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