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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 (card@masi.ibp.fr)
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 (sct@dcs.ed.ac.uk), 1993
12 * Big-endian to little-endian byte-swapping/bitmaps by
13 * David S. Miller (davem@caip.rutgers.edu), 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 if (dir)
84 percpu_counter_dec(&EXT2_SB(sb)->s_dirs_counter);
85 mark_buffer_dirty(bh);
86}
87
88/*
89 * NOTE! When we get the inode, we're the only people
90 * that have access to it, and as such there are no
91 * race conditions we have to worry about. The inode
92 * is not on the hash-lists, and it cannot be reached
93 * through the filesystem because the directory entry
94 * has been deleted earlier.
95 *
96 * HOWEVER: we must make sure that we get no aliases,
97 * which means that we have to call "clear_inode()"
98 * _before_ we mark the inode not in use in the inode
99 * bitmaps. Otherwise a newly created file might use
100 * the same inode number (not actually the same pointer
101 * though), and then we'd have two inodes sharing the
102 * same inode number and space on the harddisk.
103 */
104void ext2_free_inode (struct inode * inode)
105{
106 struct super_block * sb = inode->i_sb;
107 int is_directory;
108 unsigned long ino;
109 struct buffer_head *bitmap_bh;
110 unsigned long block_group;
111 unsigned long bit;
112 struct ext2_super_block * es;
113
114 ino = inode->i_ino;
115 ext2_debug ("freeing inode %lu\n", ino);
116
117 /*
118 * Note: we must free any quota before locking the superblock,
119 * as writing the quota to disk may need the lock as well.
120 */
121 /* Quota is already initialized in iput() */
122 dquot_free_inode(inode);
123 dquot_drop(inode);
124
125 es = EXT2_SB(sb)->s_es;
126 is_directory = S_ISDIR(inode->i_mode);
127
128 if (ino < EXT2_FIRST_INO(sb) ||
129 ino > le32_to_cpu(es->s_inodes_count)) {
130 ext2_error (sb, "ext2_free_inode",
131 "reserved or nonexistent inode %lu", ino);
132 return;
133 }
134 block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
135 bit = (ino - 1) % EXT2_INODES_PER_GROUP(sb);
136 bitmap_bh = read_inode_bitmap(sb, block_group);
137 if (!bitmap_bh)
138 return;
139
140 /* Ok, now we can actually update the inode bitmaps.. */
141 if (!ext2_clear_bit_atomic(sb_bgl_lock(EXT2_SB(sb), block_group),
142 bit, (void *) bitmap_bh->b_data))
143 ext2_error (sb, "ext2_free_inode",
144 "bit already cleared for inode %lu", ino);
145 else
146 ext2_release_inode(sb, block_group, is_directory);
147 mark_buffer_dirty(bitmap_bh);
148 if (sb->s_flags & SB_SYNCHRONOUS)
149 sync_dirty_buffer(bitmap_bh);
150
151 brelse(bitmap_bh);
152}
153
154/*
155 * We perform asynchronous prereading of the new inode's inode block when
156 * we create the inode, in the expectation that the inode will be written
157 * back soon. There are two reasons:
158 *
159 * - When creating a large number of files, the async prereads will be
160 * nicely merged into large reads
161 * - When writing out a large number of inodes, we don't need to keep on
162 * stalling the writes while we read the inode block.
163 *
164 * FIXME: ext2_get_group_desc() needs to be simplified.
165 */
166static void ext2_preread_inode(struct inode *inode)
167{
168 unsigned long block_group;
169 unsigned long offset;
170 unsigned long block;
171 struct ext2_group_desc * gdp;
172 struct backing_dev_info *bdi;
173
174 bdi = inode_to_bdi(inode);
175 if (bdi_rw_congested(bdi))
176 return;
177
178 block_group = (inode->i_ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
179 gdp = ext2_get_group_desc(inode->i_sb, block_group, NULL);
180 if (gdp == NULL)
181 return;
182
183 /*
184 * Figure out the offset within the block group inode table
185 */
186 offset = ((inode->i_ino - 1) % EXT2_INODES_PER_GROUP(inode->i_sb)) *
187 EXT2_INODE_SIZE(inode->i_sb);
188 block = le32_to_cpu(gdp->bg_inode_table) +
189 (offset >> EXT2_BLOCK_SIZE_BITS(inode->i_sb));
190 sb_breadahead(inode->i_sb, block);
191}
192
193/*
194 * There are two policies for allocating an inode. If the new inode is
195 * a directory, then a forward search is made for a block group with both
196 * free space and a low directory-to-inode ratio; if that fails, then of
197 * the groups with above-average free space, that group with the fewest
198 * directories already is chosen.
199 *
200 * For other inodes, search forward from the parent directory\'s block
201 * group to find a free inode.
202 */
203static int find_group_dir(struct super_block *sb, struct inode *parent)
204{
205 int ngroups = EXT2_SB(sb)->s_groups_count;
206 int avefreei = ext2_count_free_inodes(sb) / ngroups;
207 struct ext2_group_desc *desc, *best_desc = NULL;
208 int group, best_group = -1;
209
210 for (group = 0; group < ngroups; group++) {
211 desc = ext2_get_group_desc (sb, group, NULL);
212 if (!desc || !desc->bg_free_inodes_count)
213 continue;
214 if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)
215 continue;
216 if (!best_desc ||
217 (le16_to_cpu(desc->bg_free_blocks_count) >
218 le16_to_cpu(best_desc->bg_free_blocks_count))) {
219 best_group = group;
220 best_desc = desc;
221 }
222 }
223
224 return best_group;
225}
226
227/*
228 * Orlov's allocator for directories.
229 *
230 * We always try to spread first-level directories.
231 *
232 * If there are blockgroups with both free inodes and free blocks counts
233 * not worse than average we return one with smallest directory count.
234 * Otherwise we simply return a random group.
235 *
236 * For the rest rules look so:
237 *
238 * It's OK to put directory into a group unless
239 * it has too many directories already (max_dirs) or
240 * it has too few free inodes left (min_inodes) or
241 * it has too few free blocks left (min_blocks) or
242 * it's already running too large debt (max_debt).
243 * Parent's group is preferred, if it doesn't satisfy these
244 * conditions we search cyclically through the rest. If none
245 * of the groups look good we just look for a group with more
246 * free inodes than average (starting at parent's group).
247 *
248 * Debt is incremented each time we allocate a directory and decremented
249 * when we allocate an inode, within 0--255.
250 */
251
252#define INODE_COST 64
253#define BLOCK_COST 256
254
255static int find_group_orlov(struct super_block *sb, struct inode *parent)
256{
257 int parent_group = EXT2_I(parent)->i_block_group;
258 struct ext2_sb_info *sbi = EXT2_SB(sb);
259 struct ext2_super_block *es = sbi->s_es;
260 int ngroups = sbi->s_groups_count;
261 int inodes_per_group = EXT2_INODES_PER_GROUP(sb);
262 int freei;
263 int avefreei;
264 int free_blocks;
265 int avefreeb;
266 int blocks_per_dir;
267 int ndirs;
268 int max_debt, max_dirs, min_blocks, min_inodes;
269 int group = -1, i;
270 struct ext2_group_desc *desc;
271
272 freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter);
273 avefreei = freei / ngroups;
274 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
275 avefreeb = free_blocks / ngroups;
276 ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter);
277
278 if ((parent == d_inode(sb->s_root)) ||
279 (EXT2_I(parent)->i_flags & EXT2_TOPDIR_FL)) {
280 struct ext2_group_desc *best_desc = NULL;
281 int best_ndir = inodes_per_group;
282 int best_group = -1;
283
284 group = prandom_u32();
285 parent_group = (unsigned)group % ngroups;
286 for (i = 0; i < ngroups; i++) {
287 group = (parent_group + i) % ngroups;
288 desc = ext2_get_group_desc (sb, group, NULL);
289 if (!desc || !desc->bg_free_inodes_count)
290 continue;
291 if (le16_to_cpu(desc->bg_used_dirs_count) >= best_ndir)
292 continue;
293 if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)
294 continue;
295 if (le16_to_cpu(desc->bg_free_blocks_count) < avefreeb)
296 continue;
297 best_group = group;
298 best_ndir = le16_to_cpu(desc->bg_used_dirs_count);
299 best_desc = desc;
300 }
301 if (best_group >= 0) {
302 desc = best_desc;
303 group = best_group;
304 goto found;
305 }
306 goto fallback;
307 }
308
309 if (ndirs == 0)
310 ndirs = 1; /* percpu_counters are approximate... */
311
312 blocks_per_dir = (le32_to_cpu(es->s_blocks_count)-free_blocks) / ndirs;
313
314 max_dirs = ndirs / ngroups + inodes_per_group / 16;
315 min_inodes = avefreei - inodes_per_group / 4;
316 min_blocks = avefreeb - EXT2_BLOCKS_PER_GROUP(sb) / 4;
317
318 max_debt = EXT2_BLOCKS_PER_GROUP(sb) / max(blocks_per_dir, BLOCK_COST);
319 if (max_debt * INODE_COST > inodes_per_group)
320 max_debt = inodes_per_group / INODE_COST;
321 if (max_debt > 255)
322 max_debt = 255;
323 if (max_debt == 0)
324 max_debt = 1;
325
326 for (i = 0; i < ngroups; i++) {
327 group = (parent_group + i) % ngroups;
328 desc = ext2_get_group_desc (sb, group, NULL);
329 if (!desc || !desc->bg_free_inodes_count)
330 continue;
331 if (sbi->s_debts[group] >= max_debt)
332 continue;
333 if (le16_to_cpu(desc->bg_used_dirs_count) >= max_dirs)
334 continue;
335 if (le16_to_cpu(desc->bg_free_inodes_count) < min_inodes)
336 continue;
337 if (le16_to_cpu(desc->bg_free_blocks_count) < min_blocks)
338 continue;
339 goto found;
340 }
341
342fallback:
343 for (i = 0; i < ngroups; i++) {
344 group = (parent_group + i) % ngroups;
345 desc = ext2_get_group_desc (sb, group, NULL);
346 if (!desc || !desc->bg_free_inodes_count)
347 continue;
348 if (le16_to_cpu(desc->bg_free_inodes_count) >= avefreei)
349 goto found;
350 }
351
352 if (avefreei) {
353 /*
354 * The free-inodes counter is approximate, and for really small
355 * filesystems the above test can fail to find any blockgroups
356 */
357 avefreei = 0;
358 goto fallback;
359 }
360
361 return -1;
362
363found:
364 return group;
365}
366
367static int find_group_other(struct super_block *sb, struct inode *parent)
368{
369 int parent_group = EXT2_I(parent)->i_block_group;
370 int ngroups = EXT2_SB(sb)->s_groups_count;
371 struct ext2_group_desc *desc;
372 int group, i;
373
374 /*
375 * Try to place the inode in its parent directory
376 */
377 group = parent_group;
378 desc = ext2_get_group_desc (sb, group, NULL);
379 if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
380 le16_to_cpu(desc->bg_free_blocks_count))
381 goto found;
382
383 /*
384 * We're going to place this inode in a different blockgroup from its
385 * parent. We want to cause files in a common directory to all land in
386 * the same blockgroup. But we want files which are in a different
387 * directory which shares a blockgroup with our parent to land in a
388 * different blockgroup.
389 *
390 * So add our directory's i_ino into the starting point for the hash.
391 */
392 group = (group + parent->i_ino) % ngroups;
393
394 /*
395 * Use a quadratic hash to find a group with a free inode and some
396 * free blocks.
397 */
398 for (i = 1; i < ngroups; i <<= 1) {
399 group += i;
400 if (group >= ngroups)
401 group -= ngroups;
402 desc = ext2_get_group_desc (sb, group, NULL);
403 if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
404 le16_to_cpu(desc->bg_free_blocks_count))
405 goto found;
406 }
407
408 /*
409 * That failed: try linear search for a free inode, even if that group
410 * has no free blocks.
411 */
412 group = parent_group;
413 for (i = 0; i < ngroups; i++) {
414 if (++group >= ngroups)
415 group = 0;
416 desc = ext2_get_group_desc (sb, group, NULL);
417 if (desc && le16_to_cpu(desc->bg_free_inodes_count))
418 goto found;
419 }
420
421 return -1;
422
423found:
424 return group;
425}
426
427struct inode *ext2_new_inode(struct inode *dir, umode_t mode,
428 const struct qstr *qstr)
429{
430 struct super_block *sb;
431 struct buffer_head *bitmap_bh = NULL;
432 struct buffer_head *bh2;
433 int group, i;
434 ino_t ino = 0;
435 struct inode * inode;
436 struct ext2_group_desc *gdp;
437 struct ext2_super_block *es;
438 struct ext2_inode_info *ei;
439 struct ext2_sb_info *sbi;
440 int err;
441
442 sb = dir->i_sb;
443 inode = new_inode(sb);
444 if (!inode)
445 return ERR_PTR(-ENOMEM);
446
447 ei = EXT2_I(inode);
448 sbi = EXT2_SB(sb);
449 es = sbi->s_es;
450 if (S_ISDIR(mode)) {
451 if (test_opt(sb, OLDALLOC))
452 group = find_group_dir(sb, dir);
453 else
454 group = find_group_orlov(sb, dir);
455 } else
456 group = find_group_other(sb, dir);
457
458 if (group == -1) {
459 err = -ENOSPC;
460 goto fail;
461 }
462
463 for (i = 0; i < sbi->s_groups_count; i++) {
464 gdp = ext2_get_group_desc(sb, group, &bh2);
465 if (!gdp) {
466 if (++group == sbi->s_groups_count)
467 group = 0;
468 continue;
469 }
470 brelse(bitmap_bh);
471 bitmap_bh = read_inode_bitmap(sb, group);
472 if (!bitmap_bh) {
473 err = -EIO;
474 goto fail;
475 }
476 ino = 0;
477
478repeat_in_this_group:
479 ino = ext2_find_next_zero_bit((unsigned long *)bitmap_bh->b_data,
480 EXT2_INODES_PER_GROUP(sb), ino);
481 if (ino >= EXT2_INODES_PER_GROUP(sb)) {
482 /*
483 * Rare race: find_group_xx() decided that there were
484 * free inodes in this group, but by the time we tried
485 * to allocate one, they're all gone. This can also
486 * occur because the counters which find_group_orlov()
487 * uses are approximate. So just go and search the
488 * next block group.
489 */
490 if (++group == sbi->s_groups_count)
491 group = 0;
492 continue;
493 }
494 if (ext2_set_bit_atomic(sb_bgl_lock(sbi, group),
495 ino, bitmap_bh->b_data)) {
496 /* we lost this inode */
497 if (++ino >= EXT2_INODES_PER_GROUP(sb)) {
498 /* this group is exhausted, try next group */
499 if (++group == sbi->s_groups_count)
500 group = 0;
501 continue;
502 }
503 /* try to find free inode in the same group */
504 goto repeat_in_this_group;
505 }
506 goto got;
507 }
508
509 /*
510 * Scanned all blockgroups.
511 */
512 brelse(bitmap_bh);
513 err = -ENOSPC;
514 goto fail;
515got:
516 mark_buffer_dirty(bitmap_bh);
517 if (sb->s_flags & SB_SYNCHRONOUS)
518 sync_dirty_buffer(bitmap_bh);
519 brelse(bitmap_bh);
520
521 ino += group * EXT2_INODES_PER_GROUP(sb) + 1;
522 if (ino < EXT2_FIRST_INO(sb) || ino > le32_to_cpu(es->s_inodes_count)) {
523 ext2_error (sb, "ext2_new_inode",
524 "reserved inode or inode > inodes count - "
525 "block_group = %d,inode=%lu", group,
526 (unsigned long) ino);
527 err = -EIO;
528 goto fail;
529 }
530
531 percpu_counter_add(&sbi->s_freeinodes_counter, -1);
532 if (S_ISDIR(mode))
533 percpu_counter_inc(&sbi->s_dirs_counter);
534
535 spin_lock(sb_bgl_lock(sbi, group));
536 le16_add_cpu(&gdp->bg_free_inodes_count, -1);
537 if (S_ISDIR(mode)) {
538 if (sbi->s_debts[group] < 255)
539 sbi->s_debts[group]++;
540 le16_add_cpu(&gdp->bg_used_dirs_count, 1);
541 } else {
542 if (sbi->s_debts[group])
543 sbi->s_debts[group]--;
544 }
545 spin_unlock(sb_bgl_lock(sbi, group));
546
547 mark_buffer_dirty(bh2);
548 if (test_opt(sb, GRPID)) {
549 inode->i_mode = mode;
550 inode->i_uid = current_fsuid();
551 inode->i_gid = dir->i_gid;
552 } else
553 inode_init_owner(inode, dir, mode);
554
555 inode->i_ino = ino;
556 inode->i_blocks = 0;
557 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
558 memset(ei->i_data, 0, sizeof(ei->i_data));
559 ei->i_flags =
560 ext2_mask_flags(mode, EXT2_I(dir)->i_flags & EXT2_FL_INHERITED);
561 ei->i_faddr = 0;
562 ei->i_frag_no = 0;
563 ei->i_frag_size = 0;
564 ei->i_file_acl = 0;
565 ei->i_dir_acl = 0;
566 ei->i_dtime = 0;
567 ei->i_block_alloc_info = NULL;
568 ei->i_block_group = group;
569 ei->i_dir_start_lookup = 0;
570 ei->i_state = EXT2_STATE_NEW;
571 ext2_set_inode_flags(inode);
572 spin_lock(&sbi->s_next_gen_lock);
573 inode->i_generation = sbi->s_next_generation++;
574 spin_unlock(&sbi->s_next_gen_lock);
575 if (insert_inode_locked(inode) < 0) {
576 ext2_error(sb, "ext2_new_inode",
577 "inode number already in use - inode=%lu",
578 (unsigned long) ino);
579 err = -EIO;
580 goto fail;
581 }
582
583 err = dquot_initialize(inode);
584 if (err)
585 goto fail_drop;
586
587 err = dquot_alloc_inode(inode);
588 if (err)
589 goto fail_drop;
590
591 err = ext2_init_acl(inode, dir);
592 if (err)
593 goto fail_free_drop;
594
595 err = ext2_init_security(inode, dir, qstr);
596 if (err)
597 goto fail_free_drop;
598
599 mark_inode_dirty(inode);
600 ext2_debug("allocating inode %lu\n", inode->i_ino);
601 ext2_preread_inode(inode);
602 return inode;
603
604fail_free_drop:
605 dquot_free_inode(inode);
606
607fail_drop:
608 dquot_drop(inode);
609 inode->i_flags |= S_NOQUOTA;
610 clear_nlink(inode);
611 discard_new_inode(inode);
612 return ERR_PTR(err);
613
614fail:
615 make_bad_inode(inode);
616 iput(inode);
617 return ERR_PTR(err);
618}
619
620unsigned long ext2_count_free_inodes (struct super_block * sb)
621{
622 struct ext2_group_desc *desc;
623 unsigned long desc_count = 0;
624 int i;
625
626#ifdef EXT2FS_DEBUG
627 struct ext2_super_block *es;
628 unsigned long bitmap_count = 0;
629 struct buffer_head *bitmap_bh = NULL;
630
631 es = EXT2_SB(sb)->s_es;
632 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
633 unsigned x;
634
635 desc = ext2_get_group_desc (sb, i, NULL);
636 if (!desc)
637 continue;
638 desc_count += le16_to_cpu(desc->bg_free_inodes_count);
639 brelse(bitmap_bh);
640 bitmap_bh = read_inode_bitmap(sb, i);
641 if (!bitmap_bh)
642 continue;
643
644 x = ext2_count_free(bitmap_bh, EXT2_INODES_PER_GROUP(sb) / 8);
645 printk("group %d: stored = %d, counted = %u\n",
646 i, le16_to_cpu(desc->bg_free_inodes_count), x);
647 bitmap_count += x;
648 }
649 brelse(bitmap_bh);
650 printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n",
651 (unsigned long)
652 percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter),
653 desc_count, bitmap_count);
654 return desc_count;
655#else
656 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
657 desc = ext2_get_group_desc (sb, i, NULL);
658 if (!desc)
659 continue;
660 desc_count += le16_to_cpu(desc->bg_free_inodes_count);
661 }
662 return desc_count;
663#endif
664}
665
666/* Called at mount-time, super-block is locked */
667unsigned long ext2_count_dirs (struct super_block * sb)
668{
669 unsigned long count = 0;
670 int i;
671
672 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
673 struct ext2_group_desc *gdp = ext2_get_group_desc (sb, i, NULL);
674 if (!gdp)
675 continue;
676 count += le16_to_cpu(gdp->bg_used_dirs_count);
677 }
678 return count;
679}
680
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 (card@masi.ibp.fr)
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 (sct@dcs.ed.ac.uk), 1993
12 * Big-endian to little-endian byte-swapping/bitmaps by
13 * David S. Miller (davem@caip.rutgers.edu), 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 struct ext2_group_desc * gdp;
173 struct backing_dev_info *bdi;
174
175 bdi = inode_to_bdi(inode);
176 if (bdi_rw_congested(bdi))
177 return;
178
179 block_group = (inode->i_ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
180 gdp = ext2_get_group_desc(inode->i_sb, block_group, NULL);
181 if (gdp == NULL)
182 return;
183
184 /*
185 * Figure out the offset within the block group inode table
186 */
187 offset = ((inode->i_ino - 1) % EXT2_INODES_PER_GROUP(inode->i_sb)) *
188 EXT2_INODE_SIZE(inode->i_sb);
189 block = le32_to_cpu(gdp->bg_inode_table) +
190 (offset >> EXT2_BLOCK_SIZE_BITS(inode->i_sb));
191 sb_breadahead(inode->i_sb, block);
192}
193
194/*
195 * There are two policies for allocating an inode. If the new inode is
196 * a directory, then a forward search is made for a block group with both
197 * free space and a low directory-to-inode ratio; if that fails, then of
198 * the groups with above-average free space, that group with the fewest
199 * directories already is chosen.
200 *
201 * For other inodes, search forward from the parent directory\'s block
202 * group to find a free inode.
203 */
204static int find_group_dir(struct super_block *sb, struct inode *parent)
205{
206 int ngroups = EXT2_SB(sb)->s_groups_count;
207 int avefreei = ext2_count_free_inodes(sb) / ngroups;
208 struct ext2_group_desc *desc, *best_desc = NULL;
209 int group, best_group = -1;
210
211 for (group = 0; group < ngroups; group++) {
212 desc = ext2_get_group_desc (sb, group, NULL);
213 if (!desc || !desc->bg_free_inodes_count)
214 continue;
215 if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)
216 continue;
217 if (!best_desc ||
218 (le16_to_cpu(desc->bg_free_blocks_count) >
219 le16_to_cpu(best_desc->bg_free_blocks_count))) {
220 best_group = group;
221 best_desc = desc;
222 }
223 }
224
225 return best_group;
226}
227
228/*
229 * Orlov's allocator for directories.
230 *
231 * We always try to spread first-level directories.
232 *
233 * If there are blockgroups with both free inodes and free blocks counts
234 * not worse than average we return one with smallest directory count.
235 * Otherwise we simply return a random group.
236 *
237 * For the rest rules look so:
238 *
239 * It's OK to put directory into a group unless
240 * it has too many directories already (max_dirs) or
241 * it has too few free inodes left (min_inodes) or
242 * it has too few free blocks left (min_blocks) or
243 * it's already running too large debt (max_debt).
244 * Parent's group is preferred, if it doesn't satisfy these
245 * conditions we search cyclically through the rest. If none
246 * of the groups look good we just look for a group with more
247 * free inodes than average (starting at parent's group).
248 *
249 * Debt is incremented each time we allocate a directory and decremented
250 * when we allocate an inode, within 0--255.
251 */
252
253#define INODE_COST 64
254#define BLOCK_COST 256
255
256static int find_group_orlov(struct super_block *sb, struct inode *parent)
257{
258 int parent_group = EXT2_I(parent)->i_block_group;
259 struct ext2_sb_info *sbi = EXT2_SB(sb);
260 struct ext2_super_block *es = sbi->s_es;
261 int ngroups = sbi->s_groups_count;
262 int inodes_per_group = EXT2_INODES_PER_GROUP(sb);
263 int freei;
264 int avefreei;
265 int free_blocks;
266 int avefreeb;
267 int blocks_per_dir;
268 int ndirs;
269 int max_debt, max_dirs, min_blocks, min_inodes;
270 int group = -1, i;
271 struct ext2_group_desc *desc;
272
273 freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter);
274 avefreei = freei / ngroups;
275 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
276 avefreeb = free_blocks / ngroups;
277 ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter);
278
279 if ((parent == d_inode(sb->s_root)) ||
280 (EXT2_I(parent)->i_flags & EXT2_TOPDIR_FL)) {
281 struct ext2_group_desc *best_desc = NULL;
282 int best_ndir = inodes_per_group;
283 int best_group = -1;
284
285 group = prandom_u32();
286 parent_group = (unsigned)group % ngroups;
287 for (i = 0; i < ngroups; i++) {
288 group = (parent_group + i) % ngroups;
289 desc = ext2_get_group_desc (sb, group, NULL);
290 if (!desc || !desc->bg_free_inodes_count)
291 continue;
292 if (le16_to_cpu(desc->bg_used_dirs_count) >= best_ndir)
293 continue;
294 if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)
295 continue;
296 if (le16_to_cpu(desc->bg_free_blocks_count) < avefreeb)
297 continue;
298 best_group = group;
299 best_ndir = le16_to_cpu(desc->bg_used_dirs_count);
300 best_desc = desc;
301 }
302 if (best_group >= 0) {
303 desc = best_desc;
304 group = best_group;
305 goto found;
306 }
307 goto fallback;
308 }
309
310 if (ndirs == 0)
311 ndirs = 1; /* percpu_counters are approximate... */
312
313 blocks_per_dir = (le32_to_cpu(es->s_blocks_count)-free_blocks) / ndirs;
314
315 max_dirs = ndirs / ngroups + inodes_per_group / 16;
316 min_inodes = avefreei - inodes_per_group / 4;
317 min_blocks = avefreeb - EXT2_BLOCKS_PER_GROUP(sb) / 4;
318
319 max_debt = EXT2_BLOCKS_PER_GROUP(sb) / max(blocks_per_dir, BLOCK_COST);
320 if (max_debt * INODE_COST > inodes_per_group)
321 max_debt = inodes_per_group / INODE_COST;
322 if (max_debt > 255)
323 max_debt = 255;
324 if (max_debt == 0)
325 max_debt = 1;
326
327 for (i = 0; i < ngroups; i++) {
328 group = (parent_group + i) % ngroups;
329 desc = ext2_get_group_desc (sb, group, NULL);
330 if (!desc || !desc->bg_free_inodes_count)
331 continue;
332 if (sbi->s_debts[group] >= max_debt)
333 continue;
334 if (le16_to_cpu(desc->bg_used_dirs_count) >= max_dirs)
335 continue;
336 if (le16_to_cpu(desc->bg_free_inodes_count) < min_inodes)
337 continue;
338 if (le16_to_cpu(desc->bg_free_blocks_count) < min_blocks)
339 continue;
340 goto found;
341 }
342
343fallback:
344 for (i = 0; i < ngroups; i++) {
345 group = (parent_group + i) % ngroups;
346 desc = ext2_get_group_desc (sb, group, NULL);
347 if (!desc || !desc->bg_free_inodes_count)
348 continue;
349 if (le16_to_cpu(desc->bg_free_inodes_count) >= avefreei)
350 goto found;
351 }
352
353 if (avefreei) {
354 /*
355 * The free-inodes counter is approximate, and for really small
356 * filesystems the above test can fail to find any blockgroups
357 */
358 avefreei = 0;
359 goto fallback;
360 }
361
362 return -1;
363
364found:
365 return group;
366}
367
368static int find_group_other(struct super_block *sb, struct inode *parent)
369{
370 int parent_group = EXT2_I(parent)->i_block_group;
371 int ngroups = EXT2_SB(sb)->s_groups_count;
372 struct ext2_group_desc *desc;
373 int group, i;
374
375 /*
376 * Try to place the inode in its parent directory
377 */
378 group = parent_group;
379 desc = ext2_get_group_desc (sb, group, NULL);
380 if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
381 le16_to_cpu(desc->bg_free_blocks_count))
382 goto found;
383
384 /*
385 * We're going to place this inode in a different blockgroup from its
386 * parent. We want to cause files in a common directory to all land in
387 * the same blockgroup. But we want files which are in a different
388 * directory which shares a blockgroup with our parent to land in a
389 * different blockgroup.
390 *
391 * So add our directory's i_ino into the starting point for the hash.
392 */
393 group = (group + parent->i_ino) % ngroups;
394
395 /*
396 * Use a quadratic hash to find a group with a free inode and some
397 * free blocks.
398 */
399 for (i = 1; i < ngroups; i <<= 1) {
400 group += i;
401 if (group >= ngroups)
402 group -= ngroups;
403 desc = ext2_get_group_desc (sb, group, NULL);
404 if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
405 le16_to_cpu(desc->bg_free_blocks_count))
406 goto found;
407 }
408
409 /*
410 * That failed: try linear search for a free inode, even if that group
411 * has no free blocks.
412 */
413 group = parent_group;
414 for (i = 0; i < ngroups; i++) {
415 if (++group >= ngroups)
416 group = 0;
417 desc = ext2_get_group_desc (sb, group, NULL);
418 if (desc && le16_to_cpu(desc->bg_free_inodes_count))
419 goto found;
420 }
421
422 return -1;
423
424found:
425 return group;
426}
427
428struct inode *ext2_new_inode(struct inode *dir, umode_t mode,
429 const struct qstr *qstr)
430{
431 struct super_block *sb;
432 struct buffer_head *bitmap_bh = NULL;
433 struct buffer_head *bh2;
434 int group, i;
435 ino_t ino = 0;
436 struct inode * inode;
437 struct ext2_group_desc *gdp;
438 struct ext2_super_block *es;
439 struct ext2_inode_info *ei;
440 struct ext2_sb_info *sbi;
441 int err;
442
443 sb = dir->i_sb;
444 inode = new_inode(sb);
445 if (!inode)
446 return ERR_PTR(-ENOMEM);
447
448 ei = EXT2_I(inode);
449 sbi = EXT2_SB(sb);
450 es = sbi->s_es;
451 if (S_ISDIR(mode)) {
452 if (test_opt(sb, OLDALLOC))
453 group = find_group_dir(sb, dir);
454 else
455 group = find_group_orlov(sb, dir);
456 } else
457 group = find_group_other(sb, dir);
458
459 if (group == -1) {
460 err = -ENOSPC;
461 goto fail;
462 }
463
464 for (i = 0; i < sbi->s_groups_count; i++) {
465 gdp = ext2_get_group_desc(sb, group, &bh2);
466 if (!gdp) {
467 if (++group == sbi->s_groups_count)
468 group = 0;
469 continue;
470 }
471 brelse(bitmap_bh);
472 bitmap_bh = read_inode_bitmap(sb, group);
473 if (!bitmap_bh) {
474 err = -EIO;
475 goto fail;
476 }
477 ino = 0;
478
479repeat_in_this_group:
480 ino = ext2_find_next_zero_bit((unsigned long *)bitmap_bh->b_data,
481 EXT2_INODES_PER_GROUP(sb), ino);
482 if (ino >= EXT2_INODES_PER_GROUP(sb)) {
483 /*
484 * Rare race: find_group_xx() decided that there were
485 * free inodes in this group, but by the time we tried
486 * to allocate one, they're all gone. This can also
487 * occur because the counters which find_group_orlov()
488 * uses are approximate. So just go and search the
489 * next block group.
490 */
491 if (++group == sbi->s_groups_count)
492 group = 0;
493 continue;
494 }
495 if (ext2_set_bit_atomic(sb_bgl_lock(sbi, group),
496 ino, bitmap_bh->b_data)) {
497 /* we lost this inode */
498 if (++ino >= EXT2_INODES_PER_GROUP(sb)) {
499 /* this group is exhausted, try next group */
500 if (++group == sbi->s_groups_count)
501 group = 0;
502 continue;
503 }
504 /* try to find free inode in the same group */
505 goto repeat_in_this_group;
506 }
507 goto got;
508 }
509
510 /*
511 * Scanned all blockgroups.
512 */
513 brelse(bitmap_bh);
514 err = -ENOSPC;
515 goto fail;
516got:
517 mark_buffer_dirty(bitmap_bh);
518 if (sb->s_flags & SB_SYNCHRONOUS)
519 sync_dirty_buffer(bitmap_bh);
520 brelse(bitmap_bh);
521
522 ino += group * EXT2_INODES_PER_GROUP(sb) + 1;
523 if (ino < EXT2_FIRST_INO(sb) || ino > le32_to_cpu(es->s_inodes_count)) {
524 ext2_error (sb, "ext2_new_inode",
525 "reserved inode or inode > inodes count - "
526 "block_group = %d,inode=%lu", group,
527 (unsigned long) ino);
528 err = -EIO;
529 goto fail;
530 }
531
532 percpu_counter_dec(&sbi->s_freeinodes_counter);
533 if (S_ISDIR(mode))
534 percpu_counter_inc(&sbi->s_dirs_counter);
535
536 spin_lock(sb_bgl_lock(sbi, group));
537 le16_add_cpu(&gdp->bg_free_inodes_count, -1);
538 if (S_ISDIR(mode)) {
539 if (sbi->s_debts[group] < 255)
540 sbi->s_debts[group]++;
541 le16_add_cpu(&gdp->bg_used_dirs_count, 1);
542 } else {
543 if (sbi->s_debts[group])
544 sbi->s_debts[group]--;
545 }
546 spin_unlock(sb_bgl_lock(sbi, group));
547
548 mark_buffer_dirty(bh2);
549 if (test_opt(sb, GRPID)) {
550 inode->i_mode = mode;
551 inode->i_uid = current_fsuid();
552 inode->i_gid = dir->i_gid;
553 } else
554 inode_init_owner(inode, dir, mode);
555
556 inode->i_ino = ino;
557 inode->i_blocks = 0;
558 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
559 memset(ei->i_data, 0, sizeof(ei->i_data));
560 ei->i_flags =
561 ext2_mask_flags(mode, EXT2_I(dir)->i_flags & EXT2_FL_INHERITED);
562 ei->i_faddr = 0;
563 ei->i_frag_no = 0;
564 ei->i_frag_size = 0;
565 ei->i_file_acl = 0;
566 ei->i_dir_acl = 0;
567 ei->i_dtime = 0;
568 ei->i_block_alloc_info = NULL;
569 ei->i_block_group = group;
570 ei->i_dir_start_lookup = 0;
571 ei->i_state = EXT2_STATE_NEW;
572 ext2_set_inode_flags(inode);
573 spin_lock(&sbi->s_next_gen_lock);
574 inode->i_generation = sbi->s_next_generation++;
575 spin_unlock(&sbi->s_next_gen_lock);
576 if (insert_inode_locked(inode) < 0) {
577 ext2_error(sb, "ext2_new_inode",
578 "inode number already in use - inode=%lu",
579 (unsigned long) ino);
580 err = -EIO;
581 goto fail;
582 }
583
584 err = dquot_initialize(inode);
585 if (err)
586 goto fail_drop;
587
588 err = dquot_alloc_inode(inode);
589 if (err)
590 goto fail_drop;
591
592 err = ext2_init_acl(inode, dir);
593 if (err)
594 goto fail_free_drop;
595
596 err = ext2_init_security(inode, dir, qstr);
597 if (err)
598 goto fail_free_drop;
599
600 mark_inode_dirty(inode);
601 ext2_debug("allocating inode %lu\n", inode->i_ino);
602 ext2_preread_inode(inode);
603 return inode;
604
605fail_free_drop:
606 dquot_free_inode(inode);
607
608fail_drop:
609 dquot_drop(inode);
610 inode->i_flags |= S_NOQUOTA;
611 clear_nlink(inode);
612 discard_new_inode(inode);
613 return ERR_PTR(err);
614
615fail:
616 make_bad_inode(inode);
617 iput(inode);
618 return ERR_PTR(err);
619}
620
621unsigned long ext2_count_free_inodes (struct super_block * sb)
622{
623 struct ext2_group_desc *desc;
624 unsigned long desc_count = 0;
625 int i;
626
627#ifdef EXT2FS_DEBUG
628 struct ext2_super_block *es;
629 unsigned long bitmap_count = 0;
630 struct buffer_head *bitmap_bh = NULL;
631
632 es = EXT2_SB(sb)->s_es;
633 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
634 unsigned x;
635
636 desc = ext2_get_group_desc (sb, i, NULL);
637 if (!desc)
638 continue;
639 desc_count += le16_to_cpu(desc->bg_free_inodes_count);
640 brelse(bitmap_bh);
641 bitmap_bh = read_inode_bitmap(sb, i);
642 if (!bitmap_bh)
643 continue;
644
645 x = ext2_count_free(bitmap_bh, EXT2_INODES_PER_GROUP(sb) / 8);
646 printk("group %d: stored = %d, counted = %u\n",
647 i, le16_to_cpu(desc->bg_free_inodes_count), x);
648 bitmap_count += x;
649 }
650 brelse(bitmap_bh);
651 printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n",
652 (unsigned long)
653 percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter),
654 desc_count, bitmap_count);
655 return desc_count;
656#else
657 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
658 desc = ext2_get_group_desc (sb, i, NULL);
659 if (!desc)
660 continue;
661 desc_count += le16_to_cpu(desc->bg_free_inodes_count);
662 }
663 return desc_count;
664#endif
665}
666
667/* Called at mount-time, super-block is locked */
668unsigned long ext2_count_dirs (struct super_block * sb)
669{
670 unsigned long count = 0;
671 int i;
672
673 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
674 struct ext2_group_desc *gdp = ext2_get_group_desc (sb, i, NULL);
675 if (!gdp)
676 continue;
677 count += le16_to_cpu(gdp->bg_used_dirs_count);
678 }
679 return count;
680}
681