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