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 ext2_xattr_delete_inode(inode); 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 & MS_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 */ 166 static 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->i_mapping->backing_dev_info; 175 if (bdi_read_congested(bdi)) 176 return; 177 if (bdi_write_congested(bdi)) 178 return; 179 180 block_group = (inode->i_ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb); 181 gdp = ext2_get_group_desc(inode->i_sb, block_group, NULL); 182 if (gdp == NULL) 183 return; 184 185 /* 186 * Figure out the offset within the block group inode table 187 */ 188 offset = ((inode->i_ino - 1) % EXT2_INODES_PER_GROUP(inode->i_sb)) * 189 EXT2_INODE_SIZE(inode->i_sb); 190 block = le32_to_cpu(gdp->bg_inode_table) + 191 (offset >> EXT2_BLOCK_SIZE_BITS(inode->i_sb)); 192 sb_breadahead(inode->i_sb, block); 193 } 194 195 /* 196 * There are two policies for allocating an inode. If the new inode is 197 * a directory, then a forward search is made for a block group with both 198 * free space and a low directory-to-inode ratio; if that fails, then of 199 * the groups with above-average free space, that group with the fewest 200 * directories already is chosen. 201 * 202 * For other inodes, search forward from the parent directory\'s block 203 * group to find a free inode. 204 */ 205 static int find_group_dir(struct super_block *sb, struct inode *parent) 206 { 207 int ngroups = EXT2_SB(sb)->s_groups_count; 208 int avefreei = ext2_count_free_inodes(sb) / ngroups; 209 struct ext2_group_desc *desc, *best_desc = NULL; 210 int group, best_group = -1; 211 212 for (group = 0; group < ngroups; group++) { 213 desc = ext2_get_group_desc (sb, group, NULL); 214 if (!desc || !desc->bg_free_inodes_count) 215 continue; 216 if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei) 217 continue; 218 if (!best_desc || 219 (le16_to_cpu(desc->bg_free_blocks_count) > 220 le16_to_cpu(best_desc->bg_free_blocks_count))) { 221 best_group = group; 222 best_desc = desc; 223 } 224 } 225 if (!best_desc) 226 return -1; 227 228 return best_group; 229 } 230 231 /* 232 * Orlov's allocator for directories. 233 * 234 * We always try to spread first-level directories. 235 * 236 * If there are blockgroups with both free inodes and free blocks counts 237 * not worse than average we return one with smallest directory count. 238 * Otherwise we simply return a random group. 239 * 240 * For the rest rules look so: 241 * 242 * It's OK to put directory into a group unless 243 * it has too many directories already (max_dirs) or 244 * it has too few free inodes left (min_inodes) or 245 * it has too few free blocks left (min_blocks) or 246 * it's already running too large debt (max_debt). 247 * Parent's group is preferred, if it doesn't satisfy these 248 * conditions we search cyclically through the rest. If none 249 * of the groups look good we just look for a group with more 250 * free inodes than average (starting at parent's group). 251 * 252 * Debt is incremented each time we allocate a directory and decremented 253 * when we allocate an inode, within 0--255. 254 */ 255 256 #define INODE_COST 64 257 #define BLOCK_COST 256 258 259 static int find_group_orlov(struct super_block *sb, struct inode *parent) 260 { 261 int parent_group = EXT2_I(parent)->i_block_group; 262 struct ext2_sb_info *sbi = EXT2_SB(sb); 263 struct ext2_super_block *es = sbi->s_es; 264 int ngroups = sbi->s_groups_count; 265 int inodes_per_group = EXT2_INODES_PER_GROUP(sb); 266 int freei; 267 int avefreei; 268 int free_blocks; 269 int avefreeb; 270 int blocks_per_dir; 271 int ndirs; 272 int max_debt, max_dirs, min_blocks, min_inodes; 273 int group = -1, i; 274 struct ext2_group_desc *desc; 275 276 freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter); 277 avefreei = freei / ngroups; 278 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter); 279 avefreeb = free_blocks / ngroups; 280 ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter); 281 282 if ((parent == sb->s_root->d_inode) || 283 (EXT2_I(parent)->i_flags & EXT2_TOPDIR_FL)) { 284 struct ext2_group_desc *best_desc = NULL; 285 int best_ndir = inodes_per_group; 286 int best_group = -1; 287 288 get_random_bytes(&group, sizeof(group)); 289 parent_group = (unsigned)group % ngroups; 290 for (i = 0; i < ngroups; i++) { 291 group = (parent_group + i) % ngroups; 292 desc = ext2_get_group_desc (sb, group, NULL); 293 if (!desc || !desc->bg_free_inodes_count) 294 continue; 295 if (le16_to_cpu(desc->bg_used_dirs_count) >= best_ndir) 296 continue; 297 if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei) 298 continue; 299 if (le16_to_cpu(desc->bg_free_blocks_count) < avefreeb) 300 continue; 301 best_group = group; 302 best_ndir = le16_to_cpu(desc->bg_used_dirs_count); 303 best_desc = desc; 304 } 305 if (best_group >= 0) { 306 desc = best_desc; 307 group = best_group; 308 goto found; 309 } 310 goto fallback; 311 } 312 313 if (ndirs == 0) 314 ndirs = 1; /* percpu_counters are approximate... */ 315 316 blocks_per_dir = (le32_to_cpu(es->s_blocks_count)-free_blocks) / ndirs; 317 318 max_dirs = ndirs / ngroups + inodes_per_group / 16; 319 min_inodes = avefreei - inodes_per_group / 4; 320 min_blocks = avefreeb - EXT2_BLOCKS_PER_GROUP(sb) / 4; 321 322 max_debt = EXT2_BLOCKS_PER_GROUP(sb) / max(blocks_per_dir, BLOCK_COST); 323 if (max_debt * INODE_COST > inodes_per_group) 324 max_debt = inodes_per_group / INODE_COST; 325 if (max_debt > 255) 326 max_debt = 255; 327 if (max_debt == 0) 328 max_debt = 1; 329 330 for (i = 0; i < ngroups; i++) { 331 group = (parent_group + i) % ngroups; 332 desc = ext2_get_group_desc (sb, group, NULL); 333 if (!desc || !desc->bg_free_inodes_count) 334 continue; 335 if (sbi->s_debts[group] >= max_debt) 336 continue; 337 if (le16_to_cpu(desc->bg_used_dirs_count) >= max_dirs) 338 continue; 339 if (le16_to_cpu(desc->bg_free_inodes_count) < min_inodes) 340 continue; 341 if (le16_to_cpu(desc->bg_free_blocks_count) < min_blocks) 342 continue; 343 goto found; 344 } 345 346 fallback: 347 for (i = 0; i < ngroups; i++) { 348 group = (parent_group + i) % ngroups; 349 desc = ext2_get_group_desc (sb, group, NULL); 350 if (!desc || !desc->bg_free_inodes_count) 351 continue; 352 if (le16_to_cpu(desc->bg_free_inodes_count) >= avefreei) 353 goto found; 354 } 355 356 if (avefreei) { 357 /* 358 * The free-inodes counter is approximate, and for really small 359 * filesystems the above test can fail to find any blockgroups 360 */ 361 avefreei = 0; 362 goto fallback; 363 } 364 365 return -1; 366 367 found: 368 return group; 369 } 370 371 static int find_group_other(struct super_block *sb, struct inode *parent) 372 { 373 int parent_group = EXT2_I(parent)->i_block_group; 374 int ngroups = EXT2_SB(sb)->s_groups_count; 375 struct ext2_group_desc *desc; 376 int group, i; 377 378 /* 379 * Try to place the inode in its parent directory 380 */ 381 group = parent_group; 382 desc = ext2_get_group_desc (sb, group, NULL); 383 if (desc && le16_to_cpu(desc->bg_free_inodes_count) && 384 le16_to_cpu(desc->bg_free_blocks_count)) 385 goto found; 386 387 /* 388 * We're going to place this inode in a different blockgroup from its 389 * parent. We want to cause files in a common directory to all land in 390 * the same blockgroup. But we want files which are in a different 391 * directory which shares a blockgroup with our parent to land in a 392 * different blockgroup. 393 * 394 * So add our directory's i_ino into the starting point for the hash. 395 */ 396 group = (group + parent->i_ino) % ngroups; 397 398 /* 399 * Use a quadratic hash to find a group with a free inode and some 400 * free blocks. 401 */ 402 for (i = 1; i < ngroups; i <<= 1) { 403 group += i; 404 if (group >= ngroups) 405 group -= ngroups; 406 desc = ext2_get_group_desc (sb, group, NULL); 407 if (desc && le16_to_cpu(desc->bg_free_inodes_count) && 408 le16_to_cpu(desc->bg_free_blocks_count)) 409 goto found; 410 } 411 412 /* 413 * That failed: try linear search for a free inode, even if that group 414 * has no free blocks. 415 */ 416 group = parent_group; 417 for (i = 0; i < ngroups; i++) { 418 if (++group >= ngroups) 419 group = 0; 420 desc = ext2_get_group_desc (sb, group, NULL); 421 if (desc && le16_to_cpu(desc->bg_free_inodes_count)) 422 goto found; 423 } 424 425 return -1; 426 427 found: 428 return group; 429 } 430 431 struct inode *ext2_new_inode(struct inode *dir, umode_t mode, 432 const struct qstr *qstr) 433 { 434 struct super_block *sb; 435 struct buffer_head *bitmap_bh = NULL; 436 struct buffer_head *bh2; 437 int group, i; 438 ino_t ino = 0; 439 struct inode * inode; 440 struct ext2_group_desc *gdp; 441 struct ext2_super_block *es; 442 struct ext2_inode_info *ei; 443 struct ext2_sb_info *sbi; 444 int err; 445 446 sb = dir->i_sb; 447 inode = new_inode(sb); 448 if (!inode) 449 return ERR_PTR(-ENOMEM); 450 451 ei = EXT2_I(inode); 452 sbi = EXT2_SB(sb); 453 es = sbi->s_es; 454 if (S_ISDIR(mode)) { 455 if (test_opt(sb, OLDALLOC)) 456 group = find_group_dir(sb, dir); 457 else 458 group = find_group_orlov(sb, dir); 459 } else 460 group = find_group_other(sb, dir); 461 462 if (group == -1) { 463 err = -ENOSPC; 464 goto fail; 465 } 466 467 for (i = 0; i < sbi->s_groups_count; i++) { 468 gdp = ext2_get_group_desc(sb, group, &bh2); 469 brelse(bitmap_bh); 470 bitmap_bh = read_inode_bitmap(sb, group); 471 if (!bitmap_bh) { 472 err = -EIO; 473 goto fail; 474 } 475 ino = 0; 476 477 repeat_in_this_group: 478 ino = ext2_find_next_zero_bit((unsigned long *)bitmap_bh->b_data, 479 EXT2_INODES_PER_GROUP(sb), ino); 480 if (ino >= EXT2_INODES_PER_GROUP(sb)) { 481 /* 482 * Rare race: find_group_xx() decided that there were 483 * free inodes in this group, but by the time we tried 484 * to allocate one, they're all gone. This can also 485 * occur because the counters which find_group_orlov() 486 * uses are approximate. So just go and search the 487 * next block group. 488 */ 489 if (++group == sbi->s_groups_count) 490 group = 0; 491 continue; 492 } 493 if (ext2_set_bit_atomic(sb_bgl_lock(sbi, group), 494 ino, bitmap_bh->b_data)) { 495 /* we lost this inode */ 496 if (++ino >= EXT2_INODES_PER_GROUP(sb)) { 497 /* this group is exhausted, try next group */ 498 if (++group == sbi->s_groups_count) 499 group = 0; 500 continue; 501 } 502 /* try to find free inode in the same group */ 503 goto repeat_in_this_group; 504 } 505 goto got; 506 } 507 508 /* 509 * Scanned all blockgroups. 510 */ 511 err = -ENOSPC; 512 goto fail; 513 got: 514 mark_buffer_dirty(bitmap_bh); 515 if (sb->s_flags & MS_SYNCHRONOUS) 516 sync_dirty_buffer(bitmap_bh); 517 brelse(bitmap_bh); 518 519 ino += group * EXT2_INODES_PER_GROUP(sb) + 1; 520 if (ino < EXT2_FIRST_INO(sb) || ino > le32_to_cpu(es->s_inodes_count)) { 521 ext2_error (sb, "ext2_new_inode", 522 "reserved inode or inode > inodes count - " 523 "block_group = %d,inode=%lu", group, 524 (unsigned long) ino); 525 err = -EIO; 526 goto fail; 527 } 528 529 percpu_counter_add(&sbi->s_freeinodes_counter, -1); 530 if (S_ISDIR(mode)) 531 percpu_counter_inc(&sbi->s_dirs_counter); 532 533 spin_lock(sb_bgl_lock(sbi, group)); 534 le16_add_cpu(&gdp->bg_free_inodes_count, -1); 535 if (S_ISDIR(mode)) { 536 if (sbi->s_debts[group] < 255) 537 sbi->s_debts[group]++; 538 le16_add_cpu(&gdp->bg_used_dirs_count, 1); 539 } else { 540 if (sbi->s_debts[group]) 541 sbi->s_debts[group]--; 542 } 543 spin_unlock(sb_bgl_lock(sbi, group)); 544 545 mark_buffer_dirty(bh2); 546 if (test_opt(sb, GRPID)) { 547 inode->i_mode = mode; 548 inode->i_uid = current_fsuid(); 549 inode->i_gid = dir->i_gid; 550 } else 551 inode_init_owner(inode, dir, mode); 552 553 inode->i_ino = ino; 554 inode->i_blocks = 0; 555 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC; 556 memset(ei->i_data, 0, sizeof(ei->i_data)); 557 ei->i_flags = 558 ext2_mask_flags(mode, EXT2_I(dir)->i_flags & EXT2_FL_INHERITED); 559 ei->i_faddr = 0; 560 ei->i_frag_no = 0; 561 ei->i_frag_size = 0; 562 ei->i_file_acl = 0; 563 ei->i_dir_acl = 0; 564 ei->i_dtime = 0; 565 ei->i_block_alloc_info = NULL; 566 ei->i_block_group = group; 567 ei->i_dir_start_lookup = 0; 568 ei->i_state = EXT2_STATE_NEW; 569 ext2_set_inode_flags(inode); 570 spin_lock(&sbi->s_next_gen_lock); 571 inode->i_generation = sbi->s_next_generation++; 572 spin_unlock(&sbi->s_next_gen_lock); 573 if (insert_inode_locked(inode) < 0) { 574 ext2_error(sb, "ext2_new_inode", 575 "inode number already in use - inode=%lu", 576 (unsigned long) ino); 577 err = -EIO; 578 goto fail; 579 } 580 581 dquot_initialize(inode); 582 err = dquot_alloc_inode(inode); 583 if (err) 584 goto fail_drop; 585 586 err = ext2_init_acl(inode, dir); 587 if (err) 588 goto fail_free_drop; 589 590 err = ext2_init_security(inode, dir, qstr); 591 if (err) 592 goto fail_free_drop; 593 594 mark_inode_dirty(inode); 595 ext2_debug("allocating inode %lu\n", inode->i_ino); 596 ext2_preread_inode(inode); 597 return inode; 598 599 fail_free_drop: 600 dquot_free_inode(inode); 601 602 fail_drop: 603 dquot_drop(inode); 604 inode->i_flags |= S_NOQUOTA; 605 clear_nlink(inode); 606 unlock_new_inode(inode); 607 iput(inode); 608 return ERR_PTR(err); 609 610 fail: 611 make_bad_inode(inode); 612 iput(inode); 613 return ERR_PTR(err); 614 } 615 616 unsigned long ext2_count_free_inodes (struct super_block * sb) 617 { 618 struct ext2_group_desc *desc; 619 unsigned long desc_count = 0; 620 int i; 621 622 #ifdef EXT2FS_DEBUG 623 struct ext2_super_block *es; 624 unsigned long bitmap_count = 0; 625 struct buffer_head *bitmap_bh = NULL; 626 627 es = EXT2_SB(sb)->s_es; 628 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) { 629 unsigned x; 630 631 desc = ext2_get_group_desc (sb, i, NULL); 632 if (!desc) 633 continue; 634 desc_count += le16_to_cpu(desc->bg_free_inodes_count); 635 brelse(bitmap_bh); 636 bitmap_bh = read_inode_bitmap(sb, i); 637 if (!bitmap_bh) 638 continue; 639 640 x = ext2_count_free(bitmap_bh, EXT2_INODES_PER_GROUP(sb) / 8); 641 printk("group %d: stored = %d, counted = %u\n", 642 i, le16_to_cpu(desc->bg_free_inodes_count), x); 643 bitmap_count += x; 644 } 645 brelse(bitmap_bh); 646 printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n", 647 (unsigned long) 648 percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter), 649 desc_count, bitmap_count); 650 return desc_count; 651 #else 652 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) { 653 desc = ext2_get_group_desc (sb, i, NULL); 654 if (!desc) 655 continue; 656 desc_count += le16_to_cpu(desc->bg_free_inodes_count); 657 } 658 return desc_count; 659 #endif 660 } 661 662 /* Called at mount-time, super-block is locked */ 663 unsigned long ext2_count_dirs (struct super_block * sb) 664 { 665 unsigned long count = 0; 666 int i; 667 668 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) { 669 struct ext2_group_desc *gdp = ext2_get_group_desc (sb, i, NULL); 670 if (!gdp) 671 continue; 672 count += le16_to_cpu(gdp->bg_used_dirs_count); 673 } 674 return count; 675 } 676 677