fs/exfat/misc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Written 1992,1993 by Werner Almesberger
   4  *  22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
   5  *               and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)
   6  * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
   7  */
   8
   9 #include <linux/time.h>
  10 #include <linux/fs.h>
  11 #include <linux/slab.h>
  12 #include <linux/buffer_head.h>
  13 #include <linux/blk_types.h>
  14
  15 #include "exfat_raw.h"
  16 #include "exfat_fs.h"
  17
  18 /*
  19  * exfat_fs_error reports a file system problem that might indicate fa data
  20  * corruption/inconsistency. Depending on 'errors' mount option the
  21  * panic() is called, or error message is printed FAT and nothing is done,
  22  * or filesystem is remounted read-only (default behavior).
  23  * In case the file system is remounted read-only, it can be made writable
  24  * again by remounting it.
  25  */
  26 void __exfat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
  27 {
  28         struct exfat_mount_options *opts = &EXFAT_SB(sb)->options;
  29         va_list args;
  30         struct va_format vaf;
  31
  32         if (report) {
  33                 va_start(args, fmt);
  34                 vaf.fmt = fmt;
  35                 vaf.va = &args;
  36                 exfat_err(sb, "error, %pV", &vaf);
  37                 va_end(args);
  38         }
  39
  40         if (opts->errors == EXFAT_ERRORS_PANIC) {
  41                 panic("exFAT-fs (%s): fs panic from previous error\n",
  42                         sb->s_id);
  43         } else if (opts->errors == EXFAT_ERRORS_RO && !sb_rdonly(sb)) {
  44                 sb->s_flags |= SB_RDONLY;
  45                 exfat_err(sb, "Filesystem has been set read-only");
  46         }
  47 }
  48
  49 #define SECS_PER_MIN    (60)
  50 #define TIMEZONE_SEC(x) ((x) * 15 * SECS_PER_MIN)
  51
  52 static void exfat_adjust_tz(struct timespec64 *ts, u8 tz_off)
  53 {
  54         if (tz_off <= 0x3F)
  55                 ts->tv_sec -= TIMEZONE_SEC(tz_off);
  56         else /* 0x40 <= (tz_off & 0x7F) <=0x7F */
  57                 ts->tv_sec += TIMEZONE_SEC(0x80 - tz_off);
  58 }
  59
  60 static inline int exfat_tz_offset(struct exfat_sb_info *sbi)
  61 {
  62         if (sbi->options.sys_tz)
  63                 return -sys_tz.tz_minuteswest;
  64         return sbi->options.time_offset;
  65 }
  66
  67 /* Convert a EXFAT time/date pair to a UNIX date (seconds since 1 1 70). */
  68 void exfat_get_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts,
  69                 u8 tz, __le16 time, __le16 date, u8 time_cs)
  70 {
  71         u16 t = le16_to_cpu(time);
  72         u16 d = le16_to_cpu(date);
  73
  74         ts->tv_sec = mktime64(1980 + (d >> 9), d >> 5 & 0x000F, d & 0x001F,
  75                               t >> 11, (t >> 5) & 0x003F, (t & 0x001F) << 1);
  76
  77
  78         /* time_cs field represent 0 ~ 199cs(1990 ms) */
  79         if (time_cs) {
  80                 ts->tv_sec += time_cs / 100;
  81                 ts->tv_nsec = (time_cs % 100) * 10 * NSEC_PER_MSEC;
  82         } else
  83                 ts->tv_nsec = 0;
  84
  85         if (tz & EXFAT_TZ_VALID)
  86                 /* Adjust timezone to UTC0. */
  87                 exfat_adjust_tz(ts, tz & ~EXFAT_TZ_VALID);
  88         else
  89                 ts->tv_sec -= exfat_tz_offset(sbi) * SECS_PER_MIN;
  90 }
  91
  92 /* Convert linear UNIX date to a EXFAT time/date pair. */
  93 void exfat_set_entry_time(struct exfat_sb_info *sbi, struct timespec64 *ts,
  94                 u8 *tz, __le16 *time, __le16 *date, u8 *time_cs)
  95 {
  96         struct tm tm;
  97         u16 t, d;
  98
  99         time64_to_tm(ts->tv_sec, 0, &tm);
 100         t = (tm.tm_hour << 11) | (tm.tm_min << 5) | (tm.tm_sec >> 1);
 101         d = ((tm.tm_year - 80) <<  9) | ((tm.tm_mon + 1) << 5) | tm.tm_mday;
 102
 103         *time = cpu_to_le16(t);
 104         *date = cpu_to_le16(d);
 105
 106         /* time_cs field represent 0 ~ 199cs(1990 ms) */
 107         if (time_cs)
 108                 *time_cs = (tm.tm_sec & 1) * 100 +
 109                         ts->tv_nsec / (10 * NSEC_PER_MSEC);
 110
 111         /*
 112          * Record 00h value for OffsetFromUtc field and 1 value for OffsetValid
 113          * to indicate that local time and UTC are the same.
 114          */
 115         *tz = EXFAT_TZ_VALID;
 116 }
 117
 118 /*
 119  * The timestamp for access_time has double seconds granularity.
 120  * (There is no 10msIncrement field for access_time unlike create/modify_time)
 121  * atime also has only a 2-second resolution.
 122  */
 123 void exfat_truncate_atime(struct timespec64 *ts)
 124 {
 125         ts->tv_sec = round_down(ts->tv_sec, 2);
 126         ts->tv_nsec = 0;
 127 }
 128
 129 void exfat_truncate_inode_atime(struct inode *inode)
 130 {
 131         struct timespec64 atime = inode_get_atime(inode);
 132
 133         exfat_truncate_atime(&atime);
 134         inode_set_atime_to_ts(inode, atime);
 135 }
 136
 137 u16 exfat_calc_chksum16(void *data, int len, u16 chksum, int type)
 138 {
 139         int i;
 140         u8 *c = (u8 *)data;
 141
 142         for (i = 0; i < len; i++, c++) {
 143                 if (unlikely(type == CS_DIR_ENTRY && (i == 2 || i == 3)))
 144                         continue;
 145                 chksum = ((chksum << 15) | (chksum >> 1)) + *c;
 146         }
 147         return chksum;
 148 }
 149
 150 u32 exfat_calc_chksum32(void *data, int len, u32 chksum, int type)
 151 {
 152         int i;
 153         u8 *c = (u8 *)data;
 154
 155         for (i = 0; i < len; i++, c++) {
 156                 if (unlikely(type == CS_BOOT_SECTOR &&
 157                              (i == 106 || i == 107 || i == 112)))
 158                         continue;
 159                 chksum = ((chksum << 31) | (chksum >> 1)) + *c;
 160         }
 161         return chksum;
 162 }
 163
 164 void exfat_update_bh(struct buffer_head *bh, int sync)
 165 {
 166         set_buffer_uptodate(bh);
 167         mark_buffer_dirty(bh);
 168
 169         if (sync)
 170                 sync_dirty_buffer(bh);
 171 }
 172
 173 int exfat_update_bhs(struct buffer_head **bhs, int nr_bhs, int sync)
 174 {
 175         int i, err = 0;
 176
 177         for (i = 0; i < nr_bhs; i++) {
 178                 set_buffer_uptodate(bhs[i]);
 179                 mark_buffer_dirty(bhs[i]);
 180                 if (sync)
 181                         write_dirty_buffer(bhs[i], REQ_SYNC);
 182         }
 183
 184         for (i = 0; i < nr_bhs && sync; i++) {
 185                 wait_on_buffer(bhs[i]);
 186                 if (!err && !buffer_uptodate(bhs[i]))
 187                         err = -EIO;
 188         }
 189         return err;
 190 }
 191
 192 void exfat_chain_set(struct exfat_chain *ec, unsigned int dir,
 193                 unsigned int size, unsigned char flags)
 194 {
 195         ec->dir = dir;
 196         ec->size = size;
 197         ec->flags = flags;
 198 }
 199
 200 void exfat_chain_dup(struct exfat_chain *dup, struct exfat_chain *ec)
 201 {
 202         return exfat_chain_set(dup, ec->dir, ec->size, ec->flags);
 203 }