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 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.
  53  */
  54 void _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 */
  68 int 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 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;
 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                  */
 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                 } else
 158                         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 :     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)
 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
 190 /* Linear day numbers of the respective 1sts in non-leap years. */
 191 static 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
 196 static 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). */
 204 void 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_day
 225                    + days_in_year[month] + day
 226                    + 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. */
 240 EXPORT_SYMBOL_GPL(fat_time_fat2unix);
 241
 242 /* Convert linear UNIX date to a FAT time/date pair. */
 243 void 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 }
 277 EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 278
 279 static 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  */
 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
 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
 310 /*
 311  * truncate the various times with appropriate granularity:
 312  *   all times in root node are always 0
 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
 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 be
 331          * 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 }
 340 EXPORT_SYMBOL_GPL(fat_truncate_time);
 341
 342 int 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                 else
 354                         dirty_flags |= I_DIRTY_SYNC;
 355         }
 356
 357         __mark_inode_dirty(inode, dirty_flags);
 358         return 0;
 359 }
 360 EXPORT_SYMBOL_GPL(fat_update_time);
 361
 362 int 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 }