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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * linux/fs/fat/misc.c4 *5 * Written 1992,1993 by Werner Almesberger6 * 22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/19807 * and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)8 */9 10#include "fat.h"11#include <linux/iversion.h>12 13/*14 * fat_fs_error reports a file system problem that might indicate fa data15 * corruption/inconsistency. Depending on 'errors' mount option the16 * 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 writable19 * again by remounting it.20 */21void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...)22{23 struct fat_mount_options *opts = &MSDOS_SB(sb)->options;24 va_list args;25 struct va_format vaf;26 27 if (report) {28 va_start(args, fmt);29 vaf.fmt = fmt;30 vaf.va = &args;31 fat_msg(sb, KERN_ERR, "error, %pV", &vaf);32 va_end(args);33 }34 35 if (opts->errors == FAT_ERRORS_PANIC)36 panic("FAT-fs (%s): fs panic from previous error\n", sb->s_id);37 else if (opts->errors == FAT_ERRORS_RO && !sb_rdonly(sb)) {38 sb->s_flags |= SB_RDONLY;39 fat_msg(sb, KERN_ERR, "Filesystem has been set read-only");40 }41}42EXPORT_SYMBOL_GPL(__fat_fs_error);43 44/**45 * _fat_msg() - Print a preformatted FAT message based on a superblock.46 * @sb: A pointer to a &struct super_block47 * @level: A Kernel printk level constant48 * @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.53 */54void _fat_msg(struct super_block *sb, const char *level, const char *fmt, ...)55{56 struct va_format vaf;57 va_list args;58 59 va_start(args, fmt);60 vaf.fmt = fmt;61 vaf.va = &args;62 _printk(FAT_PRINTK_PREFIX "%pV\n", level, sb->s_id, &vaf);63 va_end(args);64}65 66/* Flushes the number of free clusters on FAT32 */67/* XXX: Need to write one per FSINFO block. Currently only writes 1 */68int fat_clusters_flush(struct super_block *sb)69{70 struct msdos_sb_info *sbi = MSDOS_SB(sb);71 struct buffer_head *bh;72 struct fat_boot_fsinfo *fsinfo;73 74 if (!is_fat32(sbi))75 return 0;76 77 bh = sb_bread(sb, sbi->fsinfo_sector);78 if (bh == NULL) {79 fat_msg(sb, KERN_ERR, "bread failed in fat_clusters_flush");80 return -EIO;81 }82 83 fsinfo = (struct fat_boot_fsinfo *)bh->b_data;84 /* Sanity check */85 if (!IS_FSINFO(fsinfo)) {86 fat_msg(sb, KERN_ERR, "Invalid FSINFO signature: "87 "0x%08x, 0x%08x (sector = %lu)",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);97 }98 brelse(bh);99 100 return 0;101}102 103/*104 * fat_chain_add() adds a new cluster to the chain of clusters represented105 * by inode.106 */107int 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 new115 * 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;141 /*142 * FIXME:Although we can add this cache, fat_cache_add() is143 * assuming to be called after linear search with fat_cache_id.144 */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 /*150 * Since generic_write_sync() synchronizes regular files later,151 * we sync here only directories.152 */153 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {154 ret = fat_sync_inode(inode);155 if (ret)156 return ret;157 } else158 mark_inode_dirty(inode);159 }160 if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {161 fat_fs_error(sb, "clusters badly computed (%d != %llu)",162 new_fclus,163 (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));164 fat_cache_inval_inode(inode);165 }166 inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);167 168 return 0;169}170 171/*172 * The epoch of FAT timestamp is 1980.173 * : bits : value174 * date: 0 - 4: day (1 - 31)175 * date: 5 - 8: month (1 - 12)176 * date: 9 - 15: year (0 - 127) from 1980177 * time: 0 - 4: sec (0 - 29) 2sec counts178 * time: 5 - 10: min (0 - 59)179 * time: 11 - 15: hour (0 - 23)180 */181#define SECS_PER_MIN 60182#define SECS_PER_HOUR (60 * 60)183#define SECS_PER_DAY (SECS_PER_HOUR * 24)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 120188#define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100)189 190/* Linear day numbers of the respective 1sts in non-leap years. */191static long days_in_year[] = {192 /* Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec */193 0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,194};195 196static inline int fat_tz_offset(const struct msdos_sb_info *sbi)197{198 return (sbi->options.tz_set ?199 -sbi->options.time_offset :200 sys_tz.tz_minuteswest) * SECS_PER_MIN;201}202 203/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */204void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,205 __le16 __time, __le16 __date, u8 time_cs)206{207 u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);208 time64_t second;209 long day, leap_day, month, year;210 211 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;224 second += (time64_t)(year * 365 + leap_day225 + days_in_year[month] + day226 + DAYS_DELTA) * SECS_PER_DAY;227 228 second += fat_tz_offset(sbi);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 }237}238 239/* Export fat_time_fat2unix() for the fat_test KUnit tests. */240EXPORT_SYMBOL_GPL(fat_time_fat2unix);241 242/* Convert linear UNIX date to a FAT time/date pair. */243void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,244 __le16 *time, __le16 *date, u8 *time_cs)245{246 struct tm tm;247 time64_to_tm(ts->tv_sec, -fat_tz_offset(sbi), &tm);248 249 /* FAT can only support year between 1980 to 2107 */250 if (tm.tm_year < 1980 - 1900) {251 *time = 0;252 *date = cpu_to_le16((0 << 9) | (1 << 5) | 1);253 if (time_cs)254 *time_cs = 0;255 return;256 }257 if (tm.tm_year > 2107 - 1900) {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 }264 265 /* 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;271 272 *time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec);273 *date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday);274 if (time_cs)275 *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;276}277EXPORT_SYMBOL_GPL(fat_time_unix2fat);278 279static inline struct timespec64 fat_timespec64_trunc_2secs(struct timespec64 ts)280{281 return (struct timespec64){ ts.tv_sec & ~1ULL, 0 };282}283 284/*285 * truncate atime to 24 hour granularity (00:00:00 in local timezone)286 */287struct 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}300 301/*302 * truncate mtime to 2 second granularity303 */304struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi,305 const struct timespec64 *ts)306{307 return fat_timespec64_trunc_2secs(*ts);308}309 310/*311 * truncate the various times with appropriate granularity:312 * all times in root node are always 0313 */314int 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 }326 327 if (flags & S_ATIME)328 inode_set_atime_to_ts(inode, fat_truncate_atime(sbi, now));329 /*330 * ctime and mtime share the same on-disk field, and should be331 * identical in memory. all mtime updates will be applied to ctime,332 * but ctime updates are ignored.333 */334 if (flags & S_MTIME)335 inode_set_mtime_to_ts(inode,336 inode_set_ctime_to_ts(inode, fat_truncate_mtime(sbi, now)));337 338 return 0;339}340EXPORT_SYMBOL_GPL(fat_truncate_time);341 342int fat_update_time(struct inode *inode, int flags)343{344 int dirty_flags = 0;345 346 if (inode->i_ino == MSDOS_ROOT_INO)347 return 0;348 349 if (flags & (S_ATIME | S_CTIME | S_MTIME)) {350 fat_truncate_time(inode, NULL, flags);351 if (inode->i_sb->s_flags & SB_LAZYTIME)352 dirty_flags |= I_DIRTY_TIME;353 else354 dirty_flags |= I_DIRTY_SYNC;355 }356 357 __mark_inode_dirty(inode, dirty_flags);358 return 0;359}360EXPORT_SYMBOL_GPL(fat_update_time);361 362int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)363{364 int i, err = 0;365 366 for (i = 0; i < nr_bhs; i++)367 write_dirty_buffer(bhs[i], 0);368 369 for (i = 0; i < nr_bhs; i++) {370 wait_on_buffer(bhs[i]);371 if (!err && !buffer_uptodate(bhs[i]))372 err = -EIO;373 }374 return err;375}376