4 * Written 1992,1993 by Werner Almesberger
5 * 22/11/2000 - Fixed fat_date_unix2dos for dates earlier than 01/01/1980
6 * and date_dos2unix for date==0 by Igor Zhbanov(bsg@uniyar.ac.ru)
10 #include <linux/msdos_fs.h>
11 #include <linux/buffer_head.h>
14 * fat_fs_panic reports a severe file system problem and sets the file system
15 * read-only. The file system can be made writable again by remounting it.
18 static char panic_msg[512];
20 void fat_fs_panic(struct super_block *s, const char *fmt, ...)
26 vsnprintf (panic_msg, sizeof(panic_msg), fmt, args);
29 not_ro = !(s->s_flags & MS_RDONLY);
31 s->s_flags |= MS_RDONLY;
33 printk(KERN_ERR "FAT: Filesystem panic (dev %s)\n"
34 " %s\n", s->s_id, panic_msg);
36 printk(KERN_ERR " File system has been set read-only\n");
39 void lock_fat(struct super_block *sb)
41 down(&(MSDOS_SB(sb)->fat_lock));
44 void unlock_fat(struct super_block *sb)
46 up(&(MSDOS_SB(sb)->fat_lock));
49 /* Flushes the number of free clusters on FAT32 */
50 /* XXX: Need to write one per FSINFO block. Currently only writes 1 */
51 void fat_clusters_flush(struct super_block *sb)
53 struct msdos_sb_info *sbi = MSDOS_SB(sb);
54 struct buffer_head *bh;
55 struct fat_boot_fsinfo *fsinfo;
57 if (sbi->fat_bits != 32)
60 bh = sb_bread(sb, sbi->fsinfo_sector);
62 printk(KERN_ERR "FAT bread failed in fat_clusters_flush\n");
66 fsinfo = (struct fat_boot_fsinfo *)bh->b_data;
68 if (!IS_FSINFO(fsinfo)) {
69 printk(KERN_ERR "FAT: Did not find valid FSINFO signature.\n"
70 " Found signature1 0x%08x signature2 0x%08x"
72 le32_to_cpu(fsinfo->signature1),
73 le32_to_cpu(fsinfo->signature2),
76 if (sbi->free_clusters != -1)
77 fsinfo->free_clusters = cpu_to_le32(sbi->free_clusters);
78 if (sbi->prev_free != -1)
79 fsinfo->next_cluster = cpu_to_le32(sbi->prev_free);
80 mark_buffer_dirty(bh);
86 * fat_add_cluster tries to allocate a new cluster and adds it to the
87 * file represented by inode.
89 int fat_add_cluster(struct inode *inode)
91 struct super_block *sb = inode->i_sb;
92 int ret, count, limit, new_dclus, new_fclus, last;
93 int cluster_bits = MSDOS_SB(sb)->cluster_bits;
96 * We must locate the last cluster of the file to add this new
97 * one (new_dclus) to the end of the link list (the FAT).
99 * In order to confirm that the cluster chain is valid, we
100 * find out EOF first.
102 last = new_fclus = 0;
103 if (MSDOS_I(inode)->i_start) {
104 int ret, fclus, dclus;
106 ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
109 new_fclus = fclus + 1;
113 /* find free FAT entry */
116 if (MSDOS_SB(sb)->free_clusters == 0) {
121 limit = MSDOS_SB(sb)->clusters + 2;
122 new_dclus = MSDOS_SB(sb)->prev_free + 1;
123 for (count = 0; count < MSDOS_SB(sb)->clusters; count++, new_dclus++) {
124 new_dclus = new_dclus % limit;
128 ret = fat_access(sb, new_dclus, -1);
132 } else if (ret == FAT_ENT_FREE)
135 if (count >= MSDOS_SB(sb)->clusters) {
136 MSDOS_SB(sb)->free_clusters = 0;
141 ret = fat_access(sb, new_dclus, FAT_ENT_EOF);
147 MSDOS_SB(sb)->prev_free = new_dclus;
148 if (MSDOS_SB(sb)->free_clusters != -1)
149 MSDOS_SB(sb)->free_clusters--;
150 fat_clusters_flush(sb);
154 /* add new one to the last of the cluster chain */
156 ret = fat_access(sb, last, new_dclus);
159 // fat_cache_add(inode, new_fclus, new_dclus);
161 MSDOS_I(inode)->i_start = new_dclus;
162 MSDOS_I(inode)->i_logstart = new_dclus;
163 mark_inode_dirty(inode);
165 if (new_fclus != (inode->i_blocks >> (cluster_bits - 9))) {
166 fat_fs_panic(sb, "clusters badly computed (%d != %lu)",
167 new_fclus, inode->i_blocks >> (cluster_bits - 9));
168 fat_cache_inval_inode(inode);
170 inode->i_blocks += MSDOS_SB(sb)->cluster_size >> 9;
175 struct buffer_head *fat_extend_dir(struct inode *inode)
177 struct super_block *sb = inode->i_sb;
178 struct buffer_head *bh, *res = NULL;
179 int nr, sec_per_clus = MSDOS_SB(sb)->sec_per_clus;
180 sector_t sector, last_sector;
182 if (MSDOS_SB(sb)->fat_bits != 32) {
183 if (inode->i_ino == MSDOS_ROOT_INO)
184 return ERR_PTR(-ENOSPC);
187 nr = fat_add_cluster(inode);
191 sector = ((sector_t)nr - 2) * sec_per_clus + MSDOS_SB(sb)->data_start;
192 last_sector = sector + sec_per_clus;
193 for ( ; sector < last_sector; sector++) {
194 if ((bh = sb_getblk(sb, sector))) {
195 memset(bh->b_data, 0, sb->s_blocksize);
196 set_buffer_uptodate(bh);
197 mark_buffer_dirty(bh);
206 if (inode->i_size & (sb->s_blocksize - 1)) {
207 fat_fs_panic(sb, "Odd directory size");
208 inode->i_size = (inode->i_size + sb->s_blocksize)
209 & ~((loff_t)sb->s_blocksize - 1);
211 inode->i_size += MSDOS_SB(sb)->cluster_size;
212 MSDOS_I(inode)->mmu_private += MSDOS_SB(sb)->cluster_size;
217 /* Linear day numbers of the respective 1sts in non-leap years. */
219 static int day_n[] = { 0,31,59,90,120,151,181,212,243,273,304,334,0,0,0,0 };
220 /* JanFebMarApr May Jun Jul Aug Sep Oct Nov Dec */
223 extern struct timezone sys_tz;
226 /* Convert a MS-DOS time/date pair to a UNIX date (seconds since 1 1 70). */
228 int date_dos2unix(unsigned short time,unsigned short date)
232 /* first subtract and mask after that... Otherwise, if
233 date == 0, bad things happen */
234 month = ((date >> 5) - 1) & 15;
236 secs = (time & 31)*2+60*((time >> 5) & 63)+(time >> 11)*3600+86400*
237 ((date & 31)-1+day_n[month]+(year/4)+year*365-((year & 3) == 0 &&
238 month < 2 ? 1 : 0)+3653);
239 /* days since 1.1.70 plus 80's leap day */
240 secs += sys_tz.tz_minuteswest*60;
245 /* Convert linear UNIX date to a MS-DOS time/date pair. */
247 void fat_date_unix2dos(int unix_date,__le16 *time, __le16 *date)
249 int day,year,nl_day,month;
251 unix_date -= sys_tz.tz_minuteswest*60;
253 /* Jan 1 GMT 00:00:00 1980. But what about another time zone? */
254 if (unix_date < 315532800)
255 unix_date = 315532800;
257 *time = cpu_to_le16((unix_date % 60)/2+(((unix_date/60) % 60) << 5)+
258 (((unix_date/3600) % 24) << 11));
259 day = unix_date/86400-3652;
261 if ((year+3)/4+365*year > day) year--;
262 day -= (year+3)/4+365*year;
263 if (day == 59 && !(year & 3)) {
268 nl_day = (year & 3) || day <= 59 ? day : day-1;
269 for (month = 0; month < 12; month++)
270 if (day_n[month] > nl_day) break;
272 *date = cpu_to_le16(nl_day-day_n[month-1]+1+(month << 5)+(year << 9));
276 /* Returns the inode number of the directory entry at offset pos. If bh is
277 non-NULL, it is brelse'd before. Pos is incremented. The buffer header is
279 AV. Most often we do it item-by-item. Makes sense to optimize.
280 AV. OK, there we go: if both bh and de are non-NULL we assume that we just
281 AV. want the next entry (took one explicit de=NULL in vfat/namei.c).
282 AV. It's done in fat_get_entry() (inlined), here the slow case lives.
283 AV. Additionally, when we return -1 (i.e. reached the end of directory)
287 int fat__get_entry(struct inode *dir, loff_t *pos,struct buffer_head **bh,
288 struct msdos_dir_entry **de, loff_t *i_pos)
290 struct super_block *sb = dir->i_sb;
291 struct msdos_sb_info *sbi = MSDOS_SB(sb);
292 sector_t phys, iblock;
302 iblock = *pos >> sb->s_blocksize_bits;
303 err = fat_bmap(dir, iblock, &phys);
305 return -1; /* beyond EOF or error */
307 *bh = sb_bread(sb, phys);
309 printk(KERN_ERR "FAT: Directory bread(block %llu) failed\n",
310 (unsigned long long)phys);
311 /* skip this block */
312 *pos = (iblock + 1) << sb->s_blocksize_bits;
316 offset &= sb->s_blocksize - 1;
317 *pos += sizeof(struct msdos_dir_entry);
318 *de = (struct msdos_dir_entry *)((*bh)->b_data + offset);
319 *i_pos = ((loff_t)phys << sbi->dir_per_block_bits) + (offset >> MSDOS_DIR_BITS);