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TOMOYO Linux Cross Reference
Linux/fs/affs/file.c

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  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          = affs_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         pr_debug("AFFS: open(%lu,%d)\n",
 50                  inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
 51         atomic_inc(&AFFS_I(inode)->i_opencnt);
 52         return 0;
 53 }
 54 
 55 static int
 56 affs_file_release(struct inode *inode, struct file *filp)
 57 {
 58         pr_debug("AFFS: release(%lu, %d)\n",
 59                  inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
 60 
 61         if (atomic_dec_and_test(&AFFS_I(inode)->i_opencnt)) {
 62                 mutex_lock(&inode->i_mutex);
 63                 if (inode->i_size != AFFS_I(inode)->mmu_private)
 64                         affs_truncate(inode);
 65                 affs_free_prealloc(inode);
 66                 mutex_unlock(&inode->i_mutex);
 67         }
 68 
 69         return 0;
 70 }
 71 
 72 static int
 73 affs_grow_extcache(struct inode *inode, u32 lc_idx)
 74 {
 75         struct super_block      *sb = inode->i_sb;
 76         struct buffer_head      *bh;
 77         u32 lc_max;
 78         int i, j, key;
 79 
 80         if (!AFFS_I(inode)->i_lc) {
 81                 char *ptr = (char *)get_zeroed_page(GFP_NOFS);
 82                 if (!ptr)
 83                         return -ENOMEM;
 84                 AFFS_I(inode)->i_lc = (u32 *)ptr;
 85                 AFFS_I(inode)->i_ac = (struct affs_ext_key *)(ptr + AFFS_CACHE_SIZE / 2);
 86         }
 87 
 88         lc_max = AFFS_LC_SIZE << AFFS_I(inode)->i_lc_shift;
 89 
 90         if (AFFS_I(inode)->i_extcnt > lc_max) {
 91                 u32 lc_shift, lc_mask, tmp, off;
 92 
 93                 /* need to recalculate linear cache, start from old size */
 94                 lc_shift = AFFS_I(inode)->i_lc_shift;
 95                 tmp = (AFFS_I(inode)->i_extcnt / AFFS_LC_SIZE) >> lc_shift;
 96                 for (; tmp; tmp >>= 1)
 97                         lc_shift++;
 98                 lc_mask = (1 << lc_shift) - 1;
 99 
100                 /* fix idx and old size to new shift */
101                 lc_idx >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
102                 AFFS_I(inode)->i_lc_size >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
103 
104                 /* first shrink old cache to make more space */
105                 off = 1 << (lc_shift - AFFS_I(inode)->i_lc_shift);
106                 for (i = 1, j = off; j < AFFS_LC_SIZE; i++, j += off)
107                         AFFS_I(inode)->i_ac[i] = AFFS_I(inode)->i_ac[j];
108 
109                 AFFS_I(inode)->i_lc_shift = lc_shift;
110                 AFFS_I(inode)->i_lc_mask = lc_mask;
111         }
112 
113         /* fill cache to the needed index */
114         i = AFFS_I(inode)->i_lc_size;
115         AFFS_I(inode)->i_lc_size = lc_idx + 1;
116         for (; i <= lc_idx; i++) {
117                 if (!i) {
118                         AFFS_I(inode)->i_lc[0] = inode->i_ino;
119                         continue;
120                 }
121                 key = AFFS_I(inode)->i_lc[i - 1];
122                 j = AFFS_I(inode)->i_lc_mask + 1;
123                 // unlock cache
124                 for (; j > 0; j--) {
125                         bh = affs_bread(sb, key);
126                         if (!bh)
127                                 goto err;
128                         key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
129                         affs_brelse(bh);
130                 }
131                 // lock cache
132                 AFFS_I(inode)->i_lc[i] = key;
133         }
134 
135         return 0;
136 
137 err:
138         // lock cache
139         return -EIO;
140 }
141 
142 static struct buffer_head *
143 affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext)
144 {
145         struct super_block *sb = inode->i_sb;
146         struct buffer_head *new_bh;
147         u32 blocknr, tmp;
148 
149         blocknr = affs_alloc_block(inode, bh->b_blocknr);
150         if (!blocknr)
151                 return ERR_PTR(-ENOSPC);
152 
153         new_bh = affs_getzeroblk(sb, blocknr);
154         if (!new_bh) {
155                 affs_free_block(sb, blocknr);
156                 return ERR_PTR(-EIO);
157         }
158 
159         AFFS_HEAD(new_bh)->ptype = cpu_to_be32(T_LIST);
160         AFFS_HEAD(new_bh)->key = cpu_to_be32(blocknr);
161         AFFS_TAIL(sb, new_bh)->stype = cpu_to_be32(ST_FILE);
162         AFFS_TAIL(sb, new_bh)->parent = cpu_to_be32(inode->i_ino);
163         affs_fix_checksum(sb, new_bh);
164 
165         mark_buffer_dirty_inode(new_bh, inode);
166 
167         tmp = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
168         if (tmp)
169                 affs_warning(sb, "alloc_ext", "previous extension set (%x)", tmp);
170         AFFS_TAIL(sb, bh)->extension = cpu_to_be32(blocknr);
171         affs_adjust_checksum(bh, blocknr - tmp);
172         mark_buffer_dirty_inode(bh, inode);
173 
174         AFFS_I(inode)->i_extcnt++;
175         mark_inode_dirty(inode);
176 
177         return new_bh;
178 }
179 
180 static inline struct buffer_head *
181 affs_get_extblock(struct inode *inode, u32 ext)
182 {
183         /* inline the simplest case: same extended block as last time */
184         struct buffer_head *bh = AFFS_I(inode)->i_ext_bh;
185         if (ext == AFFS_I(inode)->i_ext_last)
186                 get_bh(bh);
187         else
188                 /* we have to do more (not inlined) */
189                 bh = affs_get_extblock_slow(inode, ext);
190 
191         return bh;
192 }
193 
194 static struct buffer_head *
195 affs_get_extblock_slow(struct inode *inode, u32 ext)
196 {
197         struct super_block *sb = inode->i_sb;
198         struct buffer_head *bh;
199         u32 ext_key;
200         u32 lc_idx, lc_off, ac_idx;
201         u32 tmp, idx;
202 
203         if (ext == AFFS_I(inode)->i_ext_last + 1) {
204                 /* read the next extended block from the current one */
205                 bh = AFFS_I(inode)->i_ext_bh;
206                 ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
207                 if (ext < AFFS_I(inode)->i_extcnt)
208                         goto read_ext;
209                 if (ext > AFFS_I(inode)->i_extcnt)
210                         BUG();
211                 bh = affs_alloc_extblock(inode, bh, ext);
212                 if (IS_ERR(bh))
213                         return bh;
214                 goto store_ext;
215         }
216 
217         if (ext == 0) {
218                 /* we seek back to the file header block */
219                 ext_key = inode->i_ino;
220                 goto read_ext;
221         }
222 
223         if (ext >= AFFS_I(inode)->i_extcnt) {
224                 struct buffer_head *prev_bh;
225 
226                 /* allocate a new extended block */
227                 if (ext > AFFS_I(inode)->i_extcnt)
228                         BUG();
229 
230                 /* get previous extended block */
231                 prev_bh = affs_get_extblock(inode, ext - 1);
232                 if (IS_ERR(prev_bh))
233                         return prev_bh;
234                 bh = affs_alloc_extblock(inode, prev_bh, ext);
235                 affs_brelse(prev_bh);
236                 if (IS_ERR(bh))
237                         return bh;
238                 goto store_ext;
239         }
240 
241 again:
242         /* check if there is an extended cache and whether it's large enough */
243         lc_idx = ext >> AFFS_I(inode)->i_lc_shift;
244         lc_off = ext & AFFS_I(inode)->i_lc_mask;
245 
246         if (lc_idx >= AFFS_I(inode)->i_lc_size) {
247                 int err;
248 
249                 err = affs_grow_extcache(inode, lc_idx);
250                 if (err)
251                         return ERR_PTR(err);
252                 goto again;
253         }
254 
255         /* every n'th key we find in the linear cache */
256         if (!lc_off) {
257                 ext_key = AFFS_I(inode)->i_lc[lc_idx];
258                 goto read_ext;
259         }
260 
261         /* maybe it's still in the associative cache */
262         ac_idx = (ext - lc_idx - 1) & AFFS_AC_MASK;
263         if (AFFS_I(inode)->i_ac[ac_idx].ext == ext) {
264                 ext_key = AFFS_I(inode)->i_ac[ac_idx].key;
265                 goto read_ext;
266         }
267 
268         /* try to find one of the previous extended blocks */
269         tmp = ext;
270         idx = ac_idx;
271         while (--tmp, --lc_off > 0) {
272                 idx = (idx - 1) & AFFS_AC_MASK;
273                 if (AFFS_I(inode)->i_ac[idx].ext == tmp) {
274                         ext_key = AFFS_I(inode)->i_ac[idx].key;
275                         goto find_ext;
276                 }
277         }
278 
279         /* fall back to the linear cache */
280         ext_key = AFFS_I(inode)->i_lc[lc_idx];
281 find_ext:
282         /* read all extended blocks until we find the one we need */
283         //unlock cache
284         do {
285                 bh = affs_bread(sb, ext_key);
286                 if (!bh)
287                         goto err_bread;
288                 ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
289                 affs_brelse(bh);
290                 tmp++;
291         } while (tmp < ext);
292         //lock cache
293 
294         /* store it in the associative cache */
295         // recalculate ac_idx?
296         AFFS_I(inode)->i_ac[ac_idx].ext = ext;
297         AFFS_I(inode)->i_ac[ac_idx].key = ext_key;
298 
299 read_ext:
300         /* finally read the right extended block */
301         //unlock cache
302         bh = affs_bread(sb, ext_key);
303         if (!bh)
304                 goto err_bread;
305         //lock cache
306 
307 store_ext:
308         /* release old cached extended block and store the new one */
309         affs_brelse(AFFS_I(inode)->i_ext_bh);
310         AFFS_I(inode)->i_ext_last = ext;
311         AFFS_I(inode)->i_ext_bh = bh;
312         get_bh(bh);
313 
314         return bh;
315 
316 err_bread:
317         affs_brelse(bh);
318         return ERR_PTR(-EIO);
319 }
320 
321 static int
322 affs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh_result, int create)
323 {
324         struct super_block      *sb = inode->i_sb;
325         struct buffer_head      *ext_bh;
326         u32                      ext;
327 
328         pr_debug("AFFS: get_block(%u, %lu)\n", (u32)inode->i_ino, (unsigned long)block);
329 
330         BUG_ON(block > (sector_t)0x7fffffffUL);
331 
332         if (block >= AFFS_I(inode)->i_blkcnt) {
333                 if (block > AFFS_I(inode)->i_blkcnt || !create)
334                         goto err_big;
335         } else
336                 create = 0;
337 
338         //lock cache
339         affs_lock_ext(inode);
340 
341         ext = (u32)block / AFFS_SB(sb)->s_hashsize;
342         block -= ext * AFFS_SB(sb)->s_hashsize;
343         ext_bh = affs_get_extblock(inode, ext);
344         if (IS_ERR(ext_bh))
345                 goto err_ext;
346         map_bh(bh_result, sb, (sector_t)be32_to_cpu(AFFS_BLOCK(sb, ext_bh, block)));
347 
348         if (create) {
349                 u32 blocknr = affs_alloc_block(inode, ext_bh->b_blocknr);
350                 if (!blocknr)
351                         goto err_alloc;
352                 set_buffer_new(bh_result);
353                 AFFS_I(inode)->mmu_private += AFFS_SB(sb)->s_data_blksize;
354                 AFFS_I(inode)->i_blkcnt++;
355 
356                 /* store new block */
357                 if (bh_result->b_blocknr)
358                         affs_warning(sb, "get_block", "block already set (%x)", bh_result->b_blocknr);
359                 AFFS_BLOCK(sb, ext_bh, block) = cpu_to_be32(blocknr);
360                 AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(block + 1);
361                 affs_adjust_checksum(ext_bh, blocknr - bh_result->b_blocknr + 1);
362                 bh_result->b_blocknr = blocknr;
363 
364                 if (!block) {
365                         /* insert first block into header block */
366                         u32 tmp = be32_to_cpu(AFFS_HEAD(ext_bh)->first_data);
367                         if (tmp)
368                                 affs_warning(sb, "get_block", "first block already set (%d)", tmp);
369                         AFFS_HEAD(ext_bh)->first_data = cpu_to_be32(blocknr);
370                         affs_adjust_checksum(ext_bh, blocknr - tmp);
371                 }
372         }
373 
374         affs_brelse(ext_bh);
375         //unlock cache
376         affs_unlock_ext(inode);
377         return 0;
378 
379 err_big:
380         affs_error(inode->i_sb,"get_block","strange block request %d", block);
381         return -EIO;
382 err_ext:
383         // unlock cache
384         affs_unlock_ext(inode);
385         return PTR_ERR(ext_bh);
386 err_alloc:
387         brelse(ext_bh);
388         clear_buffer_mapped(bh_result);
389         bh_result->b_bdev = NULL;
390         // unlock cache
391         affs_unlock_ext(inode);
392         return -ENOSPC;
393 }
394 
395 static int affs_writepage(struct page *page, struct writeback_control *wbc)
396 {
397         return block_write_full_page(page, affs_get_block, wbc);
398 }
399 
400 static int affs_readpage(struct file *file, struct page *page)
401 {
402         return block_read_full_page(page, affs_get_block);
403 }
404 
405 static int affs_write_begin(struct file *file, struct address_space *mapping,
406                         loff_t pos, unsigned len, unsigned flags,
407                         struct page **pagep, void **fsdata)
408 {
409         *pagep = NULL;
410         return cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
411                                 affs_get_block,
412                                 &AFFS_I(mapping->host)->mmu_private);
413 }
414 
415 static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
416 {
417         return generic_block_bmap(mapping,block,affs_get_block);
418 }
419 
420 const struct address_space_operations affs_aops = {
421         .readpage = affs_readpage,
422         .writepage = affs_writepage,
423         .sync_page = block_sync_page,
424         .write_begin = affs_write_begin,
425         .write_end = generic_write_end,
426         .bmap = _affs_bmap
427 };
428 
429 static inline struct buffer_head *
430 affs_bread_ino(struct inode *inode, int block, int create)
431 {
432         struct buffer_head *bh, tmp_bh;
433         int err;
434 
435         tmp_bh.b_state = 0;
436         err = affs_get_block(inode, block, &tmp_bh, create);
437         if (!err) {
438                 bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
439                 if (bh) {
440                         bh->b_state |= tmp_bh.b_state;
441                         return bh;
442                 }
443                 err = -EIO;
444         }
445         return ERR_PTR(err);
446 }
447 
448 static inline struct buffer_head *
449 affs_getzeroblk_ino(struct inode *inode, int block)
450 {
451         struct buffer_head *bh, tmp_bh;
452         int err;
453 
454         tmp_bh.b_state = 0;
455         err = affs_get_block(inode, block, &tmp_bh, 1);
456         if (!err) {
457                 bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
458                 if (bh) {
459                         bh->b_state |= tmp_bh.b_state;
460                         return bh;
461                 }
462                 err = -EIO;
463         }
464         return ERR_PTR(err);
465 }
466 
467 static inline struct buffer_head *
468 affs_getemptyblk_ino(struct inode *inode, int block)
469 {
470         struct buffer_head *bh, tmp_bh;
471         int err;
472 
473         tmp_bh.b_state = 0;
474         err = affs_get_block(inode, block, &tmp_bh, 1);
475         if (!err) {
476                 bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
477                 if (bh) {
478                         bh->b_state |= tmp_bh.b_state;
479                         return bh;
480                 }
481                 err = -EIO;
482         }
483         return ERR_PTR(err);
484 }
485 
486 static int
487 affs_do_readpage_ofs(struct file *file, struct page *page, unsigned from, unsigned to)
488 {
489         struct inode *inode = page->mapping->host;
490         struct super_block *sb = inode->i_sb;
491         struct buffer_head *bh;
492         char *data;
493         u32 bidx, boff, bsize;
494         u32 tmp;
495 
496         pr_debug("AFFS: read_page(%u, %ld, %d, %d)\n", (u32)inode->i_ino, page->index, from, to);
497         BUG_ON(from > to || to > PAGE_CACHE_SIZE);
498         kmap(page);
499         data = page_address(page);
500         bsize = AFFS_SB(sb)->s_data_blksize;
501         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
502         bidx = tmp / bsize;
503         boff = tmp % bsize;
504 
505         while (from < to) {
506                 bh = affs_bread_ino(inode, bidx, 0);
507                 if (IS_ERR(bh))
508                         return PTR_ERR(bh);
509                 tmp = min(bsize - boff, to - from);
510                 BUG_ON(from + tmp > to || tmp > bsize);
511                 memcpy(data + from, AFFS_DATA(bh) + boff, tmp);
512                 affs_brelse(bh);
513                 bidx++;
514                 from += tmp;
515                 boff = 0;
516         }
517         flush_dcache_page(page);
518         kunmap(page);
519         return 0;
520 }
521 
522 static int
523 affs_extent_file_ofs(struct inode *inode, u32 newsize)
524 {
525         struct super_block *sb = inode->i_sb;
526         struct buffer_head *bh, *prev_bh;
527         u32 bidx, boff;
528         u32 size, bsize;
529         u32 tmp;
530 
531         pr_debug("AFFS: extent_file(%u, %d)\n", (u32)inode->i_ino, newsize);
532         bsize = AFFS_SB(sb)->s_data_blksize;
533         bh = NULL;
534         size = AFFS_I(inode)->mmu_private;
535         bidx = size / bsize;
536         boff = size % bsize;
537         if (boff) {
538                 bh = affs_bread_ino(inode, bidx, 0);
539                 if (IS_ERR(bh))
540                         return PTR_ERR(bh);
541                 tmp = min(bsize - boff, newsize - size);
542                 BUG_ON(boff + tmp > bsize || tmp > bsize);
543                 memset(AFFS_DATA(bh) + boff, 0, tmp);
544                 be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
545                 affs_fix_checksum(sb, bh);
546                 mark_buffer_dirty_inode(bh, inode);
547                 size += tmp;
548                 bidx++;
549         } else if (bidx) {
550                 bh = affs_bread_ino(inode, bidx - 1, 0);
551                 if (IS_ERR(bh))
552                         return PTR_ERR(bh);
553         }
554 
555         while (size < newsize) {
556                 prev_bh = bh;
557                 bh = affs_getzeroblk_ino(inode, bidx);
558                 if (IS_ERR(bh))
559                         goto out;
560                 tmp = min(bsize, newsize - size);
561                 BUG_ON(tmp > bsize);
562                 AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
563                 AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
564                 AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
565                 AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
566                 affs_fix_checksum(sb, bh);
567                 bh->b_state &= ~(1UL << BH_New);
568                 mark_buffer_dirty_inode(bh, inode);
569                 if (prev_bh) {
570                         u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
571                         if (tmp)
572                                 affs_warning(sb, "extent_file_ofs", "next block already set for %d (%d)", bidx, tmp);
573                         AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
574                         affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
575                         mark_buffer_dirty_inode(prev_bh, inode);
576                         affs_brelse(prev_bh);
577                 }
578                 size += bsize;
579                 bidx++;
580         }
581         affs_brelse(bh);
582         inode->i_size = AFFS_I(inode)->mmu_private = newsize;
583         return 0;
584 
585 out:
586         inode->i_size = AFFS_I(inode)->mmu_private = newsize;
587         return PTR_ERR(bh);
588 }
589 
590 static int
591 affs_readpage_ofs(struct file *file, struct page *page)
592 {
593         struct inode *inode = page->mapping->host;
594         u32 to;
595         int err;
596 
597         pr_debug("AFFS: read_page(%u, %ld)\n", (u32)inode->i_ino, page->index);
598         to = PAGE_CACHE_SIZE;
599         if (((page->index + 1) << PAGE_CACHE_SHIFT) > inode->i_size) {
600                 to = inode->i_size & ~PAGE_CACHE_MASK;
601                 memset(page_address(page) + to, 0, PAGE_CACHE_SIZE - to);
602         }
603 
604         err = affs_do_readpage_ofs(file, page, 0, to);
605         if (!err)
606                 SetPageUptodate(page);
607         unlock_page(page);
608         return err;
609 }
610 
611 static int affs_write_begin_ofs(struct file *file, struct address_space *mapping,
612                                 loff_t pos, unsigned len, unsigned flags,
613                                 struct page **pagep, void **fsdata)
614 {
615         struct inode *inode = mapping->host;
616         struct page *page;
617         pgoff_t index;
618         int err = 0;
619 
620         pr_debug("AFFS: write_begin(%u, %llu, %llu)\n", (u32)inode->i_ino, (unsigned long long)pos, (unsigned long long)pos + len);
621         if (pos > AFFS_I(inode)->mmu_private) {
622                 /* XXX: this probably leaves a too-big i_size in case of
623                  * failure. Should really be updating i_size at write_end time
624                  */
625                 err = affs_extent_file_ofs(inode, pos);
626                 if (err)
627                         return err;
628         }
629 
630         index = pos >> PAGE_CACHE_SHIFT;
631         page = grab_cache_page_write_begin(mapping, index, flags);
632         if (!page)
633                 return -ENOMEM;
634         *pagep = page;
635 
636         if (PageUptodate(page))
637                 return 0;
638 
639         /* XXX: inefficient but safe in the face of short writes */
640         err = affs_do_readpage_ofs(file, page, 0, PAGE_CACHE_SIZE);
641         if (err) {
642                 unlock_page(page);
643                 page_cache_release(page);
644         }
645         return err;
646 }
647 
648 static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
649                                 loff_t pos, unsigned len, unsigned copied,
650                                 struct page *page, void *fsdata)
651 {
652         struct inode *inode = mapping->host;
653         struct super_block *sb = inode->i_sb;
654         struct buffer_head *bh, *prev_bh;
655         char *data;
656         u32 bidx, boff, bsize;
657         unsigned from, to;
658         u32 tmp;
659         int written;
660 
661         from = pos & (PAGE_CACHE_SIZE - 1);
662         to = pos + len;
663         /*
664          * XXX: not sure if this can handle short copies (len < copied), but
665          * we don't have to, because the page should always be uptodate here,
666          * due to write_begin.
667          */
668 
669         pr_debug("AFFS: write_begin(%u, %llu, %llu)\n", (u32)inode->i_ino, (unsigned long long)pos, (unsigned long long)pos + len);
670         bsize = AFFS_SB(sb)->s_data_blksize;
671         data = page_address(page);
672 
673         bh = NULL;
674         written = 0;
675         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
676         bidx = tmp / bsize;
677         boff = tmp % bsize;
678         if (boff) {
679                 bh = affs_bread_ino(inode, bidx, 0);
680                 if (IS_ERR(bh))
681                         return PTR_ERR(bh);
682                 tmp = min(bsize - boff, to - from);
683                 BUG_ON(boff + tmp > bsize || tmp > bsize);
684                 memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
685                 be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
686                 affs_fix_checksum(sb, bh);
687                 mark_buffer_dirty_inode(bh, inode);
688                 written += tmp;
689                 from += tmp;
690                 bidx++;
691         } else if (bidx) {
692                 bh = affs_bread_ino(inode, bidx - 1, 0);
693                 if (IS_ERR(bh))
694                         return PTR_ERR(bh);
695         }
696         while (from + bsize <= to) {
697                 prev_bh = bh;
698                 bh = affs_getemptyblk_ino(inode, bidx);
699                 if (IS_ERR(bh))
700                         goto out;
701                 memcpy(AFFS_DATA(bh), data + from, bsize);
702                 if (buffer_new(bh)) {
703                         AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
704                         AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
705                         AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
706                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
707                         AFFS_DATA_HEAD(bh)->next = 0;
708                         bh->b_state &= ~(1UL << BH_New);
709                         if (prev_bh) {
710                                 u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
711                                 if (tmp)
712                                         affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
713                                 AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
714                                 affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
715                                 mark_buffer_dirty_inode(prev_bh, inode);
716                         }
717                 }
718                 affs_brelse(prev_bh);
719                 affs_fix_checksum(sb, bh);
720                 mark_buffer_dirty_inode(bh, inode);
721                 written += bsize;
722                 from += bsize;
723                 bidx++;
724         }
725         if (from < to) {
726                 prev_bh = bh;
727                 bh = affs_bread_ino(inode, bidx, 1);
728                 if (IS_ERR(bh))
729                         goto out;
730                 tmp = min(bsize, to - from);
731                 BUG_ON(tmp > bsize);
732                 memcpy(AFFS_DATA(bh), data + from, tmp);
733                 if (buffer_new(bh)) {
734                         AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
735                         AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
736                         AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
737                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
738                         AFFS_DATA_HEAD(bh)->next = 0;
739                         bh->b_state &= ~(1UL << BH_New);
740                         if (prev_bh) {
741                                 u32 tmp = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
742                                 if (tmp)
743                                         affs_warning(sb, "commit_write_ofs", "next block already set for %d (%d)", bidx, tmp);
744                                 AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
745                                 affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp);
746                                 mark_buffer_dirty_inode(prev_bh, inode);
747                         }
748                 } else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
749                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
750                 affs_brelse(prev_bh);
751                 affs_fix_checksum(sb, bh);
752                 mark_buffer_dirty_inode(bh, inode);
753                 written += tmp;
754                 from += tmp;
755                 bidx++;
756         }
757         SetPageUptodate(page);
758 
759 done:
760         affs_brelse(bh);
761         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
762         if (tmp > inode->i_size)
763                 inode->i_size = AFFS_I(inode)->mmu_private = tmp;
764 
765         unlock_page(page);
766         page_cache_release(page);
767 
768         return written;
769 
770 out:
771         bh = prev_bh;
772         if (!written)
773                 written = PTR_ERR(bh);
774         goto done;
775 }
776 
777 const struct address_space_operations affs_aops_ofs = {
778         .readpage = affs_readpage_ofs,
779         //.writepage = affs_writepage_ofs,
780         //.sync_page = affs_sync_page_ofs,
781         .write_begin = affs_write_begin_ofs,
782         .write_end = affs_write_end_ofs
783 };
784 
785 /* Free any preallocated blocks. */
786 
787 void
788 affs_free_prealloc(struct inode *inode)
789 {
790         struct super_block *sb = inode->i_sb;
791 
792         pr_debug("AFFS: free_prealloc(ino=%lu)\n", inode->i_ino);
793 
794         while (AFFS_I(inode)->i_pa_cnt) {
795                 AFFS_I(inode)->i_pa_cnt--;
796                 affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
797         }
798 }
799 
800 /* Truncate (or enlarge) a file to the requested size. */
801 
802 void
803 affs_truncate(struct inode *inode)
804 {
805         struct super_block *sb = inode->i_sb;
806         u32 ext, ext_key;
807         u32 last_blk, blkcnt, blk;
808         u32 size;
809         struct buffer_head *ext_bh;
810         int i;
811 
812         pr_debug("AFFS: truncate(inode=%d, oldsize=%u, newsize=%u)\n",
813                  (u32)inode->i_ino, (u32)AFFS_I(inode)->mmu_private, (u32)inode->i_size);
814 
815         last_blk = 0;
816         ext = 0;
817         if (inode->i_size) {
818                 last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
819                 ext = last_blk / AFFS_SB(sb)->s_hashsize;
820         }
821 
822         if (inode->i_size > AFFS_I(inode)->mmu_private) {
823                 struct address_space *mapping = inode->i_mapping;
824                 struct page *page;
825                 void *fsdata;
826                 u32 size = inode->i_size;
827                 int res;
828 
829                 res = mapping->a_ops->write_begin(NULL, mapping, size, 0, 0, &page, &fsdata);
830                 if (!res)
831                         res = mapping->a_ops->write_end(NULL, mapping, size, 0, 0, page, fsdata);
832                 else
833                         inode->i_size = AFFS_I(inode)->mmu_private;
834                 mark_inode_dirty(inode);
835                 return;
836         } else if (inode->i_size == AFFS_I(inode)->mmu_private)
837                 return;
838 
839         // lock cache
840         ext_bh = affs_get_extblock(inode, ext);
841         if (IS_ERR(ext_bh)) {
842                 affs_warning(sb, "truncate", "unexpected read error for ext block %u (%d)",
843                              ext, PTR_ERR(ext_bh));
844                 return;
845         }
846         if (AFFS_I(inode)->i_lc) {
847                 /* clear linear cache */
848                 i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
849                 if (AFFS_I(inode)->i_lc_size > i) {
850                         AFFS_I(inode)->i_lc_size = i;
851                         for (; i < AFFS_LC_SIZE; i++)
852                                 AFFS_I(inode)->i_lc[i] = 0;
853                 }
854                 /* clear associative cache */
855                 for (i = 0; i < AFFS_AC_SIZE; i++)
856                         if (AFFS_I(inode)->i_ac[i].ext >= ext)
857                                 AFFS_I(inode)->i_ac[i].ext = 0;
858         }
859         ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
860 
861         blkcnt = AFFS_I(inode)->i_blkcnt;
862         i = 0;
863         blk = last_blk;
864         if (inode->i_size) {
865                 i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
866                 blk++;
867         } else
868                 AFFS_HEAD(ext_bh)->first_data = 0;
869         AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
870         size = AFFS_SB(sb)->s_hashsize;
871         if (size > blkcnt - blk + i)
872                 size = blkcnt - blk + i;
873         for (; i < size; i++, blk++) {
874                 affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
875                 AFFS_BLOCK(sb, ext_bh, i) = 0;
876         }
877         AFFS_TAIL(sb, ext_bh)->extension = 0;
878         affs_fix_checksum(sb, ext_bh);
879         mark_buffer_dirty_inode(ext_bh, inode);
880         affs_brelse(ext_bh);
881 
882         if (inode->i_size) {
883                 AFFS_I(inode)->i_blkcnt = last_blk + 1;
884                 AFFS_I(inode)->i_extcnt = ext + 1;
885                 if (AFFS_SB(sb)->s_flags & SF_OFS) {
886                         struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
887                         u32 tmp;
888                         if (IS_ERR(ext_bh)) {
889                                 affs_warning(sb, "truncate", "unexpected read error for last block %u (%d)",
890                                              ext, PTR_ERR(ext_bh));
891                                 return;
892                         }
893                         tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
894                         AFFS_DATA_HEAD(bh)->next = 0;
895                         affs_adjust_checksum(bh, -tmp);
896                         affs_brelse(bh);
897                 }
898         } else {
899                 AFFS_I(inode)->i_blkcnt = 0;
900                 AFFS_I(inode)->i_extcnt = 1;
901         }
902         AFFS_I(inode)->mmu_private = inode->i_size;
903         // unlock cache
904 
905         while (ext_key) {
906                 ext_bh = affs_bread(sb, ext_key);
907                 size = AFFS_SB(sb)->s_hashsize;
908                 if (size > blkcnt - blk)
909                         size = blkcnt - blk;
910                 for (i = 0; i < size; i++, blk++)
911                         affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
912                 affs_free_block(sb, ext_key);
913                 ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
914                 affs_brelse(ext_bh);
915         }
916         affs_free_prealloc(inode);
917 }
918 
919 int affs_file_fsync(struct file *filp, struct dentry *dentry, int datasync)
920 {
921         struct inode * inode = dentry->d_inode;
922         int ret, err;
923 
924         ret = write_inode_now(inode, 0);
925         err = sync_blockdev(inode->i_sb->s_bdev);
926         if (!ret)
927                 ret = err;
928         return ret;
929 }
930 

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