linux/fs/fat/misc.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   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(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 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.
  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 preformated FAT specific messages. Every thing what is
  46 * not fat_fs_error() should be fat_msg().
  47 */
  48void fat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
  49{
  50        struct va_format vaf;
  51        va_list args;
  52
  53        va_start(args, fmt);
  54        vaf.fmt = fmt;
  55        vaf.va = &args;
  56        printk("%sFAT-fs (%s): %pV\n", level, sb->s_id, &vaf);
  57        va_end(args);
  58}
  59
  60/* Flushes the number of free clusters on FAT32 */
  61/* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
  62int fat_clusters_flush(struct super_block *sb)
  63{
  64        struct msdos_sb_info *sbi = MSDOS_SB(sb);
  65        struct buffer_head *bh;
  66        struct fat_boot_fsinfo *fsinfo;
  67
  68        if (!is_fat32(sbi))
  69                return 0;
  70
  71        bh = sb_bread(sb, sbi->fsinfo_sector);
  72        if (bh == NULL) {
  73                fat_msg(sb, KERN_ERR, "bread failed in fat_clusters_flush");
  74                return -EIO;
  75        }
  76
  77        fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
  78        /* Sanity check */
  79        if (!IS_FSINFO(fsinfo)) {
  80                fat_msg(sb, KERN_ERR, "Invalid FSINFO signature: "
  81                       "0x%08x, 0x%08x (sector = %lu)",
  82                       le32_to_cpu(fsinfo->signature1),
  83                       le32_to_cpu(fsinfo->signature2),
  84                       sbi->fsinfo_sector);
  85        } else {
  86                if (sbi->free_clusters != -1)
  87                        fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
  88                if (sbi->prev_free != -1)
  89                        fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
  90                mark_buffer_dirty(bh);
  91        }
  92        brelse(bh);
  93
  94        return 0;
  95}
  96
  97/*
  98 * fat_chain_add() adds a new cluster to the chain of clusters represented
  99 * by inode.
 100 */
 101int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
 102{
 103        struct super_block *sb = inode->i_sb;
 104        struct msdos_sb_info *sbi = MSDOS_SB(sb);
 105        int ret, new_fclus, last;
 106
 107        /*
 108         * We must locate the last cluster of the file to add this new
 109         * one (new_dclus) to the end of the link list (the FAT).
 110         */
 111        last = new_fclus = 0;
 112        if (MSDOS_I(inode)->i_start) {
 113                int fclus, dclus;
 114
 115                ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
 116                if (ret < 0)
 117                        return ret;
 118                new_fclus = fclus + 1;
 119                last = dclus;
 120        }
 121
 122        /* add new one to the last of the cluster chain */
 123        if (last) {
 124                struct fat_entry fatent;
 125
 126                fatent_init(&fatent);
 127                ret = fat_ent_read(inode, &fatent, last);
 128                if (ret >= 0) {
 129                        int wait = inode_needs_sync(inode);
 130                        ret = fat_ent_write(inode, &fatent, new_dclus, wait);
 131                        fatent_brelse(&fatent);
 132                }
 133                if (ret < 0)
 134                        return ret;
 135                /*
 136                 * FIXME:Although we can add this cache, fat_cache_add() is
 137                 * assuming to be called after linear search with fat_cache_id.
 138                 */
 139//              fat_cache_add(inode, new_fclus, new_dclus);
 140        } else {
 141                MSDOS_I(inode)->i_start = new_dclus;
 142                MSDOS_I(inode)->i_logstart = new_dclus;
 143                /*
 144                 * Since generic_write_sync() synchronizes regular files later,
 145                 * we sync here only directories.
 146                 */
 147                if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
 148                        ret = fat_sync_inode(inode);
 149                        if (ret)
 150                                return ret;
 151                } else
 152                        mark_inode_dirty(inode);
 153        }
 154        if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
 155                fat_fs_error(sb, "clusters badly computed (%d != %llu)",
 156                             new_fclus,
 157                             (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
 158                fat_cache_inval_inode(inode);
 159        }
 160        inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
 161
 162        return 0;
 163}
 164
 165/*
 166 * The epoch of FAT timestamp is 1980.
 167 *     :  bits :     value
 168 * date:  0 -  4: day   (1 -  31)
 169 * date:  5 -  8: month (1 -  12)
 170 * date:  9 - 15: year  (0 - 127) from 1980
 171 * time:  0 -  4: sec   (0 -  29) 2sec counts
 172 * time:  5 - 10: min   (0 -  59)
 173 * time: 11 - 15: hour  (0 -  23)
 174 */
 175#define SECS_PER_MIN    60
 176#define SECS_PER_HOUR   (60 * 60)
 177#define SECS_PER_DAY    (SECS_PER_HOUR * 24)
 178/* days between 1.1.70 and 1.1.80 (2 leap days) */
 179#define DAYS_DELTA      (365 * 10 + 2)
 180/* 120 (2100 - 1980) isn't leap year */
 181#define YEAR_2100       120
 182#define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100)
 183
 184/* Linear day numbers of the respective 1sts in non-leap years. */
 185static long days_in_year[] = {
 186        /* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
 187        0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
 188};
 189
 190static inline int fat_tz_offset(struct msdos_sb_info *sbi)
 191{
 192        return (sbi->options.tz_set ?
 193               -sbi->options.time_offset :
 194               sys_tz.tz_minuteswest) * SECS_PER_MIN;
 195}
 196
 197/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
 198void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
 199                       __le16 __time, __le16 __date, u8 time_cs)
 200{
 201        u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
 202        time64_t second;
 203        long day, leap_day, month, year;
 204
 205        year  = date >> 9;
 206        month = max(1, (date >> 5) & 0xf);
 207        day   = max(1, date & 0x1f) - 1;
 208
 209        leap_day = (year + 3) / 4;
 210        if (year > YEAR_2100)           /* 2100 isn't leap year */
 211                leap_day--;
 212        if (IS_LEAP_YEAR(year) && month > 2)
 213                leap_day++;
 214
 215        second =  (time & 0x1f) << 1;
 216        second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
 217        second += (time >> 11) * SECS_PER_HOUR;
 218        second += (time64_t)(year * 365 + leap_day
 219                   + days_in_year[month] + day
 220                   + DAYS_DELTA) * SECS_PER_DAY;
 221
 222        second += fat_tz_offset(sbi);
 223
 224        if (time_cs) {
 225                ts->tv_sec = second + (time_cs / 100);
 226                ts->tv_nsec = (time_cs % 100) * 10000000;
 227        } else {
 228                ts->tv_sec = second;
 229                ts->tv_nsec = 0;
 230        }
 231}
 232
 233/* Convert linear UNIX date to a FAT time/date pair. */
 234void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
 235                       __le16 *time, __le16 *date, u8 *time_cs)
 236{
 237        struct tm tm;
 238        time64_to_tm(ts->tv_sec, -fat_tz_offset(sbi), &tm);
 239
 240        /*  FAT can only support year between 1980 to 2107 */
 241        if (tm.tm_year < 1980 - 1900) {
 242                *time = 0;
 243                *date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
 244                if (time_cs)
 245                        *time_cs = 0;
 246                return;
 247        }
 248        if (tm.tm_year > 2107 - 1900) {
 249                *time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
 250                *date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
 251                if (time_cs)
 252                        *time_cs = 199;
 253                return;
 254        }
 255
 256        /* from 1900 -> from 1980 */
 257        tm.tm_year -= 80;
 258        /* 0~11 -> 1~12 */
 259        tm.tm_mon++;
 260        /* 0~59 -> 0~29(2sec counts) */
 261        tm.tm_sec >>= 1;
 262
 263        *time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec);
 264        *date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday);
 265        if (time_cs)
 266                *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
 267}
 268EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 269
 270static inline struct timespec64 fat_timespec64_trunc_2secs(struct timespec64 ts)
 271{
 272        return (struct timespec64){ ts.tv_sec & ~1ULL, 0 };
 273}
 274
 275static inline struct timespec64 fat_timespec64_trunc_10ms(struct timespec64 ts)
 276{
 277        if (ts.tv_nsec)
 278                ts.tv_nsec -= ts.tv_nsec % 10000000UL;
 279        return ts;
 280}
 281
 282/*
 283 * truncate the various times with appropriate granularity:
 284 *   root inode:
 285 *     all times always 0
 286 *   all other inodes:
 287 *     mtime - 2 seconds
 288 *     ctime
 289 *       msdos - 2 seconds
 290 *       vfat  - 10 milliseconds
 291 *     atime - 24 hours (00:00:00 in local timezone)
 292 */
 293int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
 294{
 295        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 296        struct timespec64 ts;
 297
 298        if (inode->i_ino == MSDOS_ROOT_INO)
 299                return 0;
 300
 301        if (now == NULL) {
 302                now = &ts;
 303                ts = current_time(inode);
 304        }
 305
 306        if (flags & S_ATIME) {
 307                /* to localtime */
 308                time64_t seconds = now->tv_sec - fat_tz_offset(sbi);
 309                s32 remainder;
 310
 311                div_s64_rem(seconds, SECS_PER_DAY, &remainder);
 312                /* to day boundary, and back to unix time */
 313                seconds = seconds + fat_tz_offset(sbi) - remainder;
 314
 315                inode->i_atime = (struct timespec64){ seconds, 0 };
 316        }
 317        if (flags & S_CTIME) {
 318                if (sbi->options.isvfat)
 319                        inode->i_ctime = fat_timespec64_trunc_10ms(*now);
 320                else
 321                        inode->i_ctime = fat_timespec64_trunc_2secs(*now);
 322        }
 323        if (flags & S_MTIME)
 324                inode->i_mtime = fat_timespec64_trunc_2secs(*now);
 325
 326        return 0;
 327}
 328EXPORT_SYMBOL_GPL(fat_truncate_time);
 329
 330int fat_update_time(struct inode *inode, struct timespec64 *now, int flags)
 331{
 332        int dirty_flags = 0;
 333
 334        if (inode->i_ino == MSDOS_ROOT_INO)
 335                return 0;
 336
 337        if (flags & (S_ATIME | S_CTIME | S_MTIME)) {
 338                fat_truncate_time(inode, now, flags);
 339                if (inode->i_sb->s_flags & SB_LAZYTIME)
 340                        dirty_flags |= I_DIRTY_TIME;
 341                else
 342                        dirty_flags |= I_DIRTY_SYNC;
 343        }
 344
 345        if ((flags & S_VERSION) && inode_maybe_inc_iversion(inode, false))
 346                dirty_flags |= I_DIRTY_SYNC;
 347
 348        __mark_inode_dirty(inode, dirty_flags);
 349        return 0;
 350}
 351EXPORT_SYMBOL_GPL(fat_update_time);
 352
 353int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 354{
 355        int i, err = 0;
 356
 357        for (i = 0; i < nr_bhs; i++)
 358                write_dirty_buffer(bhs[i], 0);
 359
 360        for (i = 0; i < nr_bhs; i++) {
 361                wait_on_buffer(bhs[i]);
 362                if (!err && !buffer_uptodate(bhs[i]))
 363                        err = -EIO;
 364        }
 365        return err;
 366}
 367
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