new file mode 100644
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Written 1992,1993 by Werner Almesberger
+ * 22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
+ * and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)
+ * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
+ */
+
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/buffer_head.h>
+
+#include "exfat_raw.h"
+#include "exfat_fs.h"
+
+/*
+ * exfat_fs_error reports a file system problem that might indicate fa data
+ * corruption/inconsistency. Depending on 'errors' mount option the
+ * panic() is called, or error message is printed FAT and nothing is done,
+ * or filesystem is remounted read-only (default behavior).
+ * In case the file system is remounted read-only, it can be made writable
+ * again by remounting it.
+ */
+void __exfat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
+{
+ struct exfat_mount_options *opts = &EXFAT_SB(sb)->options;
+ va_list args;
+ struct va_format vaf;
+
+ if (report) {
+ va_start(args, fmt);
+ vaf.fmt = fmt;
+ vaf.va = &args;
+ exfat_msg(sb, KERN_ERR, "error, %pV\n", &vaf);
+ va_end(args);
+ }
+
+ if (opts->errors == EXFAT_ERRORS_PANIC) {
+ panic("exFAT-fs (%s): fs panic from previous error\n",
+ sb->s_id);
+ } else if (opts->errors == EXFAT_ERRORS_RO && !sb_rdonly(sb)) {
+ sb->s_flags |= SB_RDONLY;
+ exfat_msg(sb, KERN_ERR, "Filesystem has been set read-only");
+ }
+}
+
+/*
+ * exfat_msg() - print preformated EXFAT specific messages.
+ * All logs except what uses exfat_fs_error() should be written by exfat_msg()
+ */
+void exfat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
+{
+ struct va_format vaf;
+ va_list args;
+
+ va_start(args, fmt);
+ vaf.fmt = fmt;
+ vaf.va = &args;
+ /* level means KERN_ pacility level */
+ printk("%sexFAT-fs (%s): %pV\n", level, sb->s_id, &vaf);
+ va_end(args);
+}
+
+/* <linux/time.h> externs sys_tz
+ * extern struct timezone sys_tz;
+ */
+#define UNIX_SECS_1980 315532800L
+
+#if BITS_PER_LONG == 64
+#define UNIX_SECS_2108 4354819200L
+#endif
+
+/* days between 1970/01/01 and 1980/01/01 (2 leap days) */
+#define DAYS_DELTA_DECADE (365 * 10 + 2)
+/* 120 (2100 - 1980) isn't leap year */
+#define NO_LEAP_YEAR_2100 (120)
+#define IS_LEAP_YEAR(y) (!((y) & 0x3) && (y) != NO_LEAP_YEAR_2100)
+
+#define SECS_PER_MIN (60)
+#define SECS_PER_HOUR (60 * SECS_PER_MIN)
+#define SECS_PER_DAY (24 * SECS_PER_HOUR)
+
+#define MAKE_LEAP_YEAR(leap_year, year) \
+ do { \
+ /* 2100 isn't leap year */ \
+ if (unlikely(year > NO_LEAP_YEAR_2100)) \
+ leap_year = ((year + 3) / 4) - 1; \
+ else \
+ leap_year = ((year + 3) / 4); \
+ } while (0)
+
+/* Linear day numbers of the respective 1sts in non-leap years. */
+static time_t accum_days_in_year[] = {
+ /* Month : N 01 02 03 04 05 06 07 08 09 10 11 12 */
+ 0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
+};
+
+/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
+void exfat_time_fat2unix(struct exfat_sb_info *sbi, struct timespec64 *ts,
+ struct exfat_date_time *tp)
+{
+ time_t year = tp->year;
+ time_t ld; /* leap day */
+
+ MAKE_LEAP_YEAR(ld, year);
+
+ if (IS_LEAP_YEAR(year) && (tp->month) > 2)
+ ld++;
+
+ ts->tv_sec = tp->second + tp->minute * SECS_PER_MIN
+ + tp->hour * SECS_PER_HOUR
+ + (year * 365 + ld + accum_days_in_year[tp->month]
+ + (tp->day - 1) + DAYS_DELTA_DECADE) * SECS_PER_DAY;
+
+ if (!sbi->options.tz_utc)
+ ts->tv_sec += sys_tz.tz_minuteswest * SECS_PER_MIN;
+
+ ts->tv_nsec = 0;
+}
+
+/* Convert linear UNIX date to a FAT time/date pair. */
+void exfat_time_unix2fat(struct exfat_sb_info *sbi, struct timespec64 *ts,
+ struct exfat_date_time *tp)
+{
+ time_t second = ts->tv_sec;
+ time_t day, month, year;
+ time_t ld; /* leap day */
+
+ 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 (second < UNIX_SECS_1980) {
+ tp->second = 0;
+ tp->minute = 0;
+ tp->hour = 0;
+ tp->day = 1;
+ tp->month = 1;
+ tp->year = 0;
+ return;
+ }
+#if (BITS_PER_LONG == 64)
+ if (second >= UNIX_SECS_2108) {
+ tp->second = 59;
+ tp->minute = 59;
+ tp->hour = 23;
+ tp->day = 31;
+ tp->month = 12;
+ tp->year = 127;
+ return;
+ }
+#endif
+
+ day = second / SECS_PER_DAY - DAYS_DELTA_DECADE;
+ year = day / 365;
+
+ MAKE_LEAP_YEAR(ld, year);
+ if (year * 365 + ld > day)
+ year--;
+
+ MAKE_LEAP_YEAR(ld, year);
+ day -= year * 365 + ld;
+
+ if (IS_LEAP_YEAR(year) && day == accum_days_in_year[3]) {
+ month = 2;
+ } else {
+ if (IS_LEAP_YEAR(year) && day > accum_days_in_year[3])
+ day--;
+ for (month = 1; month < 12; month++) {
+ if (accum_days_in_year[month + 1] > day)
+ break;
+ }
+ }
+ day -= accum_days_in_year[month];
+
+ tp->second = second % SECS_PER_MIN;
+ tp->minute = (second / SECS_PER_MIN) % 60;
+ tp->hour = (second / SECS_PER_HOUR) % 24;
+ tp->day = day + 1;
+ tp->month = month;
+ tp->year = year;
+}
+
+struct exfat_timestamp *exfat_tm_now(struct exfat_sb_info *sbi,
+ struct exfat_timestamp *tp)
+{
+ struct timespec64 ts;
+ struct exfat_date_time dt;
+
+ ktime_get_real_ts64(&ts);
+ exfat_time_unix2fat(sbi, &ts, &dt);
+
+ tp->year = dt.year;
+ tp->mon = dt.month;
+ tp->day = dt.day;
+ tp->hour = dt.hour;
+ tp->min = dt.minute;
+ tp->sec = dt.second;
+
+ return tp;
+}
+
+unsigned short exfat_calc_chksum_2byte(void *data, int len,
+ unsigned short chksum, int type)
+{
+ int i;
+ unsigned char *c = (unsigned char *)data;
+
+ for (i = 0; i < len; i++, c++) {
+ if (((i == 2) || (i == 3)) && (type == CS_DIR_ENTRY))
+ continue;
+ chksum = (((chksum & 1) << 15) | ((chksum & 0xFFFE) >> 1)) +
+ (unsigned short)*c;
+ }
+ return chksum;
+}
+
+void exfat_update_bh(struct super_block *sb, struct buffer_head *bh, int sync)
+{
+ WRITE_ONCE(EXFAT_SB(sb)->s_dirt, true);
+ set_buffer_uptodate(bh);
+ mark_buffer_dirty(bh);
+
+ if (sync)
+ sync_dirty_buffer(bh);
+}
+
+void exfat_chain_set(struct exfat_chain *ec, unsigned int dir,
+ unsigned int size, unsigned char flags)
+{
+ ec->dir = dir;
+ ec->size = size;
+ ec->flags = flags;
+}
+
+struct exfat_chain *exfat_chain_dup(struct exfat_chain *ec)
+{
+ struct exfat_chain *dup;
+
+ dup = kmalloc(sizeof(struct exfat_chain), GFP_KERNEL);
+ if (!dup)
+ return NULL;
+
+ exfat_chain_set(dup, ec->dir, ec->size, ec->flags);
+ return dup;
+}