fs/fat/misc.c

   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  */
  21 void __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 }
  42 EXPORT_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  */
  48 void 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 */
  62 int 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  */
 101 int 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. */
 185 static 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
 190 static 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). */
 198 void 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. */
 234 void 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 }
 268 EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 269
 270 static inline struct timespec64 fat_timespec64_trunc_2secs(struct timespec64 ts)
 271 {
 272         return (struct timespec64){ ts.tv_sec & ~1ULL, 0 };
 273 }
 274 /*
 275  * truncate the various times with appropriate granularity:
 276  *   root inode:
 277  *     all times always 0
 278  *   all other inodes:
 279  *     mtime - 2 seconds
 280  *     ctime
 281  *       msdos - 2 seconds
 282  *       vfat  - 10 milliseconds
 283  *     atime - 24 hours (00:00:00 in local timezone)
 284  */
 285 int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
 286 {
 287         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 288         struct timespec64 ts;
 289
 290         if (inode->i_ino == MSDOS_ROOT_INO)
 291                 return 0;
 292
 293         if (now == NULL) {
 294                 now = &ts;
 295                 ts = current_time(inode);
 296         }
 297
 298         if (flags & S_ATIME) {
 299                 /* to localtime */
 300                 time64_t seconds = now->tv_sec - fat_tz_offset(sbi);
 301                 s32 remainder;
 302
 303                 div_s64_rem(seconds, SECS_PER_DAY, &remainder);
 304                 /* to day boundary, and back to unix time */
 305                 seconds = seconds + fat_tz_offset(sbi) - remainder;
 306
 307                 inode->i_atime = (struct timespec64){ seconds, 0 };
 308         }
 309         if (flags & S_CTIME) {
 310                 if (sbi->options.isvfat)
 311                         inode->i_ctime = timespec64_trunc(*now, 10000000);
 312                 else
 313                         inode->i_ctime = fat_timespec64_trunc_2secs(*now);
 314         }
 315         if (flags & S_MTIME)
 316                 inode->i_mtime = fat_timespec64_trunc_2secs(*now);
 317
 318         return 0;
 319 }
 320 EXPORT_SYMBOL_GPL(fat_truncate_time);
 321
 322 int fat_update_time(struct inode *inode, struct timespec64 *now, int flags)
 323 {
 324         int iflags = I_DIRTY_TIME;
 325         bool dirty = false;
 326
 327         if (inode->i_ino == MSDOS_ROOT_INO)
 328                 return 0;
 329
 330         fat_truncate_time(inode, now, flags);
 331         if (flags & S_VERSION)
 332                 dirty = inode_maybe_inc_iversion(inode, false);
 333         if ((flags & (S_ATIME | S_CTIME | S_MTIME)) &&
 334             !(inode->i_sb->s_flags & SB_LAZYTIME))
 335                 dirty = true;
 336
 337         if (dirty)
 338                 iflags |= I_DIRTY_SYNC;
 339         __mark_inode_dirty(inode, iflags);
 340         return 0;
 341 }
 342 EXPORT_SYMBOL_GPL(fat_update_time);
 343
 344 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 345 {
 346         int i, err = 0;
 347
 348         for (i = 0; i < nr_bhs; i++)
 349                 write_dirty_buffer(bhs[i], 0);
 350
 351         for (i = 0; i < nr_bhs; i++) {
 352                 wait_on_buffer(bhs[i]);
 353                 if (!err && !buffer_uptodate(bhs[i]))
 354                         err = -EIO;
 355         }
 356         return err;
 357 }