[PATCH] fat: s/EXPORT_SYMBOL/EXPORT_SYMBOL_GPL/
[linux-2.6.git] / fs / fat / fatent.c
1 /*
2  * Copyright (C) 2004, OGAWA Hirofumi
3  * Released under GPL v2.
4  */
5
6 #include <linux/module.h>
7 #include <linux/fs.h>
8 #include <linux/msdos_fs.h>
9
10 struct fatent_operations {
11         void (*ent_blocknr)(struct super_block *, int, int *, sector_t *);
12         void (*ent_set_ptr)(struct fat_entry *, int);
13         int (*ent_bread)(struct super_block *, struct fat_entry *,
14                          int, sector_t);
15         int (*ent_get)(struct fat_entry *);
16         void (*ent_put)(struct fat_entry *, int);
17         int (*ent_next)(struct fat_entry *);
18 };
19
20 static void fat12_ent_blocknr(struct super_block *sb, int entry,
21                               int *offset, sector_t *blocknr)
22 {
23         struct msdos_sb_info *sbi = MSDOS_SB(sb);
24         int bytes = entry + (entry >> 1);
25         WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
26         *offset = bytes & (sb->s_blocksize - 1);
27         *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
28 }
29
30 static void fat_ent_blocknr(struct super_block *sb, int entry,
31                             int *offset, sector_t *blocknr)
32 {
33         struct msdos_sb_info *sbi = MSDOS_SB(sb);
34         int bytes = (entry << sbi->fatent_shift);
35         WARN_ON(entry < FAT_START_ENT || sbi->max_cluster <= entry);
36         *offset = bytes & (sb->s_blocksize - 1);
37         *blocknr = sbi->fat_start + (bytes >> sb->s_blocksize_bits);
38 }
39
40 static void fat12_ent_set_ptr(struct fat_entry *fatent, int offset)
41 {
42         struct buffer_head **bhs = fatent->bhs;
43         if (fatent->nr_bhs == 1) {
44                 WARN_ON(offset >= (bhs[0]->b_size - 1));
45                 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
46                 fatent->u.ent12_p[1] = bhs[0]->b_data + (offset + 1);
47         } else {
48                 WARN_ON(offset != (bhs[0]->b_size - 1));
49                 fatent->u.ent12_p[0] = bhs[0]->b_data + offset;
50                 fatent->u.ent12_p[1] = bhs[1]->b_data;
51         }
52 }
53
54 static void fat16_ent_set_ptr(struct fat_entry *fatent, int offset)
55 {
56         WARN_ON(offset & (2 - 1));
57         fatent->u.ent16_p = (__le16 *)(fatent->bhs[0]->b_data + offset);
58 }
59
60 static void fat32_ent_set_ptr(struct fat_entry *fatent, int offset)
61 {
62         WARN_ON(offset & (4 - 1));
63         fatent->u.ent32_p = (__le32 *)(fatent->bhs[0]->b_data + offset);
64 }
65
66 static int fat12_ent_bread(struct super_block *sb, struct fat_entry *fatent,
67                            int offset, sector_t blocknr)
68 {
69         struct buffer_head **bhs = fatent->bhs;
70
71         WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
72         bhs[0] = sb_bread(sb, blocknr);
73         if (!bhs[0])
74                 goto err;
75
76         if ((offset + 1) < sb->s_blocksize)
77                 fatent->nr_bhs = 1;
78         else {
79                 /* This entry is block boundary, it needs the next block */
80                 blocknr++;
81                 bhs[1] = sb_bread(sb, blocknr);
82                 if (!bhs[1])
83                         goto err_brelse;
84                 fatent->nr_bhs = 2;
85         }
86         fat12_ent_set_ptr(fatent, offset);
87         return 0;
88
89 err_brelse:
90         brelse(bhs[0]);
91 err:
92         printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
93                (unsigned long long)blocknr);
94         return -EIO;
95 }
96
97 static int fat_ent_bread(struct super_block *sb, struct fat_entry *fatent,
98                          int offset, sector_t blocknr)
99 {
100         struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
101
102         WARN_ON(blocknr < MSDOS_SB(sb)->fat_start);
103         fatent->bhs[0] = sb_bread(sb, blocknr);
104         if (!fatent->bhs[0]) {
105                 printk(KERN_ERR "FAT: FAT read failed (blocknr %llu)\n",
106                        (unsigned long long)blocknr);
107                 return -EIO;
108         }
109         fatent->nr_bhs = 1;
110         ops->ent_set_ptr(fatent, offset);
111         return 0;
112 }
113
114 static int fat12_ent_get(struct fat_entry *fatent)
115 {
116         u8 **ent12_p = fatent->u.ent12_p;
117         int next;
118
119         if (fatent->entry & 1)
120                 next = (*ent12_p[0] >> 4) | (*ent12_p[1] << 4);
121         else
122                 next = (*ent12_p[1] << 8) | *ent12_p[0];
123         next &= 0x0fff;
124         if (next >= BAD_FAT12)
125                 next = FAT_ENT_EOF;
126         return next;
127 }
128
129 static int fat16_ent_get(struct fat_entry *fatent)
130 {
131         int next = le16_to_cpu(*fatent->u.ent16_p);
132         WARN_ON((unsigned long)fatent->u.ent16_p & (2 - 1));
133         if (next >= BAD_FAT16)
134                 next = FAT_ENT_EOF;
135         return next;
136 }
137
138 static int fat32_ent_get(struct fat_entry *fatent)
139 {
140         int next = le32_to_cpu(*fatent->u.ent32_p) & 0x0fffffff;
141         WARN_ON((unsigned long)fatent->u.ent32_p & (4 - 1));
142         if (next >= BAD_FAT32)
143                 next = FAT_ENT_EOF;
144         return next;
145 }
146
147 static void fat12_ent_put(struct fat_entry *fatent, int new)
148 {
149         u8 **ent12_p = fatent->u.ent12_p;
150
151         if (new == FAT_ENT_EOF)
152                 new = EOF_FAT12;
153
154         if (fatent->entry & 1) {
155                 *ent12_p[0] = (new << 4) | (*ent12_p[0] & 0x0f);
156                 *ent12_p[1] = new >> 4;
157         } else {
158                 *ent12_p[0] = new & 0xff;
159                 *ent12_p[1] = (*ent12_p[1] & 0xf0) | (new >> 8);
160         }
161
162         mark_buffer_dirty(fatent->bhs[0]);
163         if (fatent->nr_bhs == 2)
164                 mark_buffer_dirty(fatent->bhs[1]);
165 }
166
167 static void fat16_ent_put(struct fat_entry *fatent, int new)
168 {
169         if (new == FAT_ENT_EOF)
170                 new = EOF_FAT16;
171
172         *fatent->u.ent16_p = cpu_to_le16(new);
173         mark_buffer_dirty(fatent->bhs[0]);
174 }
175
176 static void fat32_ent_put(struct fat_entry *fatent, int new)
177 {
178         if (new == FAT_ENT_EOF)
179                 new = EOF_FAT32;
180
181         WARN_ON(new & 0xf0000000);
182         new |= le32_to_cpu(*fatent->u.ent32_p) & ~0x0fffffff;
183         *fatent->u.ent32_p = cpu_to_le32(new);
184         mark_buffer_dirty(fatent->bhs[0]);
185 }
186
187 static int fat12_ent_next(struct fat_entry *fatent)
188 {
189         u8 **ent12_p = fatent->u.ent12_p;
190         struct buffer_head **bhs = fatent->bhs;
191         u8 *nextp = ent12_p[1] + 1 + (fatent->entry & 1);
192
193         fatent->entry++;
194         if (fatent->nr_bhs == 1) {
195                 WARN_ON(ent12_p[0] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 2)));
196                 WARN_ON(ent12_p[1] > (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
197                 if (nextp < (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1))) {
198                         ent12_p[0] = nextp - 1;
199                         ent12_p[1] = nextp;
200                         return 1;
201                 }
202         } else {
203                 WARN_ON(ent12_p[0] != (u8 *)(bhs[0]->b_data + (bhs[0]->b_size - 1)));
204                 WARN_ON(ent12_p[1] != (u8 *)bhs[1]->b_data);
205                 ent12_p[0] = nextp - 1;
206                 ent12_p[1] = nextp;
207                 brelse(bhs[0]);
208                 bhs[0] = bhs[1];
209                 fatent->nr_bhs = 1;
210                 return 1;
211         }
212         ent12_p[0] = NULL;
213         ent12_p[1] = NULL;
214         return 0;
215 }
216
217 static int fat16_ent_next(struct fat_entry *fatent)
218 {
219         const struct buffer_head *bh = fatent->bhs[0];
220         fatent->entry++;
221         if (fatent->u.ent16_p < (__le16 *)(bh->b_data + (bh->b_size - 2))) {
222                 fatent->u.ent16_p++;
223                 return 1;
224         }
225         fatent->u.ent16_p = NULL;
226         return 0;
227 }
228
229 static int fat32_ent_next(struct fat_entry *fatent)
230 {
231         const struct buffer_head *bh = fatent->bhs[0];
232         fatent->entry++;
233         if (fatent->u.ent32_p < (__le32 *)(bh->b_data + (bh->b_size - 4))) {
234                 fatent->u.ent32_p++;
235                 return 1;
236         }
237         fatent->u.ent32_p = NULL;
238         return 0;
239 }
240
241 static struct fatent_operations fat12_ops = {
242         .ent_blocknr    = fat12_ent_blocknr,
243         .ent_set_ptr    = fat12_ent_set_ptr,
244         .ent_bread      = fat12_ent_bread,
245         .ent_get        = fat12_ent_get,
246         .ent_put        = fat12_ent_put,
247         .ent_next       = fat12_ent_next,
248 };
249
250 static struct fatent_operations fat16_ops = {
251         .ent_blocknr    = fat_ent_blocknr,
252         .ent_set_ptr    = fat16_ent_set_ptr,
253         .ent_bread      = fat_ent_bread,
254         .ent_get        = fat16_ent_get,
255         .ent_put        = fat16_ent_put,
256         .ent_next       = fat16_ent_next,
257 };
258
259 static struct fatent_operations fat32_ops = {
260         .ent_blocknr    = fat_ent_blocknr,
261         .ent_set_ptr    = fat32_ent_set_ptr,
262         .ent_bread      = fat_ent_bread,
263         .ent_get        = fat32_ent_get,
264         .ent_put        = fat32_ent_put,
265         .ent_next       = fat32_ent_next,
266 };
267
268 static inline void lock_fat(struct msdos_sb_info *sbi)
269 {
270         down(&sbi->fat_lock);
271 }
272
273 static inline void unlock_fat(struct msdos_sb_info *sbi)
274 {
275         up(&sbi->fat_lock);
276 }
277
278 void fat_ent_access_init(struct super_block *sb)
279 {
280         struct msdos_sb_info *sbi = MSDOS_SB(sb);
281
282         init_MUTEX(&sbi->fat_lock);
283
284         switch (sbi->fat_bits) {
285         case 32:
286                 sbi->fatent_shift = 2;
287                 sbi->fatent_ops = &fat32_ops;
288                 break;
289         case 16:
290                 sbi->fatent_shift = 1;
291                 sbi->fatent_ops = &fat16_ops;
292                 break;
293         case 12:
294                 sbi->fatent_shift = -1;
295                 sbi->fatent_ops = &fat12_ops;
296                 break;
297         }
298 }
299
300 static inline int fat_ent_update_ptr(struct super_block *sb,
301                                      struct fat_entry *fatent,
302                                      int offset, sector_t blocknr)
303 {
304         struct msdos_sb_info *sbi = MSDOS_SB(sb);
305         struct fatent_operations *ops = sbi->fatent_ops;
306         struct buffer_head **bhs = fatent->bhs;
307
308         /* Is this fatent's blocks including this entry? */
309         if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
310                 return 0;
311         /* Does this entry need the next block? */
312         if (sbi->fat_bits == 12 && (offset + 1) >= sb->s_blocksize) {
313                 if (fatent->nr_bhs != 2 || bhs[1]->b_blocknr != (blocknr + 1))
314                         return 0;
315         }
316         ops->ent_set_ptr(fatent, offset);
317         return 1;
318 }
319
320 int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
321 {
322         struct super_block *sb = inode->i_sb;
323         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
324         struct fatent_operations *ops = sbi->fatent_ops;
325         int err, offset;
326         sector_t blocknr;
327
328         if (entry < FAT_START_ENT || sbi->max_cluster <= entry) {
329                 fatent_brelse(fatent);
330                 fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", entry);
331                 return -EIO;
332         }
333
334         fatent_set_entry(fatent, entry);
335         ops->ent_blocknr(sb, entry, &offset, &blocknr);
336
337         if (!fat_ent_update_ptr(sb, fatent, offset, blocknr)) {
338                 fatent_brelse(fatent);
339                 err = ops->ent_bread(sb, fatent, offset, blocknr);
340                 if (err)
341                         return err;
342         }
343         return ops->ent_get(fatent);
344 }
345
346 /* FIXME: We can write the blocks as more big chunk. */
347 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
348                           int nr_bhs)
349 {
350         struct msdos_sb_info *sbi = MSDOS_SB(sb);
351         struct buffer_head *c_bh;
352         int err, n, copy;
353
354         err = 0;
355         for (copy = 1; copy < sbi->fats; copy++) {
356                 sector_t backup_fat = sbi->fat_length * copy;
357
358                 for (n = 0; n < nr_bhs; n++) {
359                         c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
360                         if (!c_bh) {
361                                 err = -ENOMEM;
362                                 goto error;
363                         }
364                         memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
365                         set_buffer_uptodate(c_bh);
366                         mark_buffer_dirty(c_bh);
367                         if (sb->s_flags & MS_SYNCHRONOUS)
368                                 err = sync_dirty_buffer(c_bh);
369                         brelse(c_bh);
370                         if (err)
371                                 goto error;
372                 }
373         }
374 error:
375         return err;
376 }
377
378 int fat_ent_write(struct inode *inode, struct fat_entry *fatent,
379                   int new, int wait)
380 {
381         struct super_block *sb = inode->i_sb;
382         struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
383         int err;
384
385         ops->ent_put(fatent, new);
386         if (wait) {
387                 err = fat_sync_bhs(fatent->bhs, fatent->nr_bhs);
388                 if (err)
389                         return err;
390         }
391         return fat_mirror_bhs(sb, fatent->bhs, fatent->nr_bhs);
392 }
393
394 static inline int fat_ent_next(struct msdos_sb_info *sbi,
395                                struct fat_entry *fatent)
396 {
397         if (sbi->fatent_ops->ent_next(fatent)) {
398                 if (fatent->entry < sbi->max_cluster)
399                         return 1;
400         }
401         return 0;
402 }
403
404 static inline int fat_ent_read_block(struct super_block *sb,
405                                      struct fat_entry *fatent)
406 {
407         struct fatent_operations *ops = MSDOS_SB(sb)->fatent_ops;
408         sector_t blocknr;
409         int offset;
410
411         fatent_brelse(fatent);
412         ops->ent_blocknr(sb, fatent->entry, &offset, &blocknr);
413         return ops->ent_bread(sb, fatent, offset, blocknr);
414 }
415
416 static void fat_collect_bhs(struct buffer_head **bhs, int *nr_bhs,
417                             struct fat_entry *fatent)
418 {
419         int n, i;
420
421         for (n = 0; n < fatent->nr_bhs; n++) {
422                 for (i = 0; i < *nr_bhs; i++) {
423                         if (fatent->bhs[n] == bhs[i])
424                                 break;
425                 }
426                 if (i == *nr_bhs) {
427                         get_bh(fatent->bhs[n]);
428                         bhs[i] = fatent->bhs[n];
429                         (*nr_bhs)++;
430                 }
431         }
432 }
433
434 int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
435 {
436         struct super_block *sb = inode->i_sb;
437         struct msdos_sb_info *sbi = MSDOS_SB(sb);
438         struct fatent_operations *ops = sbi->fatent_ops;
439         struct fat_entry fatent, prev_ent;
440         struct buffer_head *bhs[MAX_BUF_PER_PAGE];
441         int i, count, err, nr_bhs, idx_clus;
442
443         BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2));    /* fixed limit */
444
445         lock_fat(sbi);
446         if (sbi->free_clusters != -1 && sbi->free_clusters < nr_cluster) {
447                 unlock_fat(sbi);
448                 return -ENOSPC;
449         }
450
451         err = nr_bhs = idx_clus = 0;
452         count = FAT_START_ENT;
453         fatent_init(&prev_ent);
454         fatent_init(&fatent);
455         fatent_set_entry(&fatent, sbi->prev_free + 1);
456         while (count < sbi->max_cluster) {
457                 if (fatent.entry >= sbi->max_cluster)
458                         fatent.entry = FAT_START_ENT;
459                 fatent_set_entry(&fatent, fatent.entry);
460                 err = fat_ent_read_block(sb, &fatent);
461                 if (err)
462                         goto out;
463
464                 /* Find the free entries in a block */
465                 do {
466                         if (ops->ent_get(&fatent) == FAT_ENT_FREE) {
467                                 int entry = fatent.entry;
468
469                                 /* make the cluster chain */
470                                 ops->ent_put(&fatent, FAT_ENT_EOF);
471                                 if (prev_ent.nr_bhs)
472                                         ops->ent_put(&prev_ent, entry);
473
474                                 fat_collect_bhs(bhs, &nr_bhs, &fatent);
475
476                                 sbi->prev_free = entry;
477                                 if (sbi->free_clusters != -1)
478                                         sbi->free_clusters--;
479                                 sb->s_dirt = 1;
480
481                                 cluster[idx_clus] = entry;
482                                 idx_clus++;
483                                 if (idx_clus == nr_cluster)
484                                         goto out;
485
486                                 /*
487                                  * fat_collect_bhs() gets ref-count of bhs,
488                                  * so we can still use the prev_ent.
489                                  */
490                                 prev_ent = fatent;
491                         }
492                         count++;
493                         if (count == sbi->max_cluster)
494                                 break;
495                 } while (fat_ent_next(sbi, &fatent));
496         }
497
498         /* Couldn't allocate the free entries */
499         sbi->free_clusters = 0;
500         sb->s_dirt = 1;
501         err = -ENOSPC;
502
503 out:
504         unlock_fat(sbi);
505         fatent_brelse(&fatent);
506         if (!err) {
507                 if (inode_needs_sync(inode))
508                         err = fat_sync_bhs(bhs, nr_bhs);
509                 if (!err)
510                         err = fat_mirror_bhs(sb, bhs, nr_bhs);
511         }
512         for (i = 0; i < nr_bhs; i++)
513                 brelse(bhs[i]);
514
515         if (err && idx_clus)
516                 fat_free_clusters(inode, cluster[0]);
517
518         return err;
519 }
520
521 int fat_free_clusters(struct inode *inode, int cluster)
522 {
523         struct super_block *sb = inode->i_sb;
524         struct msdos_sb_info *sbi = MSDOS_SB(sb);
525         struct fatent_operations *ops = sbi->fatent_ops;
526         struct fat_entry fatent;
527         struct buffer_head *bhs[MAX_BUF_PER_PAGE];
528         int i, err, nr_bhs;
529
530         nr_bhs = 0;
531         fatent_init(&fatent);
532         lock_fat(sbi);
533         do {
534                 cluster = fat_ent_read(inode, &fatent, cluster);
535                 if (cluster < 0) {
536                         err = cluster;
537                         goto error;
538                 } else if (cluster == FAT_ENT_FREE) {
539                         fat_fs_panic(sb, "%s: deleting FAT entry beyond EOF",
540                                      __FUNCTION__);
541                         err = -EIO;
542                         goto error;
543                 }
544
545                 ops->ent_put(&fatent, FAT_ENT_FREE);
546                 if (sbi->free_clusters != -1) {
547                         sbi->free_clusters++;
548                         sb->s_dirt = 1;
549                 }
550
551                 if (nr_bhs + fatent.nr_bhs > MAX_BUF_PER_PAGE) {
552                         if (sb->s_flags & MS_SYNCHRONOUS) {
553                                 err = fat_sync_bhs(bhs, nr_bhs);
554                                 if (err)
555                                         goto error;
556                         }
557                         err = fat_mirror_bhs(sb, bhs, nr_bhs);
558                         if (err)
559                                 goto error;
560                         for (i = 0; i < nr_bhs; i++)
561                                 brelse(bhs[i]);
562                         nr_bhs = 0;
563                 }
564                 fat_collect_bhs(bhs, &nr_bhs, &fatent);
565         } while (cluster != FAT_ENT_EOF);
566
567         if (sb->s_flags & MS_SYNCHRONOUS) {
568                 err = fat_sync_bhs(bhs, nr_bhs);
569                 if (err)
570                         goto error;
571         }
572         err = fat_mirror_bhs(sb, bhs, nr_bhs);
573 error:
574         fatent_brelse(&fatent);
575         for (i = 0; i < nr_bhs; i++)
576                 brelse(bhs[i]);
577         unlock_fat(sbi);
578
579         fat_clusters_flush(sb);
580
581         return err;
582 }
583
584 EXPORT_SYMBOL_GPL(fat_free_clusters);
585
586 int fat_count_free_clusters(struct super_block *sb)
587 {
588         struct msdos_sb_info *sbi = MSDOS_SB(sb);
589         struct fatent_operations *ops = sbi->fatent_ops;
590         struct fat_entry fatent;
591         int err = 0, free;
592
593         lock_fat(sbi);
594         if (sbi->free_clusters != -1)
595                 goto out;
596
597         free = 0;
598         fatent_init(&fatent);
599         fatent_set_entry(&fatent, FAT_START_ENT);
600         while (fatent.entry < sbi->max_cluster) {
601                 err = fat_ent_read_block(sb, &fatent);
602                 if (err)
603                         goto out;
604
605                 do {
606                         if (ops->ent_get(&fatent) == FAT_ENT_FREE)
607                                 free++;
608                 } while (fat_ent_next(sbi, &fatent));
609         }
610         sbi->free_clusters = free;
611         sb->s_dirt = 1;
612         fatent_brelse(&fatent);
613 out:
614         unlock_fat(sbi);
615         return err;
616 }