blob: f2bcccd1d6fcf42fb9ac5db739eaf33d2ad43fc4 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/sysv/itree.c
3 *
4 * Handling of indirect blocks' trees.
5 * AV, Sep--Dec 2000
6 */
7
8#include <linux/buffer_head.h>
9#include <linux/mount.h>
10#include <linux/string.h>
11#include "sysv.h"
12
13enum {DIRECT = 10, DEPTH = 4}; /* Have triple indirect */
14
15static inline void dirty_indirect(struct buffer_head *bh, struct inode *inode)
16{
17 mark_buffer_dirty_inode(bh, inode);
18 if (IS_SYNC(inode))
19 sync_dirty_buffer(bh);
20}
21
22static int block_to_path(struct inode *inode, long block, int offsets[DEPTH])
23{
24 struct super_block *sb = inode->i_sb;
25 struct sysv_sb_info *sbi = SYSV_SB(sb);
26 int ptrs_bits = sbi->s_ind_per_block_bits;
27 unsigned long indirect_blocks = sbi->s_ind_per_block,
28 double_blocks = sbi->s_ind_per_block_2;
29 int n = 0;
30
31 if (block < 0) {
32 printk("sysv_block_map: block < 0\n");
33 } else if (block < DIRECT) {
34 offsets[n++] = block;
35 } else if ( (block -= DIRECT) < indirect_blocks) {
36 offsets[n++] = DIRECT;
37 offsets[n++] = block;
38 } else if ((block -= indirect_blocks) < double_blocks) {
39 offsets[n++] = DIRECT+1;
40 offsets[n++] = block >> ptrs_bits;
41 offsets[n++] = block & (indirect_blocks - 1);
42 } else if (((block -= double_blocks) >> (ptrs_bits * 2)) < indirect_blocks) {
43 offsets[n++] = DIRECT+2;
44 offsets[n++] = block >> (ptrs_bits * 2);
45 offsets[n++] = (block >> ptrs_bits) & (indirect_blocks - 1);
46 offsets[n++] = block & (indirect_blocks - 1);
47 } else {
48 /* nothing */;
49 }
50 return n;
51}
52
53static inline int block_to_cpu(struct sysv_sb_info *sbi, sysv_zone_t nr)
54{
55 return sbi->s_block_base + fs32_to_cpu(sbi, nr);
56}
57
58typedef struct {
59 sysv_zone_t *p;
60 sysv_zone_t key;
61 struct buffer_head *bh;
62} Indirect;
63
64static DEFINE_RWLOCK(pointers_lock);
65
66static inline void add_chain(Indirect *p, struct buffer_head *bh, sysv_zone_t *v)
67{
68 p->key = *(p->p = v);
69 p->bh = bh;
70}
71
72static inline int verify_chain(Indirect *from, Indirect *to)
73{
74 while (from <= to && from->key == *from->p)
75 from++;
76 return (from > to);
77}
78
79static inline sysv_zone_t *block_end(struct buffer_head *bh)
80{
81 return (sysv_zone_t*)((char*)bh->b_data + bh->b_size);
82}
83
84/*
85 * Requires read_lock(&pointers_lock) or write_lock(&pointers_lock)
86 */
87static Indirect *get_branch(struct inode *inode,
88 int depth,
89 int offsets[],
90 Indirect chain[],
91 int *err)
92{
93 struct super_block *sb = inode->i_sb;
94 Indirect *p = chain;
95 struct buffer_head *bh;
96
97 *err = 0;
98 add_chain(chain, NULL, SYSV_I(inode)->i_data + *offsets);
99 if (!p->key)
100 goto no_block;
101 while (--depth) {
102 int block = block_to_cpu(SYSV_SB(sb), p->key);
103 bh = sb_bread(sb, block);
104 if (!bh)
105 goto failure;
106 if (!verify_chain(chain, p))
107 goto changed;
108 add_chain(++p, bh, (sysv_zone_t*)bh->b_data + *++offsets);
109 if (!p->key)
110 goto no_block;
111 }
112 return NULL;
113
114changed:
115 brelse(bh);
116 *err = -EAGAIN;
117 goto no_block;
118failure:
119 *err = -EIO;
120no_block:
121 return p;
122}
123
124static int alloc_branch(struct inode *inode,
125 int num,
126 int *offsets,
127 Indirect *branch)
128{
129 int blocksize = inode->i_sb->s_blocksize;
130 int n = 0;
131 int i;
132
133 branch[0].key = sysv_new_block(inode->i_sb);
134 if (branch[0].key) for (n = 1; n < num; n++) {
135 struct buffer_head *bh;
136 int parent;
137 /* Allocate the next block */
138 branch[n].key = sysv_new_block(inode->i_sb);
139 if (!branch[n].key)
140 break;
141 /*
142 * Get buffer_head for parent block, zero it out and set
143 * the pointer to new one, then send parent to disk.
144 */
145 parent = block_to_cpu(SYSV_SB(inode->i_sb), branch[n-1].key);
146 bh = sb_getblk(inode->i_sb, parent);
147 lock_buffer(bh);
148 memset(bh->b_data, 0, blocksize);
149 branch[n].bh = bh;
150 branch[n].p = (sysv_zone_t*) bh->b_data + offsets[n];
151 *branch[n].p = branch[n].key;
152 set_buffer_uptodate(bh);
153 unlock_buffer(bh);
154 dirty_indirect(bh, inode);
155 }
156 if (n == num)
157 return 0;
158
159 /* Allocation failed, free what we already allocated */
160 for (i = 1; i < n; i++)
161 bforget(branch[i].bh);
162 for (i = 0; i < n; i++)
163 sysv_free_block(inode->i_sb, branch[i].key);
164 return -ENOSPC;
165}
166
167static inline int splice_branch(struct inode *inode,
168 Indirect chain[],
169 Indirect *where,
170 int num)
171{
172 int i;
173
174 /* Verify that place we are splicing to is still there and vacant */
175 write_lock(&pointers_lock);
176 if (!verify_chain(chain, where-1) || *where->p)
177 goto changed;
178 *where->p = where->key;
179 write_unlock(&pointers_lock);
180
181 inode->i_ctime = CURRENT_TIME_SEC;
182
183 /* had we spliced it onto indirect block? */
184 if (where->bh)
185 dirty_indirect(where->bh, inode);
186
187 if (IS_SYNC(inode))
188 sysv_sync_inode(inode);
189 else
190 mark_inode_dirty(inode);
191 return 0;
192
193changed:
194 write_unlock(&pointers_lock);
195 for (i = 1; i < num; i++)
196 bforget(where[i].bh);
197 for (i = 0; i < num; i++)
198 sysv_free_block(inode->i_sb, where[i].key);
199 return -EAGAIN;
200}
201
202static int get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
203{
204 int err = -EIO;
205 int offsets[DEPTH];
206 Indirect chain[DEPTH];
207 struct super_block *sb = inode->i_sb;
208 Indirect *partial;
209 int left;
210 int depth = block_to_path(inode, iblock, offsets);
211
212 if (depth == 0)
213 goto out;
214
215reread:
216 read_lock(&pointers_lock);
217 partial = get_branch(inode, depth, offsets, chain, &err);
218 read_unlock(&pointers_lock);
219
220 /* Simplest case - block found, no allocation needed */
221 if (!partial) {
222got_it:
223 map_bh(bh_result, sb, block_to_cpu(SYSV_SB(sb),
224 chain[depth-1].key));
225 /* Clean up and exit */
226 partial = chain+depth-1; /* the whole chain */
227 goto cleanup;
228 }
229
230 /* Next simple case - plain lookup or failed read of indirect block */
231 if (!create || err == -EIO) {
232cleanup:
233 while (partial > chain) {
234 brelse(partial->bh);
235 partial--;
236 }
237out:
238 return err;
239 }
240
241 /*
242 * Indirect block might be removed by truncate while we were
243 * reading it. Handling of that case (forget what we've got and
244 * reread) is taken out of the main path.
245 */
246 if (err == -EAGAIN)
247 goto changed;
248
249 left = (chain + depth) - partial;
250 err = alloc_branch(inode, left, offsets+(partial-chain), partial);
251 if (err)
252 goto cleanup;
253
254 if (splice_branch(inode, chain, partial, left) < 0)
255 goto changed;
256
257 set_buffer_new(bh_result);
258 goto got_it;
259
260changed:
261 while (partial > chain) {
262 brelse(partial->bh);
263 partial--;
264 }
265 goto reread;
266}
267
268static inline int all_zeroes(sysv_zone_t *p, sysv_zone_t *q)
269{
270 while (p < q)
271 if (*p++)
272 return 0;
273 return 1;
274}
275
276static Indirect *find_shared(struct inode *inode,
277 int depth,
278 int offsets[],
279 Indirect chain[],
280 sysv_zone_t *top)
281{
282 Indirect *partial, *p;
283 int k, err;
284
285 *top = 0;
286 for (k = depth; k > 1 && !offsets[k-1]; k--)
287 ;
288
289 write_lock(&pointers_lock);
290 partial = get_branch(inode, k, offsets, chain, &err);
291 if (!partial)
292 partial = chain + k-1;
293 /*
294 * If the branch acquired continuation since we've looked at it -
295 * fine, it should all survive and (new) top doesn't belong to us.
296 */
297 if (!partial->key && *partial->p) {
298 write_unlock(&pointers_lock);
299 goto no_top;
300 }
301 for (p=partial; p>chain && all_zeroes((sysv_zone_t*)p->bh->b_data,p->p); p--)
302 ;
303 /*
304 * OK, we've found the last block that must survive. The rest of our
305 * branch should be detached before unlocking. However, if that rest
306 * of branch is all ours and does not grow immediately from the inode
307 * it's easier to cheat and just decrement partial->p.
308 */
309 if (p == chain + k - 1 && p > chain) {
310 p->p--;
311 } else {
312 *top = *p->p;
313 *p->p = 0;
314 }
315 write_unlock(&pointers_lock);
316
317 while (partial > p) {
318 brelse(partial->bh);
319 partial--;
320 }
321no_top:
322 return partial;
323}
324
325static inline void free_data(struct inode *inode, sysv_zone_t *p, sysv_zone_t *q)
326{
327 for ( ; p < q ; p++) {
328 sysv_zone_t nr = *p;
329 if (nr) {
330 *p = 0;
331 sysv_free_block(inode->i_sb, nr);
332 mark_inode_dirty(inode);
333 }
334 }
335}
336
337static void free_branches(struct inode *inode, sysv_zone_t *p, sysv_zone_t *q, int depth)
338{
339 struct buffer_head * bh;
340 struct super_block *sb = inode->i_sb;
341
342 if (depth--) {
343 for ( ; p < q ; p++) {
344 int block;
345 sysv_zone_t nr = *p;
346 if (!nr)
347 continue;
348 *p = 0;
349 block = block_to_cpu(SYSV_SB(sb), nr);
350 bh = sb_bread(sb, block);
351 if (!bh)
352 continue;
353 free_branches(inode, (sysv_zone_t*)bh->b_data,
354 block_end(bh), depth);
355 bforget(bh);
356 sysv_free_block(sb, nr);
357 mark_inode_dirty(inode);
358 }
359 } else
360 free_data(inode, p, q);
361}
362
363void sysv_truncate (struct inode * inode)
364{
365 sysv_zone_t *i_data = SYSV_I(inode)->i_data;
366 int offsets[DEPTH];
367 Indirect chain[DEPTH];
368 Indirect *partial;
369 sysv_zone_t nr = 0;
370 int n;
371 long iblock;
372 unsigned blocksize;
373
374 if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
375 S_ISLNK(inode->i_mode)))
376 return;
377
378 blocksize = inode->i_sb->s_blocksize;
379 iblock = (inode->i_size + blocksize-1)
380 >> inode->i_sb->s_blocksize_bits;
381
382 block_truncate_page(inode->i_mapping, inode->i_size, get_block);
383
384 n = block_to_path(inode, iblock, offsets);
385 if (n == 0)
386 return;
387
388 if (n == 1) {
389 free_data(inode, i_data+offsets[0], i_data + DIRECT);
390 goto do_indirects;
391 }
392
393 partial = find_shared(inode, n, offsets, chain, &nr);
394 /* Kill the top of shared branch (already detached) */
395 if (nr) {
396 if (partial == chain)
397 mark_inode_dirty(inode);
398 else
399 dirty_indirect(partial->bh, inode);
400 free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
401 }
402 /* Clear the ends of indirect blocks on the shared branch */
403 while (partial > chain) {
404 free_branches(inode, partial->p + 1, block_end(partial->bh),
405 (chain+n-1) - partial);
406 dirty_indirect(partial->bh, inode);
407 brelse (partial->bh);
408 partial--;
409 }
410do_indirects:
411 /* Kill the remaining (whole) subtrees (== subtrees deeper than...) */
412 while (n < DEPTH) {
413 nr = i_data[DIRECT + n - 1];
414 if (nr) {
415 i_data[DIRECT + n - 1] = 0;
416 mark_inode_dirty(inode);
417 free_branches(inode, &nr, &nr+1, n);
418 }
419 n++;
420 }
421 inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
422 if (IS_SYNC(inode))
423 sysv_sync_inode (inode);
424 else
425 mark_inode_dirty(inode);
426}
427
428static unsigned sysv_nblocks(struct super_block *s, loff_t size)
429{
430 struct sysv_sb_info *sbi = SYSV_SB(s);
431 int ptrs_bits = sbi->s_ind_per_block_bits;
432 unsigned blocks, res, direct = DIRECT, i = DEPTH;
433 blocks = (size + s->s_blocksize - 1) >> s->s_blocksize_bits;
434 res = blocks;
435 while (--i && blocks > direct) {
436 blocks = ((blocks - direct - 1) >> ptrs_bits) + 1;
437 res += blocks;
438 direct = 1;
439 }
440 return blocks;
441}
442
443int sysv_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
444{
445 struct super_block *s = mnt->mnt_sb;
446 generic_fillattr(dentry->d_inode, stat);
447 stat->blocks = (s->s_blocksize / 512) * sysv_nblocks(s, stat->size);
448 stat->blksize = s->s_blocksize;
449 return 0;
450}
451
452static int sysv_writepage(struct page *page, struct writeback_control *wbc)
453{
454 return block_write_full_page(page,get_block,wbc);
455}
456static int sysv_readpage(struct file *file, struct page *page)
457{
458 return block_read_full_page(page,get_block);
459}
460static int sysv_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
461{
462 return block_prepare_write(page,from,to,get_block);
463}
464static sector_t sysv_bmap(struct address_space *mapping, sector_t block)
465{
466 return generic_block_bmap(mapping,block,get_block);
467}
Christoph Hellwigf5e54d62006-06-28 04:26:44 -0700468const struct address_space_operations sysv_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 .readpage = sysv_readpage,
470 .writepage = sysv_writepage,
471 .sync_page = block_sync_page,
472 .prepare_write = sysv_prepare_write,
473 .commit_write = generic_commit_write,
474 .bmap = sysv_bmap
475};