[month]+(year/4)+year*365-((year & 3) == 0 &&
-	    month < 2 ? 1 : 0)+3653);
-			/* days since 1.1.70 plus 80's leap day */
-	if (!tz_utc)
-		secs += sys_tz.tz_minuteswest*60;
-	return secs;
+	year  = date >> 9;
+	month = max(1, (date >> 5) & 0xf);
+	day   = max(1, date & 0x1f) - 1;
+
+	leap_day = (year + 3) / 4;
+	if (year > YEAR_2100)		/* 2100 isn't leap year */
+		leap_day--;
+	if (IS_LEAP_YEAR(year) && month > 2)
+		leap_day++;
+
+	second =  (time & 0x1f) << 1;
+	second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
+	second += (time >> 11) * SECS_PER_HOUR;
+	second += (year * 365 + leap_day
+		   + days_in_year[month] + day
+		   + DAYS_DELTA) * SECS_PER_DAY;
+
+	if (!sbi->options.tz_utc)
+		second += sys_tz.tz_minuteswest * SECS_PER_MIN;
+
+	if (time_cs) {
+		ts->tv_sec = second + (time_cs / 100);
+		ts->tv_nsec = (time_cs % 100) * 10000000;
+	} else {
+		ts->tv_sec = second;
+		ts->tv_nsec = 0;
+	}
 }
 
-/* Convert linear UNIX date to a MS-DOS time/date pair. */
-void fat_date_unix2dos(int unix_date, __le16 *time, __le16 *date, int tz_utc)
+/* Convert linear UNIX date to a FAT time/date pair. */
+void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts,
+		       __le16 *time, __le16 *date, u8 *time_cs)
 {
-	int day, year, nl_day, month;
+	time_t second = ts->tv_sec;
+	time_t day, leap_day, month, year;
 
-	if (!tz_utc)
-		unix_date -= sys_tz.tz_minuteswest*60;
+	if (!sbi->options.tz_utc)
+		second -= sys_tz.tz_minuteswest * SECS_PER_MIN;
 
 	/* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
-	if (unix_date < 315532800)
-		unix_date = 315532800;
+	if (second < UNIX_SECS_1980) {
+		*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) {
+		*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
 
-	*time = cpu_to_le16((unix_date % 60)/2+(((unix_date/60) % 60) << 5)+
-	    (((unix_date/3600) % 24) << 11));
-	day = unix_date/86400-3652;
-	year = day/365;
-	if ((year+3)/4+365*year > day)
+	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--;
-	day -= (year+3)/4+365*year;
-	if (day == 59 && !(year & 3)) {
-		nl_day = day;
+	leap_day = (year + 3) / 4;
+	if (year > YEAR_2100)		/* 2100 isn't leap year */
+		leap_day--;
+	day -= year * 365 + leap_day;
+
+	if (IS_LEAP_YEAR(year) && day == days_in_year[3]) {
 		month = 2;
 	} else {
-		nl_day = (year & 3) || day <= 59 ? day : day-1;
-		for (month = 0; month < 12; month++) {
-			if (day_n[month] > nl_day)
+		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;
 		}
 	}
-	*date = cpu_to_le16(nl_day-day_n[month-1]+1+(month << 5)+(year << 9));
-}
+	day -= days_in_year[month];
 
-EXPORT_SYMBOL_GPL(fat_date_unix2dos);
+	*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));
+	if (time_cs)
+		*time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
+}
+EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 
 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 {