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(fmt: "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 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 */
54void _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 */
68int 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, block: 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 */
107int 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: &fclus, dclus: &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: &fatent);
133 ret = fat_ent_read(inode, fatent: &fatent, entry: last);
134 if (ret >= 0) {
135 int wait = inode_needs_sync(inode);
136 ret = fat_ent_write(inode, fatent: &fatent, new: new_dclus, wait);
137 fatent_brelse(fatent: &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_ratelimit(
162 sb, "clusters badly computed (%d != %llu)", 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. */
191static 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
196static 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). */
204void 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. */
240EXPORT_SYMBOL_GPL(fat_time_fat2unix);
241
242/* Convert linear UNIX date to a FAT time/date pair. */
243void 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(totalsecs: ts->tv_sec, offset: -fat_tz_offset(sbi), result: &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}
277EXPORT_SYMBOL_GPL(fat_time_unix2fat);
278
279static 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 */
287struct 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(dividend: seconds, SECS_PER_DAY, remainder: &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 */
304struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi,
305 const struct timespec64 *ts)
306{
307 return fat_timespec64_trunc_2secs(ts: *ts);
308}
309
310/*
311 * truncate the various times with appropriate granularity:
312 * all times in root node are always 0
313 */
314int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
315{
316 struct msdos_sb_info *sbi = MSDOS_SB(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, ts: fat_truncate_atime(sbi, ts: 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 ts: inode_set_ctime_to_ts(inode, ts: fat_truncate_mtime(sbi, ts: now)));
337
338 return 0;
339}
340EXPORT_SYMBOL_GPL(fat_truncate_time);
341
342int 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}
360EXPORT_SYMBOL_GPL(fat_update_time);
361
362int 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(bh: bhs[i], op_flags: 0);
368
369 for (i = 0; i < nr_bhs; i++) {
370 wait_on_buffer(bh: bhs[i]);
371 if (!err && !buffer_uptodate(bh: bhs[i]))
372 err = -EIO;
373 }
374 return err;
375}
376