android_kernel_motorola_sm6225/fs/fat/misc.c
Joe Peterson b271e067c8 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>
2008-07-25 10:53:34 -07:00

213 lines
5.5 KiB
C

/*
* linux/fs/fat/misc.c
*
* Written 1992,1993 by Werner Almesberger
* 22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
* and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/msdos_fs.h>
#include <linux/buffer_head.h>
/*
* fat_fs_panic reports a severe file system problem and sets the file system
* read-only. The file system can be made writable again by remounting it.
*/
void fat_fs_panic(struct super_block *s, const char *fmt, ...)
{
va_list args;
printk(KERN_ERR "FAT: Filesystem panic (dev %s)\n", s->s_id);
printk(KERN_ERR " ");
va_start(args, fmt);
vprintk(fmt, args);
va_end(args);
printk("\n");
if (!(s->s_flags & MS_RDONLY)) {
s->s_flags |= MS_RDONLY;
printk(KERN_ERR " File system has been set read-only\n");
}
}
EXPORT_SYMBOL_GPL(fat_fs_panic);
/* Flushes the number of free clusters on FAT32 */
/* XXX: Need to write one per FSINFO block. Currently only writes 1 */
void fat_clusters_flush(struct super_block *sb)
{
struct msdos_sb_info *sbi = MSDOS_SB(sb);
struct buffer_head *bh;
struct fat_boot_fsinfo *fsinfo;
if (sbi->fat_bits != 32)
return;
bh = sb_bread(sb, sbi->fsinfo_sector);
if (bh == NULL) {
printk(KERN_ERR "FAT: bread failed in fat_clusters_flush\n");
return;
}
fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
/* Sanity check */
if (!IS_FSINFO(fsinfo)) {
printk(KERN_ERR "FAT: Invalid FSINFO signature: "
"0x%08x, 0x%08x (sector = %lu)\n",
le32_to_cpu(fsinfo->signature1),
le32_to_cpu(fsinfo->signature2),
sbi->fsinfo_sector);
} else {
if (sbi->free_clusters != -1)
fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
if (sbi->prev_free != -1)
fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
mark_buffer_dirty(bh);
}
brelse(bh);
}
/*
* fat_chain_add() adds a new cluster to the chain of clusters represented
* by inode.
*/
int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
{
struct super_block *sb = inode->i_sb;
struct msdos_sb_info *sbi = MSDOS_SB(sb);
int ret, new_fclus, last;
/*
* We must locate the last cluster of the file to add this new
* one (new_dclus) to the end of the link list (the FAT).
*/
last = new_fclus = 0;
if (MSDOS_I(inode)->i_start) {
int fclus, dclus;
ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
if (ret < 0)
return ret;
new_fclus = fclus + 1;
last = dclus;
}
/* add new one to the last of the cluster chain */
if (last) {
struct fat_entry fatent;
fatent_init(&fatent);
ret = fat_ent_read(inode, &fatent, last);
if (ret >= 0) {
int wait = inode_needs_sync(inode);
ret = fat_ent_write(inode, &fatent, new_dclus, wait);
fatent_brelse(&fatent);
}
if (ret < 0)
return ret;
// fat_cache_add(inode, new_fclus, new_dclus);
} else {
MSDOS_I(inode)->i_start = new_dclus;
MSDOS_I(inode)->i_logstart = new_dclus;
/*
* Since generic_osync_inode() synchronize later if
* this is not directory, we don't here.
*/
if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
ret = fat_sync_inode(inode);
if (ret)
return ret;
} else
mark_inode_dirty(inode);
}
if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
fat_fs_panic(sb, "clusters badly computed (%d != %lu)",
new_fclus, inode->i_blocks >> (sbi->cluster_bits - 9));
fat_cache_inval_inode(inode);
}
inode->i_blocks += nr_cluster << (sbi->cluster_bits - 9);
return 0;
}
extern struct timezone sys_tz;
/* Linear day numbers of the respective 1sts in non-leap years. */
static int day_n[] = {
/* Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec */
0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0, 0
};
/* Convert a MS-DOS time/date pair to a UNIX date (seconds since 1 1 70). */
int date_dos2unix(unsigned short time, unsigned short date, int tz_utc)
{
int month, year, secs;
/*
* first subtract and mask after that... Otherwise, if
* date == 0, bad things happen
*/
month = ((date >> 5) - 1) & 15;
year = date >> 9;
secs = (time & 31)*2+60*((time >> 5) & 63)+(time >> 11)*3600+86400*
((date & 31)-1+day_n[month]+(year/4)+year*365-((year & 3) == 0 &&
month < 2 ? 1 : 0)+3653);
/* days since 1.1.70 plus 80's leap day */
if (!tz_utc)
secs += sys_tz.tz_minuteswest*60;
return secs;
}
/* Convert linear UNIX date to a MS-DOS time/date pair. */
void fat_date_unix2dos(int unix_date, __le16 *time, __le16 *date, int tz_utc)
{
int day, year, nl_day, month;
if (!tz_utc)
unix_date -= sys_tz.tz_minuteswest*60;
/* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
if (unix_date < 315532800)
unix_date = 315532800;
*time = cpu_to_le16((unix_date % 60)/2+(((unix_date/60) % 60) << 5)+
(((unix_date/3600) % 24) << 11));
day = unix_date/86400-3652;
year = day/365;
if ((year+3)/4+365*year > day)
year--;
day -= (year+3)/4+365*year;
if (day == 59 && !(year & 3)) {
nl_day = day;
month = 2;
} else {
nl_day = (year & 3) || day <= 59 ? day : day-1;
for (month = 0; month < 12; month++) {
if (day_n[month] > nl_day)
break;
}
}
*date = cpu_to_le16(nl_day-day_n[month-1]+1+(month << 5)+(year << 9));
}
EXPORT_SYMBOL_GPL(fat_date_unix2dos);
int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
{
int i, err = 0;
ll_rw_block(SWRITE, nr_bhs, bhs);
for (i = 0; i < nr_bhs; i++) {
wait_on_buffer(bhs[i]);
if (buffer_eopnotsupp(bhs[i])) {
clear_buffer_eopnotsupp(bhs[i]);
err = -EOPNOTSUPP;
} else if (!err && !buffer_uptodate(bhs[i]))
err = -EIO;
}
return err;
}