// 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(bsg@uniyar.ac.ru) */ #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);			int old = ret; 			ret = fat_ent_write(inode, &fatent, new_dclus, wait);			if (ret < 0)				fat_ent_write(inode, &fatent, old, 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;		mark_inode_dirty(inode);		/*		 * Since generic_write_sync() synchronizes regular files later,		 * we sync here only directories.		 */		if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {			ret = sync_inode_metadata(inode, 1);			if (ret)				return ret;		} 	}	if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {		fat_fs_error_ratelimit(			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 };}/* Export fat_truncate_atime() for the fat_test KUnit tests. */EXPORT_SYMBOL_GPL(fat_truncate_atime); /* * Update the in-inode atime and/or mtime after truncating the timestamp to the * granularity.  All timestamps in root inode are always 0. * * 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. */void fat_truncate_time(struct inode *inode, struct timespec64 *now,		unsigned int flags){	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);	struct timespec64 ts; 	if (inode->i_ino == MSDOS_ROOT_INO)		return; 	if (now == NULL) {		now = &ts;		ts = current_time(inode);	} 	if (flags & FAT_UPDATE_ATIME)		inode_set_atime_to_ts(inode, fat_truncate_atime(sbi, now));	if (flags & FAT_UPDATE_CMTIME) {		/* truncate mtime to 2 second granularity */		struct timespec64 mtime = fat_timespec64_trunc_2secs(*now); 		inode_set_mtime_to_ts(inode, mtime);		inode_set_ctime_to_ts(inode, mtime);	}}EXPORT_SYMBOL_GPL(fat_truncate_time); int fat_update_time(struct inode *inode, enum fs_update_time type,		unsigned int flags){	if (inode->i_ino != MSDOS_ROOT_INO) {		fat_truncate_time(inode, NULL, type == FS_UPD_ATIME ?				FAT_UPDATE_ATIME : FAT_UPDATE_CMTIME);		__mark_inode_dirty(inode, inode_time_dirty_flag(inode));	}	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;}