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 */ 46 static struct buffer_head * 47 read_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)); 62 error_out: 63 return bh; 64 } 65 66 static 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 */ 105 void 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 */ 167 static 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 table 181 */ 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 is 191 * a directory, then a forward search is made for a block group with both 192 * free space and a low directory-to-inode ratio; if that fails, then of 193 * the groups with above-average free space, that group with the fewest 194 * directories already is chosen. 195 * 196 * For other inodes, search forward from the parent directory\'s block 197 * group to find a free inode. 198 */ 199 static 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 64 249 #define BLOCK_COST 256 250 251 static 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 } 333 334 fallback: 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 small 347 * filesystems the above test can fail to find any blockgroups 348 */ 349 avefreei = 0; 350 goto fallback; 351 } 352 353 return -1; 354 355 found: 356 return group; 357 } 358 359 static 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 directory 368 */ 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 its 377 * parent. We want to cause files in a common directory to all land in 378 * the same blockgroup. But we want files which are in a different 379 * directory which shares a blockgroup with our parent to land in a 380 * 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 some 388 * 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 group 402 * 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; 414 415 found: 416 return group; 417 } 418 419 struct 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 else 446 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; 469 470 repeat_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 were 476 * free inodes in this group, but by the time we tried 477 * to allocate one, they're all gone. This can also 478 * occur because the counters which find_group_orlov() 479 * uses are approximate. So just go and search the 480 * 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; 507 got: 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 } else 545 inode_init_owner(&nop_mnt_idmap, inode, dir, mode); 546 547 inode->i_ino = ino; 548 inode->i_blocks = 0; 549 inode->i_mtime = inode->i_atime = inode_set_ctime_current(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; 595 596 fail_free_drop: 597 dquot_free_inode(inode); 598 599 fail_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); 605 606 fail: 607 make_bad_inode(inode); 608 iput(inode); 609 return ERR_PTR(err); 610 } 611 612 unsigned 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_DEBUG 619 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 #else 648 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 #endif 656 } 657 658 /* Called at mount-time, super-block is locked */ 659 unsigned 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