misc.c

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/*
 *  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([email protected])
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include <linux/time.h>
#include "fat.h"

/*
 * fat_fs_error reports a file system problem that might indicate fa data
 * corruption/inconsistency. Depending on 'errors' mount option the
 * panic() is called, or error message is printed FAT and nothing is done,
 * or filesystem is remounted read-only (default behavior).
 * In case the file system is remounted read-only, it can be made writable
 * again by remounting it.
 */
void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...)
{
    struct fat_mount_options *opts = &MSDOS_SB(sb)->options;
    va_list args;
    struct va_format vaf;

    if (report) {
        va_start(args, fmt);
        vaf.fmt = fmt;
        vaf.va = &args;
        printk(KERN_ERR "FAT-fs (%s): error, %pV\n", sb->s_id, &vaf);
        va_end(args);
    }

    if (opts->errors == FAT_ERRORS_PANIC)
        panic("FAT-fs (%s): fs panic from previous error\n", sb->s_id);
    else if (opts->errors == FAT_ERRORS_RO && !(sb->s_flags & MS_RDONLY)) {
        sb->s_flags |= MS_RDONLY;
        printk(KERN_ERR "FAT-fs (%s): Filesystem has been "
                "set read-only\n", sb->s_id);
    }
}
EXPORT_SYMBOL_GPL(__fat_fs_error);

void fat_msg(struct super_block *sb, const char *level, const char *fmt, ...)
{
    struct va_format vaf;
    va_list args;

    va_start(args, fmt);
    vaf.fmt = fmt;
    vaf.va = &args;
    printk("%sFAT-fs (%s): %pV\n", level, sb->s_id, &vaf);
    va_end(args);
}

/* Flushes the number of free clusters on FAT32 */
/* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
int 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 0;

    bh = sb_bread(sb, sbi->fsinfo_sector);
    if (bh == NULL) {
        fat_msg(sb, KERN_ERR, "bread failed in fat_clusters_flush");
        return -EIO;
    }

    fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
    /* Sanity check */
    if (!IS_FSINFO(fsinfo)) {
        fat_msg(sb, KERN_ERR, "Invalid FSINFO signature: "
               "0x%08x, 0x%08x (sector = %lu)",
               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);

    return 0;
}

/*
 * 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_write_sync() synchronizes regular files later,
         * we sync here only directories.
         */
        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_error(sb, "clusters badly computed (%d != %llu)",
                 new_fclus,
                 (llu)(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;

/*
 * The epoch of FAT timestamp is 1980.
 *     :  bits :     value
 * date:  0 -  4: day   (1 -  31)
 * date:  5 -  8: month (1 -  12)
 * date:  9 - 15: year  (0 - 127) from 1980
 * time:  0 -  4: sec   (0 -  29) 2sec counts
 * time:  5 - 10: min   (0 -  59)
 * time: 11 - 15: hour  (0 -  23)
 */
#define SECS_PER_MIN    60
#define SECS_PER_HOUR   (60 * 60)
#define SECS_PER_DAY    (SECS_PER_HOUR * 24)
/* days between 1.1.70 and 1.1.80 (2 leap days) */
#define DAYS_DELTA  (365 * 10 + 2)
/* 120 (2100 - 1980) isn't leap year */
#define YEAR_2100   120
#define IS_LEAP_YEAR(y) (!((y) & 3) && (y) != YEAR_2100)

/* Linear day numbers of the respective 1sts in non-leap years. */
static time_t days_in_year[] = {
    /* Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec */
    0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
};

/* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,
               __le16 __time, __le16 __date, u8 time_cs)
{
    u16 time = le16_to_cpu(__time), date = le16_to_cpu(__date);
    time_t second, day, leap_day, month, year;

    year  = date >> 9;
    month = max(1, (date >> 5) & 0xf);
    day   = max(1, date & 0x1f) - 1;

    leap_day = (year + 3) / 4;
    if (year > YEAR_2100)       /* 2100 isn't leap year */
        leap_day--;
    if (IS_LEAP_YEAR(year) && month > 2)
        leap_day++;

    second =  (time & 0x1f) << 1;
    second += ((time >> 5) & 0x3f) * SECS_PER_MIN;
    second += (time >> 11) * SECS_PER_HOUR;
    second += (year * 365 + leap_day
           + days_in_year[month] + day
           + DAYS_DELTA) * SECS_PER_DAY;

    if (!sbi->options.tz_utc)
        second += sys_tz.tz_minuteswest * SECS_PER_MIN;

    if (time_cs) {
        ts->tv_sec = second + (time_cs / 100);
        ts->tv_nsec = (time_cs % 100) * 10000000;
    } else {
        ts->tv_sec = second;
        ts->tv_nsec = 0;
    }
}

/* Convert linear UNIX date to a FAT time/date pair. */
void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec *ts,
               __le16 *time, __le16 *date, u8 *time_cs)
{
    struct tm tm;
    time_to_tm(ts->tv_sec, sbi->options.tz_utc ? 0 :
           -sys_tz.tz_minuteswest * 60, &tm);

    /*  FAT can only support year between 1980 to 2107 */
    if (tm.tm_year < 1980 - 1900) {
        *time = 0;
        *date = cpu_to_le16((0 << 9) | (1 << 5) | 1);
        if (time_cs)
            *time_cs = 0;
        return;
    }
    if (tm.tm_year > 2107 - 1900) {
        *time = cpu_to_le16((23 << 11) | (59 << 5) | 29);
        *date = cpu_to_le16((127 << 9) | (12 << 5) | 31);
        if (time_cs)
            *time_cs = 199;
        return;
    }

    /* from 1900 -> from 1980 */
    tm.tm_year -= 80;
    /* 0~11 -> 1~12 */
    tm.tm_mon++;
    /* 0~59 -> 0~29(2sec counts) */
    tm.tm_sec >>= 1;

    *time = cpu_to_le16(tm.tm_hour << 11 | tm.tm_min << 5 | tm.tm_sec);
    *date = cpu_to_le16(tm.tm_year << 9 | tm.tm_mon << 5 | tm.tm_mday);
    if (time_cs)
        *time_cs = (ts->tv_sec & 1) * 100 + ts->tv_nsec / 10000000;
}
EXPORT_SYMBOL_GPL(fat_time_unix2fat);

int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
{
    int i, err = 0;

    for (i = 0; i < nr_bhs; i++)
        write_dirty_buffer(bhs[i], WRITE);

    for (i = 0; i < nr_bhs; i++) {
        wait_on_buffer(bhs[i]);
        if (!err && !buffer_uptodate(bhs[i]))
            err = -EIO;
    }
    return err;
}