Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * linux/fs/sysv/itree.c | |
4 | * | |
5 | * Handling of indirect blocks' trees. | |
6 | * AV, Sep--Dec 2000 | |
7 | */ | |
8 | ||
9 | #include <linux/buffer_head.h> | |
10 | #include <linux/mount.h> | |
a2b92914 | 11 | #include <linux/mpage.h> |
1da177e4 LT |
12 | #include <linux/string.h> |
13 | #include "sysv.h" | |
14 | ||
15 | enum {DIRECT = 10, DEPTH = 4}; /* Have triple indirect */ | |
16 | ||
17 | static inline void dirty_indirect(struct buffer_head *bh, struct inode *inode) | |
18 | { | |
19 | mark_buffer_dirty_inode(bh, inode); | |
20 | if (IS_SYNC(inode)) | |
21 | sync_dirty_buffer(bh); | |
22 | } | |
23 | ||
24 | static int block_to_path(struct inode *inode, long block, int offsets[DEPTH]) | |
25 | { | |
26 | struct super_block *sb = inode->i_sb; | |
27 | struct sysv_sb_info *sbi = SYSV_SB(sb); | |
28 | int ptrs_bits = sbi->s_ind_per_block_bits; | |
29 | unsigned long indirect_blocks = sbi->s_ind_per_block, | |
30 | double_blocks = sbi->s_ind_per_block_2; | |
31 | int n = 0; | |
32 | ||
33 | if (block < 0) { | |
34 | printk("sysv_block_map: block < 0\n"); | |
35 | } else if (block < DIRECT) { | |
36 | offsets[n++] = block; | |
37 | } else if ( (block -= DIRECT) < indirect_blocks) { | |
38 | offsets[n++] = DIRECT; | |
39 | offsets[n++] = block; | |
40 | } else if ((block -= indirect_blocks) < double_blocks) { | |
41 | offsets[n++] = DIRECT+1; | |
42 | offsets[n++] = block >> ptrs_bits; | |
43 | offsets[n++] = block & (indirect_blocks - 1); | |
44 | } else if (((block -= double_blocks) >> (ptrs_bits * 2)) < indirect_blocks) { | |
45 | offsets[n++] = DIRECT+2; | |
46 | offsets[n++] = block >> (ptrs_bits * 2); | |
47 | offsets[n++] = (block >> ptrs_bits) & (indirect_blocks - 1); | |
48 | offsets[n++] = block & (indirect_blocks - 1); | |
49 | } else { | |
50 | /* nothing */; | |
51 | } | |
52 | return n; | |
53 | } | |
54 | ||
55 | static inline int block_to_cpu(struct sysv_sb_info *sbi, sysv_zone_t nr) | |
56 | { | |
57 | return sbi->s_block_base + fs32_to_cpu(sbi, nr); | |
58 | } | |
59 | ||
60 | typedef struct { | |
61 | sysv_zone_t *p; | |
62 | sysv_zone_t key; | |
63 | struct buffer_head *bh; | |
64 | } Indirect; | |
65 | ||
66 | static DEFINE_RWLOCK(pointers_lock); | |
67 | ||
68 | static inline void add_chain(Indirect *p, struct buffer_head *bh, sysv_zone_t *v) | |
69 | { | |
70 | p->key = *(p->p = v); | |
71 | p->bh = bh; | |
72 | } | |
73 | ||
74 | static inline int verify_chain(Indirect *from, Indirect *to) | |
75 | { | |
76 | while (from <= to && from->key == *from->p) | |
77 | from++; | |
78 | return (from > to); | |
79 | } | |
80 | ||
81 | static inline sysv_zone_t *block_end(struct buffer_head *bh) | |
82 | { | |
83 | return (sysv_zone_t*)((char*)bh->b_data + bh->b_size); | |
84 | } | |
85 | ||
86 | /* | |
87 | * Requires read_lock(&pointers_lock) or write_lock(&pointers_lock) | |
88 | */ | |
89 | static Indirect *get_branch(struct inode *inode, | |
90 | int depth, | |
91 | int offsets[], | |
92 | Indirect chain[], | |
93 | int *err) | |
94 | { | |
95 | struct super_block *sb = inode->i_sb; | |
96 | Indirect *p = chain; | |
97 | struct buffer_head *bh; | |
98 | ||
99 | *err = 0; | |
100 | add_chain(chain, NULL, SYSV_I(inode)->i_data + *offsets); | |
101 | if (!p->key) | |
102 | goto no_block; | |
103 | while (--depth) { | |
104 | int block = block_to_cpu(SYSV_SB(sb), p->key); | |
105 | bh = sb_bread(sb, block); | |
106 | if (!bh) | |
107 | goto failure; | |
108 | if (!verify_chain(chain, p)) | |
109 | goto changed; | |
110 | add_chain(++p, bh, (sysv_zone_t*)bh->b_data + *++offsets); | |
111 | if (!p->key) | |
112 | goto no_block; | |
113 | } | |
114 | return NULL; | |
115 | ||
116 | changed: | |
117 | brelse(bh); | |
118 | *err = -EAGAIN; | |
119 | goto no_block; | |
120 | failure: | |
121 | *err = -EIO; | |
122 | no_block: | |
123 | return p; | |
124 | } | |
125 | ||
126 | static int alloc_branch(struct inode *inode, | |
127 | int num, | |
128 | int *offsets, | |
129 | Indirect *branch) | |
130 | { | |
131 | int blocksize = inode->i_sb->s_blocksize; | |
132 | int n = 0; | |
133 | int i; | |
134 | ||
135 | branch[0].key = sysv_new_block(inode->i_sb); | |
136 | if (branch[0].key) for (n = 1; n < num; n++) { | |
137 | struct buffer_head *bh; | |
138 | int parent; | |
139 | /* Allocate the next block */ | |
140 | branch[n].key = sysv_new_block(inode->i_sb); | |
141 | if (!branch[n].key) | |
142 | break; | |
143 | /* | |
144 | * Get buffer_head for parent block, zero it out and set | |
145 | * the pointer to new one, then send parent to disk. | |
146 | */ | |
147 | parent = block_to_cpu(SYSV_SB(inode->i_sb), branch[n-1].key); | |
148 | bh = sb_getblk(inode->i_sb, parent); | |
ea2b62f3 PKM |
149 | if (!bh) { |
150 | sysv_free_block(inode->i_sb, branch[n].key); | |
151 | break; | |
152 | } | |
1da177e4 LT |
153 | lock_buffer(bh); |
154 | memset(bh->b_data, 0, blocksize); | |
155 | branch[n].bh = bh; | |
156 | branch[n].p = (sysv_zone_t*) bh->b_data + offsets[n]; | |
157 | *branch[n].p = branch[n].key; | |
158 | set_buffer_uptodate(bh); | |
159 | unlock_buffer(bh); | |
160 | dirty_indirect(bh, inode); | |
161 | } | |
162 | if (n == num) | |
163 | return 0; | |
164 | ||
165 | /* Allocation failed, free what we already allocated */ | |
166 | for (i = 1; i < n; i++) | |
167 | bforget(branch[i].bh); | |
168 | for (i = 0; i < n; i++) | |
169 | sysv_free_block(inode->i_sb, branch[i].key); | |
170 | return -ENOSPC; | |
171 | } | |
172 | ||
173 | static inline int splice_branch(struct inode *inode, | |
174 | Indirect chain[], | |
175 | Indirect *where, | |
176 | int num) | |
177 | { | |
178 | int i; | |
179 | ||
180 | /* Verify that place we are splicing to is still there and vacant */ | |
181 | write_lock(&pointers_lock); | |
182 | if (!verify_chain(chain, where-1) || *where->p) | |
183 | goto changed; | |
184 | *where->p = where->key; | |
185 | write_unlock(&pointers_lock); | |
186 | ||
c801b095 | 187 | inode_set_ctime_current(inode); |
1da177e4 LT |
188 | |
189 | /* had we spliced it onto indirect block? */ | |
190 | if (where->bh) | |
191 | dirty_indirect(where->bh, inode); | |
192 | ||
193 | if (IS_SYNC(inode)) | |
194 | sysv_sync_inode(inode); | |
195 | else | |
196 | mark_inode_dirty(inode); | |
197 | return 0; | |
198 | ||
199 | changed: | |
200 | write_unlock(&pointers_lock); | |
201 | for (i = 1; i < num; i++) | |
202 | bforget(where[i].bh); | |
203 | for (i = 0; i < num; i++) | |
204 | sysv_free_block(inode->i_sb, where[i].key); | |
205 | return -EAGAIN; | |
206 | } | |
207 | ||
208 | static int get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create) | |
209 | { | |
210 | int err = -EIO; | |
211 | int offsets[DEPTH]; | |
212 | Indirect chain[DEPTH]; | |
213 | struct super_block *sb = inode->i_sb; | |
214 | Indirect *partial; | |
215 | int left; | |
216 | int depth = block_to_path(inode, iblock, offsets); | |
217 | ||
218 | if (depth == 0) | |
219 | goto out; | |
220 | ||
221 | reread: | |
222 | read_lock(&pointers_lock); | |
223 | partial = get_branch(inode, depth, offsets, chain, &err); | |
224 | read_unlock(&pointers_lock); | |
225 | ||
226 | /* Simplest case - block found, no allocation needed */ | |
227 | if (!partial) { | |
228 | got_it: | |
229 | map_bh(bh_result, sb, block_to_cpu(SYSV_SB(sb), | |
230 | chain[depth-1].key)); | |
231 | /* Clean up and exit */ | |
232 | partial = chain+depth-1; /* the whole chain */ | |
233 | goto cleanup; | |
234 | } | |
235 | ||
236 | /* Next simple case - plain lookup or failed read of indirect block */ | |
237 | if (!create || err == -EIO) { | |
238 | cleanup: | |
239 | while (partial > chain) { | |
240 | brelse(partial->bh); | |
241 | partial--; | |
242 | } | |
243 | out: | |
244 | return err; | |
245 | } | |
246 | ||
247 | /* | |
248 | * Indirect block might be removed by truncate while we were | |
249 | * reading it. Handling of that case (forget what we've got and | |
250 | * reread) is taken out of the main path. | |
251 | */ | |
252 | if (err == -EAGAIN) | |
253 | goto changed; | |
254 | ||
255 | left = (chain + depth) - partial; | |
256 | err = alloc_branch(inode, left, offsets+(partial-chain), partial); | |
257 | if (err) | |
258 | goto cleanup; | |
259 | ||
260 | if (splice_branch(inode, chain, partial, left) < 0) | |
261 | goto changed; | |
262 | ||
263 | set_buffer_new(bh_result); | |
264 | goto got_it; | |
265 | ||
266 | changed: | |
267 | while (partial > chain) { | |
268 | brelse(partial->bh); | |
269 | partial--; | |
270 | } | |
271 | goto reread; | |
272 | } | |
273 | ||
274 | static inline int all_zeroes(sysv_zone_t *p, sysv_zone_t *q) | |
275 | { | |
276 | while (p < q) | |
277 | if (*p++) | |
278 | return 0; | |
279 | return 1; | |
280 | } | |
281 | ||
282 | static Indirect *find_shared(struct inode *inode, | |
283 | int depth, | |
284 | int offsets[], | |
285 | Indirect chain[], | |
286 | sysv_zone_t *top) | |
287 | { | |
288 | Indirect *partial, *p; | |
289 | int k, err; | |
290 | ||
291 | *top = 0; | |
292 | for (k = depth; k > 1 && !offsets[k-1]; k--) | |
293 | ; | |
294 | ||
295 | write_lock(&pointers_lock); | |
296 | partial = get_branch(inode, k, offsets, chain, &err); | |
297 | if (!partial) | |
298 | partial = chain + k-1; | |
299 | /* | |
300 | * If the branch acquired continuation since we've looked at it - | |
301 | * fine, it should all survive and (new) top doesn't belong to us. | |
302 | */ | |
303 | if (!partial->key && *partial->p) { | |
304 | write_unlock(&pointers_lock); | |
305 | goto no_top; | |
306 | } | |
307 | for (p=partial; p>chain && all_zeroes((sysv_zone_t*)p->bh->b_data,p->p); p--) | |
308 | ; | |
309 | /* | |
310 | * OK, we've found the last block that must survive. The rest of our | |
311 | * branch should be detached before unlocking. However, if that rest | |
312 | * of branch is all ours and does not grow immediately from the inode | |
313 | * it's easier to cheat and just decrement partial->p. | |
314 | */ | |
315 | if (p == chain + k - 1 && p > chain) { | |
316 | p->p--; | |
317 | } else { | |
318 | *top = *p->p; | |
319 | *p->p = 0; | |
320 | } | |
321 | write_unlock(&pointers_lock); | |
322 | ||
323 | while (partial > p) { | |
324 | brelse(partial->bh); | |
325 | partial--; | |
326 | } | |
327 | no_top: | |
328 | return partial; | |
329 | } | |
330 | ||
331 | static inline void free_data(struct inode *inode, sysv_zone_t *p, sysv_zone_t *q) | |
332 | { | |
333 | for ( ; p < q ; p++) { | |
334 | sysv_zone_t nr = *p; | |
335 | if (nr) { | |
336 | *p = 0; | |
337 | sysv_free_block(inode->i_sb, nr); | |
338 | mark_inode_dirty(inode); | |
339 | } | |
340 | } | |
341 | } | |
342 | ||
343 | static void free_branches(struct inode *inode, sysv_zone_t *p, sysv_zone_t *q, int depth) | |
344 | { | |
345 | struct buffer_head * bh; | |
346 | struct super_block *sb = inode->i_sb; | |
347 | ||
348 | if (depth--) { | |
349 | for ( ; p < q ; p++) { | |
350 | int block; | |
351 | sysv_zone_t nr = *p; | |
352 | if (!nr) | |
353 | continue; | |
354 | *p = 0; | |
355 | block = block_to_cpu(SYSV_SB(sb), nr); | |
356 | bh = sb_bread(sb, block); | |
357 | if (!bh) | |
358 | continue; | |
359 | free_branches(inode, (sysv_zone_t*)bh->b_data, | |
360 | block_end(bh), depth); | |
361 | bforget(bh); | |
362 | sysv_free_block(sb, nr); | |
363 | mark_inode_dirty(inode); | |
364 | } | |
365 | } else | |
366 | free_data(inode, p, q); | |
367 | } | |
368 | ||
369 | void sysv_truncate (struct inode * inode) | |
370 | { | |
371 | sysv_zone_t *i_data = SYSV_I(inode)->i_data; | |
372 | int offsets[DEPTH]; | |
373 | Indirect chain[DEPTH]; | |
374 | Indirect *partial; | |
375 | sysv_zone_t nr = 0; | |
376 | int n; | |
377 | long iblock; | |
378 | unsigned blocksize; | |
379 | ||
380 | if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) || | |
381 | S_ISLNK(inode->i_mode))) | |
382 | return; | |
383 | ||
384 | blocksize = inode->i_sb->s_blocksize; | |
385 | iblock = (inode->i_size + blocksize-1) | |
386 | >> inode->i_sb->s_blocksize_bits; | |
387 | ||
388 | block_truncate_page(inode->i_mapping, inode->i_size, get_block); | |
389 | ||
390 | n = block_to_path(inode, iblock, offsets); | |
391 | if (n == 0) | |
392 | return; | |
393 | ||
394 | if (n == 1) { | |
395 | free_data(inode, i_data+offsets[0], i_data + DIRECT); | |
396 | goto do_indirects; | |
397 | } | |
398 | ||
399 | partial = find_shared(inode, n, offsets, chain, &nr); | |
400 | /* Kill the top of shared branch (already detached) */ | |
401 | if (nr) { | |
402 | if (partial == chain) | |
403 | mark_inode_dirty(inode); | |
404 | else | |
405 | dirty_indirect(partial->bh, inode); | |
406 | free_branches(inode, &nr, &nr+1, (chain+n-1) - partial); | |
407 | } | |
408 | /* Clear the ends of indirect blocks on the shared branch */ | |
409 | while (partial > chain) { | |
410 | free_branches(inode, partial->p + 1, block_end(partial->bh), | |
411 | (chain+n-1) - partial); | |
412 | dirty_indirect(partial->bh, inode); | |
413 | brelse (partial->bh); | |
414 | partial--; | |
415 | } | |
416 | do_indirects: | |
417 | /* Kill the remaining (whole) subtrees (== subtrees deeper than...) */ | |
418 | while (n < DEPTH) { | |
419 | nr = i_data[DIRECT + n - 1]; | |
420 | if (nr) { | |
421 | i_data[DIRECT + n - 1] = 0; | |
422 | mark_inode_dirty(inode); | |
423 | free_branches(inode, &nr, &nr+1, n); | |
424 | } | |
425 | n++; | |
426 | } | |
ae3d362a | 427 | inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode)); |
1da177e4 LT |
428 | if (IS_SYNC(inode)) |
429 | sysv_sync_inode (inode); | |
430 | else | |
431 | mark_inode_dirty(inode); | |
432 | } | |
433 | ||
434 | static unsigned sysv_nblocks(struct super_block *s, loff_t size) | |
435 | { | |
436 | struct sysv_sb_info *sbi = SYSV_SB(s); | |
437 | int ptrs_bits = sbi->s_ind_per_block_bits; | |
438 | unsigned blocks, res, direct = DIRECT, i = DEPTH; | |
439 | blocks = (size + s->s_blocksize - 1) >> s->s_blocksize_bits; | |
440 | res = blocks; | |
441 | while (--i && blocks > direct) { | |
442 | blocks = ((blocks - direct - 1) >> ptrs_bits) + 1; | |
443 | res += blocks; | |
444 | direct = 1; | |
445 | } | |
e0c49bd2 | 446 | return res; |
1da177e4 LT |
447 | } |
448 | ||
b74d24f7 | 449 | int sysv_getattr(struct mnt_idmap *idmap, const struct path *path, |
549c7297 | 450 | struct kstat *stat, u32 request_mask, unsigned int flags) |
1da177e4 | 451 | { |
a528d35e | 452 | struct super_block *s = path->dentry->d_sb; |
0d72b928 JL |
453 | generic_fillattr(&nop_mnt_idmap, request_mask, d_inode(path->dentry), |
454 | stat); | |
1da177e4 LT |
455 | stat->blocks = (s->s_blocksize / 512) * sysv_nblocks(s, stat->size); |
456 | stat->blksize = s->s_blocksize; | |
457 | return 0; | |
458 | } | |
459 | ||
a2b92914 MWO |
460 | static int sysv_writepages(struct address_space *mapping, |
461 | struct writeback_control *wbc) | |
1da177e4 | 462 | { |
a2b92914 | 463 | return mpage_writepages(mapping, wbc, get_block); |
1da177e4 | 464 | } |
26a6441a | 465 | |
2c69e205 | 466 | static int sysv_read_folio(struct file *file, struct folio *folio) |
1da177e4 | 467 | { |
2c69e205 | 468 | return block_read_full_folio(folio, get_block); |
1da177e4 | 469 | } |
26a6441a | 470 | |
f4e420dc | 471 | int sysv_prepare_chunk(struct page *page, loff_t pos, unsigned len) |
1da177e4 | 472 | { |
6e1db88d | 473 | return __block_write_begin(page, pos, len, get_block); |
1da177e4 | 474 | } |
26a6441a | 475 | |
fa4d62ae MS |
476 | static void sysv_write_failed(struct address_space *mapping, loff_t to) |
477 | { | |
478 | struct inode *inode = mapping->host; | |
479 | ||
480 | if (to > inode->i_size) { | |
7caef267 | 481 | truncate_pagecache(inode, inode->i_size); |
fa4d62ae MS |
482 | sysv_truncate(inode); |
483 | } | |
484 | } | |
485 | ||
26a6441a | 486 | static int sysv_write_begin(struct file *file, struct address_space *mapping, |
9d6b0cd7 | 487 | loff_t pos, unsigned len, |
26a6441a NP |
488 | struct page **pagep, void **fsdata) |
489 | { | |
155130a4 CH |
490 | int ret; |
491 | ||
b3992d1e | 492 | ret = block_write_begin(mapping, pos, len, pagep, get_block); |
fa4d62ae MS |
493 | if (unlikely(ret)) |
494 | sysv_write_failed(mapping, pos + len); | |
155130a4 CH |
495 | |
496 | return ret; | |
26a6441a NP |
497 | } |
498 | ||
1da177e4 LT |
499 | static sector_t sysv_bmap(struct address_space *mapping, sector_t block) |
500 | { | |
501 | return generic_block_bmap(mapping,block,get_block); | |
502 | } | |
26a6441a | 503 | |
f5e54d6e | 504 | const struct address_space_operations sysv_aops = { |
e621900a | 505 | .dirty_folio = block_dirty_folio, |
7ba13abb | 506 | .invalidate_folio = block_invalidate_folio, |
2c69e205 | 507 | .read_folio = sysv_read_folio, |
a2b92914 | 508 | .writepages = sysv_writepages, |
26a6441a NP |
509 | .write_begin = sysv_write_begin, |
510 | .write_end = generic_write_end, | |
a2b92914 | 511 | .migrate_folio = buffer_migrate_folio, |
1da177e4 LT |
512 | .bmap = sysv_bmap |
513 | }; |