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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 <linux/aio.h>
 16 #include "affs.h"
 17 
 18 static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
 19 
 20 static int
 21 affs_file_open(struct inode *inode, struct file *filp)
 22 {
 23         pr_debug("open(%lu,%d)\n",
 24                  inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
 25         atomic_inc(&AFFS_I(inode)->i_opencnt);
 26         return 0;
 27 }
 28 
 29 static int
 30 affs_file_release(struct inode *inode, struct file *filp)
 31 {
 32         pr_debug("release(%lu, %d)\n",
 33                  inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
 34 
 35         if (atomic_dec_and_test(&AFFS_I(inode)->i_opencnt)) {
 36                 mutex_lock(&inode->i_mutex);
 37                 if (inode->i_size != AFFS_I(inode)->mmu_private)
 38                         affs_truncate(inode);
 39                 affs_free_prealloc(inode);
 40                 mutex_unlock(&inode->i_mutex);
 41         }
 42 
 43         return 0;
 44 }
 45 
 46 static int
 47 affs_grow_extcache(struct inode *inode, u32 lc_idx)
 48 {
 49         struct super_block      *sb = inode->i_sb;
 50         struct buffer_head      *bh;
 51         u32 lc_max;
 52         int i, j, key;
 53 
 54         if (!AFFS_I(inode)->i_lc) {
 55                 char *ptr = (char *)get_zeroed_page(GFP_NOFS);
 56                 if (!ptr)
 57                         return -ENOMEM;
 58                 AFFS_I(inode)->i_lc = (u32 *)ptr;
 59                 AFFS_I(inode)->i_ac = (struct affs_ext_key *)(ptr + AFFS_CACHE_SIZE / 2);
 60         }
 61 
 62         lc_max = AFFS_LC_SIZE << AFFS_I(inode)->i_lc_shift;
 63 
 64         if (AFFS_I(inode)->i_extcnt > lc_max) {
 65                 u32 lc_shift, lc_mask, tmp, off;
 66 
 67                 /* need to recalculate linear cache, start from old size */
 68                 lc_shift = AFFS_I(inode)->i_lc_shift;
 69                 tmp = (AFFS_I(inode)->i_extcnt / AFFS_LC_SIZE) >> lc_shift;
 70                 for (; tmp; tmp >>= 1)
 71                         lc_shift++;
 72                 lc_mask = (1 << lc_shift) - 1;
 73 
 74                 /* fix idx and old size to new shift */
 75                 lc_idx >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
 76                 AFFS_I(inode)->i_lc_size >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
 77 
 78                 /* first shrink old cache to make more space */
 79                 off = 1 << (lc_shift - AFFS_I(inode)->i_lc_shift);
 80                 for (i = 1, j = off; j < AFFS_LC_SIZE; i++, j += off)
 81                         AFFS_I(inode)->i_ac[i] = AFFS_I(inode)->i_ac[j];
 82 
 83                 AFFS_I(inode)->i_lc_shift = lc_shift;
 84                 AFFS_I(inode)->i_lc_mask = lc_mask;
 85         }
 86 
 87         /* fill cache to the needed index */
 88         i = AFFS_I(inode)->i_lc_size;
 89         AFFS_I(inode)->i_lc_size = lc_idx + 1;
 90         for (; i <= lc_idx; i++) {
 91                 if (!i) {
 92                         AFFS_I(inode)->i_lc[0] = inode->i_ino;
 93                         continue;
 94                 }
 95                 key = AFFS_I(inode)->i_lc[i - 1];
 96                 j = AFFS_I(inode)->i_lc_mask + 1;
 97                 // unlock cache
 98                 for (; j > 0; j--) {
 99                         bh = affs_bread(sb, key);
100                         if (!bh)
101                                 goto err;
102                         key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
103                         affs_brelse(bh);
104                 }
105                 // lock cache
106                 AFFS_I(inode)->i_lc[i] = key;
107         }
108 
109         return 0;
110 
111 err:
112         // lock cache
113         return -EIO;
114 }
115 
116 static struct buffer_head *
117 affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext)
118 {
119         struct super_block *sb = inode->i_sb;
120         struct buffer_head *new_bh;
121         u32 blocknr, tmp;
122 
123         blocknr = affs_alloc_block(inode, bh->b_blocknr);
124         if (!blocknr)
125                 return ERR_PTR(-ENOSPC);
126 
127         new_bh = affs_getzeroblk(sb, blocknr);
128         if (!new_bh) {
129                 affs_free_block(sb, blocknr);
130                 return ERR_PTR(-EIO);
131         }
132 
133         AFFS_HEAD(new_bh)->ptype = cpu_to_be32(T_LIST);
134         AFFS_HEAD(new_bh)->key = cpu_to_be32(blocknr);
135         AFFS_TAIL(sb, new_bh)->stype = cpu_to_be32(ST_FILE);
136         AFFS_TAIL(sb, new_bh)->parent = cpu_to_be32(inode->i_ino);
137         affs_fix_checksum(sb, new_bh);
138 
139         mark_buffer_dirty_inode(new_bh, inode);
140 
141         tmp = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
142         if (tmp)
143                 affs_warning(sb, "alloc_ext", "previous extension set (%x)", tmp);
144         AFFS_TAIL(sb, bh)->extension = cpu_to_be32(blocknr);
145         affs_adjust_checksum(bh, blocknr - tmp);
146         mark_buffer_dirty_inode(bh, inode);
147 
148         AFFS_I(inode)->i_extcnt++;
149         mark_inode_dirty(inode);
150 
151         return new_bh;
152 }
153 
154 static inline struct buffer_head *
155 affs_get_extblock(struct inode *inode, u32 ext)
156 {
157         /* inline the simplest case: same extended block as last time */
158         struct buffer_head *bh = AFFS_I(inode)->i_ext_bh;
159         if (ext == AFFS_I(inode)->i_ext_last)
160                 get_bh(bh);
161         else
162                 /* we have to do more (not inlined) */
163                 bh = affs_get_extblock_slow(inode, ext);
164 
165         return bh;
166 }
167 
168 static struct buffer_head *
169 affs_get_extblock_slow(struct inode *inode, u32 ext)
170 {
171         struct super_block *sb = inode->i_sb;
172         struct buffer_head *bh;
173         u32 ext_key;
174         u32 lc_idx, lc_off, ac_idx;
175         u32 tmp, idx;
176 
177         if (ext == AFFS_I(inode)->i_ext_last + 1) {
178                 /* read the next extended block from the current one */
179                 bh = AFFS_I(inode)->i_ext_bh;
180                 ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
181                 if (ext < AFFS_I(inode)->i_extcnt)
182                         goto read_ext;
183                 BUG_ON(ext > AFFS_I(inode)->i_extcnt);
184                 bh = affs_alloc_extblock(inode, bh, ext);
185                 if (IS_ERR(bh))
186                         return bh;
187                 goto store_ext;
188         }
189 
190         if (ext == 0) {
191                 /* we seek back to the file header block */
192                 ext_key = inode->i_ino;
193                 goto read_ext;
194         }
195 
196         if (ext >= AFFS_I(inode)->i_extcnt) {
197                 struct buffer_head *prev_bh;
198 
199                 /* allocate a new extended block */
200                 BUG_ON(ext > AFFS_I(inode)->i_extcnt);
201 
202                 /* get previous extended block */
203                 prev_bh = affs_get_extblock(inode, ext - 1);
204                 if (IS_ERR(prev_bh))
205                         return prev_bh;
206                 bh = affs_alloc_extblock(inode, prev_bh, ext);
207                 affs_brelse(prev_bh);
208                 if (IS_ERR(bh))
209                         return bh;
210                 goto store_ext;
211         }
212 
213 again:
214         /* check if there is an extended cache and whether it's large enough */
215         lc_idx = ext >> AFFS_I(inode)->i_lc_shift;
216         lc_off = ext & AFFS_I(inode)->i_lc_mask;
217 
218         if (lc_idx >= AFFS_I(inode)->i_lc_size) {
219                 int err;
220 
221                 err = affs_grow_extcache(inode, lc_idx);
222                 if (err)
223                         return ERR_PTR(err);
224                 goto again;
225         }
226 
227         /* every n'th key we find in the linear cache */
228         if (!lc_off) {
229                 ext_key = AFFS_I(inode)->i_lc[lc_idx];
230                 goto read_ext;
231         }
232 
233         /* maybe it's still in the associative cache */
234         ac_idx = (ext - lc_idx - 1) & AFFS_AC_MASK;
235         if (AFFS_I(inode)->i_ac[ac_idx].ext == ext) {
236                 ext_key = AFFS_I(inode)->i_ac[ac_idx].key;
237                 goto read_ext;
238         }
239 
240         /* try to find one of the previous extended blocks */
241         tmp = ext;
242         idx = ac_idx;
243         while (--tmp, --lc_off > 0) {
244                 idx = (idx - 1) & AFFS_AC_MASK;
245                 if (AFFS_I(inode)->i_ac[idx].ext == tmp) {
246                         ext_key = AFFS_I(inode)->i_ac[idx].key;
247                         goto find_ext;
248                 }
249         }
250 
251         /* fall back to the linear cache */
252         ext_key = AFFS_I(inode)->i_lc[lc_idx];
253 find_ext:
254         /* read all extended blocks until we find the one we need */
255         //unlock cache
256         do {
257                 bh = affs_bread(sb, ext_key);
258                 if (!bh)
259                         goto err_bread;
260                 ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
261                 affs_brelse(bh);
262                 tmp++;
263         } while (tmp < ext);
264         //lock cache
265 
266         /* store it in the associative cache */
267         // recalculate ac_idx?
268         AFFS_I(inode)->i_ac[ac_idx].ext = ext;
269         AFFS_I(inode)->i_ac[ac_idx].key = ext_key;
270 
271 read_ext:
272         /* finally read the right extended block */
273         //unlock cache
274         bh = affs_bread(sb, ext_key);
275         if (!bh)
276                 goto err_bread;
277         //lock cache
278 
279 store_ext:
280         /* release old cached extended block and store the new one */
281         affs_brelse(AFFS_I(inode)->i_ext_bh);
282         AFFS_I(inode)->i_ext_last = ext;
283         AFFS_I(inode)->i_ext_bh = bh;
284         get_bh(bh);
285 
286         return bh;
287 
288 err_bread:
289         affs_brelse(bh);
290         return ERR_PTR(-EIO);
291 }
292 
293 static int
294 affs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh_result, int create)
295 {
296         struct super_block      *sb = inode->i_sb;
297         struct buffer_head      *ext_bh;
298         u32                      ext;
299 
300         pr_debug("%s(%lu, %llu)\n", __func__, inode->i_ino,
301                  (unsigned long long)block);
302 
303         BUG_ON(block > (sector_t)0x7fffffffUL);
304 
305         if (block >= AFFS_I(inode)->i_blkcnt) {
306                 if (block > AFFS_I(inode)->i_blkcnt || !create)
307                         goto err_big;
308         } else
309                 create = 0;
310 
311         //lock cache
312         affs_lock_ext(inode);
313 
314         ext = (u32)block / AFFS_SB(sb)->s_hashsize;
315         block -= ext * AFFS_SB(sb)->s_hashsize;
316         ext_bh = affs_get_extblock(inode, ext);
317         if (IS_ERR(ext_bh))
318                 goto err_ext;
319         map_bh(bh_result, sb, (sector_t)be32_to_cpu(AFFS_BLOCK(sb, ext_bh, block)));
320 
321         if (create) {
322                 u32 blocknr = affs_alloc_block(inode, ext_bh->b_blocknr);
323                 if (!blocknr)
324                         goto err_alloc;
325                 set_buffer_new(bh_result);
326                 AFFS_I(inode)->mmu_private += AFFS_SB(sb)->s_data_blksize;
327                 AFFS_I(inode)->i_blkcnt++;
328 
329                 /* store new block */
330                 if (bh_result->b_blocknr)
331                         affs_warning(sb, "get_block",
332                                      "block already set (%llx)",
333                                      (unsigned long long)bh_result->b_blocknr);
334                 AFFS_BLOCK(sb, ext_bh, block) = cpu_to_be32(blocknr);
335                 AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(block + 1);
336                 affs_adjust_checksum(ext_bh, blocknr - bh_result->b_blocknr + 1);
337                 bh_result->b_blocknr = blocknr;
338 
339                 if (!block) {
340                         /* insert first block into header block */
341                         u32 tmp = be32_to_cpu(AFFS_HEAD(ext_bh)->first_data);
342                         if (tmp)
343                                 affs_warning(sb, "get_block", "first block already set (%d)", tmp);
344                         AFFS_HEAD(ext_bh)->first_data = cpu_to_be32(blocknr);
345                         affs_adjust_checksum(ext_bh, blocknr - tmp);
346                 }
347         }
348 
349         affs_brelse(ext_bh);
350         //unlock cache
351         affs_unlock_ext(inode);
352         return 0;
353 
354 err_big:
355         affs_error(inode->i_sb, "get_block", "strange block request %llu",
356                    (unsigned long long)block);
357         return -EIO;
358 err_ext:
359         // unlock cache
360         affs_unlock_ext(inode);
361         return PTR_ERR(ext_bh);
362 err_alloc:
363         brelse(ext_bh);
364         clear_buffer_mapped(bh_result);
365         bh_result->b_bdev = NULL;
366         // unlock cache
367         affs_unlock_ext(inode);
368         return -ENOSPC;
369 }
370 
371 static int affs_writepage(struct page *page, struct writeback_control *wbc)
372 {
373         return block_write_full_page(page, affs_get_block, wbc);
374 }
375 
376 static int affs_readpage(struct file *file, struct page *page)
377 {
378         return block_read_full_page(page, affs_get_block);
379 }
380 
381 static void affs_write_failed(struct address_space *mapping, loff_t to)
382 {
383         struct inode *inode = mapping->host;
384 
385         if (to > inode->i_size) {
386                 truncate_pagecache(inode, inode->i_size);
387                 affs_truncate(inode);
388         }
389 }
390 
391 static ssize_t
392 affs_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
393                loff_t offset)
394 {
395         struct file *file = iocb->ki_filp;
396         struct address_space *mapping = file->f_mapping;
397         struct inode *inode = mapping->host;
398         size_t count = iov_iter_count(iter);
399         ssize_t ret;
400 
401         if (rw == WRITE) {
402                 loff_t size = offset + count;
403 
404                 if (AFFS_I(inode)->mmu_private < size)
405                         return 0;
406         }
407 
408         ret = blockdev_direct_IO(rw, iocb, inode, iter, offset, affs_get_block);
409         if (ret < 0 && (rw & WRITE))
410                 affs_write_failed(mapping, offset + count);
411         return ret;
412 }
413 
414 static int affs_write_begin(struct file *file, struct address_space *mapping,
415                         loff_t pos, unsigned len, unsigned flags,
416                         struct page **pagep, void **fsdata)
417 {
418         int ret;
419 
420         *pagep = NULL;
421         ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
422                                 affs_get_block,
423                                 &AFFS_I(mapping->host)->mmu_private);
424         if (unlikely(ret))
425                 affs_write_failed(mapping, pos + len);
426 
427         return ret;
428 }
429 
430 static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
431 {
432         return generic_block_bmap(mapping,block,affs_get_block);
433 }
434 
435 const struct address_space_operations affs_aops = {
436         .readpage = affs_readpage,
437         .writepage = affs_writepage,
438         .write_begin = affs_write_begin,
439         .write_end = generic_write_end,
440         .direct_IO = affs_direct_IO,
441         .bmap = _affs_bmap
442 };
443 
444 static inline struct buffer_head *
445 affs_bread_ino(struct inode *inode, int block, int create)
446 {
447         struct buffer_head *bh, tmp_bh;
448         int err;
449 
450         tmp_bh.b_state = 0;
451         err = affs_get_block(inode, block, &tmp_bh, create);
452         if (!err) {
453                 bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
454                 if (bh) {
455                         bh->b_state |= tmp_bh.b_state;
456                         return bh;
457                 }
458                 err = -EIO;
459         }
460         return ERR_PTR(err);
461 }
462 
463 static inline struct buffer_head *
464 affs_getzeroblk_ino(struct inode *inode, int block)
465 {
466         struct buffer_head *bh, tmp_bh;
467         int err;
468 
469         tmp_bh.b_state = 0;
470         err = affs_get_block(inode, block, &tmp_bh, 1);
471         if (!err) {
472                 bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
473                 if (bh) {
474                         bh->b_state |= tmp_bh.b_state;
475                         return bh;
476                 }
477                 err = -EIO;
478         }
479         return ERR_PTR(err);
480 }
481 
482 static inline struct buffer_head *
483 affs_getemptyblk_ino(struct inode *inode, int block)
484 {
485         struct buffer_head *bh, tmp_bh;
486         int err;
487 
488         tmp_bh.b_state = 0;
489         err = affs_get_block(inode, block, &tmp_bh, 1);
490         if (!err) {
491                 bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
492                 if (bh) {
493                         bh->b_state |= tmp_bh.b_state;
494                         return bh;
495                 }
496                 err = -EIO;
497         }
498         return ERR_PTR(err);
499 }
500 
501 static int
502 affs_do_readpage_ofs(struct page *page, unsigned to)
503 {
504         struct inode *inode = page->mapping->host;
505         struct super_block *sb = inode->i_sb;
506         struct buffer_head *bh;
507         char *data;
508         unsigned pos = 0;
509         u32 bidx, boff, bsize;
510         u32 tmp;
511 
512         pr_debug("%s(%lu, %ld, 0, %d)\n", __func__, inode->i_ino,
513                  page->index, to);
514         BUG_ON(to > PAGE_CACHE_SIZE);
515         kmap(page);
516         data = page_address(page);
517         bsize = AFFS_SB(sb)->s_data_blksize;
518         tmp = page->index << PAGE_CACHE_SHIFT;
519         bidx = tmp / bsize;
520         boff = tmp % bsize;
521 
522         while (pos < to) {
523                 bh = affs_bread_ino(inode, bidx, 0);
524                 if (IS_ERR(bh))
525                         return PTR_ERR(bh);
526                 tmp = min(bsize - boff, to - pos);
527                 BUG_ON(pos + tmp > to || tmp > bsize);
528                 memcpy(data + pos, AFFS_DATA(bh) + boff, tmp);
529                 affs_brelse(bh);
530                 bidx++;
531                 pos += tmp;
532                 boff = 0;
533         }
534         flush_dcache_page(page);
535         kunmap(page);
536         return 0;
537 }
538 
539 static int
540 affs_extent_file_ofs(struct inode *inode, u32 newsize)
541 {
542         struct super_block *sb = inode->i_sb;
543         struct buffer_head *bh, *prev_bh;
544         u32 bidx, boff;
545         u32 size, bsize;
546         u32 tmp;
547 
548         pr_debug("%s(%lu, %d)\n", __func__, inode->i_ino, newsize);
549         bsize = AFFS_SB(sb)->s_data_blksize;
550         bh = NULL;
551         size = AFFS_I(inode)->mmu_private;
552         bidx = size / bsize;
553         boff = size % bsize;
554         if (boff) {
555                 bh = affs_bread_ino(inode, bidx, 0);
556                 if (IS_ERR(bh))
557                         return PTR_ERR(bh);
558                 tmp = min(bsize - boff, newsize - size);
559                 BUG_ON(boff + tmp > bsize || tmp > bsize);
560                 memset(AFFS_DATA(bh) + boff, 0, tmp);
561                 be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
562                 affs_fix_checksum(sb, bh);
563                 mark_buffer_dirty_inode(bh, inode);
564                 size += tmp;
565                 bidx++;
566         } else if (bidx) {
567                 bh = affs_bread_ino(inode, bidx - 1, 0);
568                 if (IS_ERR(bh))
569                         return PTR_ERR(bh);
570         }
571 
572         while (size < newsize) {
573                 prev_bh = bh;
574                 bh = affs_getzeroblk_ino(inode, bidx);
575                 if (IS_ERR(bh))
576                         goto out;
577                 tmp = min(bsize, newsize - size);
578                 BUG_ON(tmp > bsize);
579                 AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
580                 AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
581                 AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
582                 AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
583                 affs_fix_checksum(sb, bh);
584                 bh->b_state &= ~(1UL << BH_New);
585                 mark_buffer_dirty_inode(bh, inode);
586                 if (prev_bh) {
587                         u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
588 
589                         if (tmp_next)
590                                 affs_warning(sb, "extent_file_ofs",
591                                              "next block already set for %d (%d)",
592                                              bidx, tmp_next);
593                         AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
594                         affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
595                         mark_buffer_dirty_inode(prev_bh, inode);
596                         affs_brelse(prev_bh);
597                 }
598                 size += bsize;
599                 bidx++;
600         }
601         affs_brelse(bh);
602         inode->i_size = AFFS_I(inode)->mmu_private = newsize;
603         return 0;
604 
605 out:
606         inode->i_size = AFFS_I(inode)->mmu_private = newsize;
607         return PTR_ERR(bh);
608 }
609 
610 static int
611 affs_readpage_ofs(struct file *file, struct page *page)
612 {
613         struct inode *inode = page->mapping->host;
614         u32 to;
615         int err;
616 
617         pr_debug("%s(%lu, %ld)\n", __func__, inode->i_ino, page->index);
618         to = PAGE_CACHE_SIZE;
619         if (((page->index + 1) << PAGE_CACHE_SHIFT) > inode->i_size) {
620                 to = inode->i_size & ~PAGE_CACHE_MASK;
621                 memset(page_address(page) + to, 0, PAGE_CACHE_SIZE - to);
622         }
623 
624         err = affs_do_readpage_ofs(page, to);
625         if (!err)
626                 SetPageUptodate(page);
627         unlock_page(page);
628         return err;
629 }
630 
631 static int affs_write_begin_ofs(struct file *file, struct address_space *mapping,
632                                 loff_t pos, unsigned len, unsigned flags,
633                                 struct page **pagep, void **fsdata)
634 {
635         struct inode *inode = mapping->host;
636         struct page *page;
637         pgoff_t index;
638         int err = 0;
639 
640         pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
641                  pos + len);
642         if (pos > AFFS_I(inode)->mmu_private) {
643                 /* XXX: this probably leaves a too-big i_size in case of
644                  * failure. Should really be updating i_size at write_end time
645                  */
646                 err = affs_extent_file_ofs(inode, pos);
647                 if (err)
648                         return err;
649         }
650 
651         index = pos >> PAGE_CACHE_SHIFT;
652         page = grab_cache_page_write_begin(mapping, index, flags);
653         if (!page)
654                 return -ENOMEM;
655         *pagep = page;
656 
657         if (PageUptodate(page))
658                 return 0;
659 
660         /* XXX: inefficient but safe in the face of short writes */
661         err = affs_do_readpage_ofs(page, PAGE_CACHE_SIZE);
662         if (err) {
663                 unlock_page(page);
664                 page_cache_release(page);
665         }
666         return err;
667 }
668 
669 static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
670                                 loff_t pos, unsigned len, unsigned copied,
671                                 struct page *page, void *fsdata)
672 {
673         struct inode *inode = mapping->host;
674         struct super_block *sb = inode->i_sb;
675         struct buffer_head *bh, *prev_bh;
676         char *data;
677         u32 bidx, boff, bsize;
678         unsigned from, to;
679         u32 tmp;
680         int written;
681 
682         from = pos & (PAGE_CACHE_SIZE - 1);
683         to = pos + len;
684         /*
685          * XXX: not sure if this can handle short copies (len < copied), but
686          * we don't have to, because the page should always be uptodate here,
687          * due to write_begin.
688          */
689 
690         pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
691                  pos + len);
692         bsize = AFFS_SB(sb)->s_data_blksize;
693         data = page_address(page);
694 
695         bh = NULL;
696         written = 0;
697         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
698         bidx = tmp / bsize;
699         boff = tmp % bsize;
700         if (boff) {
701                 bh = affs_bread_ino(inode, bidx, 0);
702                 if (IS_ERR(bh)) {
703                         written = PTR_ERR(bh);
704                         goto err_first_bh;
705                 }
706                 tmp = min(bsize - boff, to - from);
707                 BUG_ON(boff + tmp > bsize || tmp > bsize);
708                 memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
709                 be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
710                 affs_fix_checksum(sb, bh);
711                 mark_buffer_dirty_inode(bh, inode);
712                 written += tmp;
713                 from += tmp;
714                 bidx++;
715         } else if (bidx) {
716                 bh = affs_bread_ino(inode, bidx - 1, 0);
717                 if (IS_ERR(bh)) {
718                         written = PTR_ERR(bh);
719                         goto err_first_bh;
720                 }
721         }
722         while (from + bsize <= to) {
723                 prev_bh = bh;
724                 bh = affs_getemptyblk_ino(inode, bidx);
725                 if (IS_ERR(bh))
726                         goto err_bh;
727                 memcpy(AFFS_DATA(bh), data + from, bsize);
728                 if (buffer_new(bh)) {
729                         AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
730                         AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
731                         AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
732                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
733                         AFFS_DATA_HEAD(bh)->next = 0;
734                         bh->b_state &= ~(1UL << BH_New);
735                         if (prev_bh) {
736                                 u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
737 
738                                 if (tmp_next)
739                                         affs_warning(sb, "commit_write_ofs",
740                                                      "next block already set for %d (%d)",
741                                                      bidx, tmp_next);
742                                 AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
743                                 affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
744                                 mark_buffer_dirty_inode(prev_bh, inode);
745                         }
746                 }
747                 affs_brelse(prev_bh);
748                 affs_fix_checksum(sb, bh);
749                 mark_buffer_dirty_inode(bh, inode);
750                 written += bsize;
751                 from += bsize;
752                 bidx++;
753         }
754         if (from < to) {
755                 prev_bh = bh;
756                 bh = affs_bread_ino(inode, bidx, 1);
757                 if (IS_ERR(bh))
758                         goto err_bh;
759                 tmp = min(bsize, to - from);
760                 BUG_ON(tmp > bsize);
761                 memcpy(AFFS_DATA(bh), data + from, tmp);
762                 if (buffer_new(bh)) {
763                         AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
764                         AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
765                         AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
766                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
767                         AFFS_DATA_HEAD(bh)->next = 0;
768                         bh->b_state &= ~(1UL << BH_New);
769                         if (prev_bh) {
770                                 u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
771 
772                                 if (tmp_next)
773                                         affs_warning(sb, "commit_write_ofs",
774                                                      "next block already set for %d (%d)",
775                                                      bidx, tmp_next);
776                                 AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
777                                 affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
778                                 mark_buffer_dirty_inode(prev_bh, inode);
779                         }
780                 } else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
781                         AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
782                 affs_brelse(prev_bh);
783                 affs_fix_checksum(sb, bh);
784                 mark_buffer_dirty_inode(bh, inode);
785                 written += tmp;
786                 from += tmp;
787                 bidx++;
788         }
789         SetPageUptodate(page);
790 
791 done:
792         affs_brelse(bh);
793         tmp = (page->index << PAGE_CACHE_SHIFT) + from;
794         if (tmp > inode->i_size)
795                 inode->i_size = AFFS_I(inode)->mmu_private = tmp;
796 
797 err_first_bh:
798         unlock_page(page);
799         page_cache_release(page);
800 
801         return written;
802 
803 err_bh:
804         bh = prev_bh;
805         if (!written)
806                 written = PTR_ERR(bh);
807         goto done;
808 }
809 
810 const struct address_space_operations affs_aops_ofs = {
811         .readpage = affs_readpage_ofs,
812         //.writepage = affs_writepage_ofs,
813         .write_begin = affs_write_begin_ofs,
814         .write_end = affs_write_end_ofs
815 };
816 
817 /* Free any preallocated blocks. */
818 
819 void
820 affs_free_prealloc(struct inode *inode)
821 {
822         struct super_block *sb = inode->i_sb;
823 
824         pr_debug("free_prealloc(ino=%lu)\n", inode->i_ino);
825 
826         while (AFFS_I(inode)->i_pa_cnt) {
827                 AFFS_I(inode)->i_pa_cnt--;
828                 affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
829         }
830 }
831 
832 /* Truncate (or enlarge) a file to the requested size. */
833 
834 void
835 affs_truncate(struct inode *inode)
836 {
837         struct super_block *sb = inode->i_sb;
838         u32 ext, ext_key;
839         u32 last_blk, blkcnt, blk;
840         u32 size;
841         struct buffer_head *ext_bh;
842         int i;
843 
844         pr_debug("truncate(inode=%lu, oldsize=%llu, newsize=%llu)\n",
845                  inode->i_ino, AFFS_I(inode)->mmu_private, inode->i_size);
846 
847         last_blk = 0;
848         ext = 0;
849         if (inode->i_size) {
850                 last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
851                 ext = last_blk / AFFS_SB(sb)->s_hashsize;
852         }
853 
854         if (inode->i_size > AFFS_I(inode)->mmu_private) {
855                 struct address_space *mapping = inode->i_mapping;
856                 struct page *page;
857                 void *fsdata;
858                 loff_t isize = inode->i_size;
859                 int res;
860 
861                 res = mapping->a_ops->write_begin(NULL, mapping, isize, 0, 0, &page, &fsdata);
862                 if (!res)
863                         res = mapping->a_ops->write_end(NULL, mapping, isize, 0, 0, page, fsdata);
864                 else
865                         inode->i_size = AFFS_I(inode)->mmu_private;
866                 mark_inode_dirty(inode);
867                 return;
868         } else if (inode->i_size == AFFS_I(inode)->mmu_private)
869                 return;
870 
871         // lock cache
872         ext_bh = affs_get_extblock(inode, ext);
873         if (IS_ERR(ext_bh)) {
874                 affs_warning(sb, "truncate",
875                              "unexpected read error for ext block %u (%ld)",
876                              ext, PTR_ERR(ext_bh));
877                 return;
878         }
879         if (AFFS_I(inode)->i_lc) {
880                 /* clear linear cache */
881                 i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
882                 if (AFFS_I(inode)->i_lc_size > i) {
883                         AFFS_I(inode)->i_lc_size = i;
884                         for (; i < AFFS_LC_SIZE; i++)
885                                 AFFS_I(inode)->i_lc[i] = 0;
886                 }
887                 /* clear associative cache */
888                 for (i = 0; i < AFFS_AC_SIZE; i++)
889                         if (AFFS_I(inode)->i_ac[i].ext >= ext)
890                                 AFFS_I(inode)->i_ac[i].ext = 0;
891         }
892         ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
893 
894         blkcnt = AFFS_I(inode)->i_blkcnt;
895         i = 0;
896         blk = last_blk;
897         if (inode->i_size) {
898                 i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
899                 blk++;
900         } else
901                 AFFS_HEAD(ext_bh)->first_data = 0;
902         AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
903         size = AFFS_SB(sb)->s_hashsize;
904         if (size > blkcnt - blk + i)
905                 size = blkcnt - blk + i;
906         for (; i < size; i++, blk++) {
907                 affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
908                 AFFS_BLOCK(sb, ext_bh, i) = 0;
909         }
910         AFFS_TAIL(sb, ext_bh)->extension = 0;
911         affs_fix_checksum(sb, ext_bh);
912         mark_buffer_dirty_inode(ext_bh, inode);
913         affs_brelse(ext_bh);
914 
915         if (inode->i_size) {
916                 AFFS_I(inode)->i_blkcnt = last_blk + 1;
917                 AFFS_I(inode)->i_extcnt = ext + 1;
918                 if (AFFS_SB(sb)->s_flags & SF_OFS) {
919                         struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
920                         u32 tmp;
921                         if (IS_ERR(bh)) {
922                                 affs_warning(sb, "truncate",
923                                              "unexpected read error for last block %u (%ld)",
924                                              ext, PTR_ERR(bh));
925                                 return;
926                         }
927                         tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
928                         AFFS_DATA_HEAD(bh)->next = 0;
929                         affs_adjust_checksum(bh, -tmp);
930                         affs_brelse(bh);
931                 }
932         } else {
933                 AFFS_I(inode)->i_blkcnt = 0;
934                 AFFS_I(inode)->i_extcnt = 1;
935         }
936         AFFS_I(inode)->mmu_private = inode->i_size;
937         // unlock cache
938 
939         while (ext_key) {
940                 ext_bh = affs_bread(sb, ext_key);
941                 size = AFFS_SB(sb)->s_hashsize;
942                 if (size > blkcnt - blk)
943                         size = blkcnt - blk;
944                 for (i = 0; i < size; i++, blk++)
945                         affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
946                 affs_free_block(sb, ext_key);
947                 ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
948                 affs_brelse(ext_bh);
949         }
950         affs_free_prealloc(inode);
951 }
952 
953 int affs_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
954 {
955         struct inode *inode = filp->f_mapping->host;
956         int ret, err;
957 
958         err = filemap_write_and_wait_range(inode->i_mapping, start, end);
959         if (err)
960                 return err;
961 
962         mutex_lock(&inode->i_mutex);
963         ret = write_inode_now(inode, 0);
964         err = sync_blockdev(inode->i_sb->s_bdev);
965         if (!ret)
966                 ret = err;
967         mutex_unlock(&inode->i_mutex);
968         return ret;
969 }
970 const struct file_operations affs_file_operations = {
971         .llseek         = generic_file_llseek,
972         .read           = new_sync_read,
973         .read_iter      = generic_file_read_iter,
974         .write          = new_sync_write,
975         .write_iter     = generic_file_write_iter,
976         .mmap           = generic_file_mmap,
977         .open           = affs_file_open,
978         .release        = affs_file_release,
979         .fsync          = affs_file_fsync,
980         .splice_read    = generic_file_splice_read,
981 };
982 
983 const struct inode_operations affs_file_inode_operations = {
984         .setattr        = affs_notify_change,
985 };
986 

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