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 /* Export fat_time_fat2unix() for the fat_test KUnit tests. */ 234 EXPORT_SYMBOL_GPL(fat_time_fat2unix); 235 236 /* Convert linear UNIX date to a FAT time/date pair. */ 237 void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts, 238 __le16 *time, __le16 *date, u8 *time_cs) 239 { 240 struct tm tm; 241 time64_to_tm(ts->tv_sec, -fat_tz_offset(sbi), &tm); 242 243 /* FAT can only support year between 1980 to 2107 */ 244 if (tm.tm_year < 1980 - 1900) { 245 *time = 0; 246 *date = cpu_to_le16((0 << 9) | (1 << 5) | 1); 247 if (time_cs) 248 *time_cs = 0; 249 return; 250 } 251 if (tm.tm_year > 2107 - 1900) { 252 *time = cpu_to_le16((23 << 11) | (59 << 5) | 29); 253 *date = cpu_to_le16((127 << 9) | (12 << 5) | 31); 254 if (time_cs) 255 *time_cs = 199; 256 return; 257 } 258 259 /* from 1900 -> from 1980 */ 260 tm.tm_year -= 80; 261 /* 0~11 -> 1~12 */ 262 tm.tm_mon++; 263 /* 0~59 -> 0~29(2sec counts) */ 264 tm.tm_sec >>= 1; 265 266 *time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec); 267 *date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday); 268 if (time_cs) 269 *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000; 270 } 271 EXPORT_SYMBOL_GPL(fat_time_unix2fat); 272 273 static inline struct timespec64 fat_timespec64_trunc_2secs(struct timespec64 ts) 274 { 275 return (struct timespec64){ ts.tv_sec & ~1ULL, 0 }; 276 } 277 278 static inline struct timespec64 fat_timespec64_trunc_10ms(struct timespec64 ts) 279 { 280 if (ts.tv_nsec) 281 ts.tv_nsec -= ts.tv_nsec % 10000000UL; 282 return ts; 283 } 284 285 /* 286 * truncate the various times with appropriate granularity: 287 * root inode: 288 * all times always 0 289 * all other inodes: 290 * mtime - 2 seconds 291 * ctime 292 * msdos - 2 seconds 293 * vfat - 10 milliseconds 294 * atime - 24 hours (00:00:00 in local timezone) 295 */ 296 int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags) 297 { 298 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 299 struct timespec64 ts; 300 301 if (inode->i_ino == MSDOS_ROOT_INO) 302 return 0; 303 304 if (now == NULL) { 305 now = &ts; 306 ts = current_time(inode); 307 } 308 309 if (flags & S_ATIME) { 310 /* to localtime */ 311 time64_t seconds = now->tv_sec - fat_tz_offset(sbi); 312 s32 remainder; 313 314 div_s64_rem(seconds, SECS_PER_DAY, &remainder); 315 /* to day boundary, and back to unix time */ 316 seconds = seconds + fat_tz_offset(sbi) - remainder; 317 318 inode->i_atime = (struct timespec64){ seconds, 0 }; 319 } 320 if (flags & S_CTIME) { 321 if (sbi->options.isvfat) 322 inode->i_ctime = fat_timespec64_trunc_10ms(*now); 323 else 324 inode->i_ctime = fat_timespec64_trunc_2secs(*now); 325 } 326 if (flags & S_MTIME) 327 inode->i_mtime = fat_timespec64_trunc_2secs(*now); 328 329 return 0; 330 } 331 EXPORT_SYMBOL_GPL(fat_truncate_time); 332 333 int fat_update_time(struct inode *inode, struct timespec64 *now, int flags) 334 { 335 int dirty_flags = 0; 336 337 if (inode->i_ino == MSDOS_ROOT_INO) 338 return 0; 339 340 if (flags & (S_ATIME | S_CTIME | S_MTIME)) { 341 fat_truncate_time(inode, now, flags); 342 if (inode->i_sb->s_flags & SB_LAZYTIME) 343 dirty_flags |= I_DIRTY_TIME; 344 else 345 dirty_flags |= I_DIRTY_SYNC; 346 } 347 348 if ((flags & S_VERSION) && inode_maybe_inc_iversion(inode, false)) 349 dirty_flags |= I_DIRTY_SYNC; 350 351 __mark_inode_dirty(inode, dirty_flags); 352 return 0; 353 } 354 EXPORT_SYMBOL_GPL(fat_update_time); 355 356 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs) 357 { 358 int i, err = 0; 359 360 for (i = 0; i < nr_bhs; i++) 361 write_dirty_buffer(bhs[i], 0); 362 363 for (i = 0; i < nr_bhs; i++) { 364 wait_on_buffer(bhs[i]); 365 if (!err && !buffer_uptodate(bhs[i])) 366 err = -EIO; 367 } 368 return err; 369 } 370