/* * 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/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. */ static char panic_msg[512]; void fat_fs_panic(struct super_block *s, const char *fmt, ...) { int not_ro; va_list args; va_start (args, fmt); vsnprintf (panic_msg, sizeof(panic_msg), fmt, args); va_end (args); not_ro = !(s->s_flags & MS_RDONLY); if (not_ro) s->s_flags |= MS_RDONLY; printk(KERN_ERR "FAT: Filesystem panic (dev %s)\n" " %s\n", s->s_id, panic_msg); if (not_ro) printk(KERN_ERR " File system has been set read-only\n"); } void lock_fat(struct super_block *sb) { down(&(MSDOS_SB(sb)->fat_lock)); } void unlock_fat(struct super_block *sb) { up(&(MSDOS_SB(sb)->fat_lock)); } /* 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: Did not find valid FSINFO signature.\n" " Found signature1 0x%08x signature2 0x%08x" " (sector = %lu)\n", CF_LE_L(fsinfo->signature1), CF_LE_L(fsinfo->signature2), sbi->fsinfo_sector); } else { if (sbi->free_clusters != -1) fsinfo->free_clusters = CF_LE_L(sbi->free_clusters); if (sbi->prev_free) fsinfo->next_cluster = CF_LE_L(sbi->prev_free); mark_buffer_dirty(bh); } brelse(bh); } /* * fat_add_cluster tries to allocate a new cluster and adds it to the * file represented by inode. */ int fat_add_cluster(struct inode *inode) { struct super_block *sb = inode->i_sb; int count, nr, limit, last, curr, file_cluster; int cluster_bits = MSDOS_SB(sb)->cluster_bits; /* * We must locate the last cluster of the file to add this new * one (nr) to the end of the link list (the FAT). * * In order to confirm that the cluster chain is valid, we * find out EOF first. */ nr = -EIO; last = file_cluster = 0; if ((curr = MSDOS_I(inode)->i_start) != 0) { int max_cluster = MSDOS_I(inode)->mmu_private >> cluster_bits; fat_cache_lookup(inode, INT_MAX, &last, &curr); file_cluster = last; while (curr && curr != FAT_ENT_EOF) { file_cluster++; curr = fat_access(sb, last = curr, -1); if (curr < 0) return curr; else if (curr == FAT_ENT_FREE) { fat_fs_panic(sb, "%s: invalid cluster chain" " (ino %lu)", __FUNCTION__, inode->i_ino); goto out; } if (file_cluster > max_cluster) { fat_fs_panic(sb, "%s: bad cluster counts" " (ino %lu)", __FUNCTION__, inode->i_ino); goto out; } } } /* find free FAT entry */ lock_fat(sb); if (MSDOS_SB(sb)->free_clusters == 0) { unlock_fat(sb); return -ENOSPC; } limit = MSDOS_SB(sb)->clusters + 2; nr = MSDOS_SB(sb)->prev_free + 1; for (count = 0; count < MSDOS_SB(sb)->clusters; count++, nr++) { nr = nr % limit; if (nr < 2) nr = 2; if (fat_access(sb, nr, -1) == FAT_ENT_FREE) break; } if (count >= MSDOS_SB(sb)->clusters) { MSDOS_SB(sb)->free_clusters = 0; unlock_fat(sb); return -ENOSPC; } MSDOS_SB(sb)->prev_free = nr; fat_access(sb, nr, FAT_ENT_EOF); if (MSDOS_SB(sb)->free_clusters != -1) MSDOS_SB(sb)->free_clusters--; fat_clusters_flush(sb); unlock_fat(sb); /* add new one to the last of the cluster chain */ if (last) { fat_access(sb, last, nr); fat_cache_add(inode, file_cluster, nr); } else { MSDOS_I(inode)->i_start = nr; MSDOS_I(inode)->i_logstart = nr; mark_inode_dirty(inode); } if (file_cluster != (inode->i_blocks >> (cluster_bits - 9))) { printk (KERN_ERR "file_cluster badly computed!!! %d <> %ld\n", file_cluster, inode->i_blocks >> (cluster_bits - 9)); fat_cache_inval_inode(inode); } inode->i_blocks += (1 << cluster_bits) >> 9; out: return nr; } struct buffer_head *fat_extend_dir(struct inode *inode) { struct super_block *sb = inode->i_sb; struct buffer_head *bh, *res = NULL; int nr, cluster_size = MSDOS_SB(sb)->cluster_size; sector_t sector, last_sector; if (MSDOS_SB(sb)->fat_bits != 32) { if (inode->i_ino == MSDOS_ROOT_INO) return ERR_PTR(-ENOSPC); } nr = fat_add_cluster(inode); if (nr < 0) return ERR_PTR(nr); sector = ((sector_t)nr - 2) * cluster_size + MSDOS_SB(sb)->data_start; last_sector = sector + cluster_size; for ( ; sector < last_sector; sector++) { if ((bh = sb_getblk(sb, sector))) { memset(bh->b_data, 0, sb->s_blocksize); set_buffer_uptodate(bh); mark_buffer_dirty(bh); if (!res) res = bh; else brelse(bh); } } if (res == NULL) res = ERR_PTR(-EIO); if (inode->i_size & (sb->s_blocksize - 1)) { fat_fs_panic(sb, "Odd directory size"); inode->i_size = (inode->i_size + sb->s_blocksize) & ~(sb->s_blocksize - 1); } inode->i_size += 1 << MSDOS_SB(sb)->cluster_bits; MSDOS_I(inode)->mmu_private += 1 << MSDOS_SB(sb)->cluster_bits; return res; } /* Linear day numbers of the respective 1sts in non-leap years. */ static int day_n[] = { 0,31,59,90,120,151,181,212,243,273,304,334,0,0,0,0 }; /* JanFebMarApr May Jun Jul Aug Sep Oct Nov Dec */ extern struct timezone sys_tz; /* 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 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 */ 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,unsigned short *time, unsigned short *date) { int day,year,nl_day,month; 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 = (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 = nl_day-day_n[month-1]+1+(month << 5)+(year << 9); } /* Returns the inode number of the directory entry at offset pos. If bh is non-NULL, it is brelse'd before. Pos is incremented. The buffer header is returned in bh. AV. Most often we do it item-by-item. Makes sense to optimize. AV. OK, there we go: if both bh and de are non-NULL we assume that we just AV. want the next entry (took one explicit de=NULL in vfat/namei.c). AV. It's done in fat_get_entry() (inlined), here the slow case lives. AV. Additionally, when we return -1 (i.e. reached the end of directory) AV. we make bh NULL. */ int fat__get_entry(struct inode *dir, loff_t *pos,struct buffer_head **bh, struct msdos_dir_entry **de, loff_t *i_pos) { struct super_block *sb = dir->i_sb; struct msdos_sb_info *sbi = MSDOS_SB(sb); sector_t phys, iblock; loff_t offset; int err; next: offset = *pos; if (*bh) brelse(*bh); *bh = NULL; iblock = *pos >> sb->s_blocksize_bits; err = fat_bmap(dir, iblock, &phys); if (err || !phys) return -1; /* beyond EOF or error */ *bh = sb_bread(sb, phys); if (*bh == NULL) { printk(KERN_ERR "FAT: Directory bread(block %llu) failed\n", (unsigned long long)phys); /* skip this block */ *pos = (iblock + 1) << sb->s_blocksize_bits; goto next; } offset &= sb->s_blocksize - 1; *pos += sizeof(struct msdos_dir_entry); *de = (struct msdos_dir_entry *)((*bh)->b_data + offset); *i_pos = ((loff_t)phys << sbi->dir_per_block_bits) + (offset >> MSDOS_DIR_BITS); return 0; } static int fat_get_short_entry(struct inode *dir, loff_t *pos, struct buffer_head **bh, struct msdos_dir_entry **de, loff_t *i_pos) { struct super_block *sb = dir->i_sb; while (fat_get_entry(dir, pos, bh, de, i_pos) >= 0) { if (*pos >= FAT_MAX_DIR_SIZE) { fat_fs_panic(sb, "Directory %llu: " "exceeded the maximum size of directory", MSDOS_I(dir)->i_pos); return -EIO; } /* free entry or long name entry or volume label */ if (!IS_FREE((*de)->name) && !((*de)->attr & ATTR_VOLUME)) return 0; } return -ENOENT; } /* * fat_subdirs counts the number of sub-directories of dir. It can be run * on directories being created. */ int fat_subdirs(struct inode *dir) { struct buffer_head *bh; struct msdos_dir_entry *de; loff_t cpos, i_pos; int count = 0; bh = NULL; cpos = 0; while (fat_get_short_entry(dir, &cpos, &bh, &de, &i_pos) >= 0) { if (de->attr & ATTR_DIR) count++; } brelse(bh); return count; } /* * Scans a directory for a given file (name points to its formatted name). * Returns an error code or zero. */ int fat_scan(struct inode *dir, const char *name, struct buffer_head **bh, struct msdos_dir_entry **de, loff_t *i_pos) { loff_t cpos; *bh = NULL; cpos = 0; while (fat_get_short_entry(dir, &cpos, bh, de, i_pos) >= 0) { if (!strncmp((*de)->name, name, MSDOS_NAME)) return 0; } return -ENOENT; }