2 * Copyright (C) 2004, OGAWA Hirofumi
3 * Released under GPL v2.
6 #include <linux/module.h>
8 #include <linux/msdos_fs.h>
9 #include <linux/blkdev.h>
11 struct fatent_operations
{
12 void (*ent_blocknr
)(struct super_block
*, int, int *, sector_t
*);
13 void (*ent_set_ptr
)(struct fat_entry
*, int);
14 int (*ent_bread
)(struct super_block
*, struct fat_entry
*,
16 int (*ent_get
)(struct fat_entry
*);
17 void (*ent_put
)(struct fat_entry
*, int);
18 int (*ent_next
)(struct fat_entry
*);
21 static DEFINE_SPINLOCK(fat12_entry_lock
);
23 static void fat12_ent_blocknr(struct super_block
*sb
, int entry
,
24 int *offset
, sector_t
*blocknr
)
26 struct msdos_sb_info
*sbi
= MSDOS_SB(sb
);
27 int bytes
= entry
+ (entry
>> 1);
28 WARN_ON(entry
< FAT_START_ENT
|| sbi
->max_cluster
<= entry
);
29 *offset
= bytes
& (sb
->s_blocksize
- 1);
30 *blocknr
= sbi
->fat_start
+ (bytes
>> sb
->s_blocksize_bits
);
33 static void fat_ent_blocknr(struct super_block
*sb
, int entry
,
34 int *offset
, sector_t
*blocknr
)
36 struct msdos_sb_info
*sbi
= MSDOS_SB(sb
);
37 int bytes
= (entry
<< sbi
->fatent_shift
);
38 WARN_ON(entry
< FAT_START_ENT
|| sbi
->max_cluster
<= entry
);
39 *offset
= bytes
& (sb
->s_blocksize
- 1);
40 *blocknr
= sbi
->fat_start
+ (bytes
>> sb
->s_blocksize_bits
);
43 static void fat12_ent_set_ptr(struct fat_entry
*fatent
, int offset
)
45 struct buffer_head
**bhs
= fatent
->bhs
;
46 if (fatent
->nr_bhs
== 1) {
47 WARN_ON(offset
>= (bhs
[0]->b_size
- 1));
48 fatent
->u
.ent12_p
[0] = bhs
[0]->b_data
+ offset
;
49 fatent
->u
.ent12_p
[1] = bhs
[0]->b_data
+ (offset
+ 1);
51 WARN_ON(offset
!= (bhs
[0]->b_size
- 1));
52 fatent
->u
.ent12_p
[0] = bhs
[0]->b_data
+ offset
;
53 fatent
->u
.ent12_p
[1] = bhs
[1]->b_data
;
57 static void fat16_ent_set_ptr(struct fat_entry
*fatent
, int offset
)
59 WARN_ON(offset
& (2 - 1));
60 fatent
->u
.ent16_p
= (__le16
*)(fatent
->bhs
[0]->b_data
+ offset
);
63 static void fat32_ent_set_ptr(struct fat_entry
*fatent
, int offset
)
65 WARN_ON(offset
& (4 - 1));
66 fatent
->u
.ent32_p
= (__le32
*)(fatent
->bhs
[0]->b_data
+ offset
);
69 static int fat12_ent_bread(struct super_block
*sb
, struct fat_entry
*fatent
,
70 int offset
, sector_t blocknr
)
72 struct buffer_head
**bhs
= fatent
->bhs
;
74 WARN_ON(blocknr
< MSDOS_SB(sb
)->fat_start
);
75 bhs
[0] = sb_bread(sb
, blocknr
);
79 if ((offset
+ 1) < sb
->s_blocksize
)
82 /* This entry is block boundary, it needs the next block */
84 bhs
[1] = sb_bread(sb
, blocknr
);
89 fat12_ent_set_ptr(fatent
, offset
);
95 printk(KERN_ERR
"FAT: FAT read failed (blocknr %llu)\n",
96 (unsigned long long)blocknr
);
100 static int fat_ent_bread(struct super_block
*sb
, struct fat_entry
*fatent
,
101 int offset
, sector_t blocknr
)
103 struct fatent_operations
*ops
= MSDOS_SB(sb
)->fatent_ops
;
105 WARN_ON(blocknr
< MSDOS_SB(sb
)->fat_start
);
106 fatent
->bhs
[0] = sb_bread(sb
, blocknr
);
107 if (!fatent
->bhs
[0]) {
108 printk(KERN_ERR
"FAT: FAT read failed (blocknr %llu)\n",
109 (unsigned long long)blocknr
);
113 ops
->ent_set_ptr(fatent
, offset
);
117 static int fat12_ent_get(struct fat_entry
*fatent
)
119 u8
**ent12_p
= fatent
->u
.ent12_p
;
122 spin_lock(&fat12_entry_lock
);
123 if (fatent
->entry
& 1)
124 next
= (*ent12_p
[0] >> 4) | (*ent12_p
[1] << 4);
126 next
= (*ent12_p
[1] << 8) | *ent12_p
[0];
127 spin_unlock(&fat12_entry_lock
);
130 if (next
>= BAD_FAT12
)
135 static int fat16_ent_get(struct fat_entry
*fatent
)
137 int next
= le16_to_cpu(*fatent
->u
.ent16_p
);
138 WARN_ON((unsigned long)fatent
->u
.ent16_p
& (2 - 1));
139 if (next
>= BAD_FAT16
)
144 static int fat32_ent_get(struct fat_entry
*fatent
)
146 int next
= le32_to_cpu(*fatent
->u
.ent32_p
) & 0x0fffffff;
147 WARN_ON((unsigned long)fatent
->u
.ent32_p
& (4 - 1));
148 if (next
>= BAD_FAT32
)
153 static void fat12_ent_put(struct fat_entry
*fatent
, int new)
155 u8
**ent12_p
= fatent
->u
.ent12_p
;
157 if (new == FAT_ENT_EOF
)
160 spin_lock(&fat12_entry_lock
);
161 if (fatent
->entry
& 1) {
162 *ent12_p
[0] = (new << 4) | (*ent12_p
[0] & 0x0f);
163 *ent12_p
[1] = new >> 4;
165 *ent12_p
[0] = new & 0xff;
166 *ent12_p
[1] = (*ent12_p
[1] & 0xf0) | (new >> 8);
168 spin_unlock(&fat12_entry_lock
);
170 mark_buffer_dirty(fatent
->bhs
[0]);
171 if (fatent
->nr_bhs
== 2)
172 mark_buffer_dirty(fatent
->bhs
[1]);
175 static void fat16_ent_put(struct fat_entry
*fatent
, int new)
177 if (new == FAT_ENT_EOF
)
180 *fatent
->u
.ent16_p
= cpu_to_le16(new);
181 mark_buffer_dirty(fatent
->bhs
[0]);
184 static void fat32_ent_put(struct fat_entry
*fatent
, int new)
186 if (new == FAT_ENT_EOF
)
189 WARN_ON(new & 0xf0000000);
190 new |= le32_to_cpu(*fatent
->u
.ent32_p
) & ~0x0fffffff;
191 *fatent
->u
.ent32_p
= cpu_to_le32(new);
192 mark_buffer_dirty(fatent
->bhs
[0]);
195 static int fat12_ent_next(struct fat_entry
*fatent
)
197 u8
**ent12_p
= fatent
->u
.ent12_p
;
198 struct buffer_head
**bhs
= fatent
->bhs
;
199 u8
*nextp
= ent12_p
[1] + 1 + (fatent
->entry
& 1);
202 if (fatent
->nr_bhs
== 1) {
203 WARN_ON(ent12_p
[0] > (u8
*)(bhs
[0]->b_data
+ (bhs
[0]->b_size
- 2)));
204 WARN_ON(ent12_p
[1] > (u8
*)(bhs
[0]->b_data
+ (bhs
[0]->b_size
- 1)));
205 if (nextp
< (u8
*)(bhs
[0]->b_data
+ (bhs
[0]->b_size
- 1))) {
206 ent12_p
[0] = nextp
- 1;
211 WARN_ON(ent12_p
[0] != (u8
*)(bhs
[0]->b_data
+ (bhs
[0]->b_size
- 1)));
212 WARN_ON(ent12_p
[1] != (u8
*)bhs
[1]->b_data
);
213 ent12_p
[0] = nextp
- 1;
225 static int fat16_ent_next(struct fat_entry
*fatent
)
227 const struct buffer_head
*bh
= fatent
->bhs
[0];
229 if (fatent
->u
.ent16_p
< (__le16
*)(bh
->b_data
+ (bh
->b_size
- 2))) {
233 fatent
->u
.ent16_p
= NULL
;
237 static int fat32_ent_next(struct fat_entry
*fatent
)
239 const struct buffer_head
*bh
= fatent
->bhs
[0];
241 if (fatent
->u
.ent32_p
< (__le32
*)(bh
->b_data
+ (bh
->b_size
- 4))) {
245 fatent
->u
.ent32_p
= NULL
;
249 static struct fatent_operations fat12_ops
= {
250 .ent_blocknr
= fat12_ent_blocknr
,
251 .ent_set_ptr
= fat12_ent_set_ptr
,
252 .ent_bread
= fat12_ent_bread
,
253 .ent_get
= fat12_ent_get
,
254 .ent_put
= fat12_ent_put
,
255 .ent_next
= fat12_ent_next
,
258 static struct fatent_operations fat16_ops
= {
259 .ent_blocknr
= fat_ent_blocknr
,
260 .ent_set_ptr
= fat16_ent_set_ptr
,
261 .ent_bread
= fat_ent_bread
,
262 .ent_get
= fat16_ent_get
,
263 .ent_put
= fat16_ent_put
,
264 .ent_next
= fat16_ent_next
,
267 static struct fatent_operations fat32_ops
= {
268 .ent_blocknr
= fat_ent_blocknr
,
269 .ent_set_ptr
= fat32_ent_set_ptr
,
270 .ent_bread
= fat_ent_bread
,
271 .ent_get
= fat32_ent_get
,
272 .ent_put
= fat32_ent_put
,
273 .ent_next
= fat32_ent_next
,
276 static inline void lock_fat(struct msdos_sb_info
*sbi
)
278 mutex_lock(&sbi
->fat_lock
);
281 static inline void unlock_fat(struct msdos_sb_info
*sbi
)
283 mutex_unlock(&sbi
->fat_lock
);
286 void fat_ent_access_init(struct super_block
*sb
)
288 struct msdos_sb_info
*sbi
= MSDOS_SB(sb
);
290 mutex_init(&sbi
->fat_lock
);
292 switch (sbi
->fat_bits
) {
294 sbi
->fatent_shift
= 2;
295 sbi
->fatent_ops
= &fat32_ops
;
298 sbi
->fatent_shift
= 1;
299 sbi
->fatent_ops
= &fat16_ops
;
302 sbi
->fatent_shift
= -1;
303 sbi
->fatent_ops
= &fat12_ops
;
308 static inline int fat_ent_update_ptr(struct super_block
*sb
,
309 struct fat_entry
*fatent
,
310 int offset
, sector_t blocknr
)
312 struct msdos_sb_info
*sbi
= MSDOS_SB(sb
);
313 struct fatent_operations
*ops
= sbi
->fatent_ops
;
314 struct buffer_head
**bhs
= fatent
->bhs
;
316 /* Is this fatent's blocks including this entry? */
317 if (!fatent
->nr_bhs
|| bhs
[0]->b_blocknr
!= blocknr
)
319 /* Does this entry need the next block? */
320 if (sbi
->fat_bits
== 12 && (offset
+ 1) >= sb
->s_blocksize
) {
321 if (fatent
->nr_bhs
!= 2 || bhs
[1]->b_blocknr
!= (blocknr
+ 1))
324 ops
->ent_set_ptr(fatent
, offset
);
328 int fat_ent_read(struct inode
*inode
, struct fat_entry
*fatent
, int entry
)
330 struct super_block
*sb
= inode
->i_sb
;
331 struct msdos_sb_info
*sbi
= MSDOS_SB(inode
->i_sb
);
332 struct fatent_operations
*ops
= sbi
->fatent_ops
;
336 if (entry
< FAT_START_ENT
|| sbi
->max_cluster
<= entry
) {
337 fatent_brelse(fatent
);
338 fat_fs_panic(sb
, "invalid access to FAT (entry 0x%08x)", entry
);
342 fatent_set_entry(fatent
, entry
);
343 ops
->ent_blocknr(sb
, entry
, &offset
, &blocknr
);
345 if (!fat_ent_update_ptr(sb
, fatent
, offset
, blocknr
)) {
346 fatent_brelse(fatent
);
347 err
= ops
->ent_bread(sb
, fatent
, offset
, blocknr
);
351 return ops
->ent_get(fatent
);
354 /* FIXME: We can write the blocks as more big chunk. */
355 static int fat_mirror_bhs(struct super_block
*sb
, struct buffer_head
**bhs
,
358 struct msdos_sb_info
*sbi
= MSDOS_SB(sb
);
359 struct buffer_head
*c_bh
;
363 for (copy
= 1; copy
< sbi
->fats
; copy
++) {
364 sector_t backup_fat
= sbi
->fat_length
* copy
;
366 for (n
= 0; n
< nr_bhs
; n
++) {
367 c_bh
= sb_getblk(sb
, backup_fat
+ bhs
[n
]->b_blocknr
);
372 memcpy(c_bh
->b_data
, bhs
[n
]->b_data
, sb
->s_blocksize
);
373 set_buffer_uptodate(c_bh
);
374 mark_buffer_dirty(c_bh
);
375 if (sb
->s_flags
& MS_SYNCHRONOUS
)
376 err
= sync_dirty_buffer(c_bh
);
386 int fat_ent_write(struct inode
*inode
, struct fat_entry
*fatent
,
389 struct super_block
*sb
= inode
->i_sb
;
390 struct fatent_operations
*ops
= MSDOS_SB(sb
)->fatent_ops
;
393 ops
->ent_put(fatent
, new);
395 err
= fat_sync_bhs(fatent
->bhs
, fatent
->nr_bhs
);
399 return fat_mirror_bhs(sb
, fatent
->bhs
, fatent
->nr_bhs
);
402 static inline int fat_ent_next(struct msdos_sb_info
*sbi
,
403 struct fat_entry
*fatent
)
405 if (sbi
->fatent_ops
->ent_next(fatent
)) {
406 if (fatent
->entry
< sbi
->max_cluster
)
412 static inline int fat_ent_read_block(struct super_block
*sb
,
413 struct fat_entry
*fatent
)
415 struct fatent_operations
*ops
= MSDOS_SB(sb
)->fatent_ops
;
419 fatent_brelse(fatent
);
420 ops
->ent_blocknr(sb
, fatent
->entry
, &offset
, &blocknr
);
421 return ops
->ent_bread(sb
, fatent
, offset
, blocknr
);
424 static void fat_collect_bhs(struct buffer_head
**bhs
, int *nr_bhs
,
425 struct fat_entry
*fatent
)
429 for (n
= 0; n
< fatent
->nr_bhs
; n
++) {
430 for (i
= 0; i
< *nr_bhs
; i
++) {
431 if (fatent
->bhs
[n
] == bhs
[i
])
435 get_bh(fatent
->bhs
[n
]);
436 bhs
[i
] = fatent
->bhs
[n
];
442 int fat_alloc_clusters(struct inode
*inode
, int *cluster
, int nr_cluster
)
444 struct super_block
*sb
= inode
->i_sb
;
445 struct msdos_sb_info
*sbi
= MSDOS_SB(sb
);
446 struct fatent_operations
*ops
= sbi
->fatent_ops
;
447 struct fat_entry fatent
, prev_ent
;
448 struct buffer_head
*bhs
[MAX_BUF_PER_PAGE
];
449 int i
, count
, err
, nr_bhs
, idx_clus
;
451 BUG_ON(nr_cluster
> (MAX_BUF_PER_PAGE
/ 2)); /* fixed limit */
454 if (sbi
->free_clusters
!= -1 && sbi
->free_clus_valid
&&
455 sbi
->free_clusters
< nr_cluster
) {
460 err
= nr_bhs
= idx_clus
= 0;
461 count
= FAT_START_ENT
;
462 fatent_init(&prev_ent
);
463 fatent_init(&fatent
);
464 fatent_set_entry(&fatent
, sbi
->prev_free
+ 1);
465 while (count
< sbi
->max_cluster
) {
466 if (fatent
.entry
>= sbi
->max_cluster
)
467 fatent
.entry
= FAT_START_ENT
;
468 fatent_set_entry(&fatent
, fatent
.entry
);
469 err
= fat_ent_read_block(sb
, &fatent
);
473 /* Find the free entries in a block */
475 if (ops
->ent_get(&fatent
) == FAT_ENT_FREE
) {
476 int entry
= fatent
.entry
;
478 /* make the cluster chain */
479 ops
->ent_put(&fatent
, FAT_ENT_EOF
);
481 ops
->ent_put(&prev_ent
, entry
);
483 fat_collect_bhs(bhs
, &nr_bhs
, &fatent
);
485 sbi
->prev_free
= entry
;
486 if (sbi
->free_clusters
!= -1)
487 sbi
->free_clusters
--;
490 cluster
[idx_clus
] = entry
;
492 if (idx_clus
== nr_cluster
)
496 * fat_collect_bhs() gets ref-count of bhs,
497 * so we can still use the prev_ent.
502 if (count
== sbi
->max_cluster
)
504 } while (fat_ent_next(sbi
, &fatent
));
507 /* Couldn't allocate the free entries */
508 sbi
->free_clusters
= 0;
509 sbi
->free_clus_valid
= 1;
515 fatent_brelse(&fatent
);
517 if (inode_needs_sync(inode
))
518 err
= fat_sync_bhs(bhs
, nr_bhs
);
520 err
= fat_mirror_bhs(sb
, bhs
, nr_bhs
);
522 for (i
= 0; i
< nr_bhs
; i
++)
526 fat_free_clusters(inode
, cluster
[0]);
531 int fat_free_clusters(struct inode
*inode
, int cluster
)
533 struct super_block
*sb
= inode
->i_sb
;
534 struct msdos_sb_info
*sbi
= MSDOS_SB(sb
);
535 struct fatent_operations
*ops
= sbi
->fatent_ops
;
536 struct fat_entry fatent
;
537 struct buffer_head
*bhs
[MAX_BUF_PER_PAGE
];
539 int first_cl
= cluster
;
542 fatent_init(&fatent
);
545 cluster
= fat_ent_read(inode
, &fatent
, cluster
);
549 } else if (cluster
== FAT_ENT_FREE
) {
550 fat_fs_panic(sb
, "%s: deleting FAT entry beyond EOF",
557 * Issue discard for the sectors we no longer care about,
558 * batching contiguous clusters into one request
560 if (cluster
!= fatent
.entry
+ 1) {
561 int nr_clus
= fatent
.entry
- first_cl
+ 1;
563 sb_issue_discard(sb
, fat_clus_to_blknr(sbi
, first_cl
),
564 nr_clus
* sbi
->sec_per_clus
);
568 ops
->ent_put(&fatent
, FAT_ENT_FREE
);
569 if (sbi
->free_clusters
!= -1) {
570 sbi
->free_clusters
++;
574 if (nr_bhs
+ fatent
.nr_bhs
> MAX_BUF_PER_PAGE
) {
575 if (sb
->s_flags
& MS_SYNCHRONOUS
) {
576 err
= fat_sync_bhs(bhs
, nr_bhs
);
580 err
= fat_mirror_bhs(sb
, bhs
, nr_bhs
);
583 for (i
= 0; i
< nr_bhs
; i
++)
587 fat_collect_bhs(bhs
, &nr_bhs
, &fatent
);
588 } while (cluster
!= FAT_ENT_EOF
);
590 if (sb
->s_flags
& MS_SYNCHRONOUS
) {
591 err
= fat_sync_bhs(bhs
, nr_bhs
);
595 err
= fat_mirror_bhs(sb
, bhs
, nr_bhs
);
597 fatent_brelse(&fatent
);
598 for (i
= 0; i
< nr_bhs
; i
++)
605 EXPORT_SYMBOL_GPL(fat_free_clusters
);
607 /* 128kb is the whole sectors for FAT12 and FAT16 */
608 #define FAT_READA_SIZE (128 * 1024)
610 static void fat_ent_reada(struct super_block
*sb
, struct fat_entry
*fatent
,
611 unsigned long reada_blocks
)
613 struct fatent_operations
*ops
= MSDOS_SB(sb
)->fatent_ops
;
617 ops
->ent_blocknr(sb
, fatent
->entry
, &offset
, &blocknr
);
619 for (i
= 0; i
< reada_blocks
; i
++)
620 sb_breadahead(sb
, blocknr
+ i
);
623 int fat_count_free_clusters(struct super_block
*sb
)
625 struct msdos_sb_info
*sbi
= MSDOS_SB(sb
);
626 struct fatent_operations
*ops
= sbi
->fatent_ops
;
627 struct fat_entry fatent
;
628 unsigned long reada_blocks
, reada_mask
, cur_block
;
632 if (sbi
->free_clusters
!= -1 && sbi
->free_clus_valid
)
635 reada_blocks
= FAT_READA_SIZE
>> sb
->s_blocksize_bits
;
636 reada_mask
= reada_blocks
- 1;
640 fatent_init(&fatent
);
641 fatent_set_entry(&fatent
, FAT_START_ENT
);
642 while (fatent
.entry
< sbi
->max_cluster
) {
643 /* readahead of fat blocks */
644 if ((cur_block
& reada_mask
) == 0) {
645 unsigned long rest
= sbi
->fat_length
- cur_block
;
646 fat_ent_reada(sb
, &fatent
, min(reada_blocks
, rest
));
650 err
= fat_ent_read_block(sb
, &fatent
);
655 if (ops
->ent_get(&fatent
) == FAT_ENT_FREE
)
657 } while (fat_ent_next(sbi
, &fatent
));
659 sbi
->free_clusters
= free
;
660 sbi
->free_clus_valid
= 1;
662 fatent_brelse(&fatent
);