[PATCH 2/4] fat: create function to calculate timezone offset

[Frank Sorenson <sorenson@xxxxxxxxxx>]

Add a function to calculate the timezone offset in minutes.

Signed-off-by: Frank Sorenson <sorenson@xxxxxxxxxx>
---
 fs/fat/fat.h  | 12 ++++++++++++
 fs/fat/misc.c | 12 ++----------
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 9d7d2d5da28b..c40f7e69f078 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -412,6 +412,18 @@ void fat_msg(struct super_block *sb, const char *level, const char *fmt, ...);
 	 } while (0)
 extern int fat_clusters_flush(struct super_block *sb);
 extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster);
+
+#define SECS_PER_MIN    60
+#define SECS_PER_HOUR   (60 * 60)
+#define SECS_PER_DAY    (SECS_PER_HOUR * 24)
+
+static inline int fat_tz_offset(struct msdos_sb_info *sbi)
+{
+	return  (sbi->options.tz_set ?
+		- sbi->options.time_offset :
+		sys_tz.tz_minuteswest) * SECS_PER_MIN;
+}
+
 extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
 			      __le16 __time, __le16 __date, u8 time_cs);
 extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index 573836dcaefc..58580c7e558e 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -170,9 +170,6 @@ int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
  * 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)
 /* 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 */
@@ -210,10 +207,7 @@ void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
 		   + days_in_year[month] + day
 		   + DAYS_DELTA) * SECS_PER_DAY;
 
-	if (!sbi->options.tz_set)
-		second += sys_tz.tz_minuteswest * SECS_PER_MIN;
-	else
-		second -= sbi->options.time_offset * SECS_PER_MIN;
+	second += fat_tz_offset(sbi);
 
 	if (time_cs) {
 		ts->tv_sec = second + (time_cs / 100);
@@ -229,9 +223,7 @@ void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
 		       __le16 *time, __le16 *date, u8 *time_cs)
 {
 	struct tm tm;
-	time64_to_tm(ts->tv_sec,
-		   (sbi->options.tz_set ? sbi->options.time_offset :
-		   -sys_tz.tz_minuteswest) * SECS_PER_MIN, &tm);
+	time64_to_tm(ts->tv_sec, -fat_tz_offset(sbi), &tm);
 
 	/*  FAT can only support year between 1980 to 2107 */
 	if (tm.tm_year < 1980 - 1900) {
-- 
2.13.6