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