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

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *  linux/fs/affs/file.c
  4  *
  5  *  (c) 1996  Hans-Joachim Widmaier - Rewritten
  6  *
  7  *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
  8  *
  9  *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
 10  *
 11  *  (C) 1991  Linus Torvalds - minix filesystem
 12  *
 13  *  affs regular file handling primitives
 14  */
 15 
 16 #include <linux/uio.h>
 17 #include "affs.h"
 18 
 19 static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
 20 
 21 static int
 22 affs_file_open(struct inode *inode, struct file *filp)
 23 {
 24         pr_debug("open(%lu,%d)\n",
 25                  inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
 26         atomic_inc(&AFFS_I(inode)->i_opencnt);
 27         return 0;
 28 }
 29 
 30 static int
 31 affs_file_release(struct inode *inode, struct file *filp)
 32 {
 33         pr_debug("release(%lu, %d)\n",
 34                  inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
 35 
 36         if (atomic_dec_and_test(&AFFS_I(inode)->i_opencnt)) {
 37                 inode_lock(inode);
 38                 if (inode->i_size != AFFS_I(inode)->mmu_private)
 39                         affs_truncate(inode);
 40                 affs_free_prealloc(inode);
 41                 inode_unlock(inode);
 42         }
 43 
 44         return 0;
 45 }
 46 
 47 static int
 48 affs_grow_extcache(struct inode *inode, u32 lc_idx)
 49 {
 50         struct super_block      *sb = inode->i_sb;
 51         struct buffer_head      *bh;
 52         u32 lc_max;
 53         int i, j, key;
 54 
 55         if (!AFFS_I(inode)->i_lc) {
 56                 char *ptr = (char *)get_zeroed_page(GFP_NOFS);
 57                 if (!ptr)
 58                         return -ENOMEM;
 59                 AFFS_I(inode)->i_lc = (u32 *)ptr;
 60                 AFFS_I(inode)->i_ac = (struct affs_ext_key *)(ptr + AFFS_CACHE_SIZE / 2);
 61         }
 62 
 63         lc_max = AFFS_LC_SIZE << AFFS_I(inode)->i_lc_shift;
 64 
 65         if (AFFS_I(inode)->i_extcnt > lc_max) {
 66                 u32 lc_shift, lc_mask, tmp, off;
 67 
 68                 /* need to recalculate linear cache, start from old size */
 69                 lc_shift = AFFS_I(inode)->i_lc_shift;
 70                 tmp = (AFFS_I(inode)->i_extcnt / AFFS_LC_SIZE) >> lc_shift;
 71                 for (; tmp; tmp >>= 1)
 72                         lc_shift++;
 73                 lc_mask = (1 << lc_shift) - 1;
 74 
 75                 /* fix idx and old size to new shift */
 76                 lc_idx >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
 77                 AFFS_I(inode)->i_lc_size >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
 78 
 79                 /* first shrink old cache to make more space */
 80                 off = 1 << (lc_shift - AFFS_I(inode)->i_lc_shift);
 81                 for (i = 1, j = off; j < AFFS_LC_SIZE; i++, j += off)
 82                         AFFS_I(inode)->i_ac[i] = AFFS_I(inode)->i_ac[j];
 83 
 84                 AFFS_I(inode)->i_lc_shift = lc_shift;
 85                 AFFS_I(inode)->i_lc_mask = lc_mask;
 86         }
 87 
 88         /* fill cache to the needed index */
 89         i = AFFS_I(inode)->i_lc_size;
 90         AFFS_I(inode)->i_lc_size = lc_idx + 1;
 91         for (; i <= lc_idx; i++) {
 92                 if (!i) {
 93                         AFFS_I(inode)->i_lc[0] = inode->i_ino;
 94                         continue;
 95                 }
 96                 key = AFFS_I(inode)->i_lc[i - 1];
 97                 j = AFFS_I(inode)->i_lc_mask + 1;
 98                 // unlock cache
 99                 for (; j > 0; j--) {
100                         bh = affs_bread(sb, key);
101                         if (!bh)
102                                 goto err;
103                         key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
104                         affs_brelse(bh);
105                 }
106                 // lock cache
107                 AFFS_I(inode)->i_lc[i] = key;
108         }
109 
110         return 0;
111 
112 err:
113         // lock cache
114         return -EIO;
115 }
116 
117 static struct buffer_head *
118 affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext)
119 {
120         struct super_block *sb = inode->i_sb;
121         struct buffer_head *new_bh;
122         u32 blocknr, tmp;
123 
124         blocknr = affs_alloc_block(inode, bh->b_blocknr);
125         if (!blocknr)
126                 return ERR_PTR(-ENOSPC);
127 
128         new_bh = affs_getzeroblk(sb, blocknr);
129         if (!new_bh) {
130                 affs_free_block(sb, blocknr);
131                 return ERR_PTR(-EIO);
132         }
133 
134         AFFS_HEAD(new_bh)->ptype = cpu_to_be32(T_LIST);
135         AFFS_HEAD(new_bh)->key = cpu_to_be32(blocknr);
136         AFFS_TAIL(sb, new_bh)->stype = cpu_to_be32(ST_FILE);
137         AFFS_TAIL(sb, new_bh)->parent = cpu_to_be32(inode->i_ino);
138         affs_fix_checksum(sb, new_bh);
139 
140         mark_buffer_dirty_inode(new_bh, inode);
141 
142         tmp = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
143         if (tmp)
144                 affs_warning(sb, "alloc_ext", "previous extension set (%x)", tmp);
145         AFFS_TAIL(sb, bh)->extension = cpu_to_be32(blocknr);
146         affs_adjust_checksum(bh, blocknr - tmp);
147         mark_buffer_dirty_inode(bh, inode);
148 
149         AFFS_I(inode)->i_extcnt++;
150         mark_inode_dirty(inode);
151 
152         return new_bh;
153 }
154 
155 static inline struct buffer_head *
156 affs_get_extblock(struct inode *inode, u32 ext)
157 {
158         /* inline the simplest case: same extended block as last time */
159         struct buffer_head *bh = AFFS_I(inode)->i_ext_bh;
160         if (ext == AFFS_I(inode)->i_ext_last)
161                 get_bh(bh);
162         else
163                 /* we have to do more (not inlined) */
164                 bh = affs_get_extblock_slow(inode, ext);
165 
166         return bh;
167 }
168 
169 static struct buffer_head *
170 affs_get_extblock_slow(struct inode *inode, u32 ext)
171 {
172         struct super_block *sb = inode->i_sb;
173         struct buffer_head *bh;
174         u32 ext_key;
175         u32 lc_idx, lc_off, ac_idx;
176         u32 tmp, idx;
177 
178         if (ext == AFFS_I(inode)->i_ext_last + 1) {
179                 /* read the next extended block from the current one */
180                 bh = AFFS_I(inode)->i_ext_bh;
181                 ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
182                 if (ext < AFFS_I(inode)->i_extcnt)
183                         goto read_ext;
184                 BUG_ON(ext > AFFS_I(inode)->i_extcnt);
185                 bh = affs_alloc_extblock(inode, bh, ext);
186                 if (IS_ERR(bh))
187                         return bh;
188                 goto store_ext;
189         }
190 
191         if (ext == 0) {
192                 /* we seek back to the file header block */
193                 ext_key = inode->i_ino;
194                 goto read_ext;
195         }
196 
197         if (ext >= AFFS_I(inode)->i_extcnt) {
198                 struct buffer_head *prev_bh;
199 
200                 /* allocate a new extended block */
201                 BUG_ON(ext > AFFS_I(inode)->i_extcnt);
202 
203                 /* get previous extended block */
204                 prev_bh = affs_get_extblock(inode, ext - 1);
205                 if (IS_ERR(prev_bh))
206                         return prev_bh;
207                 bh = affs_alloc_extblock(inode, prev_bh, ext);
208                 affs_brelse(prev_bh);
209                 if (IS_ERR(bh))
210                         return bh;
211                 goto store_ext;
212         }
213 
214 again:
215         /* check if there is an extended cache and whether it's large enough */
216         lc_idx = ext >> AFFS_I(inode)->i_lc_shift;
217         lc_off = ext & AFFS_I(inode)->i_lc_mask;
218 
219         if (lc_idx >= AFFS_I(inode)->i_lc_size) {
220                 int err;
221 
222                 err = affs_grow_extcache(inode, lc_idx);
223                 if (err)
224                         return ERR_PTR(err);
225                 goto again;
226         }
227 
228         /* every n'th key we find in the linear cache */
229         if (!lc_off) {
230                 ext_key = AFFS_I(inode)->i_lc[lc_idx];
231                 goto read_ext;
232         }
233 
234         /* maybe it's still in the associative cache */
235         ac_idx = (ext - lc_idx - 1) & AFFS_AC_MASK;
236         if (AFFS_I(inode)->i_ac[ac_idx].ext == ext) {
237                 ext_key = AFFS_I(inode)->i_ac[ac_idx].key;
238                 goto read_ext;
239         }
240 
241         /* try to find one of the previous extended blocks */
242         tmp = ext;
243         idx = ac_idx;
244         while (--tmp, --lc_off > 0) {
245                 idx = (idx - 1) & AFFS_AC_MASK;
246                 if (AFFS_I(inode)->i_ac[idx].ext == tmp) {
247                         ext_key = AFFS_I(inode)->i_ac[idx].key;
248                         goto find_ext;
249                 }
250         }
251 
252         /* fall back to the linear cache */
253         ext_key = AFFS_I(inode)->i_lc[lc_idx];
254 find_ext:
255         /* read all extended blocks until we find the one we need */
256         //unlock cache
257         do {
258                 bh = affs_bread(sb, ext_key);
259                 if (!bh)
260                         goto err_bread;
261                 ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
262                 affs_brelse(bh);
263                 tmp++;
264         } while (tmp < ext);
265         //lock cache
266 
267         /* store it in the associative cache */
268         // recalculate ac_idx?
269         AFFS_I(inode)->i_ac[ac_idx].ext = ext;
270         AFFS_I(inode)->i_ac[ac_idx].key = ext_key;
271 
272 read_ext:
273         /* finally read the right extended block */
274         //unlock cache
275         bh = affs_bread(sb, ext_key);
276         if (!bh)
277                 goto err_bread;
278         //lock cache
279 
280 store_ext:
281         /* release old cached extended block and store the new one */
282         affs_brelse(AFFS_I(inode)->i_ext_bh);
283         AFFS_I(inode)->i_ext_last = ext;
284         AFFS_I(inode)->i_ext_bh = bh;
285         get_bh(bh);
286 
287         return bh;
288 
289 err_bread:
290         affs_brelse(bh);
291         return ERR_PTR(-EIO);
292 }
293 
294 static int
295 affs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh_result, int create)
296 {
297         struct super_block      *sb = inode->i_sb;
298         struct buffer_head      *ext_bh;
299         u32                      ext;
300 
301         pr_debug("%s(%lu, %llu)\n", __func__, inode->i_ino,
302                  (unsigned long long)block);
303 
304         BUG_ON(block > (sector_t)0x7fffffffUL);
305 
306         if (block >= AFFS_I(inode)->i_blkcnt) {
307                 if (block > AFFS_I(inode)->i_blkcnt || !create)
308                         goto err_big;
309         } else
310                 create = 0;
311 
312         //lock cache
313         affs_lock_ext(inode);
314 
315         ext = (u32)block / AFFS_SB(sb)->s_hashsize;
316         block -= ext * AFFS_SB(sb)->s_hashsize;
317         ext_bh = affs_get_extblock(inode, ext);
318         if (IS_ERR(ext_bh))
319                 goto err_ext;
320         map_bh(bh_result, sb, (sector_t)be32_to_cpu(AFFS_BLOCK(sb, ext_bh, block)));
321 
322         if (create) {
323                 u32 blocknr = affs_alloc_block(inode, ext_bh->b_blocknr);
324                 if (!blocknr)
325                         goto err_alloc;
326                 set_buffer_new(bh_result);
327                 AFFS_I(inode)->mmu_private += AFFS_SB(sb)->s_data_blksize;
328                 AFFS_I(inode)->i_blkcnt++;
329 
330                 /* store new block */
331                 if (bh_result->b_blocknr)
332                         affs_warning(sb, "get_block",
333                                      "block already set (%llx)",
334                                      (unsigned long long)bh_result->b_blocknr);
335                 AFFS_BLOCK(sb, ext_bh, block) = cpu_to_be32(blocknr);
336                 AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(block + 1);
337                 affs_adjust_checksum(ext_bh, blocknr - bh_result->b_blocknr + 1);
338                 bh_result->b_blocknr = blocknr;
339 
340                 if (!block) {
341                         /* insert first block into header block */
342                         u32 tmp = be32_to_cpu(AFFS_HEAD(ext_bh)->first_data);
343                         if (tmp)
344                                 affs_warning(sb, "get_block", "first block already set (%d)", tmp);
345                         AFFS_HEAD(ext_bh)->first_data = cpu_to_be32(blocknr);
346                         affs_adjust_checksum(ext_bh, blocknr - tmp);
347                 }
348         }
349 
350         affs_brelse(ext_bh);
351         //unlock cache
352         affs_unlock_ext(inode);
353         return 0;
354 
355 err_big:
356         affs_error(inode->i_sb, "get_block", "strange block request %llu",
357                    (unsigned long long)block);
358         return -EIO;
359 err_ext:
360         // unlock cache
361         affs_unlock_ext(inode);
362         return PTR_ERR(ext_bh);
363 err_alloc:
364         brelse(ext_bh);
365         clear_buffer_mapped(bh_result);
366         bh_result->b_bdev = NULL;
367         // unlock cache
368         affs_unlock_ext(inode);
369         return -ENOSPC;
370 }
371 
372 static int affs_writepage(struct page *page, struct writeback_control *wbc)
373 {
374         return block_write_full_page(page, affs_get_block, wbc);
375 }
376 
377 static int affs_readpage(struct file *file, struct page *page)
378 {
379         return block_read_full_page(page, affs_get_block);
380 }
381 
382 static void affs_write_failed(struct address_space *mapping, loff_t to)
383 {
384         struct inode *inode = mapping->host;
385 
386         if (to > inode->i_size) {
387                 truncate_pagecache(inode, inode->i_size);
388                 affs_truncate(inode);
389         }
390 }
391 
392 static ssize_t
393 affs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
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         loff_t offset = iocb->ki_pos;
400         ssize_t ret;
401 
402         if (iov_iter_rw(iter) == WRITE) {
403                 loff_t size = offset + count;
404 
405                 if (AFFS_I(inode)->mmu_private < size)
406                         return 0;
407         }
408 
409         ret = blockdev_direct_IO(iocb, inode, iter, affs_get_block);
410         if (ret < 0 && iov_iter_rw(iter) == WRITE)
411                 affs_write_failed(mapping, offset + count);
412         return ret;
413 }
414 
415 static int affs_write_begin(struct file *file, struct address_space *mapping,
416                         loff_t pos, unsigned len, unsigned flags,
417                         struct page **pagep, void **fsdata)
418 {
419         int ret;
420 
421         *pagep = NULL;
422         ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
423                                 affs_get_block,
424                                 &AFFS_I(mapping->host)->mmu_private);
425         if (unlikely(ret))
426                 affs_write_failed(mapping, pos + len);
427 
428         return ret;
429 }
430 
431 static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
432 {
433         return generic_block_bmap(mapping,block,affs_get_block);
434 }
435 
436 const struct address_space_operations affs_aops = {
437         .readpage = affs_readpage,
438         .writepage = affs_writepage,
439         .write_begin = affs_write_begin,
440         .write_end = generic_write_end,
441         .direct_IO = affs_direct_IO,
442         .bmap = _affs_bmap
443 };
444 
445 static inline struct buffer_head *
446 affs_bread_ino(struct inode *inode, int block, int create)
447 {
448         struct buffer_head *bh, tmp_bh;
449         int err;
450 
451         tmp_bh.b_state = 0;
452         err = affs_get_block(inode, block, &tmp_bh, create);
453         if (!err) {
454                 bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
455                 if (bh) {
456                         bh->b_state |= tmp_bh.b_state;
457                         return bh;
458                 }
459                 err = -EIO;
460         }
461         return ERR_PTR(err);
462 }
463 
464 static inline struct buffer_head *
465 affs_getzeroblk_ino(struct inode *inode, int block)
466 {
467         struct buffer_head *bh, tmp_bh;
468         int err;
469 
470         tmp_bh.b_state = 0;
471         err = affs_get_block(inode, block, &tmp_bh, 1);
472         if (!err) {
473                 bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
474                 if (bh) {
475                         bh->b_state |= tmp_bh.b_state;
476                         return bh;
477                 }
478                 err = -EIO;
479         }
480         return ERR_PTR(err);
481 }
482 
483 static inline struct buffer_head *
484 affs_getemptyblk_ino(struct inode *inode, int block)
485 {
486         struct buffer_head *bh, tmp_bh;
487         int err;
488 
489         tmp_bh.b_state = 0;
490         err = affs_get_block(inode, block, &tmp_bh, 1);
491         if (!err) {
492                 bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
493                 if (bh) {
494                         bh->b_state |= tmp_bh.b_state;
495                         return bh;
496                 }
497                 err = -EIO;
498         }
499         return ERR_PTR(err);
500 }
501 
502 static int
503 affs_do_readpage_ofs(struct page *page, unsigned to, int create)
504 {
505         struct inode *inode = page->mapping->host;
506         struct super_block *sb = inode->i_sb;
507         struct buffer_head *bh;
508         char *data;
509         unsigned pos = 0;
510         u32 bidx, boff, bsize;
511         u32 tmp;
512 
513         pr_debug("%s(%lu, %ld, 0, %d)\n", __func__, inode->i_ino,
514                  page->index, to);
515         BUG_ON(to > PAGE_SIZE);
516         bsize = AFFS_SB(sb)->s_data_blksize;
517         tmp = page->index << PAGE_SHIFT;
518         bidx = tmp / bsize;
519         boff = tmp % bsize;
520 
521         while (pos < to) {
522                 bh = affs_bread_ino(inode, bidx, create);
523                 if (IS_ERR(bh))
524                         return PTR_ERR(bh);
525                 tmp = min(bsize - boff, to - pos);
526                 BUG_ON(pos + tmp > to || tmp > bsize);
527                 data = kmap_atomic(page);
528                 memcpy(data + pos, AFFS_DATA(bh) + boff, tmp);
529                 kunmap_atomic(data);
530                 affs_brelse(bh);
531                 bidx++;
532                 pos += tmp;
533                 boff = 0;
534         }
535         flush_dcache_page(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_SIZE;
619         if (((page->index + 1) << PAGE_SHIFT) > inode->i_size) {
620                 to = inode->i_size & ~PAGE_MASK;
621                 memset(page_address(page) + to, 0, PAGE_SIZE - to);
622         }
623 
624         err = affs_do_readpage_ofs(page, to, 0);
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_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_SIZE, 1);
662         if (err) {
663                 unlock_page(page);
664                 put_page(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_SIZE - 1);
683         to = from + 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_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_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         put_page(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_test_opt(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 = file_write_and_wait_range(filp, start, end);
959         if (err)
960                 return err;
961 
962         inode_lock(inode);
963         ret = write_inode_now(inode, 0);
964         err = sync_blockdev(inode->i_sb->s_bdev);
965         if (!ret)
966                 ret = err;
967         inode_unlock(inode);
968         return ret;
969 }
970 const struct file_operations affs_file_operations = {
971         .llseek         = generic_file_llseek,
972         .read_iter      = generic_file_read_iter,
973         .write_iter     = generic_file_write_iter,
974         .mmap           = generic_file_mmap,
975         .open           = affs_file_open,
976         .release        = affs_file_release,
977         .fsync          = affs_file_fsync,
978         .splice_read    = generic_file_splice_read,
979 };
980 
981 const struct inode_operations affs_file_inode_operations = {
982         .setattr        = affs_notify_change,
983 };
984 

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