fs/sdfat/misc.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  *  Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
  *
  *  This program is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU General Public License
  *  as published by the Free Software Foundation; either version 2
  *  of the License, or (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  */

 /*
  *  linux/fs/fat/misc.c
  *
  *  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)
  */

 /************************************************************************/
 /*                                                                      */
 /*  PROJECT : exFAT & FAT12/16/32 File System                           */
 /*  FILE    : misc.c                                                    */
 /*  PURPOSE : Helper function for checksum and handing sdFAT error      */
 /*                                                                      */
 /*----------------------------------------------------------------------*/
 /*  NOTES                                                               */
 /*                                                                      */
 /*                                                                      */
 /************************************************************************/

 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/buffer_head.h>
 #include <linux/time.h>
 #include <linux/blkdev.h>
 #include "sdfat.h"
 #include "version.h"


 #ifdef CONFIG_SDFAT_SUPPORT_STLOG
 #ifdef CONFIG_PROC_FSLOG
 #include <linux/fslog.h>
 #else
 #include <linux/stlog.h>
 #endif
 #else
 #define ST_LOG(fmt, ...)
 #endif

 #if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 0)
 #include <linux/ktime.h>
 #ifndef _TIME_T
 #define _TIME_T
 typedef ktime_t         time_t;
 #endif
 #endif

 /*************************************************************************
  * FUNCTIONS WHICH HAS KERNEL VERSION DEPENDENCY
  *************************************************************************/
 #ifdef CONFIG_SDFAT_UEVENT
 static struct kobject sdfat_uevent_kobj;

 int sdfat_uevent_init(struct kset *sdfat_kset)
 {
 	int err;
 	struct kobj_type *ktype = get_ktype(&sdfat_kset->kobj);

 	sdfat_uevent_kobj.kset = sdfat_kset;
 	err = kobject_init_and_add(&sdfat_uevent_kobj, ktype, NULL, "uevent");
 	if (err)
 		pr_err("[SDFAT] Unable to create sdfat uevent kobj\n");

 	return err;
 }

 void sdfat_uevent_uninit(void)
 {
 	kobject_del(&sdfat_uevent_kobj);
 	memset(&sdfat_uevent_kobj, 0, sizeof(struct kobject));
 }

 void sdfat_uevent_ro_remount(struct super_block *sb)
 {
 	struct block_device *bdev = sb->s_bdev;
 	dev_t bd_dev = bdev ? bdev->bd_dev : 0;

 	char major[16], minor[16];
 	char *envp[] = { major, minor, NULL };

 	/* Do not trigger uevent if a device has been ejected */
 	if (fsapi_check_bdi_valid(sb))
 		return;

 	snprintf(major, sizeof(major), "MAJOR=%d", MAJOR(bd_dev));
 	snprintf(minor, sizeof(minor), "MINOR=%d", MINOR(bd_dev));

 	kobject_uevent_env(&sdfat_uevent_kobj, KOBJ_CHANGE, envp);

 	ST_LOG("[SDFAT](%s[%d:%d]): Uevent triggered\n",
 			sb->s_id, MAJOR(bd_dev), MINOR(bd_dev));
 }
 #endif

 /*
  * sdfat_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 __sdfat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
 {
 	struct sdfat_mount_options *opts = &SDFAT_SB(sb)->options;
 	va_list args;
 	struct va_format vaf;
 	struct block_device *bdev = sb->s_bdev;
 	dev_t bd_dev = bdev ? bdev->bd_dev : 0;

 	if (report) {
 		va_start(args, fmt);
 		vaf.fmt = fmt;
 		vaf.va = &args;
 		pr_err("[SDFAT](%s[%d:%d]):ERR: %pV\n",
 			sb->s_id, MAJOR(bd_dev), MINOR(bd_dev), &vaf);
 #ifdef CONFIG_SDFAT_SUPPORT_STLOG
 		if (opts->errors == SDFAT_ERRORS_RO && !sb_rdonly(sb)) {
 			ST_LOG("[SDFAT](%s[%d:%d]):ERR: %pV\n",
 				sb->s_id, MAJOR(bd_dev), MINOR(bd_dev), &vaf);
 		}
 #endif
 		va_end(args);
 	}

 	if (opts->errors == SDFAT_ERRORS_PANIC) {
 		panic("[SDFAT](%s[%d:%d]): fs panic from previous error\n",
 			sb->s_id, MAJOR(bd_dev), MINOR(bd_dev));
 	} else if (opts->errors == SDFAT_ERRORS_RO && !sb_rdonly(sb)) {
 		sb->s_flags |= SB_RDONLY;
 		sdfat_statistics_set_mnt_ro();
 		pr_err("[SDFAT](%s[%d:%d]): Filesystem has been set "
 			"read-only\n", sb->s_id, MAJOR(bd_dev), MINOR(bd_dev));
 #ifdef CONFIG_SDFAT_SUPPORT_STLOG
 		ST_LOG("[SDFAT](%s[%d:%d]): Filesystem has been set read-only\n",
 			sb->s_id, MAJOR(bd_dev), MINOR(bd_dev));
 #endif
 		sdfat_uevent_ro_remount(sb);
 	}
 }
 EXPORT_SYMBOL(__sdfat_fs_error);

 /**
  * __sdfat_msg() - print preformated SDFAT specific messages.
  * All logs except what uses sdfat_fs_error() should be written by __sdfat_msg()
  * If 'st' is set, the log is propagated to ST_LOG.
  */
 void __sdfat_msg(struct super_block *sb, const char *level, int st, const char *fmt, ...)
 {
 	struct va_format vaf;
 	va_list args;
 	struct block_device *bdev = sb->s_bdev;
 	dev_t bd_dev = bdev ? bdev->bd_dev : 0;

 	va_start(args, fmt);
 	vaf.fmt = fmt;
 	vaf.va = &args;
 	/* level means KERN_ pacility level */
 	printk("%s[SDFAT](%s[%d:%d]): %pV\n", level,
 			sb->s_id, MAJOR(bd_dev), MINOR(bd_dev), &vaf);
 #ifdef CONFIG_SDFAT_SUPPORT_STLOG
 	if (st) {
 		ST_LOG("[SDFAT](%s[%d:%d]): %pV\n",
 				sb->s_id, MAJOR(bd_dev), MINOR(bd_dev), &vaf);
 	}
 #endif
 	va_end(args);
 }
 EXPORT_SYMBOL(__sdfat_msg);

 void sdfat_log_version(void)
 {
 	pr_info("[SDFAT] Filesystem version %s\n", SDFAT_VERSION);
 #ifdef CONFIG_SDFAT_SUPPORT_STLOG
 	ST_LOG("[SDFAT] Filesystem version %s\n", SDFAT_VERSION);
 #endif
 }
 EXPORT_SYMBOL(sdfat_log_version);

 /* <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)

 /* do not use time_t directly to prevent compile errors on 32bit kernel */
 #define time_do_div(ori, base)	\
 ({				\
 	u64 __ori = ori;	\
 	do_div(__ori, base);	\
 	(time_t)__ori;		\
 })

 #define time_do_mod(ori, base)		\
 ({					\
 	u64 __ori = ori;		\
 	(time_t)do_div(__ori, base);	\
 })

 #define MAKE_LEAP_YEAR(leap_year, year)                         \
 ({								\
 	/* 2100 isn't leap year */				\
 	if (unlikely(year > NO_LEAP_YEAR_2100))			\
 		leap_year = time_do_div((year + 3), 4) - 1;	\
 	else							\
 		leap_year = time_do_div((year + 3), 4);		\
 })

 /* 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,
 };

 #define TIMEZONE_SEC(x)	((x) * 15 * SECS_PER_MIN)
 /* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
 void sdfat_time_fat2unix(struct sdfat_sb_info *sbi, sdfat_timespec_t *ts,
 								DATE_TIME_T *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;

 	ts->tv_nsec = 0;

 	/* Treat as local time */
 	if (!sbi->options.tz_utc && !tp->Timezone.valid) {
 		ts->tv_sec += sys_tz.tz_minuteswest * SECS_PER_MIN;
 		return;
 	}

 	/* Treat as UTC time */
 	if (!tp->Timezone.valid)
 		return;

 	/* Treat as UTC time, but need to adjust timezone to UTC0 */
 	if (tp->Timezone.off <= 0x3F)
 		ts->tv_sec -= TIMEZONE_SEC(tp->Timezone.off);
 	else /* 0x40 <= (tp->Timezone & 0x7F) <=0x7F */
 		ts->tv_sec += TIMEZONE_SEC(0x80 - tp->Timezone.off);
 }

 #define TIMEZONE_CUR_OFFSET()	((sys_tz.tz_minuteswest / (-15)) & 0x7F)
 /* Convert linear UNIX date to a FAT time/date pair. */
 void sdfat_time_unix2fat(struct sdfat_sb_info *sbi, sdfat_timespec_t *ts,
 								DATE_TIME_T *tp)
 {
 	bool tz_valid = (sbi->fsi.vol_type == EXFAT) ? true : false;
 	time_t second = ts->tv_sec;
 	time_t day, month, year;
 	time_t ld; /* leap day */

 	tp->Timezone.value = 0x00;

 	/* Treats as local time with proper time */
 	if (tz_valid || !sbi->options.tz_utc) {
 		second -= sys_tz.tz_minuteswest * SECS_PER_MIN;
 		if (tz_valid) {
 			tp->Timezone.valid = 1;
 			tp->Timezone.off = TIMEZONE_CUR_OFFSET();
 		}
 	}

 	/* 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 = time_do_div(second, SECS_PER_DAY) - DAYS_DELTA_DECADE;
 	year = time_do_div(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 = (u16)time_do_mod(second, SECS_PER_MIN);
 	tp->Minute = (u16)time_do_mod(time_do_div(second, SECS_PER_MIN), 60);
 	tp->Hour = (u16)time_do_mod(time_do_div(second, SECS_PER_HOUR), 24);
 	tp->Day  = (u16)(day + 1);
 	tp->Month  = (u16)month;
 	tp->Year = (u16)year;
 }

 TIMESTAMP_T *tm_now(struct inode *inode, TIMESTAMP_T *tp)
 {
 	sdfat_timespec_t ts = current_time(inode);
 	DATE_TIME_T dt;

 	sdfat_time_unix2fat(SDFAT_SB(inode->i_sb), &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;
 	tp->tz.value = dt.Timezone.value;

 	return tp;
 }

 u8 calc_chksum_1byte(void *data, s32 len, u8 chksum)
 {
 	s32 i;
 	u8 *c = (u8 *) data;

 	for (i = 0; i < len; i++, c++)
 		chksum = (((chksum & 1) << 7) | ((chksum & 0xFE) >> 1)) + *c;

 	return chksum;
 }

 u16 calc_chksum_2byte(void *data, s32 len, u16 chksum, s32 type)
 {
 	s32 i;
 	u8 *c = (u8 *) 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)) + (u16) *c;
 	}
 	return chksum;
 }

 #ifdef CONFIG_SDFAT_TRACE_ELAPSED_TIME
 struct timeval __t1, __t2;
 u32 sdfat_time_current_usec(struct timeval *tv)
 {
 	do_gettimeofday(tv);
 	return (u32)(tv->tv_sec*1000000 + tv->tv_usec);
 }
 #endif /* CONFIG_SDFAT_TRACE_ELAPSED_TIME */

 #ifdef CONFIG_SDFAT_DBG_CAREFUL
 /* Check the consistency of i_size_ondisk (FAT32, or flags 0x01 only) */
 void sdfat_debug_check_clusters(struct inode *inode)
 {
 	unsigned int num_clusters;
 	volatile uint32_t tmp_fat_chain[50];
 	volatile int tmp_i = 0;
 	volatile unsigned int num_clusters_org, tmp_i = 0;
 	CHAIN_T clu;
 	FILE_ID_T *fid = &(SDFAT_I(inode)->fid);
 	FS_INFO_T *fsi = &(SDFAT_SB(inode->i_sb)->fsi);

 	if (SDFAT_I(inode)->i_size_ondisk == 0)
 		num_clusters = 0;
 	else
 		num_clusters = ((SDFAT_I(inode)->i_size_ondisk-1) >> fsi->cluster_size_bits) + 1;

 	clu.dir = fid->start_clu;
 	clu.size = num_clusters;
 	clu.flags = fid->flags;

 	num_clusters_org = num_clusters;

 	if (clu.flags == 0x03)
 		return;

 	while (num_clusters > 0) {
 		/* FAT chain logging */
 		tmp_fat_chain[tmp_i] = clu.dir;
 		tmp_i++;
 		if (tmp_i >= 50)
 			tmp_i = 0;

 		BUG_ON(IS_CLUS_EOF(clu.dir) || IS_CLUS_FREE(clu.dir));

 		if (get_next_clus_safe(inode->i_sb, &(clu.dir)))
 			EMSG("%s: failed to access to FAT\n");

 		num_clusters--;
 	}

 	BUG_ON(!IS_CLUS_EOF(clu.dir));
 }

 #endif /* CONFIG_SDFAT_DBG_CAREFUL */

 #ifdef CONFIG_SDFAT_DBG_MSG
 void __sdfat_dmsg(int level, const char *fmt, ...)
 {
 #ifdef CONFIG_SDFAT_DBG_SHOW_PID
 	struct va_format vaf;
 	va_list args;

 	/* should check type */
 	if (level > SDFAT_MSG_LEVEL)
 		return;

 	va_start(args, fmt);
 	vaf.fmt = fmt;
 	vaf.va = &args;
 	/* fmt already includes KERN_ pacility level */
 	printk("[%u] %pV", current->pid,  &vaf);
 	va_end(args);
 #else
 	va_list args;

 	/* should check type */
 	if (level > SDFAT_MSG_LEVEL)
 		return;

 	va_start(args, fmt);
 	/* fmt already includes KERN_ pacility level */
 	vprintk(fmt, args);
 	va_end(args);
 #endif
 }
 #endif
	/*
	* Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version 2
	* of the License, or (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, see <http://www.gnu.org/licenses/>.
	*/

	/*
	* linux/fs/fat/misc.c
	*
	* 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)
	*/

	/************************************************************************/
	/* */
	/* PROJECT : exFAT & FAT12/16/32 File System */
	/* FILE : misc.c */
	/* PURPOSE : Helper function for checksum and handing sdFAT error */
	/* */
	/----------------------------------------------------------------------/
	/* NOTES */
	/* */
	/* */
	/************************************************************************/

	#include <linux/module.h>
	#include <linux/fs.h>
	#include <linux/buffer_head.h>
	#include <linux/time.h>
	#include <linux/blkdev.h>
	#include "sdfat.h"
	#include "version.h"


	#ifdef CONFIG_SDFAT_SUPPORT_STLOG
	#ifdef CONFIG_PROC_FSLOG
	#include <linux/fslog.h>
	#else
	#include <linux/stlog.h>
	#endif
	#else
	#define ST_LOG(fmt, ...)
	#endif

	#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 0)
	#include <linux/ktime.h>
	#ifndef _TIME_T
	#define _TIME_T
	typedef ktime_t time_t;
	#endif
	#endif

	/*************************************************************************
	* FUNCTIONS WHICH HAS KERNEL VERSION DEPENDENCY
	*************************************************************************/
	#ifdef CONFIG_SDFAT_UEVENT
	static struct kobject sdfat_uevent_kobj;

	int sdfat_uevent_init(struct kset *sdfat_kset)
	{
	int err;
	struct kobj_type *ktype = get_ktype(&sdfat_kset->kobj);

	sdfat_uevent_kobj.kset = sdfat_kset;
	err = kobject_init_and_add(&sdfat_uevent_kobj, ktype, NULL, "uevent");
	if (err)
	pr_err("[SDFAT] Unable to create sdfat uevent kobj\n");

	return err;
	}

	void sdfat_uevent_uninit(void)
	{
	kobject_del(&sdfat_uevent_kobj);
	memset(&sdfat_uevent_kobj, 0, sizeof(struct kobject));
	}

	void sdfat_uevent_ro_remount(struct super_block *sb)
	{
	struct block_device *bdev = sb->s_bdev;
	dev_t bd_dev = bdev ? bdev->bd_dev : 0;

	char major[16], minor[16];
	char *envp[] = { major, minor, NULL };

	/* Do not trigger uevent if a device has been ejected */
	if (fsapi_check_bdi_valid(sb))
	return;

	snprintf(major, sizeof(major), "MAJOR=%d", MAJOR(bd_dev));
	snprintf(minor, sizeof(minor), "MINOR=%d", MINOR(bd_dev));

	kobject_uevent_env(&sdfat_uevent_kobj, KOBJ_CHANGE, envp);

	ST_LOG("[SDFAT](%s[%d:%d]): Uevent triggered\n",
	sb->s_id, MAJOR(bd_dev), MINOR(bd_dev));
	}
	#endif

	/*
	* sdfat_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 __sdfat_fs_error(struct super_block sb, int report, const char fmt, ...)
	{
	struct sdfat_mount_options *opts = &SDFAT_SB(sb)->options;
	va_list args;
	struct va_format vaf;
	struct block_device *bdev = sb->s_bdev;
	dev_t bd_dev = bdev ? bdev->bd_dev : 0;

	if (report) {
	va_start(args, fmt);
	vaf.fmt = fmt;
	vaf.va = &args;
	pr_err("[SDFAT](%s[%d:%d]):ERR: %pV\n",
	sb->s_id, MAJOR(bd_dev), MINOR(bd_dev), &vaf);
	#ifdef CONFIG_SDFAT_SUPPORT_STLOG
	if (opts->errors == SDFAT_ERRORS_RO && !sb_rdonly(sb)) {
	ST_LOG("[SDFAT](%s[%d:%d]):ERR: %pV\n",
	sb->s_id, MAJOR(bd_dev), MINOR(bd_dev), &vaf);
	}
	#endif
	va_end(args);
	}

	if (opts->errors == SDFAT_ERRORS_PANIC) {
	panic("[SDFAT](%s[%d:%d]): fs panic from previous error\n",
	sb->s_id, MAJOR(bd_dev), MINOR(bd_dev));
	} else if (opts->errors == SDFAT_ERRORS_RO && !sb_rdonly(sb)) {
	sb->s_flags \|= SB_RDONLY;
	sdfat_statistics_set_mnt_ro();
	pr_err("[SDFAT](%s[%d:%d]): Filesystem has been set "
	"read-only\n", sb->s_id, MAJOR(bd_dev), MINOR(bd_dev));
	#ifdef CONFIG_SDFAT_SUPPORT_STLOG
	ST_LOG("[SDFAT](%s[%d:%d]): Filesystem has been set read-only\n",
	sb->s_id, MAJOR(bd_dev), MINOR(bd_dev));
	#endif
	sdfat_uevent_ro_remount(sb);
	}
	}
	EXPORT_SYMBOL(__sdfat_fs_error);

	/**
	* __sdfat_msg() - print preformated SDFAT specific messages.
	* All logs except what uses sdfat_fs_error() should be written by __sdfat_msg()
	* If 'st' is set, the log is propagated to ST_LOG.
	*/
	void __sdfat_msg(struct super_block sb, const char level, int st, const char *fmt, ...)
	{
	struct va_format vaf;
	va_list args;
	struct block_device *bdev = sb->s_bdev;
	dev_t bd_dev = bdev ? bdev->bd_dev : 0;

	va_start(args, fmt);
	vaf.fmt = fmt;
	vaf.va = &args;
	/* level means KERN_ pacility level */
	printk("%s[SDFAT](%s[%d:%d]): %pV\n", level,
	sb->s_id, MAJOR(bd_dev), MINOR(bd_dev), &vaf);
	#ifdef CONFIG_SDFAT_SUPPORT_STLOG
	if (st) {
	ST_LOG("[SDFAT](%s[%d:%d]): %pV\n",
	sb->s_id, MAJOR(bd_dev), MINOR(bd_dev), &vaf);
	}
	#endif
	va_end(args);
	}
	EXPORT_SYMBOL(__sdfat_msg);

	void sdfat_log_version(void)
	{
	pr_info("[SDFAT] Filesystem version %s\n", SDFAT_VERSION);
	#ifdef CONFIG_SDFAT_SUPPORT_STLOG
	ST_LOG("[SDFAT] Filesystem version %s\n", SDFAT_VERSION);
	#endif
	}
	EXPORT_SYMBOL(sdfat_log_version);

	/* <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)

	/* do not use time_t directly to prevent compile errors on 32bit kernel */
	#define time_do_div(ori, base) \
	({ \
	u64 __ori = ori; \
	do_div(__ori, base); \
	(time_t)__ori; \
	})

	#define time_do_mod(ori, base) \
	({ \
	u64 __ori = ori; \
	(time_t)do_div(__ori, base); \
	})

	#define MAKE_LEAP_YEAR(leap_year, year) \
	({ \
	/* 2100 isn't leap year */ \
	if (unlikely(year > NO_LEAP_YEAR_2100)) \
	leap_year = time_do_div((year + 3), 4) - 1; \
	else \
	leap_year = time_do_div((year + 3), 4); \
	})

	/* 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,
	};

	#define TIMEZONE_SEC(x) ((x) * 15 * SECS_PER_MIN)
	/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
	void sdfat_time_fat2unix(struct sdfat_sb_info sbi, sdfat_timespec_t ts,
	DATE_TIME_T *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;

	ts->tv_nsec = 0;

	/* Treat as local time */
	if (!sbi->options.tz_utc && !tp->Timezone.valid) {
	ts->tv_sec += sys_tz.tz_minuteswest * SECS_PER_MIN;
	return;
	}

	/* Treat as UTC time */
	if (!tp->Timezone.valid)
	return;

	/* Treat as UTC time, but need to adjust timezone to UTC0 */
	if (tp->Timezone.off <= 0x3F)
	ts->tv_sec -= TIMEZONE_SEC(tp->Timezone.off);
	else /* 0x40 <= (tp->Timezone & 0x7F) <=0x7F */
	ts->tv_sec += TIMEZONE_SEC(0x80 - tp->Timezone.off);
	}

	#define TIMEZONE_CUR_OFFSET() ((sys_tz.tz_minuteswest / (-15)) & 0x7F)
	/* Convert linear UNIX date to a FAT time/date pair. */
	void sdfat_time_unix2fat(struct sdfat_sb_info sbi, sdfat_timespec_t ts,
	DATE_TIME_T *tp)
	{
	bool tz_valid = (sbi->fsi.vol_type == EXFAT) ? true : false;
	time_t second = ts->tv_sec;
	time_t day, month, year;
	time_t ld; /* leap day */

	tp->Timezone.value = 0x00;

	/* Treats as local time with proper time */
	if (tz_valid \|\| !sbi->options.tz_utc) {
	second -= sys_tz.tz_minuteswest * SECS_PER_MIN;
	if (tz_valid) {
	tp->Timezone.valid = 1;
	tp->Timezone.off = TIMEZONE_CUR_OFFSET();
	}
	}

	/* 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 = time_do_div(second, SECS_PER_DAY) - DAYS_DELTA_DECADE;
	year = time_do_div(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 = (u16)time_do_mod(second, SECS_PER_MIN);
	tp->Minute = (u16)time_do_mod(time_do_div(second, SECS_PER_MIN), 60);
	tp->Hour = (u16)time_do_mod(time_do_div(second, SECS_PER_HOUR), 24);
	tp->Day = (u16)(day + 1);
	tp->Month = (u16)month;
	tp->Year = (u16)year;
	}

	TIMESTAMP_T tm_now(struct inode inode, TIMESTAMP_T *tp)
	{
	sdfat_timespec_t ts = current_time(inode);
	DATE_TIME_T dt;

	sdfat_time_unix2fat(SDFAT_SB(inode->i_sb), &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;
	tp->tz.value = dt.Timezone.value;

	return tp;
	}

	u8 calc_chksum_1byte(void *data, s32 len, u8 chksum)
	{
	s32 i;
	u8 c = (u8 ) data;

	for (i = 0; i < len; i++, c++)
	chksum = (((chksum & 1) << 7) \| ((chksum & 0xFE) >> 1)) + *c;

	return chksum;
	}

	u16 calc_chksum_2byte(void *data, s32 len, u16 chksum, s32 type)
	{
	s32 i;
	u8 c = (u8 ) 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)) + (u16) *c;
	}
	return chksum;
	}

	#ifdef CONFIG_SDFAT_TRACE_ELAPSED_TIME
	struct timeval __t1, __t2;
	u32 sdfat_time_current_usec(struct timeval *tv)
	{
	do_gettimeofday(tv);
	return (u32)(tv->tv_sec*1000000 + tv->tv_usec);
	}
	#endif /* CONFIG_SDFAT_TRACE_ELAPSED_TIME */

	#ifdef CONFIG_SDFAT_DBG_CAREFUL
	/* Check the consistency of i_size_ondisk (FAT32, or flags 0x01 only) */
	void sdfat_debug_check_clusters(struct inode *inode)
	{
	unsigned int num_clusters;
	volatile uint32_t tmp_fat_chain[50];
	volatile int tmp_i = 0;
	volatile unsigned int num_clusters_org, tmp_i = 0;
	CHAIN_T clu;
	FILE_ID_T *fid = &(SDFAT_I(inode)->fid);
	FS_INFO_T *fsi = &(SDFAT_SB(inode->i_sb)->fsi);

	if (SDFAT_I(inode)->i_size_ondisk == 0)
	num_clusters = 0;
	else
	num_clusters = ((SDFAT_I(inode)->i_size_ondisk-1) >> fsi->cluster_size_bits) + 1;

	clu.dir = fid->start_clu;
	clu.size = num_clusters;
	clu.flags = fid->flags;

	num_clusters_org = num_clusters;

	if (clu.flags == 0x03)
	return;

	while (num_clusters > 0) {
	/* FAT chain logging */
	tmp_fat_chain[tmp_i] = clu.dir;
	tmp_i++;
	if (tmp_i >= 50)
	tmp_i = 0;

	BUG_ON(IS_CLUS_EOF(clu.dir) \|\| IS_CLUS_FREE(clu.dir));

	if (get_next_clus_safe(inode->i_sb, &(clu.dir)))
	EMSG("%s: failed to access to FAT\n");

	num_clusters--;
	}

	BUG_ON(!IS_CLUS_EOF(clu.dir));
	}

	#endif /* CONFIG_SDFAT_DBG_CAREFUL */

	#ifdef CONFIG_SDFAT_DBG_MSG
	void __sdfat_dmsg(int level, const char *fmt, ...)
	{
	#ifdef CONFIG_SDFAT_DBG_SHOW_PID
	struct va_format vaf;
	va_list args;

	/* should check type */
	if (level > SDFAT_MSG_LEVEL)
	return;

	va_start(args, fmt);
	vaf.fmt = fmt;
	vaf.va = &args;
	/* fmt already includes KERN_ pacility level */
	printk("[%u] %pV", current->pid, &vaf);
	va_end(args);
	#else
	va_list args;

	/* should check type */
	if (level > SDFAT_MSG_LEVEL)
	return;

	va_start(args, fmt);
	/* fmt already includes KERN_ pacility level */
	vprintk(fmt, args);
	va_end(args);
	#endif
	}
	#endif