[linux.git] / fs / fat / misc.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  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([email protected])
 */

#include "fat.h"
#include <linux/iversion.h>

/*
 * fat_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 __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
{
	struct fat_mount_options *opts = &MSDOS_SB(sb)->options;
	va_list args;
	struct va_format vaf;

	if (report) {
		va_start(args, fmt);
		vaf.fmt = fmt;
		vaf.va = &args;
		fat_msg(sb, KERN_ERR, "error, %pV", &vaf);
		va_end(args);
	}

	if (opts->errors == FAT_ERRORS_PANIC)
		panic("FAT-fs (%s): fs panic from previous error\n", sb->s_id);
	else if (opts->errors == FAT_ERRORS_RO && !sb_rdonly(sb)) {
		sb->s_flags |= SB_RDONLY;
		fat_msg(sb, KERN_ERR, "Filesystem has been set read-only");
	}
}
EXPORT_SYMBOL_GPL(__fat_fs_error);

/**
 * _fat_msg() - Print a preformatted FAT message based on a superblock.
 * @sb: A pointer to a &struct super_block
 * @level: A Kernel printk level constant
 * @fmt: The printf-style format string to print.
 *
 * Everything that is not fat_fs_error() should be fat_msg().
 *
 * fat_msg() wraps _fat_msg() for printk indexing.
 */
void _fat_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;
	_printk(FAT_PRINTK_PREFIX "%pV\n", level, sb->s_id, &vaf);
	va_end(args);
}

/* Flushes the number of free clusters on FAT32 */
/* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
int fat_clusters_flush(struct super_block *sb)
{
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	struct buffer_head *bh;
	struct fat_boot_fsinfo *fsinfo;

	if (!is_fat32(sbi))
		return 0;

	bh = sb_bread(sb, sbi->fsinfo_sector);
	if (bh == NULL) {
		fat_msg(sb, KERN_ERR, "bread failed in fat_clusters_flush");
		return -EIO;
	}

	fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
	/* Sanity check */
	if (!IS_FSINFO(fsinfo)) {
		fat_msg(sb, KERN_ERR, "Invalid FSINFO signature: "
		       "0x%08x, 0x%08x (sector = %lu)",
		       le32_to_cpu(fsinfo->signature1),
		       le32_to_cpu(fsinfo->signature2),
		       sbi->fsinfo_sector);
	} else {
		if (sbi->free_clusters != -1)
			fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
		if (sbi->prev_free != -1)
			fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
		mark_buffer_dirty(bh);
	}
	brelse(bh);

	return 0;
}

/*
 * fat_chain_add() adds a new cluster to the chain of clusters represented
 * by inode.
 */
int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
{
	struct super_block *sb = inode->i_sb;
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	int ret, new_fclus, last;

	/*
	 * We must locate the last cluster of the file to add this new
	 * one (new_dclus) to the end of the link list (the FAT).
	 */
	last = new_fclus = 0;
	if (MSDOS_I(inode)->i_start) {
		int fclus, dclus;

		ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
		if (ret < 0)
			return ret;
		new_fclus = fclus + 1;
		last = dclus;
	}

	/* add new one to the last of the cluster chain */
	if (last) {
		struct fat_entry fatent;

		fatent_init(&fatent);
		ret = fat_ent_read(inode, &fatent, last);
		if (ret >= 0) {
			int wait = inode_needs_sync(inode);
			ret = fat_ent_write(inode, &fatent, new_dclus, wait);
			fatent_brelse(&fatent);
		}
		if (ret < 0)
			return ret;
		/*
		 * FIXME:Although we can add this cache, fat_cache_add() is
		 * assuming to be called after linear search with fat_cache_id.
		 */
//		fat_cache_add(inode, new_fclus, new_dclus);
	} else {
		MSDOS_I(inode)->i_start = new_dclus;
		MSDOS_I(inode)->i_logstart = new_dclus;
		/*
		 * Since generic_write_sync() synchronizes regular files later,
		 * we sync here only directories.
		 */
		if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
			ret = fat_sync_inode(inode);
			if (ret)
				return ret;
		} else
			mark_inode_dirty(inode);
	}
	if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
		fat_fs_error(sb, "clusters badly computed (%d != %llu)",
			     new_fclus,
			     (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
		fat_cache_inval_inode(inode);
	}
	inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);

	return 0;
}

/*
 * 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)
/* 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 long 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,
};

static inline int fat_tz_offset(const struct msdos_sb_info *sbi)
{
	return (sbi->options.tz_set ?
	       -sbi->options.time_offset :
	       sys_tz.tz_minuteswest) * SECS_PER_MIN;
}

/* 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 timespec64 *ts,
		       __le16 __time, __le16 __date, u8 time_cs)
{
	u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
	time64_t second;
	long day, leap_day, month, year;

	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 += (time64_t)(year * 365 + leap_day
		   + days_in_year[month] + day
		   + DAYS_DELTA) * SECS_PER_DAY;

	second += fat_tz_offset(sbi);

	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;
	}
}

/* Export fat_time_fat2unix() for the fat_test KUnit tests. */
EXPORT_SYMBOL_GPL(fat_time_fat2unix);

/* Convert linear UNIX date to a FAT time/date pair. */
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, -fat_tz_offset(sbi), &tm);

	/*  FAT can only support year between 1980 to 2107 */
	if (tm.tm_year < 1980 - 1900) {
		*time = 0;
		*date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
		if (time_cs)
			*time_cs = 0;
		return;
	}
	if (tm.tm_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;
	}

	/* from 1900 -> from 1980 */
	tm.tm_year -= 80;
	/* 0~11 -> 1~12 */
	tm.tm_mon++;
	/* 0~59 -> 0~29(2sec counts) */
	tm.tm_sec >>= 1;

	*time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec);
	*date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday);
	if (time_cs)
		*time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
}
EXPORT_SYMBOL_GPL(fat_time_unix2fat);

static inline struct timespec64 fat_timespec64_trunc_2secs(struct timespec64 ts)
{
	return (struct timespec64){ ts.tv_sec & ~1ULL, 0 };
}

/*
 * truncate atime to 24 hour granularity (00:00:00 in local timezone)
 */
struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi,
				     const struct timespec64 *ts)
{
	/* to localtime */
	time64_t seconds = ts->tv_sec - fat_tz_offset(sbi);
	s32 remainder;

	div_s64_rem(seconds, SECS_PER_DAY, &remainder);
	/* to day boundary, and back to unix time */
	seconds = seconds + fat_tz_offset(sbi) - remainder;

	return (struct timespec64){ seconds, 0 };
}

/*
 * truncate mtime to 2 second granularity
 */
struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi,
				     const struct timespec64 *ts)
{
	return fat_timespec64_trunc_2secs(*ts);
}

/*
 * truncate the various times with appropriate granularity:
 *   all times in root node are always 0
 */
int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
{
	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
	struct timespec64 ts;

	if (inode->i_ino == MSDOS_ROOT_INO)
		return 0;

	if (now == NULL) {
		now = &ts;
		ts = current_time(inode);
	}

	if (flags & S_ATIME)
		inode_set_atime_to_ts(inode, fat_truncate_atime(sbi, now));
	/*
	 * ctime and mtime share the same on-disk field, and should be
	 * identical in memory. all mtime updates will be applied to ctime,
	 * but ctime updates are ignored.
	 */
	if (flags & S_MTIME)
		inode_set_mtime_to_ts(inode,
				      inode_set_ctime_to_ts(inode, fat_truncate_mtime(sbi, now)));

	return 0;
}
EXPORT_SYMBOL_GPL(fat_truncate_time);

int fat_update_time(struct inode *inode, int flags)
{
	int dirty_flags = 0;

	if (inode->i_ino == MSDOS_ROOT_INO)
		return 0;

	if (flags & (S_ATIME | S_CTIME | S_MTIME)) {
		fat_truncate_time(inode, NULL, flags);
		if (inode->i_sb->s_flags & SB_LAZYTIME)
			dirty_flags |= I_DIRTY_TIME;
		else
			dirty_flags |= I_DIRTY_SYNC;
	}

	__mark_inode_dirty(inode, dirty_flags);
	return 0;
}
EXPORT_SYMBOL_GPL(fat_update_time);

int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
{
	int i, err = 0;

	for (i = 0; i < nr_bhs; i++)
		write_dirty_buffer(bhs[i], 0);

	for (i = 0; i < nr_bhs; i++) {
		wait_on_buffer(bhs[i]);
		if (!err && !buffer_uptodate(bhs[i]))
			err = -EIO;
	}
	return err;
}
Commit	Line	Data
457c8996	1	// SPDX-License-Identifier: GPL-2.0-only
1da177e4 LT	2	/*
	3	* linux/fs/fat/misc.c
	4	*
	5	* Written 1992,1993 by Werner Almesberger
	6	* 22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
	7	* and date_dos2unix for date==0 by Igor Zhbanov([email protected])
	8	*/
	9
9e975dae	10	#include "fat.h"
6bb885ec	11	#include <linux/iversion.h>
1da177e4 LT	12
1da177e4 LT	13	/*
85c78591 DK	14	* fat_fs_error reports a file system problem that might indicate fa data
	15	* corruption/inconsistency. Depending on 'errors' mount option the
	16	* panic() is called, or error message is printed FAT and nothing is done,
	17	* or filesystem is remounted read-only (default behavior).
	18	* In case the file system is remounted read-only, it can be made writable
	19	* again by remounting it.
1da177e4	20	*/
2c8a5ffb	21	void __fat_fs_error(struct super_block sb, int report, const char fmt, ...)
1da177e4	22	{
2c8a5ffb	23	struct fat_mount_options *opts = &MSDOS_SB(sb)->options;
1da177e4	24	va_list args;
2c8a5ffb	25	struct va_format vaf;
1da177e4	26
aaa04b48	27	if (report) {
aaa04b48	28	va_start(args, fmt);
2c8a5ffb OR	29	vaf.fmt = fmt;
2c8a5ffb OR	30	vaf.va = &args;
e68e96d2	31	fat_msg(sb, KERN_ERR, "error, %pV", &vaf);
aaa04b48	32	va_end(args);
aaa04b48	33	}
1da177e4	34
85c78591	35	if (opts->errors == FAT_ERRORS_PANIC)
2c8a5ffb	36	panic("FAT-fs (%s): fs panic from previous error\n", sb->s_id);
bc98a42c	37	else if (opts->errors == FAT_ERRORS_RO && !sb_rdonly(sb)) {
1751e8a6	38	sb->s_flags \|= SB_RDONLY;
e68e96d2	39	fat_msg(sb, KERN_ERR, "Filesystem has been set read-only");
1da177e4 LT	40	}
1da177e4 LT	41	}
aaa04b48	42	EXPORT_SYMBOL_GPL(__fat_fs_error);
1da177e4	43
81ac21d3	44	/**
e057aaec JL	45	* _fat_msg() - Print a preformatted FAT message based on a superblock.
	46	* @sb: A pointer to a &struct super_block
	47	* @level: A Kernel printk level constant
	48	* @fmt: The printf-style format string to print.
	49	*
	50	* Everything that is not fat_fs_error() should be fat_msg().
	51	*
	52	* fat_msg() wraps _fat_msg() for printk indexing.
81ac21d3	53	*/
e057aaec	54	void _fat_msg(struct super_block sb, const char level, const char *fmt, ...)
81ac21d3 OR	55	{
	56	struct va_format vaf;
	57	va_list args;
	58
	59	va_start(args, fmt);
	60	vaf.fmt = fmt;
	61	vaf.va = &args;
e057aaec	62	_printk(FAT_PRINTK_PREFIX "%pV\n", level, sb->s_id, &vaf);
81ac21d3 OR	63	va_end(args);
	64	}
	65
1da177e4 LT	66	/* Flushes the number of free clusters on FAT32 */
1da177e4 LT	67	/* XXX: Need to write one per FSINFO block. Currently only writes 1 */
ed248b29	68	int fat_clusters_flush(struct super_block *sb)
1da177e4 LT	69	{
	70	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	71	struct buffer_head *bh;
	72	struct fat_boot_fsinfo *fsinfo;
	73
306790f7	74	if (!is_fat32(sbi))
ed248b29	75	return 0;
1da177e4 LT	76
	77	bh = sb_bread(sb, sbi->fsinfo_sector);
	78	if (bh == NULL) {
869f58c0	79	fat_msg(sb, KERN_ERR, "bread failed in fat_clusters_flush");
ed248b29	80	return -EIO;
1da177e4 LT	81	}
	82
	83	fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
	84	/* Sanity check */
	85	if (!IS_FSINFO(fsinfo)) {
869f58c0 OR	86	fat_msg(sb, KERN_ERR, "Invalid FSINFO signature: "
869f58c0 OR	87	"0x%08x, 0x%08x (sector = %lu)",
1da177e4 LT	88	le32_to_cpu(fsinfo->signature1),
	89	le32_to_cpu(fsinfo->signature2),
	90	sbi->fsinfo_sector);
	91	} else {
	92	if (sbi->free_clusters != -1)
	93	fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
	94	if (sbi->prev_free != -1)
	95	fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
	96	mark_buffer_dirty(bh);
1da177e4 LT	97	}
1da177e4 LT	98	brelse(bh);
ed248b29 OH	99
ed248b29 OH	100	return 0;
1da177e4 LT	101	}
	102
	103	/*
	104	* fat_chain_add() adds a new cluster to the chain of clusters represented
	105	* by inode.
	106	*/
	107	int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
	108	{
	109	struct super_block *sb = inode->i_sb;
	110	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	111	int ret, new_fclus, last;
	112
	113	/*
	114	* We must locate the last cluster of the file to add this new
	115	* one (new_dclus) to the end of the link list (the FAT).
	116	*/
	117	last = new_fclus = 0;
	118	if (MSDOS_I(inode)->i_start) {
	119	int fclus, dclus;
	120
	121	ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
	122	if (ret < 0)
	123	return ret;
	124	new_fclus = fclus + 1;
	125	last = dclus;
	126	}
	127
	128	/* add new one to the last of the cluster chain */
	129	if (last) {
	130	struct fat_entry fatent;
	131
	132	fatent_init(&fatent);
	133	ret = fat_ent_read(inode, &fatent, last);
	134	if (ret >= 0) {
	135	int wait = inode_needs_sync(inode);
	136	ret = fat_ent_write(inode, &fatent, new_dclus, wait);
	137	fatent_brelse(&fatent);
	138	}
	139	if (ret < 0)
	140	return ret;
c39540c6 R	141	/*
	142	* FIXME:Although we can add this cache, fat_cache_add() is
	143	* assuming to be called after linear search with fat_cache_id.
	144	*/
1da177e4 LT	145	// fat_cache_add(inode, new_fclus, new_dclus);
	146	} else {
	147	MSDOS_I(inode)->i_start = new_dclus;
	148	MSDOS_I(inode)->i_logstart = new_dclus;
	149	/*
2f3d675b JK	150	* Since generic_write_sync() synchronizes regular files later,
2f3d675b JK	151	* we sync here only directories.
1da177e4 LT	152	*/
	153	if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
	154	ret = fat_sync_inode(inode);
	155	if (ret)
	156	return ret;
	157	} else
	158	mark_inode_dirty(inode);
	159	}
	160	if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
85c78591	161	fat_fs_error(sb, "clusters badly computed (%d != %llu)",
c3302931 OH	162	new_fclus,
c3302931 OH	163	(llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
1da177e4 LT	164	fat_cache_inval_inode(inode);
	165	}
	166	inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
	167
	168	return 0;
	169	}
	170
7decd1cb OH	171	/*
	172	* The epoch of FAT timestamp is 1980.
	173	* : bits : value
	174	* date: 0 - 4: day (1 - 31)
	175	* date: 5 - 8: month (1 - 12)
	176	* date: 9 - 15: year (0 - 127) from 1980
	177	* time: 0 - 4: sec (0 - 29) 2sec counts
	178	* time: 5 - 10: min (0 - 59)
	179	* time: 11 - 15: hour (0 - 23)
	180	*/
	181	#define SECS_PER_MIN 60
	182	#define SECS_PER_HOUR (60 * 60)
	183	#define SECS_PER_DAY (SECS_PER_HOUR * 24)
7decd1cb OH	184	/* days between 1.1.70 and 1.1.80 (2 leap days) */
	185	#define DAYS_DELTA (365 * 10 + 2)
	186	/* 120 (2100 - 1980) isn't leap year */
	187	#define YEAR_2100 120
	188	#define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100)
	189
1da177e4	190	/* Linear day numbers of the respective 1sts in non-leap years. */
f423420c	191	static long days_in_year[] = {
7decd1cb OH	192	/* Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec */
7decd1cb OH	193	0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
1da177e4 LT	194	};
1da177e4 LT	195
4dcc3f96	196	static inline int fat_tz_offset(const struct msdos_sb_info *sbi)
d9f4d942 FS	197	{
	198	return (sbi->options.tz_set ?
	199	-sbi->options.time_offset :
	200	sys_tz.tz_minuteswest) * SECS_PER_MIN;
	201	}
	202
7decd1cb	203	/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
f423420c	204	void fat_time_fat2unix(struct msdos_sb_info sbi, struct timespec64 ts,
7decd1cb	205	__le16 __time, __le16 __date, u8 time_cs)
1da177e4	206	{
7decd1cb	207	u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
f423420c AB	208	time64_t second;
f423420c AB	209	long day, leap_day, month, year;
1da177e4	210
7decd1cb OH	211	year = date >> 9;
	212	month = max(1, (date >> 5) & 0xf);
	213	day = max(1, date & 0x1f) - 1;
	214
	215	leap_day = (year + 3) / 4;
	216	if (year > YEAR_2100) /* 2100 isn't leap year */
	217	leap_day--;
	218	if (IS_LEAP_YEAR(year) && month > 2)
	219	leap_day++;
	220
	221	second = (time & 0x1f) << 1;
	222	second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
	223	second += (time >> 11) * SECS_PER_HOUR;
f423420c	224	second += (time64_t)(year * 365 + leap_day
7decd1cb OH	225	+ days_in_year[month] + day
	226	+ DAYS_DELTA) * SECS_PER_DAY;
	227
d9f4d942	228	second += fat_tz_offset(sbi);
7decd1cb OH	229
	230	if (time_cs) {
	231	ts->tv_sec = second + (time_cs / 100);
	232	ts->tv_nsec = (time_cs % 100) * 10000000;
	233	} else {
	234	ts->tv_sec = second;
	235	ts->tv_nsec = 0;
	236	}
1da177e4 LT	237	}
1da177e4 LT	238
b0d4adaf DG	239	/* Export fat_time_fat2unix() for the fat_test KUnit tests. */
	240	EXPORT_SYMBOL_GPL(fat_time_fat2unix);
	241
7decd1cb	242	/* Convert linear UNIX date to a FAT time/date pair. */
f423420c	243	void fat_time_unix2fat(struct msdos_sb_info sbi, struct timespec64 ts,
7decd1cb	244	__le16 time, __le16 date, u8 *time_cs)
1da177e4	245	{
1d81a181	246	struct tm tm;
d9f4d942	247	time64_to_tm(ts->tv_sec, -fat_tz_offset(sbi), &tm);
1da177e4	248
1d81a181 Z	249	/* FAT can only support year between 1980 to 2107 */
1d81a181 Z	250	if (tm.tm_year < 1980 - 1900) {
7decd1cb OH	251	*time = 0;
	252	*date = cpu_to_le16((0 << 9) \| (1 << 5) \| 1);
	253	if (time_cs)
	254	*time_cs = 0;
	255	return;
	256	}
1d81a181	257	if (tm.tm_year > 2107 - 1900) {
7decd1cb OH	258	*time = cpu_to_le16((23 << 11) \| (59 << 5) \| 29);
	259	*date = cpu_to_le16((127 << 9) \| (12 << 5) \| 31);
	260	if (time_cs)
	261	*time_cs = 199;
	262	return;
	263	}
7decd1cb	264
1d81a181 Z	265	/* from 1900 -> from 1980 */
	266	tm.tm_year -= 80;
	267	/* 0~11 -> 1~12 */
	268	tm.tm_mon++;
	269	/* 0~59 -> 0~29(2sec counts) */
	270	tm.tm_sec >>= 1;
1da177e4	271
1d81a181 Z	272	*time = cpu_to_le16(tm.tm_hour << 11 \| tm.tm_min << 5 \| tm.tm_sec);
1d81a181 Z	273	*date = cpu_to_le16(tm.tm_year << 9 \| tm.tm_mon << 5 \| tm.tm_mday);
7decd1cb OH	274	if (time_cs)
	275	time_cs = (ts->tv_sec & 1) 100 + ts->tv_nsec / 10000000;
	276	}
	277	EXPORT_SYMBOL_GPL(fat_time_unix2fat);
1da177e4	278
6bb885ec FS	279	static inline struct timespec64 fat_timespec64_trunc_2secs(struct timespec64 ts)
	280	{
	281	return (struct timespec64){ ts.tv_sec & ~1ULL, 0 };
	282	}
97acf83d	283
4dcc3f96 CCC	284	/*
	285	* truncate atime to 24 hour granularity (00:00:00 in local timezone)
	286	*/
	287	struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi,
	288	const struct timespec64 *ts)
	289	{
	290	/* to localtime */
	291	time64_t seconds = ts->tv_sec - fat_tz_offset(sbi);
	292	s32 remainder;
	293
	294	div_s64_rem(seconds, SECS_PER_DAY, &remainder);
	295	/* to day boundary, and back to unix time */
	296	seconds = seconds + fat_tz_offset(sbi) - remainder;
	297
	298	return (struct timespec64){ seconds, 0 };
	299	}
	300
4dcc3f96 CCC	301	/*
	302	* truncate mtime to 2 second granularity
	303	*/
	304	struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi,
	305	const struct timespec64 *ts)
	306	{
	307	return fat_timespec64_trunc_2secs(*ts);
	308	}
	309
6bb885ec FS	310	/*
6bb885ec FS	311	* truncate the various times with appropriate granularity:
4dcc3f96	312	* all times in root node are always 0
6bb885ec FS	313	*/
	314	int fat_truncate_time(struct inode inode, struct timespec64 now, int flags)
	315	{
	316	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
	317	struct timespec64 ts;
	318
	319	if (inode->i_ino == MSDOS_ROOT_INO)
	320	return 0;
	321
	322	if (now == NULL) {
	323	now = &ts;
	324	ts = current_time(inode);
	325	}
	326
4dcc3f96	327	if (flags & S_ATIME)
daaf2bf0	328	inode_set_atime_to_ts(inode, fat_truncate_atime(sbi, now));
0f9d1481 CCC	329	/*
	330	* ctime and mtime share the same on-disk field, and should be
	331	* identical in memory. all mtime updates will be applied to ctime,
	332	* but ctime updates are ignored.
	333	*/
6bb885ec	334	if (flags & S_MTIME)
daaf2bf0 JL	335	inode_set_mtime_to_ts(inode,
daaf2bf0 JL	336	inode_set_ctime_to_ts(inode, fat_truncate_mtime(sbi, now)));
6bb885ec FS	337
	338	return 0;
	339	}
	340	EXPORT_SYMBOL_GPL(fat_truncate_time);
	341
913e9928	342	int fat_update_time(struct inode *inode, int flags)
6bb885ec	343	{
ff4136e6	344	int dirty_flags = 0;
6bb885ec FS	345
	346	if (inode->i_ino == MSDOS_ROOT_INO)
	347	return 0;
	348
ff4136e6	349	if (flags & (S_ATIME \| S_CTIME \| S_MTIME)) {
6f4aaee3	350	fat_truncate_time(inode, NULL, flags);
ff4136e6 EB	351	if (inode->i_sb->s_flags & SB_LAZYTIME)
	352	dirty_flags \|= I_DIRTY_TIME;
	353	else
	354	dirty_flags \|= I_DIRTY_SYNC;
	355	}
	356
ff4136e6	357	__mark_inode_dirty(inode, dirty_flags);
6bb885ec FS	358	return 0;
	359	}
	360	EXPORT_SYMBOL_GPL(fat_update_time);
	361
1da177e4 LT	362	int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
1da177e4 LT	363	{
5b00226d	364	int i, err = 0;
1da177e4	365
9cb569d6	366	for (i = 0; i < nr_bhs; i++)
2a222ca9	367	write_dirty_buffer(bhs[i], 0);
9cb569d6	368
1da177e4 LT	369	for (i = 0; i < nr_bhs; i++) {
1da177e4 LT	370	wait_on_buffer(bhs[i]);
0edd55fa	371	if (!err && !buffer_uptodate(bhs[i]))
1da177e4 LT	372	err = -EIO;
	373	}
	374	return err;
	375	}