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authorJoe Peterson <joe@skyrush.com>2008-07-25 04:46:47 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-25 13:53:34 -0400
commitb271e067c896ad4082b15e96077675d08db40625 (patch)
tree1837d1c988226116e277c4f71b7f57aed5a7df05 /fs/fat/inode.c
parente8938a62a85d1f487e02c3b01955b47c9598f6d2 (diff)
fatfs: add UTC timestamp option
Provide a new mount option ("tz=UTC") for DOS (vfat/msdos) filesystems, allowing timestamps to be in coordinated universal time (UTC) rather than local time in applications where doing this is advantageous. In particular, portable devices that use fat/vfat (such as digital cameras) can benefit from using UTC in their internal clocks, thus avoiding daylight saving time errors and general time ambiguity issues. The user of the device does not have to worry about changing the time when moving from place or when daylight saving changes. The new mount option, when set, disables the counter-adjustment that Linux currently makes to FAT timestamp info in anticipation of the normal userspace time zone correction. When used in this new mode, all daylight saving time and time zone handling is done in userspace as is normal for many other filesystems (like ext3). The default mode, which remains unchanged, is still appropriate when mounting volumes written in Windows (because of its use of local time). I originally based this patch on one submitted last year by Paul Collins, but I updated it to work with current source and changed variable/option naming. Ogawa Hirofumi (who maintains these filesystems) and I discussed this patch at length on lkml, and he suggested using the option name in the attached version of the patch. Barry Bouwsma pointed out a good addition to the patch as well. Signed-off-by: Joe Peterson <joe@skyrush.com> Signed-off-by: Paul Collins <paul@ondioline.org> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Barry Bouwsma <free_beer_for_all@yahoo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/fat/inode.c')
-rw-r--r--fs/fat/inode.c27
1 files changed, 20 insertions, 7 deletions
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 60deb5fd1188..23676f9d79ce 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -382,17 +382,20 @@ static int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
382 inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1)) 382 inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
383 & ~((loff_t)sbi->cluster_size - 1)) >> 9; 383 & ~((loff_t)sbi->cluster_size - 1)) >> 9;
384 inode->i_mtime.tv_sec = 384 inode->i_mtime.tv_sec =
385 date_dos2unix(le16_to_cpu(de->time), le16_to_cpu(de->date)); 385 date_dos2unix(le16_to_cpu(de->time), le16_to_cpu(de->date),
386 sbi->options.tz_utc);
386 inode->i_mtime.tv_nsec = 0; 387 inode->i_mtime.tv_nsec = 0;
387 if (sbi->options.isvfat) { 388 if (sbi->options.isvfat) {
388 int secs = de->ctime_cs / 100; 389 int secs = de->ctime_cs / 100;
389 int csecs = de->ctime_cs % 100; 390 int csecs = de->ctime_cs % 100;
390 inode->i_ctime.tv_sec = 391 inode->i_ctime.tv_sec =
391 date_dos2unix(le16_to_cpu(de->ctime), 392 date_dos2unix(le16_to_cpu(de->ctime),
392 le16_to_cpu(de->cdate)) + secs; 393 le16_to_cpu(de->cdate),
394 sbi->options.tz_utc) + secs;
393 inode->i_ctime.tv_nsec = csecs * 10000000; 395 inode->i_ctime.tv_nsec = csecs * 10000000;
394 inode->i_atime.tv_sec = 396 inode->i_atime.tv_sec =
395 date_dos2unix(0, le16_to_cpu(de->adate)); 397 date_dos2unix(0, le16_to_cpu(de->adate),
398 sbi->options.tz_utc);
396 inode->i_atime.tv_nsec = 0; 399 inode->i_atime.tv_nsec = 0;
397 } else 400 } else
398 inode->i_ctime = inode->i_atime = inode->i_mtime; 401 inode->i_ctime = inode->i_atime = inode->i_mtime;
@@ -591,11 +594,14 @@ retry:
591 raw_entry->attr = fat_attr(inode); 594 raw_entry->attr = fat_attr(inode);
592 raw_entry->start = cpu_to_le16(MSDOS_I(inode)->i_logstart); 595 raw_entry->start = cpu_to_le16(MSDOS_I(inode)->i_logstart);
593 raw_entry->starthi = cpu_to_le16(MSDOS_I(inode)->i_logstart >> 16); 596 raw_entry->starthi = cpu_to_le16(MSDOS_I(inode)->i_logstart >> 16);
594 fat_date_unix2dos(inode->i_mtime.tv_sec, &raw_entry->time, &raw_entry->date); 597 fat_date_unix2dos(inode->i_mtime.tv_sec, &raw_entry->time,
598 &raw_entry->date, sbi->options.tz_utc);
595 if (sbi->options.isvfat) { 599 if (sbi->options.isvfat) {
596 __le16 atime; 600 __le16 atime;
597 fat_date_unix2dos(inode->i_ctime.tv_sec,&raw_entry->ctime,&raw_entry->cdate); 601 fat_date_unix2dos(inode->i_ctime.tv_sec, &raw_entry->ctime,
598 fat_date_unix2dos(inode->i_atime.tv_sec,&atime,&raw_entry->adate); 602 &raw_entry->cdate, sbi->options.tz_utc);
603 fat_date_unix2dos(inode->i_atime.tv_sec, &atime,
604 &raw_entry->adate, sbi->options.tz_utc);
599 raw_entry->ctime_cs = (inode->i_ctime.tv_sec & 1) * 100 + 605 raw_entry->ctime_cs = (inode->i_ctime.tv_sec & 1) * 100 +
600 inode->i_ctime.tv_nsec / 10000000; 606 inode->i_ctime.tv_nsec / 10000000;
601 } 607 }
@@ -836,6 +842,8 @@ static int fat_show_options(struct seq_file *m, struct vfsmount *mnt)
836 } 842 }
837 if (sbi->options.flush) 843 if (sbi->options.flush)
838 seq_puts(m, ",flush"); 844 seq_puts(m, ",flush");
845 if (opts->tz_utc)
846 seq_puts(m, ",tz=UTC");
839 847
840 return 0; 848 return 0;
841} 849}
@@ -848,7 +856,7 @@ enum {
848 Opt_charset, Opt_shortname_lower, Opt_shortname_win95, 856 Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
849 Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes, 857 Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
850 Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes, 858 Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
851 Opt_obsolate, Opt_flush, Opt_err, 859 Opt_obsolate, Opt_flush, Opt_tz_utc, Opt_err,
852}; 860};
853 861
854static match_table_t fat_tokens = { 862static match_table_t fat_tokens = {
@@ -883,6 +891,7 @@ static match_table_t fat_tokens = {
883 {Opt_obsolate, "cvf_options=%100s"}, 891 {Opt_obsolate, "cvf_options=%100s"},
884 {Opt_obsolate, "posix"}, 892 {Opt_obsolate, "posix"},
885 {Opt_flush, "flush"}, 893 {Opt_flush, "flush"},
894 {Opt_tz_utc, "tz=UTC"},
886 {Opt_err, NULL}, 895 {Opt_err, NULL},
887}; 896};
888static match_table_t msdos_tokens = { 897static match_table_t msdos_tokens = {
@@ -947,6 +956,7 @@ static int parse_options(char *options, int is_vfat, int silent, int *debug,
947 opts->utf8 = opts->unicode_xlate = 0; 956 opts->utf8 = opts->unicode_xlate = 0;
948 opts->numtail = 1; 957 opts->numtail = 1;
949 opts->usefree = opts->nocase = 0; 958 opts->usefree = opts->nocase = 0;
959 opts->tz_utc = 0;
950 *debug = 0; 960 *debug = 0;
951 961
952 if (!options) 962 if (!options)
@@ -1036,6 +1046,9 @@ static int parse_options(char *options, int is_vfat, int silent, int *debug,
1036 case Opt_flush: 1046 case Opt_flush:
1037 opts->flush = 1; 1047 opts->flush = 1;
1038 break; 1048 break;
1049 case Opt_tz_utc:
1050 opts->tz_utc = 1;
1051 break;
1039 1052
1040 /* msdos specific */ 1053 /* msdos specific */
1041 case Opt_dots: 1054 case Opt_dots: