673 lines · c
1// SPDX-License-Identifier: GPL-2.02/*3 * linux/fs/ext2/ialloc.c4 *5 * Copyright (C) 1992, 1993, 1994, 19956 * Remy Card (card@masi.ibp.fr)7 * Laboratoire MASI - Institut Blaise Pascal8 * 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), 199312 * Big-endian to little-endian byte-swapping/bitmaps by13 * David S. Miller (davem@caip.rutgers.edu), 199514 */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 routines27 */28 29/*30 * The free inodes are managed by bitmaps. A file system contains several31 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap32 * block for inodes, N blocks for the inode table and data blocks.33 *34 * The file system contains group descriptors which are located after the35 * super block. Each descriptor contains the number of the bitmap block and36 * the free blocks count in the block.37 */38 39 40/*41 * Read the inode allocation bitmap for a given block_group, reading42 * 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 people91 * that have access to it, and as such there are no92 * race conditions we have to worry about. The inode93 * is not on the hash-lists, and it cannot be reached94 * through the filesystem because the directory entry95 * 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 inode100 * bitmaps. Otherwise a newly created file might use101 * the same inode number (not actually the same pointer102 * though), and then we'd have two inodes sharing the103 * 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 else147 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 when157 * we create the inode, in the expectation that the inode will be written158 * back soon. There are two reasons:159 *160 * - When creating a large number of files, the async prereads will be161 * nicely merged into large reads162 * - When writing out a large number of inodes, we don't need to keep on163 * 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;173 174 block_group = (inode->i_ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);175 gdp = ext2_get_group_desc(inode->i_sb, block_group, NULL);176 if (gdp == NULL)177 return;178 179 /*180 * Figure out the offset within the block group inode table181 */182 offset = ((inode->i_ino - 1) % EXT2_INODES_PER_GROUP(inode->i_sb)) *183 EXT2_INODE_SIZE(inode->i_sb);184 block = le32_to_cpu(gdp->bg_inode_table) +185 (offset >> EXT2_BLOCK_SIZE_BITS(inode->i_sb));186 sb_breadahead(inode->i_sb, block);187}188 189/*190 * There are two policies for allocating an inode. If the new inode is191 * a directory, then a forward search is made for a block group with both192 * free space and a low directory-to-inode ratio; if that fails, then of193 * the groups with above-average free space, that group with the fewest194 * directories already is chosen.195 *196 * For other inodes, search forward from the parent directory\'s block197 * group to find a free inode.198 */199static int find_group_dir(struct super_block *sb, struct inode *parent)200{201 int ngroups = EXT2_SB(sb)->s_groups_count;202 int avefreei = ext2_count_free_inodes(sb) / ngroups;203 struct ext2_group_desc *desc, *best_desc = NULL;204 int group, best_group = -1;205 206 for (group = 0; group < ngroups; group++) {207 desc = ext2_get_group_desc (sb, group, NULL);208 if (!desc || !desc->bg_free_inodes_count)209 continue;210 if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)211 continue;212 if (!best_desc || 213 (le16_to_cpu(desc->bg_free_blocks_count) >214 le16_to_cpu(best_desc->bg_free_blocks_count))) {215 best_group = group;216 best_desc = desc;217 }218 }219 220 return best_group;221}222 223/* 224 * Orlov's allocator for directories. 225 * 226 * We always try to spread first-level directories.227 *228 * If there are blockgroups with both free inodes and free blocks counts 229 * not worse than average we return one with smallest directory count. 230 * Otherwise we simply return a random group. 231 * 232 * For the rest rules look so: 233 * 234 * It's OK to put directory into a group unless 235 * it has too many directories already (max_dirs) or 236 * it has too few free inodes left (min_inodes) or 237 * it has too few free blocks left (min_blocks) or 238 * it's already running too large debt (max_debt). 239 * Parent's group is preferred, if it doesn't satisfy these 240 * conditions we search cyclically through the rest. If none 241 * of the groups look good we just look for a group with more 242 * free inodes than average (starting at parent's group). 243 * 244 * Debt is incremented each time we allocate a directory and decremented 245 * when we allocate an inode, within 0--255. 246 */ 247 248#define INODE_COST 64249#define BLOCK_COST 256250 251static int find_group_orlov(struct super_block *sb, struct inode *parent)252{253 int parent_group = EXT2_I(parent)->i_block_group;254 struct ext2_sb_info *sbi = EXT2_SB(sb);255 struct ext2_super_block *es = sbi->s_es;256 int ngroups = sbi->s_groups_count;257 int inodes_per_group = EXT2_INODES_PER_GROUP(sb);258 int freei;259 int avefreei;260 int free_blocks;261 int avefreeb;262 int blocks_per_dir;263 int ndirs;264 int max_debt, max_dirs, min_blocks, min_inodes;265 int group = -1, i;266 struct ext2_group_desc *desc;267 268 freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter);269 avefreei = freei / ngroups;270 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);271 avefreeb = free_blocks / ngroups;272 ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter);273 274 if ((parent == d_inode(sb->s_root)) ||275 (EXT2_I(parent)->i_flags & EXT2_TOPDIR_FL)) {276 int best_ndir = inodes_per_group;277 int best_group = -1;278 279 parent_group = get_random_u32_below(ngroups);280 for (i = 0; i < ngroups; i++) {281 group = (parent_group + i) % ngroups;282 desc = ext2_get_group_desc (sb, group, NULL);283 if (!desc || !desc->bg_free_inodes_count)284 continue;285 if (le16_to_cpu(desc->bg_used_dirs_count) >= best_ndir)286 continue;287 if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)288 continue;289 if (le16_to_cpu(desc->bg_free_blocks_count) < avefreeb)290 continue;291 best_group = group;292 best_ndir = le16_to_cpu(desc->bg_used_dirs_count);293 }294 if (best_group >= 0) {295 group = best_group;296 goto found;297 }298 goto fallback;299 }300 301 if (ndirs == 0)302 ndirs = 1; /* percpu_counters are approximate... */303 304 blocks_per_dir = (le32_to_cpu(es->s_blocks_count)-free_blocks) / ndirs;305 306 max_dirs = ndirs / ngroups + inodes_per_group / 16;307 min_inodes = avefreei - inodes_per_group / 4;308 min_blocks = avefreeb - EXT2_BLOCKS_PER_GROUP(sb) / 4;309 310 max_debt = EXT2_BLOCKS_PER_GROUP(sb) / max(blocks_per_dir, BLOCK_COST);311 if (max_debt * INODE_COST > inodes_per_group)312 max_debt = inodes_per_group / INODE_COST;313 if (max_debt > 255)314 max_debt = 255;315 if (max_debt == 0)316 max_debt = 1;317 318 for (i = 0; i < ngroups; i++) {319 group = (parent_group + i) % ngroups;320 desc = ext2_get_group_desc (sb, group, NULL);321 if (!desc || !desc->bg_free_inodes_count)322 continue;323 if (sbi->s_debts[group] >= max_debt)324 continue;325 if (le16_to_cpu(desc->bg_used_dirs_count) >= max_dirs)326 continue;327 if (le16_to_cpu(desc->bg_free_inodes_count) < min_inodes)328 continue;329 if (le16_to_cpu(desc->bg_free_blocks_count) < min_blocks)330 continue;331 goto found;332 }333 334fallback:335 for (i = 0; i < ngroups; i++) {336 group = (parent_group + i) % ngroups;337 desc = ext2_get_group_desc (sb, group, NULL);338 if (!desc || !desc->bg_free_inodes_count)339 continue;340 if (le16_to_cpu(desc->bg_free_inodes_count) >= avefreei)341 goto found;342 }343 344 if (avefreei) {345 /*346 * The free-inodes counter is approximate, and for really small347 * filesystems the above test can fail to find any blockgroups348 */349 avefreei = 0;350 goto fallback;351 }352 353 return -1;354 355found:356 return group;357}358 359static int find_group_other(struct super_block *sb, struct inode *parent)360{361 int parent_group = EXT2_I(parent)->i_block_group;362 int ngroups = EXT2_SB(sb)->s_groups_count;363 struct ext2_group_desc *desc;364 int group, i;365 366 /*367 * Try to place the inode in its parent directory368 */369 group = parent_group;370 desc = ext2_get_group_desc (sb, group, NULL);371 if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&372 le16_to_cpu(desc->bg_free_blocks_count))373 goto found;374 375 /*376 * We're going to place this inode in a different blockgroup from its377 * parent. We want to cause files in a common directory to all land in378 * the same blockgroup. But we want files which are in a different379 * directory which shares a blockgroup with our parent to land in a380 * different blockgroup.381 *382 * So add our directory's i_ino into the starting point for the hash.383 */384 group = (group + parent->i_ino) % ngroups;385 386 /*387 * Use a quadratic hash to find a group with a free inode and some388 * free blocks.389 */390 for (i = 1; i < ngroups; i <<= 1) {391 group += i;392 if (group >= ngroups)393 group -= ngroups;394 desc = ext2_get_group_desc (sb, group, NULL);395 if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&396 le16_to_cpu(desc->bg_free_blocks_count))397 goto found;398 }399 400 /*401 * That failed: try linear search for a free inode, even if that group402 * has no free blocks.403 */404 group = parent_group;405 for (i = 0; i < ngroups; i++) {406 if (++group >= ngroups)407 group = 0;408 desc = ext2_get_group_desc (sb, group, NULL);409 if (desc && le16_to_cpu(desc->bg_free_inodes_count))410 goto found;411 }412 413 return -1;414 415found:416 return group;417}418 419struct inode *ext2_new_inode(struct inode *dir, umode_t mode,420 const struct qstr *qstr)421{422 struct super_block *sb;423 struct buffer_head *bitmap_bh = NULL;424 struct buffer_head *bh2;425 int group, i;426 ino_t ino = 0;427 struct inode * inode;428 struct ext2_group_desc *gdp;429 struct ext2_super_block *es;430 struct ext2_inode_info *ei;431 struct ext2_sb_info *sbi;432 int err;433 434 sb = dir->i_sb;435 inode = new_inode(sb);436 if (!inode)437 return ERR_PTR(-ENOMEM);438 439 ei = EXT2_I(inode);440 sbi = EXT2_SB(sb);441 es = sbi->s_es;442 if (S_ISDIR(mode)) {443 if (test_opt(sb, OLDALLOC))444 group = find_group_dir(sb, dir);445 else446 group = find_group_orlov(sb, dir);447 } else 448 group = find_group_other(sb, dir);449 450 if (group == -1) {451 err = -ENOSPC;452 goto fail;453 }454 455 for (i = 0; i < sbi->s_groups_count; i++) {456 gdp = ext2_get_group_desc(sb, group, &bh2);457 if (!gdp) {458 if (++group == sbi->s_groups_count)459 group = 0;460 continue;461 }462 brelse(bitmap_bh);463 bitmap_bh = read_inode_bitmap(sb, group);464 if (!bitmap_bh) {465 err = -EIO;466 goto fail;467 }468 ino = 0;469 470repeat_in_this_group:471 ino = ext2_find_next_zero_bit((unsigned long *)bitmap_bh->b_data,472 EXT2_INODES_PER_GROUP(sb), ino);473 if (ino >= EXT2_INODES_PER_GROUP(sb)) {474 /*475 * Rare race: find_group_xx() decided that there were476 * free inodes in this group, but by the time we tried477 * to allocate one, they're all gone. This can also478 * occur because the counters which find_group_orlov()479 * uses are approximate. So just go and search the480 * next block group.481 */482 if (++group == sbi->s_groups_count)483 group = 0;484 continue;485 }486 if (ext2_set_bit_atomic(sb_bgl_lock(sbi, group),487 ino, bitmap_bh->b_data)) {488 /* we lost this inode */489 if (++ino >= EXT2_INODES_PER_GROUP(sb)) {490 /* this group is exhausted, try next group */491 if (++group == sbi->s_groups_count)492 group = 0;493 continue;494 }495 /* try to find free inode in the same group */496 goto repeat_in_this_group;497 }498 goto got;499 }500 501 /*502 * Scanned all blockgroups.503 */504 brelse(bitmap_bh);505 err = -ENOSPC;506 goto fail;507got:508 mark_buffer_dirty(bitmap_bh);509 if (sb->s_flags & SB_SYNCHRONOUS)510 sync_dirty_buffer(bitmap_bh);511 brelse(bitmap_bh);512 513 ino += group * EXT2_INODES_PER_GROUP(sb) + 1;514 if (ino < EXT2_FIRST_INO(sb) || ino > le32_to_cpu(es->s_inodes_count)) {515 ext2_error (sb, "ext2_new_inode",516 "reserved inode or inode > inodes count - "517 "block_group = %d,inode=%lu", group,518 (unsigned long) ino);519 err = -EIO;520 goto fail;521 }522 523 percpu_counter_dec(&sbi->s_freeinodes_counter);524 if (S_ISDIR(mode))525 percpu_counter_inc(&sbi->s_dirs_counter);526 527 spin_lock(sb_bgl_lock(sbi, group));528 le16_add_cpu(&gdp->bg_free_inodes_count, -1);529 if (S_ISDIR(mode)) {530 if (sbi->s_debts[group] < 255)531 sbi->s_debts[group]++;532 le16_add_cpu(&gdp->bg_used_dirs_count, 1);533 } else {534 if (sbi->s_debts[group])535 sbi->s_debts[group]--;536 }537 spin_unlock(sb_bgl_lock(sbi, group));538 539 mark_buffer_dirty(bh2);540 if (test_opt(sb, GRPID)) {541 inode->i_mode = mode;542 inode->i_uid = current_fsuid();543 inode->i_gid = dir->i_gid;544 } else545 inode_init_owner(&nop_mnt_idmap, inode, dir, mode);546 547 inode->i_ino = ino;548 inode->i_blocks = 0;549 simple_inode_init_ts(inode);550 memset(ei->i_data, 0, sizeof(ei->i_data));551 ei->i_flags =552 ext2_mask_flags(mode, EXT2_I(dir)->i_flags & EXT2_FL_INHERITED);553 ei->i_faddr = 0;554 ei->i_frag_no = 0;555 ei->i_frag_size = 0;556 ei->i_file_acl = 0;557 ei->i_dir_acl = 0;558 ei->i_dtime = 0;559 ei->i_block_alloc_info = NULL;560 ei->i_block_group = group;561 ei->i_dir_start_lookup = 0;562 ei->i_state = EXT2_STATE_NEW;563 ext2_set_inode_flags(inode);564 spin_lock(&sbi->s_next_gen_lock);565 inode->i_generation = sbi->s_next_generation++;566 spin_unlock(&sbi->s_next_gen_lock);567 if (insert_inode_locked(inode) < 0) {568 ext2_error(sb, "ext2_new_inode",569 "inode number already in use - inode=%lu",570 (unsigned long) ino);571 err = -EIO;572 goto fail;573 }574 575 err = dquot_initialize(inode);576 if (err)577 goto fail_drop;578 579 err = dquot_alloc_inode(inode);580 if (err)581 goto fail_drop;582 583 err = ext2_init_acl(inode, dir);584 if (err)585 goto fail_free_drop;586 587 err = ext2_init_security(inode, dir, qstr);588 if (err)589 goto fail_free_drop;590 591 mark_inode_dirty(inode);592 ext2_debug("allocating inode %lu\n", inode->i_ino);593 ext2_preread_inode(inode);594 return inode;595 596fail_free_drop:597 dquot_free_inode(inode);598 599fail_drop:600 dquot_drop(inode);601 inode->i_flags |= S_NOQUOTA;602 clear_nlink(inode);603 discard_new_inode(inode);604 return ERR_PTR(err);605 606fail:607 make_bad_inode(inode);608 iput(inode);609 return ERR_PTR(err);610}611 612unsigned long ext2_count_free_inodes (struct super_block * sb)613{614 struct ext2_group_desc *desc;615 unsigned long desc_count = 0;616 int i; 617 618#ifdef EXT2FS_DEBUG619 struct ext2_super_block *es;620 unsigned long bitmap_count = 0;621 struct buffer_head *bitmap_bh = NULL;622 623 es = EXT2_SB(sb)->s_es;624 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {625 unsigned x;626 627 desc = ext2_get_group_desc (sb, i, NULL);628 if (!desc)629 continue;630 desc_count += le16_to_cpu(desc->bg_free_inodes_count);631 brelse(bitmap_bh);632 bitmap_bh = read_inode_bitmap(sb, i);633 if (!bitmap_bh)634 continue;635 636 x = ext2_count_free(bitmap_bh, EXT2_INODES_PER_GROUP(sb) / 8);637 printk("group %d: stored = %d, counted = %u\n",638 i, le16_to_cpu(desc->bg_free_inodes_count), x);639 bitmap_count += x;640 }641 brelse(bitmap_bh);642 printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n",643 (unsigned long)644 percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter),645 desc_count, bitmap_count);646 return desc_count;647#else648 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {649 desc = ext2_get_group_desc (sb, i, NULL);650 if (!desc)651 continue;652 desc_count += le16_to_cpu(desc->bg_free_inodes_count);653 }654 return desc_count;655#endif656}657 658/* Called at mount-time, super-block is locked */659unsigned long ext2_count_dirs (struct super_block * sb)660{661 unsigned long count = 0;662 int i;663 664 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {665 struct ext2_group_desc *gdp = ext2_get_group_desc (sb, i, NULL);666 if (!gdp)667 continue;668 count += le16_to_cpu(gdp->bg_used_dirs_count);669 }670 return count;671}672 673