projects/linux·blob assoc-array-fixes · refs

673 lines · 18.2 KiB

1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext2/ialloc.c
4 *
5 * Copyright (C) 1992, 1993, 1994, 1995
6 * Remy Card ([email protected])
7 * Laboratoire MASI - Institut Blaise Pascal
8 * Universite Pierre et Marie Curie (Paris VI)
9 *
10 * BSD ufs-inspired inode and directory allocation by
11 * Stephen Tweedie ([email protected]), 1993
12 * Big-endian to little-endian byte-swapping/bitmaps by
13 * David S. Miller ([email protected]), 1995
14 */
15
16#include <linux/quotaops.h>
17#include <linux/sched.h>
18#include <linux/backing-dev.h>
19#include <linux/buffer_head.h>
20#include <linux/random.h>
21#include "ext2.h"
22#include "xattr.h"
23#include "acl.h"
24
25/*
26 * ialloc.c contains the inodes allocation and deallocation routines
27 */
28
29/*
30 * The free inodes are managed by bitmaps. A file system contains several
31 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
32 * block for inodes, N blocks for the inode table and data blocks.
33 *
34 * The file system contains group descriptors which are located after the
35 * super block. Each descriptor contains the number of the bitmap block and
36 * the free blocks count in the block.
37 */
38
39
40/*
41 * Read the inode allocation bitmap for a given block_group, reading
42 * into the specified slot in the superblock's bitmap cache.
43 *
44 * Return buffer_head of bitmap on success or NULL.
45 */
46static struct buffer_head *
47read_inode_bitmap(struct super_block * sb, unsigned long block_group)
48{
49 struct ext2_group_desc *desc;
50 struct buffer_head *bh = NULL;
51
52 desc = ext2_get_group_desc(sb, block_group, NULL);
53 if (!desc)
54 goto error_out;
55
56 bh = sb_bread(sb, le32_to_cpu(desc->bg_inode_bitmap));
57 if (!bh)
58 ext2_error(sb, "read_inode_bitmap",
59 "Cannot read inode bitmap - "
60 "block_group = %lu, inode_bitmap = %u",
61 block_group, le32_to_cpu(desc->bg_inode_bitmap));
62error_out:
63 return bh;
64}
65
66static void ext2_release_inode(struct super_block *sb, int group, int dir)
67{
68 struct ext2_group_desc * desc;
69 struct buffer_head *bh;
70
71 desc = ext2_get_group_desc(sb, group, &bh);
72 if (!desc) {
73 ext2_error(sb, "ext2_release_inode",
74 "can't get descriptor for group %d", group);
75 return;
76 }
77
78 spin_lock(sb_bgl_lock(EXT2_SB(sb), group));
79 le16_add_cpu(&desc->bg_free_inodes_count, 1);
80 if (dir)
81 le16_add_cpu(&desc->bg_used_dirs_count, -1);
82 spin_unlock(sb_bgl_lock(EXT2_SB(sb), group));
83 percpu_counter_inc(&EXT2_SB(sb)->s_freeinodes_counter);
84 if (dir)
85 percpu_counter_dec(&EXT2_SB(sb)->s_dirs_counter);
86 mark_buffer_dirty(bh);
87}
88
89/*
90 * NOTE! When we get the inode, we're the only people
91 * that have access to it, and as such there are no
92 * race conditions we have to worry about. The inode
93 * is not on the hash-lists, and it cannot be reached
94 * through the filesystem because the directory entry
95 * has been deleted earlier.
96 *
97 * HOWEVER: we must make sure that we get no aliases,
98 * which means that we have to call "clear_inode()"
99 * _before_ we mark the inode not in use in the inode
100 * bitmaps. Otherwise a newly created file might use
101 * the same inode number (not actually the same pointer
102 * though), and then we'd have two inodes sharing the
103 * same inode number and space on the harddisk.
104 */
105void ext2_free_inode (struct inode * inode)
106{
107 struct super_block * sb = inode->i_sb;
108 int is_directory;
109 unsigned long ino;
110 struct buffer_head *bitmap_bh;
111 unsigned long block_group;
112 unsigned long bit;
113 struct ext2_super_block * es;
114
115 ino = inode->i_ino;
116 ext2_debug ("freeing inode %lu\n", ino);
117
118 /*
119 * Note: we must free any quota before locking the superblock,
120 * as writing the quota to disk may need the lock as well.
121 */
122 /* Quota is already initialized in iput() */
123 dquot_free_inode(inode);
124 dquot_drop(inode);
125
126 es = EXT2_SB(sb)->s_es;
127 is_directory = S_ISDIR(inode->i_mode);
128
129 if (ino < EXT2_FIRST_INO(sb) ||
130 ino > le32_to_cpu(es->s_inodes_count)) {
131 ext2_error (sb, "ext2_free_inode",
132 "reserved or nonexistent inode %lu", ino);
133 return;
134 }
135 block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
136 bit = (ino - 1) % EXT2_INODES_PER_GROUP(sb);
137 bitmap_bh = read_inode_bitmap(sb, block_group);
138 if (!bitmap_bh)
139 return;
140
141 /* Ok, now we can actually update the inode bitmaps.. */
142 if (!ext2_clear_bit_atomic(sb_bgl_lock(EXT2_SB(sb), block_group),
143 bit, (void *) bitmap_bh->b_data))
144 ext2_error (sb, "ext2_free_inode",
145 "bit already cleared for inode %lu", ino);
146 else
147 ext2_release_inode(sb, block_group, is_directory);
148 mark_buffer_dirty(bitmap_bh);
149 if (sb->s_flags & SB_SYNCHRONOUS)
150 sync_dirty_buffer(bitmap_bh);
151
152 brelse(bitmap_bh);
153}
154
155/*
156 * We perform asynchronous prereading of the new inode's inode block when
157 * we create the inode, in the expectation that the inode will be written
158 * back soon. There are two reasons:
159 *
160 * - When creating a large number of files, the async prereads will be
161 * nicely merged into large reads
162 * - When writing out a large number of inodes, we don't need to keep on
163 * stalling the writes while we read the inode block.
164 *
165 * FIXME: ext2_get_group_desc() needs to be simplified.
166 */
167static void ext2_preread_inode(struct inode *inode)
168{
169 unsigned long block_group;
170 unsigned long offset;
171 unsigned long block;
172 unsigned int ino = inode->i_ino;
173 struct ext2_group_desc * gdp;
174
175 block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
176 gdp = ext2_get_group_desc(inode->i_sb, block_group, NULL);
177 if (gdp == NULL)
178 return;
179
180 /*
181 * Figure out the offset within the block group inode table
182 */
183 offset = ((ino - 1) % EXT2_INODES_PER_GROUP(inode->i_sb)) *
184 EXT2_INODE_SIZE(inode->i_sb);
185 block = le32_to_cpu(gdp->bg_inode_table) +
186 (offset >> EXT2_BLOCK_SIZE_BITS(inode->i_sb));
187 sb_breadahead(inode->i_sb, block);
188}
189
190/*
191 * There are two policies for allocating an inode. If the new inode is
192 * a directory, then a forward search is made for a block group with both
193 * free space and a low directory-to-inode ratio; if that fails, then of
194 * the groups with above-average free space, that group with the fewest
195 * directories already is chosen.
196 *
197 * For other inodes, search forward from the parent directory\'s block
198 * group to find a free inode.
199 */
200static int find_group_dir(struct super_block *sb, struct inode *parent)
201{
202 int ngroups = EXT2_SB(sb)->s_groups_count;
203 int avefreei = ext2_count_free_inodes(sb) / ngroups;
204 struct ext2_group_desc *desc, *best_desc = NULL;
205 int group, best_group = -1;
206
207 for (group = 0; group < ngroups; group++) {
208 desc = ext2_get_group_desc (sb, group, NULL);
209 if (!desc || !desc->bg_free_inodes_count)
210 continue;
211 if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)
212 continue;
213 if (!best_desc ||
214 (le16_to_cpu(desc->bg_free_blocks_count) >
215 le16_to_cpu(best_desc->bg_free_blocks_count))) {
216 best_group = group;
217 best_desc = desc;
218 }
219 }
220
221 return best_group;
222}
223
224/*
225 * Orlov's allocator for directories.
226 *
227 * We always try to spread first-level directories.
228 *
229 * If there are blockgroups with both free inodes and free blocks counts
230 * not worse than average we return one with smallest directory count.
231 * Otherwise we simply return a random group.
232 *
233 * For the rest rules look so:
234 *
235 * It's OK to put directory into a group unless
236 * it has too many directories already (max_dirs) or
237 * it has too few free inodes left (min_inodes) or
238 * it has too few free blocks left (min_blocks) or
239 * it's already running too large debt (max_debt).
240 * Parent's group is preferred, if it doesn't satisfy these
241 * conditions we search cyclically through the rest. If none
242 * of the groups look good we just look for a group with more
243 * free inodes than average (starting at parent's group).
244 *
245 * Debt is incremented each time we allocate a directory and decremented
246 * when we allocate an inode, within 0--255.
247 */
248
249#define INODE_COST 64
250#define BLOCK_COST 256
251
252static int find_group_orlov(struct super_block *sb, struct inode *parent)
253{
254 int parent_group = EXT2_I(parent)->i_block_group;
255 struct ext2_sb_info *sbi = EXT2_SB(sb);
256 struct ext2_super_block *es = sbi->s_es;
257 int ngroups = sbi->s_groups_count;
258 int inodes_per_group = EXT2_INODES_PER_GROUP(sb);
259 int freei;
260 int avefreei;
261 int free_blocks;
262 int avefreeb;
263 int blocks_per_dir;
264 int ndirs;
265 int max_debt, max_dirs, min_blocks, min_inodes;
266 int group = -1, i;
267 struct ext2_group_desc *desc;
268
269 freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter);
270 avefreei = freei / ngroups;
271 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
272 avefreeb = free_blocks / ngroups;
273 ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter);
274
275 if ((parent == d_inode(sb->s_root)) ||
276 (EXT2_I(parent)->i_flags & EXT2_TOPDIR_FL)) {
277 int best_ndir = inodes_per_group;
278 int best_group = -1;
279
280 parent_group = get_random_u32_below(ngroups);
281 for (i = 0; i < ngroups; i++) {
282 group = (parent_group + i) % ngroups;
283 desc = ext2_get_group_desc (sb, group, NULL);
284 if (!desc || !desc->bg_free_inodes_count)
285 continue;
286 if (le16_to_cpu(desc->bg_used_dirs_count) >= best_ndir)
287 continue;
288 if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)
289 continue;
290 if (le16_to_cpu(desc->bg_free_blocks_count) < avefreeb)
291 continue;
292 best_group = group;
293 best_ndir = le16_to_cpu(desc->bg_used_dirs_count);
294 }
295 if (best_group >= 0) {
296 group = best_group;
297 goto found;
298 }
299 goto fallback;
300 }
301
302 if (ndirs == 0)
303 ndirs = 1; /* percpu_counters are approximate... */
304
305 blocks_per_dir = (le32_to_cpu(es->s_blocks_count)-free_blocks) / ndirs;
306
307 max_dirs = ndirs / ngroups + inodes_per_group / 16;
308 min_inodes = avefreei - inodes_per_group / 4;
309 min_blocks = avefreeb - EXT2_BLOCKS_PER_GROUP(sb) / 4;
310
311 max_debt = EXT2_BLOCKS_PER_GROUP(sb) / max(blocks_per_dir, BLOCK_COST);
312 if (max_debt * INODE_COST > inodes_per_group)
313 max_debt = inodes_per_group / INODE_COST;
314 if (max_debt > 255)
315 max_debt = 255;
316 if (max_debt == 0)
317 max_debt = 1;
318
319 for (i = 0; i < ngroups; i++) {
320 group = (parent_group + i) % ngroups;
321 desc = ext2_get_group_desc (sb, group, NULL);
322 if (!desc || !desc->bg_free_inodes_count)
323 continue;
324 if (sbi->s_debts[group] >= max_debt)
325 continue;
326 if (le16_to_cpu(desc->bg_used_dirs_count) >= max_dirs)
327 continue;
328 if (le16_to_cpu(desc->bg_free_inodes_count) < min_inodes)
329 continue;
330 if (le16_to_cpu(desc->bg_free_blocks_count) < min_blocks)
331 continue;
332 goto found;
333 }
334
335fallback:
336 for (i = 0; i < ngroups; i++) {
337 group = (parent_group + i) % ngroups;
338 desc = ext2_get_group_desc (sb, group, NULL);
339 if (!desc || !desc->bg_free_inodes_count)
340 continue;
341 if (le16_to_cpu(desc->bg_free_inodes_count) >= avefreei)
342 goto found;
343 }
344
345 if (avefreei) {
346 /*
347 * The free-inodes counter is approximate, and for really small
348 * filesystems the above test can fail to find any blockgroups
349 */
350 avefreei = 0;
351 goto fallback;
352 }
353
354 return -1;
355
356found:
357 return group;
358}
359
360static int find_group_other(struct super_block *sb, struct inode *parent)
361{
362 int parent_group = EXT2_I(parent)->i_block_group;
363 int ngroups = EXT2_SB(sb)->s_groups_count;
364 struct ext2_group_desc *desc;
365 int group, i;
366
367 /*
368 * Try to place the inode in its parent directory
369 */
370 group = parent_group;
371 desc = ext2_get_group_desc (sb, group, NULL);
372 if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
373 le16_to_cpu(desc->bg_free_blocks_count))
374 goto found;
375
376 /*
377 * We're going to place this inode in a different blockgroup from its
378 * parent. We want to cause files in a common directory to all land in
379 * the same blockgroup. But we want files which are in a different
380 * directory which shares a blockgroup with our parent to land in a
381 * different blockgroup.
382 *
383 * So add our directory's i_ino into the starting point for the hash.
384 */
385 group = (group + (unsigned int)parent->i_ino) % ngroups;
386
387 /*
388 * Use a quadratic hash to find a group with a free inode and some
389 * free blocks.
390 */
391 for (i = 1; i < ngroups; i <<= 1) {
392 group += i;
393 if (group >= ngroups)
394 group -= ngroups;
395 desc = ext2_get_group_desc (sb, group, NULL);
396 if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
397 le16_to_cpu(desc->bg_free_blocks_count))
398 goto found;
399 }
400
401 /*
402 * That failed: try linear search for a free inode, even if that group
403 * has no free blocks.
404 */
405 group = parent_group;
406 for (i = 0; i < ngroups; i++) {
407 if (++group >= ngroups)
408 group = 0;
409 desc = ext2_get_group_desc (sb, group, NULL);
410 if (desc && le16_to_cpu(desc->bg_free_inodes_count))
411 goto found;
412 }
413
414 return -1;
415
416found:
417 return group;
418}
419
420struct inode *ext2_new_inode(struct inode *dir, umode_t mode,
421 const struct qstr *qstr)
422{
423 struct super_block *sb;
424 struct buffer_head *bitmap_bh = NULL;
425 struct buffer_head *bh2;
426 int group, i;
427 ino_t ino = 0;
428 struct inode * inode;
429 struct ext2_group_desc *gdp;
430 struct ext2_super_block *es;
431 struct ext2_inode_info *ei;
432 struct ext2_sb_info *sbi;
433 int err;
434
435 sb = dir->i_sb;
436 inode = new_inode(sb);
437 if (!inode)
438 return ERR_PTR(-ENOMEM);
439
440 ei = EXT2_I(inode);
441 sbi = EXT2_SB(sb);
442 es = sbi->s_es;
443 if (S_ISDIR(mode)) {
444 if (test_opt(sb, OLDALLOC))
445 group = find_group_dir(sb, dir);
446 else
447 group = find_group_orlov(sb, dir);
448 } else
449 group = find_group_other(sb, dir);
450
451 if (group == -1) {
452 err = -ENOSPC;
453 goto fail;
454 }
455
456 for (i = 0; i < sbi->s_groups_count; i++) {
457 gdp = ext2_get_group_desc(sb, group, &bh2);
458 if (!gdp) {
459 if (++group == sbi->s_groups_count)
460 group = 0;
461 continue;
462 }
463 brelse(bitmap_bh);
464 bitmap_bh = read_inode_bitmap(sb, group);
465 if (!bitmap_bh) {
466 err = -EIO;
467 goto fail;
468 }
469 ino = 0;
470
471repeat_in_this_group:
472 ino = ext2_find_next_zero_bit((unsigned long *)bitmap_bh->b_data,
473 EXT2_INODES_PER_GROUP(sb), ino);
474 if (ino >= EXT2_INODES_PER_GROUP(sb)) {
475 /*
476 * Rare race: find_group_xx() decided that there were
477 * free inodes in this group, but by the time we tried
478 * to allocate one, they're all gone. This can also
479 * occur because the counters which find_group_orlov()
480 * uses are approximate. So just go and search the
481 * next block group.
482 */
483 if (++group == sbi->s_groups_count)
484 group = 0;
485 continue;
486 }
487 if (ext2_set_bit_atomic(sb_bgl_lock(sbi, group),
488 ino, bitmap_bh->b_data)) {
489 /* we lost this inode */
490 if (++ino >= EXT2_INODES_PER_GROUP(sb)) {
491 /* this group is exhausted, try next group */
492 if (++group == sbi->s_groups_count)
493 group = 0;
494 continue;
495 }
496 /* try to find free inode in the same group */
497 goto repeat_in_this_group;
498 }
499 goto got;
500 }
501
502 /*
503 * Scanned all blockgroups.
504 */
505 brelse(bitmap_bh);
506 err = -ENOSPC;
507 goto fail;
508got:
509 mark_buffer_dirty(bitmap_bh);
510 if (sb->s_flags & SB_SYNCHRONOUS)
511 sync_dirty_buffer(bitmap_bh);
512 brelse(bitmap_bh);
513
514 ino += group * EXT2_INODES_PER_GROUP(sb) + 1;
515 if (ino < EXT2_FIRST_INO(sb) || ino > le32_to_cpu(es->s_inodes_count)) {
516 ext2_error (sb, "ext2_new_inode",
517 "reserved inode or inode > inodes count - "
518 "block_group = %d,inode=%lu", group,
519 (unsigned long) ino);
520 err = -EIO;
521 goto fail;
522 }
523
524 percpu_counter_dec(&sbi->s_freeinodes_counter);
525 if (S_ISDIR(mode))
526 percpu_counter_inc(&sbi->s_dirs_counter);
527
528 spin_lock(sb_bgl_lock(sbi, group));
529 le16_add_cpu(&gdp->bg_free_inodes_count, -1);
530 if (S_ISDIR(mode)) {
531 if (sbi->s_debts[group] < 255)
532 sbi->s_debts[group]++;
533 le16_add_cpu(&gdp->bg_used_dirs_count, 1);
534 } else {
535 if (sbi->s_debts[group])
536 sbi->s_debts[group]--;
537 }
538 spin_unlock(sb_bgl_lock(sbi, group));
539
540 mark_buffer_dirty(bh2);
541 if (test_opt(sb, GRPID)) {
542 inode->i_mode = mode;
543 inode->i_uid = current_fsuid();
544 inode->i_gid = dir->i_gid;
545 } else
546 inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
547
548 inode->i_ino = ino;
549 inode->i_blocks = 0;
550 simple_inode_init_ts(inode);
551 memset(ei->i_data, 0, sizeof(ei->i_data));
552 ei->i_flags =
553 ext2_mask_flags(mode, EXT2_I(dir)->i_flags & EXT2_FL_INHERITED);
554 ei->i_faddr = 0;
555 ei->i_frag_no = 0;
556 ei->i_frag_size = 0;
557 ei->i_file_acl = 0;
558 ei->i_dir_acl = 0;
559 ei->i_dtime = 0;
560 ei->i_block_alloc_info = NULL;
561 ei->i_block_group = group;
562 ei->i_dir_start_lookup = 0;
563 ei->i_state = EXT2_STATE_NEW;
564 ext2_set_inode_flags(inode);
565 spin_lock(&sbi->s_next_gen_lock);
566 inode->i_generation = sbi->s_next_generation++;
567 spin_unlock(&sbi->s_next_gen_lock);
568 if (insert_inode_locked(inode) < 0) {
569 ext2_error(sb, "ext2_new_inode",
570 "inode number already in use - inode=%lu",
571 (unsigned long) ino);
572 err = -EIO;
573 goto fail;
574 }
575
576 err = dquot_initialize(inode);
577 if (err)
578 goto fail_drop;
579
580 err = dquot_alloc_inode(inode);
581 if (err)
582 goto fail_drop;
583
584 err = ext2_init_acl(inode, dir);
585 if (err)
586 goto fail_free_drop;
587
588 err = ext2_init_security(inode, dir, qstr);
589 if (err)
590 goto fail_free_drop;
591
592 mark_inode_dirty(inode);
593 ext2_debug("allocating inode %llu\n", inode->i_ino);
594 ext2_preread_inode(inode);
595 return inode;
596
597fail_free_drop:
598 dquot_free_inode(inode);
599
600fail_drop:
601 dquot_drop(inode);
602 inode->i_flags |= S_NOQUOTA;
603 clear_nlink(inode);
604 discard_new_inode(inode);
605 return ERR_PTR(err);
606
607fail:
608 make_bad_inode(inode);
609 iput(inode);
610 return ERR_PTR(err);
611}
612
613unsigned long ext2_count_free_inodes (struct super_block * sb)
614{
615 struct ext2_group_desc *desc;
616 unsigned long desc_count = 0;
617 int i;
618
619#ifdef EXT2FS_DEBUG
620 struct ext2_super_block *es;
621 unsigned long bitmap_count = 0;
622 struct buffer_head *bitmap_bh = NULL;
623
624 es = EXT2_SB(sb)->s_es;
625 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
626 unsigned x;
627
628 desc = ext2_get_group_desc (sb, i, NULL);
629 if (!desc)
630 continue;
631 desc_count += le16_to_cpu(desc->bg_free_inodes_count);
632 brelse(bitmap_bh);
633 bitmap_bh = read_inode_bitmap(sb, i);
634 if (!bitmap_bh)
635 continue;
636
637 x = ext2_count_free(bitmap_bh, EXT2_INODES_PER_GROUP(sb) / 8);
638 printk("group %d: stored = %d, counted = %u\n",
639 i, le16_to_cpu(desc->bg_free_inodes_count), x);
640 bitmap_count += x;
641 }
642 brelse(bitmap_bh);
643 printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n",
644 (unsigned long)
645 percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter),
646 desc_count, bitmap_count);
647 return desc_count;
648#else
649 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
650 desc = ext2_get_group_desc (sb, i, NULL);
651 if (!desc)
652 continue;
653 desc_count += le16_to_cpu(desc->bg_free_inodes_count);
654 }
655 return desc_count;
656#endif
657}
658
659/* Called at mount-time, super-block is locked */
660unsigned long ext2_count_dirs (struct super_block * sb)
661{
662 unsigned long count = 0;
663 int i;
664
665 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
666 struct ext2_group_desc *gdp = ext2_get_group_desc (sb, i, NULL);
667 if (!gdp)
668 continue;
669 count += le16_to_cpu(gdp->bg_used_dirs_count);
670 }
671 return count;
672}
673