1 /* 2 * linux/fs/ext2/ialloc.c 3 * 4 * Copyright (C) 1992, 1993, 1994, 1995 5 * Remy Card (card@masi.ibp.fr) 6 * Laboratoire MASI - Institut Blaise Pascal 7 * Universite Pierre et Marie Curie (Paris VI) 8 * 9 * BSD ufs-inspired inode and directory allocation by 10 * Stephen Tweedie (sct@dcs.ed.ac.uk), 1993 11 * Big-endian to little-endian byte-swapping/bitmaps by 12 * David S. Miller (davem@caip.rutgers.edu), 1995 13 */ 14 15 #include <linux/quotaops.h> 16 #include <linux/sched.h> 17 #include <linux/backing-dev.h> 18 #include <linux/buffer_head.h> 19 #include <linux/random.h> 20 #include "ext2.h" 21 #include "xattr.h" 22 #include "acl.h" 23 24 /* 25 * ialloc.c contains the inodes allocation and deallocation routines 26 */ 27 28 /* 29 * The free inodes are managed by bitmaps. A file system contains several 30 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap 31 * block for inodes, N blocks for the inode table and data blocks. 32 * 33 * The file system contains group descriptors which are located after the 34 * super block. Each descriptor contains the number of the bitmap block and 35 * the free blocks count in the block. 36 */ 37 38 39 /* 40 * Read the inode allocation bitmap for a given block_group, reading 41 * into the specified slot in the superblock's bitmap cache. 42 * 43 * Return buffer_head of bitmap on success or NULL. 44 */ 45 static struct buffer_head * 46 read_inode_bitmap(struct super_block * sb, unsigned long block_group) 47 { 48 struct ext2_group_desc *desc; 49 struct buffer_head *bh = NULL; 50 51 desc = ext2_get_group_desc(sb, block_group, NULL); 52 if (!desc) 53 goto error_out; 54 55 bh = sb_bread(sb, le32_to_cpu(desc->bg_inode_bitmap)); 56 if (!bh) 57 ext2_error(sb, "read_inode_bitmap", 58 "Cannot read inode bitmap - " 59 "block_group = %lu, inode_bitmap = %u", 60 block_group, le32_to_cpu(desc->bg_inode_bitmap)); 61 error_out: 62 return bh; 63 } 64 65 static void ext2_release_inode(struct super_block *sb, int group, int dir) 66 { 67 struct ext2_group_desc * desc; 68 struct buffer_head *bh; 69 70 desc = ext2_get_group_desc(sb, group, &bh); 71 if (!desc) { 72 ext2_error(sb, "ext2_release_inode", 73 "can't get descriptor for group %d", group); 74 return; 75 } 76 77 spin_lock(sb_bgl_lock(EXT2_SB(sb), group)); 78 le16_add_cpu(&desc->bg_free_inodes_count, 1); 79 if (dir) 80 le16_add_cpu(&desc->bg_used_dirs_count, -1); 81 spin_unlock(sb_bgl_lock(EXT2_SB(sb), group)); 82 if (dir) 83 percpu_counter_dec(&EXT2_SB(sb)->s_dirs_counter); 84 sb->s_dirt = 1; 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 */ 104 void 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 if (!is_bad_inode(inode)) { 122 /* Quota is already initialized in iput() */ 123 ext2_xattr_delete_inode(inode); 124 dquot_free_inode(inode); 125 dquot_drop(inode); 126 } 127 128 es = EXT2_SB(sb)->s_es; 129 is_directory = S_ISDIR(inode->i_mode); 130 131 /* Do this BEFORE marking the inode not in use or returning an error */ 132 clear_inode (inode); 133 134 if (ino < EXT2_FIRST_INO(sb) || 135 ino > le32_to_cpu(es->s_inodes_count)) { 136 ext2_error (sb, "ext2_free_inode", 137 "reserved or nonexistent inode %lu", ino); 138 return; 139 } 140 block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb); 141 bit = (ino - 1) % EXT2_INODES_PER_GROUP(sb); 142 bitmap_bh = read_inode_bitmap(sb, block_group); 143 if (!bitmap_bh) 144 return; 145 146 /* Ok, now we can actually update the inode bitmaps.. */ 147 if (!ext2_clear_bit_atomic(sb_bgl_lock(EXT2_SB(sb), block_group), 148 bit, (void *) bitmap_bh->b_data)) 149 ext2_error (sb, "ext2_free_inode", 150 "bit already cleared for inode %lu", ino); 151 else 152 ext2_release_inode(sb, block_group, is_directory); 153 mark_buffer_dirty(bitmap_bh); 154 if (sb->s_flags & MS_SYNCHRONOUS) 155 sync_dirty_buffer(bitmap_bh); 156 157 brelse(bitmap_bh); 158 } 159 160 /* 161 * We perform asynchronous prereading of the new inode's inode block when 162 * we create the inode, in the expectation that the inode will be written 163 * back soon. There are two reasons: 164 * 165 * - When creating a large number of files, the async prereads will be 166 * nicely merged into large reads 167 * - When writing out a large number of inodes, we don't need to keep on 168 * stalling the writes while we read the inode block. 169 * 170 * FIXME: ext2_get_group_desc() needs to be simplified. 171 */ 172 static void ext2_preread_inode(struct inode *inode) 173 { 174 unsigned long block_group; 175 unsigned long offset; 176 unsigned long block; 177 struct ext2_group_desc * gdp; 178 struct backing_dev_info *bdi; 179 180 bdi = inode->i_mapping->backing_dev_info; 181 if (bdi_read_congested(bdi)) 182 return; 183 if (bdi_write_congested(bdi)) 184 return; 185 186 block_group = (inode->i_ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb); 187 gdp = ext2_get_group_desc(inode->i_sb, block_group, NULL); 188 if (gdp == NULL) 189 return; 190 191 /* 192 * Figure out the offset within the block group inode table 193 */ 194 offset = ((inode->i_ino - 1) % EXT2_INODES_PER_GROUP(inode->i_sb)) * 195 EXT2_INODE_SIZE(inode->i_sb); 196 block = le32_to_cpu(gdp->bg_inode_table) + 197 (offset >> EXT2_BLOCK_SIZE_BITS(inode->i_sb)); 198 sb_breadahead(inode->i_sb, block); 199 } 200 201 /* 202 * There are two policies for allocating an inode. If the new inode is 203 * a directory, then a forward search is made for a block group with both 204 * free space and a low directory-to-inode ratio; if that fails, then of 205 * the groups with above-average free space, that group with the fewest 206 * directories already is chosen. 207 * 208 * For other inodes, search forward from the parent directory\'s block 209 * group to find a free inode. 210 */ 211 static int find_group_dir(struct super_block *sb, struct inode *parent) 212 { 213 int ngroups = EXT2_SB(sb)->s_groups_count; 214 int avefreei = ext2_count_free_inodes(sb) / ngroups; 215 struct ext2_group_desc *desc, *best_desc = NULL; 216 int group, best_group = -1; 217 218 for (group = 0; group < ngroups; group++) { 219 desc = ext2_get_group_desc (sb, group, NULL); 220 if (!desc || !desc->bg_free_inodes_count) 221 continue; 222 if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei) 223 continue; 224 if (!best_desc || 225 (le16_to_cpu(desc->bg_free_blocks_count) > 226 le16_to_cpu(best_desc->bg_free_blocks_count))) { 227 best_group = group; 228 best_desc = desc; 229 } 230 } 231 if (!best_desc) 232 return -1; 233 234 return best_group; 235 } 236 237 /* 238 * Orlov's allocator for directories. 239 * 240 * We always try to spread first-level directories. 241 * 242 * If there are blockgroups with both free inodes and free blocks counts 243 * not worse than average we return one with smallest directory count. 244 * Otherwise we simply return a random group. 245 * 246 * For the rest rules look so: 247 * 248 * It's OK to put directory into a group unless 249 * it has too many directories already (max_dirs) or 250 * it has too few free inodes left (min_inodes) or 251 * it has too few free blocks left (min_blocks) or 252 * it's already running too large debt (max_debt). 253 * Parent's group is preferred, if it doesn't satisfy these 254 * conditions we search cyclically through the rest. If none 255 * of the groups look good we just look for a group with more 256 * free inodes than average (starting at parent's group). 257 * 258 * Debt is incremented each time we allocate a directory and decremented 259 * when we allocate an inode, within 0--255. 260 */ 261 262 #define INODE_COST 64 263 #define BLOCK_COST 256 264 265 static int find_group_orlov(struct super_block *sb, struct inode *parent) 266 { 267 int parent_group = EXT2_I(parent)->i_block_group; 268 struct ext2_sb_info *sbi = EXT2_SB(sb); 269 struct ext2_super_block *es = sbi->s_es; 270 int ngroups = sbi->s_groups_count; 271 int inodes_per_group = EXT2_INODES_PER_GROUP(sb); 272 int freei; 273 int avefreei; 274 int free_blocks; 275 int avefreeb; 276 int blocks_per_dir; 277 int ndirs; 278 int max_debt, max_dirs, min_blocks, min_inodes; 279 int group = -1, i; 280 struct ext2_group_desc *desc; 281 282 freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter); 283 avefreei = freei / ngroups; 284 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter); 285 avefreeb = free_blocks / ngroups; 286 ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter); 287 288 if ((parent == sb->s_root->d_inode) || 289 (EXT2_I(parent)->i_flags & EXT2_TOPDIR_FL)) { 290 struct ext2_group_desc *best_desc = NULL; 291 int best_ndir = inodes_per_group; 292 int best_group = -1; 293 294 get_random_bytes(&group, sizeof(group)); 295 parent_group = (unsigned)group % ngroups; 296 for (i = 0; i < ngroups; i++) { 297 group = (parent_group + i) % ngroups; 298 desc = ext2_get_group_desc (sb, group, NULL); 299 if (!desc || !desc->bg_free_inodes_count) 300 continue; 301 if (le16_to_cpu(desc->bg_used_dirs_count) >= best_ndir) 302 continue; 303 if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei) 304 continue; 305 if (le16_to_cpu(desc->bg_free_blocks_count) < avefreeb) 306 continue; 307 best_group = group; 308 best_ndir = le16_to_cpu(desc->bg_used_dirs_count); 309 best_desc = desc; 310 } 311 if (best_group >= 0) { 312 desc = best_desc; 313 group = best_group; 314 goto found; 315 } 316 goto fallback; 317 } 318 319 if (ndirs == 0) 320 ndirs = 1; /* percpu_counters are approximate... */ 321 322 blocks_per_dir = (le32_to_cpu(es->s_blocks_count)-free_blocks) / ndirs; 323 324 max_dirs = ndirs / ngroups + inodes_per_group / 16; 325 min_inodes = avefreei - inodes_per_group / 4; 326 min_blocks = avefreeb - EXT2_BLOCKS_PER_GROUP(sb) / 4; 327 328 max_debt = EXT2_BLOCKS_PER_GROUP(sb) / max(blocks_per_dir, BLOCK_COST); 329 if (max_debt * INODE_COST > inodes_per_group) 330 max_debt = inodes_per_group / INODE_COST; 331 if (max_debt > 255) 332 max_debt = 255; 333 if (max_debt == 0) 334 max_debt = 1; 335 336 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 (sbi->s_debts[group] >= max_debt) 342 continue; 343 if (le16_to_cpu(desc->bg_used_dirs_count) >= max_dirs) 344 continue; 345 if (le16_to_cpu(desc->bg_free_inodes_count) < min_inodes) 346 continue; 347 if (le16_to_cpu(desc->bg_free_blocks_count) < min_blocks) 348 continue; 349 goto found; 350 } 351 352 fallback: 353 for (i = 0; i < ngroups; i++) { 354 group = (parent_group + i) % ngroups; 355 desc = ext2_get_group_desc (sb, group, NULL); 356 if (!desc || !desc->bg_free_inodes_count) 357 continue; 358 if (le16_to_cpu(desc->bg_free_inodes_count) >= avefreei) 359 goto found; 360 } 361 362 if (avefreei) { 363 /* 364 * The free-inodes counter is approximate, and for really small 365 * filesystems the above test can fail to find any blockgroups 366 */ 367 avefreei = 0; 368 goto fallback; 369 } 370 371 return -1; 372 373 found: 374 return group; 375 } 376 377 static int find_group_other(struct super_block *sb, struct inode *parent) 378 { 379 int parent_group = EXT2_I(parent)->i_block_group; 380 int ngroups = EXT2_SB(sb)->s_groups_count; 381 struct ext2_group_desc *desc; 382 int group, i; 383 384 /* 385 * Try to place the inode in its parent directory 386 */ 387 group = parent_group; 388 desc = ext2_get_group_desc (sb, group, NULL); 389 if (desc && le16_to_cpu(desc->bg_free_inodes_count) && 390 le16_to_cpu(desc->bg_free_blocks_count)) 391 goto found; 392 393 /* 394 * We're going to place this inode in a different blockgroup from its 395 * parent. We want to cause files in a common directory to all land in 396 * the same blockgroup. But we want files which are in a different 397 * directory which shares a blockgroup with our parent to land in a 398 * different blockgroup. 399 * 400 * So add our directory's i_ino into the starting point for the hash. 401 */ 402 group = (group + parent->i_ino) % ngroups; 403 404 /* 405 * Use a quadratic hash to find a group with a free inode and some 406 * free blocks. 407 */ 408 for (i = 1; i < ngroups; i <<= 1) { 409 group += i; 410 if (group >= ngroups) 411 group -= ngroups; 412 desc = ext2_get_group_desc (sb, group, NULL); 413 if (desc && le16_to_cpu(desc->bg_free_inodes_count) && 414 le16_to_cpu(desc->bg_free_blocks_count)) 415 goto found; 416 } 417 418 /* 419 * That failed: try linear search for a free inode, even if that group 420 * has no free blocks. 421 */ 422 group = parent_group; 423 for (i = 0; i < ngroups; i++) { 424 if (++group >= ngroups) 425 group = 0; 426 desc = ext2_get_group_desc (sb, group, NULL); 427 if (desc && le16_to_cpu(desc->bg_free_inodes_count)) 428 goto found; 429 } 430 431 return -1; 432 433 found: 434 return group; 435 } 436 437 struct inode *ext2_new_inode(struct inode *dir, int mode) 438 { 439 struct super_block *sb; 440 struct buffer_head *bitmap_bh = NULL; 441 struct buffer_head *bh2; 442 int group, i; 443 ino_t ino = 0; 444 struct inode * inode; 445 struct ext2_group_desc *gdp; 446 struct ext2_super_block *es; 447 struct ext2_inode_info *ei; 448 struct ext2_sb_info *sbi; 449 int err; 450 451 sb = dir->i_sb; 452 inode = new_inode(sb); 453 if (!inode) 454 return ERR_PTR(-ENOMEM); 455 456 ei = EXT2_I(inode); 457 sbi = EXT2_SB(sb); 458 es = sbi->s_es; 459 if (S_ISDIR(mode)) { 460 if (test_opt(sb, OLDALLOC)) 461 group = find_group_dir(sb, dir); 462 else 463 group = find_group_orlov(sb, dir); 464 } else 465 group = find_group_other(sb, dir); 466 467 if (group == -1) { 468 err = -ENOSPC; 469 goto fail; 470 } 471 472 for (i = 0; i < sbi->s_groups_count; i++) { 473 gdp = ext2_get_group_desc(sb, group, &bh2); 474 brelse(bitmap_bh); 475 bitmap_bh = read_inode_bitmap(sb, group); 476 if (!bitmap_bh) { 477 err = -EIO; 478 goto fail; 479 } 480 ino = 0; 481 482 repeat_in_this_group: 483 ino = ext2_find_next_zero_bit((unsigned long *)bitmap_bh->b_data, 484 EXT2_INODES_PER_GROUP(sb), ino); 485 if (ino >= EXT2_INODES_PER_GROUP(sb)) { 486 /* 487 * Rare race: find_group_xx() decided that there were 488 * free inodes in this group, but by the time we tried 489 * to allocate one, they're all gone. This can also 490 * occur because the counters which find_group_orlov() 491 * uses are approximate. So just go and search the 492 * next block group. 493 */ 494 if (++group == sbi->s_groups_count) 495 group = 0; 496 continue; 497 } 498 if (ext2_set_bit_atomic(sb_bgl_lock(sbi, group), 499 ino, bitmap_bh->b_data)) { 500 /* we lost this inode */ 501 if (++ino >= EXT2_INODES_PER_GROUP(sb)) { 502 /* this group is exhausted, try next group */ 503 if (++group == sbi->s_groups_count) 504 group = 0; 505 continue; 506 } 507 /* try to find free inode in the same group */ 508 goto repeat_in_this_group; 509 } 510 goto got; 511 } 512 513 /* 514 * Scanned all blockgroups. 515 */ 516 err = -ENOSPC; 517 goto fail; 518 got: 519 mark_buffer_dirty(bitmap_bh); 520 if (sb->s_flags & MS_SYNCHRONOUS) 521 sync_dirty_buffer(bitmap_bh); 522 brelse(bitmap_bh); 523 524 ino += group * EXT2_INODES_PER_GROUP(sb) + 1; 525 if (ino < EXT2_FIRST_INO(sb) || ino > le32_to_cpu(es->s_inodes_count)) { 526 ext2_error (sb, "ext2_new_inode", 527 "reserved inode or inode > inodes count - " 528 "block_group = %d,inode=%lu", group, 529 (unsigned long) ino); 530 err = -EIO; 531 goto fail; 532 } 533 534 percpu_counter_add(&sbi->s_freeinodes_counter, -1); 535 if (S_ISDIR(mode)) 536 percpu_counter_inc(&sbi->s_dirs_counter); 537 538 spin_lock(sb_bgl_lock(sbi, group)); 539 le16_add_cpu(&gdp->bg_free_inodes_count, -1); 540 if (S_ISDIR(mode)) { 541 if (sbi->s_debts[group] < 255) 542 sbi->s_debts[group]++; 543 le16_add_cpu(&gdp->bg_used_dirs_count, 1); 544 } else { 545 if (sbi->s_debts[group]) 546 sbi->s_debts[group]--; 547 } 548 spin_unlock(sb_bgl_lock(sbi, group)); 549 550 sb->s_dirt = 1; 551 mark_buffer_dirty(bh2); 552 if (test_opt(sb, GRPID)) { 553 inode->i_mode = mode; 554 inode->i_uid = current_fsuid(); 555 inode->i_gid = dir->i_gid; 556 } else 557 inode_init_owner(inode, dir, mode); 558 559 inode->i_ino = ino; 560 inode->i_blocks = 0; 561 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC; 562 memset(ei->i_data, 0, sizeof(ei->i_data)); 563 ei->i_flags = 564 ext2_mask_flags(mode, EXT2_I(dir)->i_flags & EXT2_FL_INHERITED); 565 ei->i_faddr = 0; 566 ei->i_frag_no = 0; 567 ei->i_frag_size = 0; 568 ei->i_file_acl = 0; 569 ei->i_dir_acl = 0; 570 ei->i_dtime = 0; 571 ei->i_block_alloc_info = NULL; 572 ei->i_block_group = group; 573 ei->i_dir_start_lookup = 0; 574 ei->i_state = EXT2_STATE_NEW; 575 ext2_set_inode_flags(inode); 576 spin_lock(&sbi->s_next_gen_lock); 577 inode->i_generation = sbi->s_next_generation++; 578 spin_unlock(&sbi->s_next_gen_lock); 579 if (insert_inode_locked(inode) < 0) { 580 err = -EINVAL; 581 goto fail_drop; 582 } 583 584 dquot_initialize(inode); 585 err = dquot_alloc_inode(inode); 586 if (err) 587 goto fail_drop; 588 589 err = ext2_init_acl(inode, dir); 590 if (err) 591 goto fail_free_drop; 592 593 err = ext2_init_security(inode,dir); 594 if (err) 595 goto fail_free_drop; 596 597 mark_inode_dirty(inode); 598 ext2_debug("allocating inode %lu\n", inode->i_ino); 599 ext2_preread_inode(inode); 600 return inode; 601 602 fail_free_drop: 603 dquot_free_inode(inode); 604 605 fail_drop: 606 dquot_drop(inode); 607 inode->i_flags |= S_NOQUOTA; 608 inode->i_nlink = 0; 609 unlock_new_inode(inode); 610 iput(inode); 611 return ERR_PTR(err); 612 613 fail: 614 make_bad_inode(inode); 615 iput(inode); 616 return ERR_PTR(err); 617 } 618 619 unsigned long ext2_count_free_inodes (struct super_block * sb) 620 { 621 struct ext2_group_desc *desc; 622 unsigned long desc_count = 0; 623 int i; 624 625 #ifdef EXT2FS_DEBUG 626 struct ext2_super_block *es; 627 unsigned long bitmap_count = 0; 628 struct buffer_head *bitmap_bh = NULL; 629 630 es = EXT2_SB(sb)->s_es; 631 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) { 632 unsigned x; 633 634 desc = ext2_get_group_desc (sb, i, NULL); 635 if (!desc) 636 continue; 637 desc_count += le16_to_cpu(desc->bg_free_inodes_count); 638 brelse(bitmap_bh); 639 bitmap_bh = read_inode_bitmap(sb, i); 640 if (!bitmap_bh) 641 continue; 642 643 x = ext2_count_free(bitmap_bh, EXT2_INODES_PER_GROUP(sb) / 8); 644 printk("group %d: stored = %d, counted = %u\n", 645 i, le16_to_cpu(desc->bg_free_inodes_count), x); 646 bitmap_count += x; 647 } 648 brelse(bitmap_bh); 649 printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n", 650 percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter), 651 desc_count, bitmap_count); 652 return desc_count; 653 #else 654 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) { 655 desc = ext2_get_group_desc (sb, i, NULL); 656 if (!desc) 657 continue; 658 desc_count += le16_to_cpu(desc->bg_free_inodes_count); 659 } 660 return desc_count; 661 #endif 662 } 663 664 /* Called at mount-time, super-block is locked */ 665 unsigned long ext2_count_dirs (struct super_block * sb) 666 { 667 unsigned long count = 0; 668 int i; 669 670 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) { 671 struct ext2_group_desc *gdp = ext2_get_group_desc (sb, i, NULL); 672 if (!gdp) 673 continue; 674 count += le16_to_cpu(gdp->bg_used_dirs_count); 675 } 676 return count; 677 } 678 679