1 /*
2 * linux/fs/hfs/extent.c
3 *
4 * Copyright (C) 1995-1997 Paul H. Hargrove
5 * (C) 2003 Ardis Technologies <roman@ardistech.com>
6 * This file may be distributed under the terms of the GNU General Public License.
7 *
8 * This file contains the functions related to the extents B-tree.
9 */
10
11 #include <linux/pagemap.h>
12
13 #include "hfs_fs.h"
14 #include "btree.h"
15
16 /*================ File-local functions ================*/
17
18 /*
19 * build_key
20 */
hfs_ext_build_key(hfs_btree_key * key,u32 cnid,u16 block,u8 type)21 static void hfs_ext_build_key(hfs_btree_key *key, u32 cnid, u16 block, u8 type)
22 {
23 key->key_len = 7;
24 key->ext.FkType = type;
25 key->ext.FNum = cpu_to_be32(cnid);
26 key->ext.FABN = cpu_to_be16(block);
27 }
28
29 /*
30 * hfs_ext_compare()
31 *
32 * Description:
33 * This is the comparison function used for the extents B-tree. In
34 * comparing extent B-tree entries, the file id is the most
35 * significant field (compared as unsigned ints); the fork type is
36 * the second most significant field (compared as unsigned chars);
37 * and the allocation block number field is the least significant
38 * (compared as unsigned ints).
39 * Input Variable(s):
40 * struct hfs_ext_key *key1: pointer to the first key to compare
41 * struct hfs_ext_key *key2: pointer to the second key to compare
42 * Output Variable(s):
43 * NONE
44 * Returns:
45 * int: negative if key1<key2, positive if key1>key2, and 0 if key1==key2
46 * Preconditions:
47 * key1 and key2 point to "valid" (struct hfs_ext_key)s.
48 * Postconditions:
49 * This function has no side-effects */
hfs_ext_keycmp(const btree_key * key1,const btree_key * key2)50 int hfs_ext_keycmp(const btree_key *key1, const btree_key *key2)
51 {
52 __be32 fnum1, fnum2;
53 __be16 block1, block2;
54
55 fnum1 = key1->ext.FNum;
56 fnum2 = key2->ext.FNum;
57 if (fnum1 != fnum2)
58 return be32_to_cpu(fnum1) < be32_to_cpu(fnum2) ? -1 : 1;
59 if (key1->ext.FkType != key2->ext.FkType)
60 return key1->ext.FkType < key2->ext.FkType ? -1 : 1;
61
62 block1 = key1->ext.FABN;
63 block2 = key2->ext.FABN;
64 if (block1 == block2)
65 return 0;
66 return be16_to_cpu(block1) < be16_to_cpu(block2) ? -1 : 1;
67 }
68
69 /*
70 * hfs_ext_find_block
71 *
72 * Find a block within an extent record
73 */
hfs_ext_find_block(struct hfs_extent * ext,u16 off)74 static u16 hfs_ext_find_block(struct hfs_extent *ext, u16 off)
75 {
76 int i;
77 u16 count;
78
79 for (i = 0; i < 3; ext++, i++) {
80 count = be16_to_cpu(ext->count);
81 if (off < count)
82 return be16_to_cpu(ext->block) + off;
83 off -= count;
84 }
85 /* panic? */
86 return 0;
87 }
88
hfs_ext_block_count(struct hfs_extent * ext)89 static int hfs_ext_block_count(struct hfs_extent *ext)
90 {
91 int i;
92 u16 count = 0;
93
94 for (i = 0; i < 3; ext++, i++)
95 count += be16_to_cpu(ext->count);
96 return count;
97 }
98
hfs_ext_lastblock(struct hfs_extent * ext)99 static u16 hfs_ext_lastblock(struct hfs_extent *ext)
100 {
101 int i;
102
103 ext += 2;
104 for (i = 0; i < 2; ext--, i++)
105 if (ext->count)
106 break;
107 return be16_to_cpu(ext->block) + be16_to_cpu(ext->count);
108 }
109
__hfs_ext_write_extent(struct inode * inode,struct hfs_find_data * fd)110 static int __hfs_ext_write_extent(struct inode *inode, struct hfs_find_data *fd)
111 {
112 int res;
113
114 hfs_ext_build_key(fd->search_key, inode->i_ino, HFS_I(inode)->cached_start,
115 HFS_IS_RSRC(inode) ? HFS_FK_RSRC : HFS_FK_DATA);
116 res = hfs_brec_find(fd);
117 if (HFS_I(inode)->flags & HFS_FLG_EXT_NEW) {
118 if (res != -ENOENT)
119 return res;
120 /* Fail early and avoid ENOSPC during the btree operation */
121 res = hfs_bmap_reserve(fd->tree, fd->tree->depth + 1);
122 if (res)
123 return res;
124 hfs_brec_insert(fd, HFS_I(inode)->cached_extents, sizeof(hfs_extent_rec));
125 HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
126 } else {
127 if (res)
128 return res;
129 hfs_bnode_write(fd->bnode, HFS_I(inode)->cached_extents, fd->entryoffset, fd->entrylength);
130 HFS_I(inode)->flags &= ~HFS_FLG_EXT_DIRTY;
131 }
132 return 0;
133 }
134
hfs_ext_write_extent(struct inode * inode)135 int hfs_ext_write_extent(struct inode *inode)
136 {
137 struct hfs_find_data fd;
138 int res = 0;
139
140 if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY) {
141 res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
142 if (res)
143 return res;
144 res = __hfs_ext_write_extent(inode, &fd);
145 hfs_find_exit(&fd);
146 }
147 return res;
148 }
149
__hfs_ext_read_extent(struct hfs_find_data * fd,struct hfs_extent * extent,u32 cnid,u32 block,u8 type)150 static inline int __hfs_ext_read_extent(struct hfs_find_data *fd, struct hfs_extent *extent,
151 u32 cnid, u32 block, u8 type)
152 {
153 int res;
154
155 hfs_ext_build_key(fd->search_key, cnid, block, type);
156 fd->key->ext.FNum = 0;
157 res = hfs_brec_find(fd);
158 if (res && res != -ENOENT)
159 return res;
160 if (fd->key->ext.FNum != fd->search_key->ext.FNum ||
161 fd->key->ext.FkType != fd->search_key->ext.FkType)
162 return -ENOENT;
163 if (fd->entrylength != sizeof(hfs_extent_rec))
164 return -EIO;
165 hfs_bnode_read(fd->bnode, extent, fd->entryoffset, sizeof(hfs_extent_rec));
166 return 0;
167 }
168
__hfs_ext_cache_extent(struct hfs_find_data * fd,struct inode * inode,u32 block)169 static inline int __hfs_ext_cache_extent(struct hfs_find_data *fd, struct inode *inode, u32 block)
170 {
171 int res;
172
173 if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY) {
174 res = __hfs_ext_write_extent(inode, fd);
175 if (res)
176 return res;
177 }
178
179 res = __hfs_ext_read_extent(fd, HFS_I(inode)->cached_extents, inode->i_ino,
180 block, HFS_IS_RSRC(inode) ? HFS_FK_RSRC : HFS_FK_DATA);
181 if (!res) {
182 HFS_I(inode)->cached_start = be16_to_cpu(fd->key->ext.FABN);
183 HFS_I(inode)->cached_blocks = hfs_ext_block_count(HFS_I(inode)->cached_extents);
184 } else {
185 HFS_I(inode)->cached_start = HFS_I(inode)->cached_blocks = 0;
186 HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
187 }
188 return res;
189 }
190
hfs_ext_read_extent(struct inode * inode,u16 block)191 static int hfs_ext_read_extent(struct inode *inode, u16 block)
192 {
193 struct hfs_find_data fd;
194 int res;
195
196 if (block >= HFS_I(inode)->cached_start &&
197 block < HFS_I(inode)->cached_start + HFS_I(inode)->cached_blocks)
198 return 0;
199
200 res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
201 if (!res) {
202 res = __hfs_ext_cache_extent(&fd, inode, block);
203 hfs_find_exit(&fd);
204 }
205 return res;
206 }
207
hfs_dump_extent(struct hfs_extent * extent)208 static void hfs_dump_extent(struct hfs_extent *extent)
209 {
210 int i;
211
212 hfs_dbg(EXTENT, " ");
213 for (i = 0; i < 3; i++)
214 hfs_dbg_cont(EXTENT, " %u:%u",
215 be16_to_cpu(extent[i].block),
216 be16_to_cpu(extent[i].count));
217 hfs_dbg_cont(EXTENT, "\n");
218 }
219
hfs_add_extent(struct hfs_extent * extent,u16 offset,u16 alloc_block,u16 block_count)220 static int hfs_add_extent(struct hfs_extent *extent, u16 offset,
221 u16 alloc_block, u16 block_count)
222 {
223 u16 count, start;
224 int i;
225
226 hfs_dump_extent(extent);
227 for (i = 0; i < 3; extent++, i++) {
228 count = be16_to_cpu(extent->count);
229 if (offset == count) {
230 start = be16_to_cpu(extent->block);
231 if (alloc_block != start + count) {
232 if (++i >= 3)
233 return -ENOSPC;
234 extent++;
235 extent->block = cpu_to_be16(alloc_block);
236 } else
237 block_count += count;
238 extent->count = cpu_to_be16(block_count);
239 return 0;
240 } else if (offset < count)
241 break;
242 offset -= count;
243 }
244 /* panic? */
245 return -EIO;
246 }
247
hfs_free_extents(struct super_block * sb,struct hfs_extent * extent,u16 offset,u16 block_nr)248 static int hfs_free_extents(struct super_block *sb, struct hfs_extent *extent,
249 u16 offset, u16 block_nr)
250 {
251 u16 count, start;
252 int i;
253
254 hfs_dump_extent(extent);
255 for (i = 0; i < 3; extent++, i++) {
256 count = be16_to_cpu(extent->count);
257 if (offset == count)
258 goto found;
259 else if (offset < count)
260 break;
261 offset -= count;
262 }
263 /* panic? */
264 return -EIO;
265 found:
266 for (;;) {
267 start = be16_to_cpu(extent->block);
268 if (count <= block_nr) {
269 hfs_clear_vbm_bits(sb, start, count);
270 extent->block = 0;
271 extent->count = 0;
272 block_nr -= count;
273 } else {
274 count -= block_nr;
275 hfs_clear_vbm_bits(sb, start + count, block_nr);
276 extent->count = cpu_to_be16(count);
277 block_nr = 0;
278 }
279 if (!block_nr || !i)
280 return 0;
281 i--;
282 extent--;
283 count = be16_to_cpu(extent->count);
284 }
285 }
286
hfs_free_fork(struct super_block * sb,struct hfs_cat_file * file,int type)287 int hfs_free_fork(struct super_block *sb, struct hfs_cat_file *file, int type)
288 {
289 struct hfs_find_data fd;
290 u32 total_blocks, blocks, start;
291 u32 cnid = be32_to_cpu(file->FlNum);
292 struct hfs_extent *extent;
293 int res, i;
294
295 if (type == HFS_FK_DATA) {
296 total_blocks = be32_to_cpu(file->PyLen);
297 extent = file->ExtRec;
298 } else {
299 total_blocks = be32_to_cpu(file->RPyLen);
300 extent = file->RExtRec;
301 }
302 total_blocks /= HFS_SB(sb)->alloc_blksz;
303 if (!total_blocks)
304 return 0;
305
306 blocks = 0;
307 for (i = 0; i < 3; i++)
308 blocks += be16_to_cpu(extent[i].count);
309
310 res = hfs_free_extents(sb, extent, blocks, blocks);
311 if (res)
312 return res;
313 if (total_blocks == blocks)
314 return 0;
315
316 res = hfs_find_init(HFS_SB(sb)->ext_tree, &fd);
317 if (res)
318 return res;
319 do {
320 res = __hfs_ext_read_extent(&fd, extent, cnid, total_blocks, type);
321 if (res)
322 break;
323 start = be16_to_cpu(fd.key->ext.FABN);
324 hfs_free_extents(sb, extent, total_blocks - start, total_blocks);
325 hfs_brec_remove(&fd);
326 total_blocks = start;
327 } while (total_blocks > blocks);
328 hfs_find_exit(&fd);
329
330 return res;
331 }
332
333 /*
334 * hfs_get_block
335 */
hfs_get_block(struct inode * inode,sector_t block,struct buffer_head * bh_result,int create)336 int hfs_get_block(struct inode *inode, sector_t block,
337 struct buffer_head *bh_result, int create)
338 {
339 struct super_block *sb;
340 u16 dblock, ablock;
341 int res;
342
343 sb = inode->i_sb;
344 /* Convert inode block to disk allocation block */
345 ablock = (u32)block / HFS_SB(sb)->fs_div;
346
347 if (block >= HFS_I(inode)->fs_blocks) {
348 if (!create)
349 return 0;
350 if (block > HFS_I(inode)->fs_blocks)
351 return -EIO;
352 if (ablock >= HFS_I(inode)->alloc_blocks) {
353 res = hfs_extend_file(inode);
354 if (res)
355 return res;
356 }
357 } else
358 create = 0;
359
360 if (ablock < HFS_I(inode)->first_blocks) {
361 dblock = hfs_ext_find_block(HFS_I(inode)->first_extents, ablock);
362 goto done;
363 }
364
365 mutex_lock(&HFS_I(inode)->extents_lock);
366 res = hfs_ext_read_extent(inode, ablock);
367 if (!res)
368 dblock = hfs_ext_find_block(HFS_I(inode)->cached_extents,
369 ablock - HFS_I(inode)->cached_start);
370 else {
371 mutex_unlock(&HFS_I(inode)->extents_lock);
372 return -EIO;
373 }
374 mutex_unlock(&HFS_I(inode)->extents_lock);
375
376 done:
377 map_bh(bh_result, sb, HFS_SB(sb)->fs_start +
378 dblock * HFS_SB(sb)->fs_div +
379 (u32)block % HFS_SB(sb)->fs_div);
380
381 if (create) {
382 set_buffer_new(bh_result);
383 HFS_I(inode)->phys_size += sb->s_blocksize;
384 HFS_I(inode)->fs_blocks++;
385 inode_add_bytes(inode, sb->s_blocksize);
386 mark_inode_dirty(inode);
387 }
388 return 0;
389 }
390
hfs_extend_file(struct inode * inode)391 int hfs_extend_file(struct inode *inode)
392 {
393 struct super_block *sb = inode->i_sb;
394 u32 start, len, goal;
395 int res;
396
397 mutex_lock(&HFS_I(inode)->extents_lock);
398 if (HFS_I(inode)->alloc_blocks == HFS_I(inode)->first_blocks)
399 goal = hfs_ext_lastblock(HFS_I(inode)->first_extents);
400 else {
401 res = hfs_ext_read_extent(inode, HFS_I(inode)->alloc_blocks);
402 if (res)
403 goto out;
404 goal = hfs_ext_lastblock(HFS_I(inode)->cached_extents);
405 }
406
407 len = HFS_I(inode)->clump_blocks;
408 start = hfs_vbm_search_free(sb, goal, &len);
409 if (!len) {
410 res = -ENOSPC;
411 goto out;
412 }
413
414 hfs_dbg(EXTENT, "extend %lu: %u,%u\n", inode->i_ino, start, len);
415 if (HFS_I(inode)->alloc_blocks == HFS_I(inode)->first_blocks) {
416 if (!HFS_I(inode)->first_blocks) {
417 hfs_dbg(EXTENT, "first extents\n");
418 /* no extents yet */
419 HFS_I(inode)->first_extents[0].block = cpu_to_be16(start);
420 HFS_I(inode)->first_extents[0].count = cpu_to_be16(len);
421 res = 0;
422 } else {
423 /* try to append to extents in inode */
424 res = hfs_add_extent(HFS_I(inode)->first_extents,
425 HFS_I(inode)->alloc_blocks,
426 start, len);
427 if (res == -ENOSPC)
428 goto insert_extent;
429 }
430 if (!res) {
431 hfs_dump_extent(HFS_I(inode)->first_extents);
432 HFS_I(inode)->first_blocks += len;
433 }
434 } else {
435 res = hfs_add_extent(HFS_I(inode)->cached_extents,
436 HFS_I(inode)->alloc_blocks -
437 HFS_I(inode)->cached_start,
438 start, len);
439 if (!res) {
440 hfs_dump_extent(HFS_I(inode)->cached_extents);
441 HFS_I(inode)->flags |= HFS_FLG_EXT_DIRTY;
442 HFS_I(inode)->cached_blocks += len;
443 } else if (res == -ENOSPC)
444 goto insert_extent;
445 }
446 out:
447 mutex_unlock(&HFS_I(inode)->extents_lock);
448 if (!res) {
449 HFS_I(inode)->alloc_blocks += len;
450 mark_inode_dirty(inode);
451 if (inode->i_ino < HFS_FIRSTUSER_CNID)
452 set_bit(HFS_FLG_ALT_MDB_DIRTY, &HFS_SB(sb)->flags);
453 set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags);
454 hfs_mark_mdb_dirty(sb);
455 }
456 return res;
457
458 insert_extent:
459 hfs_dbg(EXTENT, "insert new extent\n");
460 res = hfs_ext_write_extent(inode);
461 if (res)
462 goto out;
463
464 memset(HFS_I(inode)->cached_extents, 0, sizeof(hfs_extent_rec));
465 HFS_I(inode)->cached_extents[0].block = cpu_to_be16(start);
466 HFS_I(inode)->cached_extents[0].count = cpu_to_be16(len);
467 hfs_dump_extent(HFS_I(inode)->cached_extents);
468 HFS_I(inode)->flags |= HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW;
469 HFS_I(inode)->cached_start = HFS_I(inode)->alloc_blocks;
470 HFS_I(inode)->cached_blocks = len;
471
472 res = 0;
473 goto out;
474 }
475
hfs_file_truncate(struct inode * inode)476 void hfs_file_truncate(struct inode *inode)
477 {
478 struct super_block *sb = inode->i_sb;
479 struct hfs_find_data fd;
480 u16 blk_cnt, alloc_cnt, start;
481 u32 size;
482 int res;
483
484 hfs_dbg(INODE, "truncate: %lu, %Lu -> %Lu\n",
485 inode->i_ino, (long long)HFS_I(inode)->phys_size,
486 inode->i_size);
487 if (inode->i_size > HFS_I(inode)->phys_size) {
488 struct address_space *mapping = inode->i_mapping;
489 void *fsdata = NULL;
490 struct page *page;
491
492 /* XXX: Can use generic_cont_expand? */
493 size = inode->i_size - 1;
494 res = hfs_write_begin(NULL, mapping, size + 1, 0, &page,
495 &fsdata);
496 if (!res) {
497 res = generic_write_end(NULL, mapping, size + 1, 0, 0,
498 page, fsdata);
499 }
500 if (res)
501 inode->i_size = HFS_I(inode)->phys_size;
502 return;
503 } else if (inode->i_size == HFS_I(inode)->phys_size)
504 return;
505 size = inode->i_size + HFS_SB(sb)->alloc_blksz - 1;
506 blk_cnt = size / HFS_SB(sb)->alloc_blksz;
507 alloc_cnt = HFS_I(inode)->alloc_blocks;
508 if (blk_cnt == alloc_cnt)
509 goto out;
510
511 mutex_lock(&HFS_I(inode)->extents_lock);
512 res = hfs_find_init(HFS_SB(sb)->ext_tree, &fd);
513 if (res) {
514 mutex_unlock(&HFS_I(inode)->extents_lock);
515 /* XXX: We lack error handling of hfs_file_truncate() */
516 return;
517 }
518 while (1) {
519 if (alloc_cnt == HFS_I(inode)->first_blocks) {
520 hfs_free_extents(sb, HFS_I(inode)->first_extents,
521 alloc_cnt, alloc_cnt - blk_cnt);
522 hfs_dump_extent(HFS_I(inode)->first_extents);
523 HFS_I(inode)->first_blocks = blk_cnt;
524 break;
525 }
526 res = __hfs_ext_cache_extent(&fd, inode, alloc_cnt);
527 if (res)
528 break;
529 start = HFS_I(inode)->cached_start;
530 hfs_free_extents(sb, HFS_I(inode)->cached_extents,
531 alloc_cnt - start, alloc_cnt - blk_cnt);
532 hfs_dump_extent(HFS_I(inode)->cached_extents);
533 if (blk_cnt > start) {
534 HFS_I(inode)->flags |= HFS_FLG_EXT_DIRTY;
535 break;
536 }
537 alloc_cnt = start;
538 HFS_I(inode)->cached_start = HFS_I(inode)->cached_blocks = 0;
539 HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW);
540 hfs_brec_remove(&fd);
541 }
542 hfs_find_exit(&fd);
543 mutex_unlock(&HFS_I(inode)->extents_lock);
544
545 HFS_I(inode)->alloc_blocks = blk_cnt;
546 out:
547 HFS_I(inode)->phys_size = inode->i_size;
548 HFS_I(inode)->fs_blocks = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
549 inode_set_bytes(inode, HFS_I(inode)->fs_blocks << sb->s_blocksize_bits);
550 mark_inode_dirty(inode);
551 }
552