Merge git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 into for-linus
[linux-2.6] / fs / affs / file.c
1 /*
2  *  linux/fs/affs/file.c
3  *
4  *  (c) 1996  Hans-Joachim Widmaier - Rewritten
5  *
6  *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
7  *
8  *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
9  *
10  *  (C) 1991  Linus Torvalds - minix filesystem
11  *
12  *  affs regular file handling primitives
13  */
14
15 #include "affs.h"
16
17 #if PAGE_SIZE < 4096
18 #error PAGE_SIZE must be at least 4096
19 #endif
20
21 static int affs_grow_extcache(struct inode *inode, u32 lc_idx);
22 static struct buffer_head *affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext);
23 static inline struct buffer_head *affs_get_extblock(struct inode *inode, u32 ext);
24 static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
25 static int affs_file_open(struct inode *inode, struct file *filp);
26 static int affs_file_release(struct inode *inode, struct file *filp);
27
28 const struct file_operations affs_file_operations = {
29         .llseek         = generic_file_llseek,
30         .read           = do_sync_read,
31         .aio_read       = generic_file_aio_read,
32         .write          = do_sync_write,
33         .aio_write      = generic_file_aio_write,
34         .mmap           = generic_file_mmap,
35         .open           = affs_file_open,
36         .release        = affs_file_release,
37         .fsync          = file_fsync,
38         .splice_read    = generic_file_splice_read,
39 };
40
41 const struct inode_operations affs_file_inode_operations = {
42         .truncate       = affs_truncate,
43         .setattr        = affs_notify_change,
44 };
45
46 static int
47 affs_file_open(struct inode *inode, struct file *filp)
48 {
49         if (atomic_read(&filp->f_count) != 1)
50                 return 0;
51         pr_debug("AFFS: open(%lu,%d)\n",
52                  inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
53         atomic_inc(&AFFS_I(inode)->i_opencnt);
54         return 0;
55 }
56
57 static int
58 affs_file_release(struct inode *inode, struct file *filp)
59 {
60         if (atomic_read(&filp->f_count) != 0)
61                 return 0;
62         pr_debug("AFFS: release(%lu, %d)\n",
63                  inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
64
65         if (atomic_dec_and_test(&AFFS_I(inode)->i_opencnt)) {
66                 mutex_lock(&inode->i_mutex);
67                 if (inode->i_size != AFFS_I(inode)->mmu_private)
68                         affs_truncate(inode);
69                 affs_free_prealloc(inode);
70                 mutex_unlock(&inode->i_mutex);
71         }
72
73         return 0;
74 }
75
76 static int
77 affs_grow_extcache(struct inode *inode, u32 lc_idx)
78 {
79         struct super_block      *sb = inode->i_sb;
80         struct buffer_head      *bh;
81         u32 lc_max;
82         int i, j, key;
83
84         if (!AFFS_I(inode)->i_lc) {
85                 char *ptr = (char *)get_zeroed_page(GFP_NOFS);
86                 if (!ptr)
87                         return -ENOMEM;
88                 AFFS_I(inode)->i_lc = (u32 *)ptr;
89                 AFFS_I(inode)->i_ac = (struct affs_ext_key *)(ptr + AFFS_CACHE_SIZE / 2);
90         }
91
92         lc_max = AFFS_LC_SIZE << AFFS_I(inode)->i_lc_shift;
93
94         if (AFFS_I(inode)->i_extcnt > lc_max) {
95                 u32 lc_shift, lc_mask, tmp, off;
96
97                 /* need to recalculate linear cache, start from old size */
98                 lc_shift = AFFS_I(inode)->i_lc_shift;
99                 tmp = (AFFS_I(inode)->i_extcnt / AFFS_LC_SIZE) >> lc_shift;
100                 for (; tmp; tmp >>= 1)
101                         lc_shift++;
102                 lc_mask = (1 << lc_shift) - 1;
103
104                 /* fix idx and old size to new shift */
105                 lc_idx >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
106                 AFFS_I(inode)->i_lc_size >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
107
108                 /* first shrink old cache to make more space */
109                 off = 1 << (lc_shift - AFFS_I(inode)->i_lc_shift);
110                 for (i = 1, j = off; j < AFFS_LC_SIZE; i++, j += off)
111                         AFFS_I(inode)->i_ac[i] = AFFS_I(inode)->i_ac[j];
112
113                 AFFS_I(inode)->i_lc_shift = lc_shift;
114                 AFFS_I(inode)->i_lc_mask = lc_mask;
115         }
116
117         /* fill cache to the needed index */
118         i = AFFS_I(inode)->i_lc_size;
119         AFFS_I(inode)->i_lc_size = lc_idx + 1;
120         for (; i <= lc_idx; i++) {
121                 if (!i) {
122                         AFFS_I(inode)->i_lc[0] = inode->i_ino;
123                         continue;
124                 }
125                 key = AFFS_I(inode)->i_lc[i - 1];
126                 j = AFFS_I(inode)->i_lc_mask + 1;
127                 // unlock cache
128                 for (; j > 0; j--) {
129                         bh = affs_bread(sb, key);
130                         if (!bh)
131                                 goto err;
132                         key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
133                         affs_brelse(bh);
134                 }
135                 // lock cache
136                 AFFS_I(inode)->i_lc[i] = key;
137         }
138
139         return 0;
140
141 err:
142         // lock cache
143         return -EIO;
144 }
145
146 static struct buffer_head *
147 affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext)
148 {
149         struct super_block *sb = inode->i_sb;
150         struct buffer_head *new_bh;
151         u32 blocknr, tmp;
152
153         blocknr = affs_alloc_block(inode, bh->b_blocknr);
154         if (!blocknr)
155                 return ERR_PTR(-ENOSPC);
156
157         new_bh = affs_getzeroblk(sb, blocknr);
158         if (!new_bh) {
159                 affs_free_block(sb, blocknr);
160                 return ERR_PTR(-EIO);
161         }
162
163         AFFS_HEAD(new_bh)->ptype = cpu_to_be32(T_LIST);
164         AFFS_HEAD(new_bh)->key = cpu_to_be32(blocknr);
165         AFFS_TAIL(sb, new_bh)->stype = cpu_to_be32(ST_FILE);
166         AFFS_TAIL(sb, new_bh)->parent = cpu_to_be32(inode->i_ino);
167         affs_fix_checksum(sb, new_bh);
168
169         mark_buffer_dirty_inode(new_bh, inode);
170
171         tmp = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
172         if (tmp)
173                 affs_warning(sb, "alloc_ext", "previous extension set (%x)", tmp);
174         AFFS_TAIL(sb, bh)->extension = cpu_to_be32(blocknr);
175         affs_adjust_checksum(bh, blocknr - tmp);
176         mark_buffer_dirty_inode(bh, inode);
177
178         AFFS_I(inode)->i_extcnt++;
179         mark_inode_dirty(inode);
180
181         return new_bh;
182 }
183
184 static inline struct buffer_head *
185 affs_get_extblock(struct inode *inode, u32 ext)
186 {
187         /* inline the simplest case: same extended block as last time */
188         struct buffer_head *bh = AFFS_I(inode)->i_ext_bh;
189         if (ext == AFFS_I(inode)->i_ext_last)
190                 get_bh(bh);
191         else
192                 /* we have to do more (not inlined) */
193                 bh = affs_get_extblock_slow(inode, ext);
194
195         return bh;
196 }
197
198 static struct buffer_head *
199 affs_get_extblock_slow(struct inode *inode, u32 ext)
200 {
201         struct super_block *sb = inode->i_sb;
202         struct buffer_head *bh;
203         u32 ext_key;
204         u32 lc_idx, lc_off, ac_idx;
205         u32 tmp, idx;
206
207         if (ext == AFFS_I(inode)->i_ext_last + 1) {
208                 /* read the next extended block from the current one */
209                 bh = AFFS_I(inode)->i_ext_bh;
210                 ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
211                 if (ext < AFFS_I(inode)->i_extcnt)
212                         goto read_ext;
213                 if (ext > AFFS_I(inode)->i_extcnt)
214                         BUG();
215                 bh = affs_alloc_extblock(inode, bh, ext);
216                 if (IS_ERR(bh))
217                         return bh;
218                 goto store_ext;
219         }
220
221         if (ext == 0) {
222                 /* we seek back to the file header block */
223                 ext_key = inode->i_ino;
224                 goto read_ext;
225         }
226
227         if (ext >= AFFS_I(inode)->i_extcnt) {
228                 struct buffer_head *prev_bh;
229
230                 /* allocate a new extended block */
231                 if (ext > AFFS_I(inode)->i_extcnt)
232                         BUG();
233
234                 /* get previous extended block */
235                 prev_bh = affs_get_extblock(inode, ext - 1);
236                 if (IS_ERR(prev_bh))
237                         return prev_bh;
238                 bh = affs_alloc_extblock(inode, prev_bh, ext);
239                 affs_brelse(prev_bh);
240                 if (IS_ERR(bh))
241                         return bh;
242                 goto store_ext;
243         }
244
245 again:
246         /* check if there is an extended cache and whether it's large enough */
247         lc_idx = ext >> AFFS_I(inode)->i_lc_shift;
248         lc_off = ext & AFFS_I(inode)->i_lc_mask;
249
250         if (lc_idx >= AFFS_I(inode)->i_lc_size) {
251                 int err;
252
253                 err = affs_grow_extcache(inode, lc_idx);
254                 if (err)
255                         return ERR_PTR(err);
256                 goto again;
257         }
258
259         /* every n'th key we find in the linear cache */
260         if (!lc_off) {
261                 ext_key = AFFS_I(inode)->i_lc[lc_idx];
262                 goto read_ext;
263         }
264
265         /* maybe it's still in the associative cache */
266         ac_idx = (ext - lc_idx - 1) & AFFS_AC_MASK;
267         if (AFFS_I(inode)->i_ac[ac_idx].ext == ext) {
268                 ext_key = AFFS_I(inode)->i_ac[ac_idx].key;
269                 goto read_ext;
270         }
271
272         /* try to find one of the previous extended blocks */
273         tmp = ext;
274         idx = ac_idx;
275         while (--tmp, --lc_off > 0) {
276                 idx = (idx - 1) & AFFS_AC_MASK;
277                 if (AFFS_I(inode)->i_ac[idx].ext == tmp) {
278                         ext_key = AFFS_I(inode)->i_ac[idx].key;
279                         goto find_ext;
280                 }
281         }
282
283         /* fall back to the linear cache */
284         ext_key = AFFS_I(inode)->i_lc[lc_idx];
285 find_ext:
286         /* read all extended blocks until we find the one we need */
287         //unlock cache
288         do {
289                 bh = affs_bread(sb, ext_key);
290                 if (!bh)
291                         goto err_bread;
292                 ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
293                 affs_brelse(bh);
294                 tmp++;
295         } while (tmp < ext);
296         //lock cache
297
298         /* store it in the associative cache */
299         // recalculate ac_idx?
300         AFFS_I(inode)->i_ac[ac_idx].ext = ext;
301         AFFS_I(inode)->i_ac[ac_idx].key = ext_key;
302
303 read_ext:
304         /* finally read the right extended block */
305         //unlock cache
306         bh = affs_bread(sb, ext_key);
307         if (!bh)
308                 goto err_bread;
309         //lock cache
310
311 store_ext:
312         /* release old cached extended block and store the new one */
313         affs_brelse(AFFS_I(inode)->i_ext_bh);
314         AFFS_I(inode)->i_ext_last = ext;
315         AFFS_I(inode)->i_ext_bh = bh;
316         get_bh(bh);
317
318         return bh;
319
320 err_bread:
321         affs_brelse(bh);
322         return ERR_PTR(-EIO);
323 }
324
325 static int
326 affs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh_result, int create)
327 {
328         struct super_block      *sb = inode->i_sb;
329         struct buffer_head      *ext_bh;
330         u32                      ext;
331
332         pr_debug("AFFS: get_block(%u, %lu)\n", (u32)inode->i_ino, (unsigned long)block);
333
334         BUG_ON(block > (sector_t)0x7fffffffUL);
335
336         if (block >= AFFS_I(inode)->i_blkcnt) {
337                 if (block > AFFS_I(inode)->i_blkcnt || !create)
338                         goto err_big;
339         } else
340                 create = 0;
341
342         //lock cache
343         affs_lock_ext(inode);
344
345         ext = (u32)block / AFFS_SB(sb)->s_hashsize;
346         block -= ext * AFFS_SB(sb)->s_hashsize;
347         ext_bh = affs_get_extblock(inode, ext);
348         if (IS_ERR(ext_bh))
349                 goto err_ext;
350         map_bh(bh_result, sb, (sector_t)be32_to_cpu(AFFS_BLOCK(sb, ext_bh, block)));
351
352         if (create) {
353                 u32 blocknr = affs_alloc_block(inode, ext_bh->b_blocknr);
354                 if (!blocknr)
355                         goto err_alloc;
356                 set_buffer_new(bh_result);
357                 AFFS_I(inode)->mmu_private += AFFS_SB(sb)->s_data_blksize;
358                 AFFS_I(inode)->i_blkcnt++;
359
360                 /* store new block */
361                 if (bh_result->b_blocknr)
362                         affs_warning(sb, "get_block", "block already set (%x)", bh_result->b_blocknr);
363                 AFFS_BLOCK(sb, ext_bh, block) = cpu_to_be32(blocknr);
364                 AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(block + 1);
365                 affs_adjust_checksum(ext_bh, blocknr - bh_result->b_blocknr + 1);
366                 bh_result->b_blocknr = blocknr;
367
368                 if (!block) {
369                         /* insert first block into header block */
370                         u32 tmp = be32_to_cpu(AFFS_HEAD(ext_bh)->first_data);
371                         if (tmp)
372                                 affs_warning(sb, "get_block", "first block already set (%d)", tmp);
373                         AFFS_HEAD(ext_bh)->first_data = cpu_to_be32(blocknr);
374                         affs_adjust_checksum(ext_bh, blocknr - tmp);
375                 }
376         }
377
378         affs_brelse(ext_bh);
379         //unlock cache
380         affs_unlock_ext(inode);
381         return 0;
382
383 err_big:
384         affs_error(inode->i_sb,"get_block","strange block request %d", block);
385         return -EIO;
386 err_ext:
387         // unlock cache
388         affs_unlock_ext(inode);
389         return PTR_ERR(ext_bh);
390 err_alloc:
391         brelse(ext_bh);
392         clear_buffer_mapped(bh_result);
393         bh_result->b_bdev = NULL;
394         // unlock cache
395         affs_unlock_ext(inode);
396         return -ENOSPC;
397 }
398
399 static int affs_writepage(struct page *page, struct writeback_control *wbc)
400 {
401         return block_write_full_page(page, affs_get_block, wbc);
402 }
403
404 static int affs_readpage(struct file *file, struct page *page)
405 {
406         return block_read_full_page(page, affs_get_block);
407 }
408
409 static int affs_write_begin(struct file *file, struct address_space *mapping,
410                         loff_t pos, unsigned len, unsigned flags,
411                         struct page **pagep, void **fsdata)
412 {
413         *pagep = NULL;
414         return cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
415                                 affs_get_block,
416                                 &AFFS_I(mapping->host)->mmu_private);
417 }
418
419 static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
420 {
421         return generic_block_bmap(mapping,block,affs_get_block);
422 }
423
424 const struct address_space_operations affs_aops = {
425         .readpage = affs_readpage,
426         .writepage = affs_writepage,
427         .sync_page = block_sync_page,
428         .write_begin = affs_write_begin,
429         .write_end = generic_write_end,
430         .bmap = _affs_bmap
431 };
432
433 static inline struct buffer_head *
434 affs_bread_ino(struct inode *inode, int block, int create)
435 {
436         struct buffer_head *bh, tmp_bh;
437         int err;
438
439         tmp_bh.b_state = 0;
440         err = affs_get_block(inode, block, &tmp_bh, create);
441         if (!err) {
442                 bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
443                 if (bh) {
444                         bh->b_state |= tmp_bh.b_state;
445                         return bh;
446                 }
447                 err = -EIO;
448         }
449         return ERR_PTR(err);
450 }
451
452 static inline struct buffer_head *
453 affs_getzeroblk_ino(struct inode *inode, int block)
454 {
455         struct buffer_head *bh, tmp_bh;
456         int err;
457
458         tmp_bh.b_state = 0;
459         err = affs_get_block(inode, block, &tmp_bh, 1);
460         if (!err) {
461                 bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
462                 if (bh) {
463                         bh->b_state |= tmp_bh.b_state;
464                         return bh;
465                 }
466                 err = -EIO;
467         }
468         return ERR_PTR(err);
469 }
470
471 static inline struct buffer_head *
472 affs_getemptyblk_ino(struct inode *inode, int block)
473 {
474         struct buffer_head *bh, tmp_bh;
475         int err;
476
477         tmp_bh.b_state = 0;
478         err = affs_get_block(inode, block, &tmp_bh, 1);
479         if (!err) {
480                 bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
481                 if (bh) {
482                         bh->b_state |= tmp_bh.b_state;
483                         return bh;
484                 }
485                 err = -EIO;
486         }
487         return ERR_PTR(err);
488 }
489
490 static int
491 affs_do_readpage_ofs(struct file *file, struct page *page, unsigned from, unsigned to)
492 {
493         struct inode *inode = page->mapping->host;
494         struct super_block *sb = inode->i_sb;
495         struct buffer_head *bh;
496         char *data;
497         u32 bidx, boff, bsize;
498         u32 tmp;
499
500         pr_debug("AFFS: read_page(%u, %ld, %d, %d)\n", (u32)inode->i_ino, page->index, from, to);
501         BUG_ON(from > to || to > PAGE_CACHE_SIZE);
502         kmap(page);
503         data = page_address(page);
504         bsize = AFFS_SB(sb)->s_data_blksize;
505         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
506         bidx = tmp / bsize;
507         boff = tmp % bsize;
508
509         while (from < to) {
510                 bh = affs_bread_ino(inode, bidx, 0);
511                 if (IS_ERR(bh))
512                         return PTR_ERR(bh);
513                 tmp = min(bsize - boff, to - from);
514                 BUG_ON(from + tmp > to || tmp > bsize);
515                 memcpy(data + from, AFFS_DATA(bh) + boff, tmp);
516                 affs_brelse(bh);
517                 bidx++;
518                 from += tmp;
519                 boff = 0;
520         }
521         flush_dcache_page(page);
522         kunmap(page);
523         return 0;
524 }
525
526 static int
527 affs_extent_file_ofs(struct inode *inode, u32 newsize)
528 {
529         struct super_block *sb = inode->i_sb;
530         struct buffer_head *bh, *prev_bh;
531         u32 bidx, boff;
532         u32 size, bsize;
533         u32 tmp;
534
535         pr_debug("AFFS: extent_file(%u, %d)\n", (u32)inode->i_ino, newsize);
536         bsize = AFFS_SB(sb)->s_data_blksize;
537         bh = NULL;
538         size = AFFS_I(inode)->mmu_private;
539         bidx = size / bsize;
540         boff = size % bsize;
541         if (boff) {
542                 bh = affs_bread_ino(inode, bidx, 0);
543                 if (IS_ERR(bh))
544                         return PTR_ERR(bh);
545                 tmp = min(bsize - boff, newsize - size);
546                 BUG_ON(boff + tmp > bsize || tmp > bsize);
547                 memset(AFFS_DATA(bh) + boff, 0, tmp);
548                 be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
549                 affs_fix_checksum(sb, bh);
550                 mark_buffer_dirty_inode(bh, inode);
551                 size += tmp;
552                 bidx++;
553         } else if (bidx) {
554                 bh = affs_bread_ino(inode, bidx - 1, 0);
555                 if (IS_ERR(bh))
556                         return PTR_ERR(bh);
557         }
558
559         while (size < newsize) {
560                 prev_bh = bh;
561                 bh = affs_getzeroblk_ino(inode, bidx);
562                 if (IS_ERR(bh))
563                         goto out;
564                 tmp = min(bsize, newsize - size);
565                 BUG_ON(tmp > bsize);
566                 AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
567                 AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
568                 AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
569                 AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
570                 affs_fix_checksum(sb, bh);
571                 bh->b_state &= ~(1UL << BH_New);
572                 mark_buffer_dirty_inode(bh, inode);
573                 if (prev_bh) {
574                         u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
575                         if (tmp)
576                                 affs_warning(sb, "extent_file_ofs", "next block already set for %d (%d)", bidx, tmp);
577                         AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
578                         affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
579                         mark_buffer_dirty_inode(prev_bh, inode);
580                         affs_brelse(prev_bh);
581                 }
582                 size += bsize;
583                 bidx++;
584         }
585         affs_brelse(bh);
586         inode->i_size = AFFS_I(inode)->mmu_private = newsize;
587         return 0;
588
589 out:
590         inode->i_size = AFFS_I(inode)->mmu_private = newsize;
591         return PTR_ERR(bh);
592 }
593
594 static int
595 affs_readpage_ofs(struct file *file, struct page *page)
596 {
597         struct inode *inode = page->mapping->host;
598         u32 to;
599         int err;
600
601         pr_debug("AFFS: read_page(%u, %ld)\n", (u32)inode->i_ino, page->index);
602         to = PAGE_CACHE_SIZE;
603         if (((page->index + 1) << PAGE_CACHE_SHIFT) > inode->i_size) {
604                 to = inode->i_size & ~PAGE_CACHE_MASK;
605                 memset(page_address(page) + to, 0, PAGE_CACHE_SIZE - to);
606         }
607
608         err = affs_do_readpage_ofs(file, page, 0, to);
609         if (!err)
610                 SetPageUptodate(page);
611         unlock_page(page);
612         return err;
613 }
614
615 static int affs_write_begin_ofs(struct file *file, struct address_space *mapping,
616                                 loff_t pos, unsigned len, unsigned flags,
617                                 struct page **pagep, void **fsdata)
618 {
619         struct inode *inode = mapping->host;
620         struct page *page;
621         pgoff_t index;
622         int err = 0;
623
624         pr_debug("AFFS: write_begin(%u, %llu, %llu)\n", (u32)inode->i_ino, (unsigned long long)pos, (unsigned long long)pos + len);
625         if (pos > AFFS_I(inode)->mmu_private) {
626                 /* XXX: this probably leaves a too-big i_size in case of
627                  * failure. Should really be updating i_size at write_end time
628                  */
629                 err = affs_extent_file_ofs(inode, pos);
630                 if (err)
631                         return err;
632         }
633
634         index = pos >> PAGE_CACHE_SHIFT;
635         page = __grab_cache_page(mapping, index);
636         if (!page)
637                 return -ENOMEM;
638         *pagep = page;
639
640         if (PageUptodate(page))
641                 return 0;
642
643         /* XXX: inefficient but safe in the face of short writes */
644         err = affs_do_readpage_ofs(file, page, 0, PAGE_CACHE_SIZE);
645         if (err) {
646                 unlock_page(page);
647                 page_cache_release(page);
648         }
649         return err;
650 }
651
652 static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
653                                 loff_t pos, unsigned len, unsigned copied,
654                                 struct page *page, void *fsdata)
655 {
656         struct inode *inode = mapping->host;
657         struct super_block *sb = inode->i_sb;
658         struct buffer_head *bh, *prev_bh;
659         char *data;
660         u32 bidx, boff, bsize;
661         unsigned from, to;
662         u32 tmp;
663         int written;
664
665         from = pos & (PAGE_CACHE_SIZE - 1);
666         to = pos + len;
667         /*
668          * XXX: not sure if this can handle short copies (len < copied), but
669          * we don't have to, because the page should always be uptodate here,
670          * due to write_begin.
671          */
672
673         pr_debug("AFFS: write_begin(%u, %llu, %llu)\n", (u32)inode->i_ino, (unsigned long long)pos, (unsigned long long)pos + len);
674         bsize = AFFS_SB(sb)->s_data_blksize;
675         data = page_address(page);
676
677         bh = NULL;
678         written = 0;
679         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
680         bidx = tmp / bsize;
681         boff = tmp % bsize;
682         if (boff) {
683                 bh = affs_bread_ino(inode, bidx, 0);
684                 if (IS_ERR(bh))
685                         return PTR_ERR(bh);
686                 tmp = min(bsize - boff, to - from);
687                 BUG_ON(boff + tmp > bsize || tmp > bsize);
688                 memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
689                 be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
690                 affs_fix_checksum(sb, bh);
691                 mark_buffer_dirty_inode(bh, inode);
692                 written += tmp;
693                 from += tmp;
694                 bidx++;
695         } else if (bidx) {
696                 bh = affs_bread_ino(inode, bidx - 1, 0);
697                 if (IS_ERR(bh))
698                         return PTR_ERR(bh);
699         }
700         while (from + bsize <= to) {
701                 prev_bh = bh;
702                 bh = affs_getemptyblk_ino(inode, bidx);
703                 if (IS_ERR(bh))
704                         goto out;
705                 memcpy(AFFS_DATA(bh), data + from, bsize);
706                 if (buffer_new(bh)) {
707                         AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
708                         AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
709                         AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
710                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
711                         AFFS_DATA_HEAD(bh)->next = 0;
712                         bh->b_state &= ~(1UL << BH_New);
713                         if (prev_bh) {
714                                 u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
715                                 if (tmp)
716                                         affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
717                                 AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
718                                 affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
719                                 mark_buffer_dirty_inode(prev_bh, inode);
720                         }
721                 }
722                 affs_brelse(prev_bh);
723                 affs_fix_checksum(sb, bh);
724                 mark_buffer_dirty_inode(bh, inode);
725                 written += bsize;
726                 from += bsize;
727                 bidx++;
728         }
729         if (from < to) {
730                 prev_bh = bh;
731                 bh = affs_bread_ino(inode, bidx, 1);
732                 if (IS_ERR(bh))
733                         goto out;
734                 tmp = min(bsize, to - from);
735                 BUG_ON(tmp > bsize);
736                 memcpy(AFFS_DATA(bh), data + from, tmp);
737                 if (buffer_new(bh)) {
738                         AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
739                         AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
740                         AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
741                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
742                         AFFS_DATA_HEAD(bh)->next = 0;
743                         bh->b_state &= ~(1UL << BH_New);
744                         if (prev_bh) {
745                                 u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
746                                 if (tmp)
747                                         affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
748                                 AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
749                                 affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
750                                 mark_buffer_dirty_inode(prev_bh, inode);
751                         }
752                 } else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
753                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
754                 affs_brelse(prev_bh);
755                 affs_fix_checksum(sb, bh);
756                 mark_buffer_dirty_inode(bh, inode);
757                 written += tmp;
758                 from += tmp;
759                 bidx++;
760         }
761         SetPageUptodate(page);
762
763 done:
764         affs_brelse(bh);
765         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
766         if (tmp > inode->i_size)
767                 inode->i_size = AFFS_I(inode)->mmu_private = tmp;
768
769         unlock_page(page);
770         page_cache_release(page);
771
772         return written;
773
774 out:
775         bh = prev_bh;
776         if (!written)
777                 written = PTR_ERR(bh);
778         goto done;
779 }
780
781 const struct address_space_operations affs_aops_ofs = {
782         .readpage = affs_readpage_ofs,
783         //.writepage = affs_writepage_ofs,
784         //.sync_page = affs_sync_page_ofs,
785         .write_begin = affs_write_begin_ofs,
786         .write_end = affs_write_end_ofs
787 };
788
789 /* Free any preallocated blocks. */
790
791 void
792 affs_free_prealloc(struct inode *inode)
793 {
794         struct super_block *sb = inode->i_sb;
795
796         pr_debug("AFFS: free_prealloc(ino=%lu)\n", inode->i_ino);
797
798         while (AFFS_I(inode)->i_pa_cnt) {
799                 AFFS_I(inode)->i_pa_cnt--;
800                 affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
801         }
802 }
803
804 /* Truncate (or enlarge) a file to the requested size. */
805
806 void
807 affs_truncate(struct inode *inode)
808 {
809         struct super_block *sb = inode->i_sb;
810         u32 ext, ext_key;
811         u32 last_blk, blkcnt, blk;
812         u32 size;
813         struct buffer_head *ext_bh;
814         int i;
815
816         pr_debug("AFFS: truncate(inode=%d, oldsize=%u, newsize=%u)\n",
817                  (u32)inode->i_ino, (u32)AFFS_I(inode)->mmu_private, (u32)inode->i_size);
818
819         last_blk = 0;
820         ext = 0;
821         if (inode->i_size) {
822                 last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
823                 ext = last_blk / AFFS_SB(sb)->s_hashsize;
824         }
825
826         if (inode->i_size > AFFS_I(inode)->mmu_private) {
827                 struct address_space *mapping = inode->i_mapping;
828                 struct page *page;
829                 void *fsdata;
830                 u32 size = inode->i_size;
831                 int res;
832
833                 res = mapping->a_ops->write_begin(NULL, mapping, size, 0, 0, &page, &fsdata);
834                 if (!res)
835                         res = mapping->a_ops->write_end(NULL, mapping, size, 0, 0, page, fsdata);
836                 else
837                         inode->i_size = AFFS_I(inode)->mmu_private;
838                 mark_inode_dirty(inode);
839                 return;
840         } else if (inode->i_size == AFFS_I(inode)->mmu_private)
841                 return;
842
843         // lock cache
844         ext_bh = affs_get_extblock(inode, ext);
845         if (IS_ERR(ext_bh)) {
846                 affs_warning(sb, "truncate", "unexpected read error for ext block %u (%d)",
847                              ext, PTR_ERR(ext_bh));
848                 return;
849         }
850         if (AFFS_I(inode)->i_lc) {
851                 /* clear linear cache */
852                 i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
853                 if (AFFS_I(inode)->i_lc_size > i) {
854                         AFFS_I(inode)->i_lc_size = i;
855                         for (; i < AFFS_LC_SIZE; i++)
856                                 AFFS_I(inode)->i_lc[i] = 0;
857                 }
858                 /* clear associative cache */
859                 for (i = 0; i < AFFS_AC_SIZE; i++)
860                         if (AFFS_I(inode)->i_ac[i].ext >= ext)
861                                 AFFS_I(inode)->i_ac[i].ext = 0;
862         }
863         ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
864
865         blkcnt = AFFS_I(inode)->i_blkcnt;
866         i = 0;
867         blk = last_blk;
868         if (inode->i_size) {
869                 i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
870                 blk++;
871         } else
872                 AFFS_HEAD(ext_bh)->first_data = 0;
873         AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
874         size = AFFS_SB(sb)->s_hashsize;
875         if (size > blkcnt - blk + i)
876                 size = blkcnt - blk + i;
877         for (; i < size; i++, blk++) {
878                 affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
879                 AFFS_BLOCK(sb, ext_bh, i) = 0;
880         }
881         AFFS_TAIL(sb, ext_bh)->extension = 0;
882         affs_fix_checksum(sb, ext_bh);
883         mark_buffer_dirty_inode(ext_bh, inode);
884         affs_brelse(ext_bh);
885
886         if (inode->i_size) {
887                 AFFS_I(inode)->i_blkcnt = last_blk + 1;
888                 AFFS_I(inode)->i_extcnt = ext + 1;
889                 if (AFFS_SB(sb)->s_flags & SF_OFS) {
890                         struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
891                         u32 tmp;
892                         if (IS_ERR(ext_bh)) {
893                                 affs_warning(sb, "truncate", "unexpected read error for last block %u (%d)",
894                                              ext, PTR_ERR(ext_bh));
895                                 return;
896                         }
897                         tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
898                         AFFS_DATA_HEAD(bh)->next = 0;
899                         affs_adjust_checksum(bh, -tmp);
900                         affs_brelse(bh);
901                 }
902         } else {
903                 AFFS_I(inode)->i_blkcnt = 0;
904                 AFFS_I(inode)->i_extcnt = 1;
905         }
906         AFFS_I(inode)->mmu_private = inode->i_size;
907         // unlock cache
908
909         while (ext_key) {
910                 ext_bh = affs_bread(sb, ext_key);
911                 size = AFFS_SB(sb)->s_hashsize;
912                 if (size > blkcnt - blk)
913                         size = blkcnt - blk;
914                 for (i = 0; i < size; i++, blk++)
915                         affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
916                 affs_free_block(sb, ext_key);
917                 ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
918                 affs_brelse(ext_bh);
919         }
920         affs_free_prealloc(inode);
921 }