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->i_atime = 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->i_mtime = inode->i_ctime = fat_truncate_mtime(sbi, now); 336 337 return 0; 338 } 339 EXPORT_SYMBOL_GPL(fat_truncate_time); 340 341 int fat_update_time(struct inode *inode, struct timespec64 *now, int flags) 342 { 343 int dirty_flags = 0; 344 345 if (inode->i_ino == MSDOS_ROOT_INO) 346 return 0; 347 348 if (flags & (S_ATIME | S_CTIME | S_MTIME)) { 349 fat_truncate_time(inode, now, flags); 350 if (inode->i_sb->s_flags & SB_LAZYTIME) 351 dirty_flags |= I_DIRTY_TIME; 352 else 353 dirty_flags |= I_DIRTY_SYNC; 354 } 355 356 if ((flags & S_VERSION) && inode_maybe_inc_iversion(inode, false)) 357 dirty_flags |= I_DIRTY_SYNC; 358 359 __mark_inode_dirty(inode, dirty_flags); 360 return 0; 361 } 362 EXPORT_SYMBOL_GPL(fat_update_time); 363 364 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs) 365 { 366 int i, err = 0; 367 368 for (i = 0; i < nr_bhs; i++) 369 write_dirty_buffer(bhs[i], 0); 370 371 for (i = 0; i < nr_bhs; i++) { 372 wait_on_buffer(bhs[i]); 373 if (!err && !buffer_uptodate(bhs[i])) 374 err = -EIO; 375 } 376 return err; 377 } 378