1 /* 2 * linux/fs/ext4/balloc.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 * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993 10 * Big-endian to little-endian byte-swapping/bitmaps by 11 * David S. Miller (davem@caip.rutgers.edu), 1995 12 */ 13 14 #include <linux/time.h> 15 #include <linux/capability.h> 16 #include <linux/fs.h> 17 #include <linux/jbd2.h> 18 #include <linux/quotaops.h> 19 #include <linux/buffer_head.h> 20 #include "ext4.h" 21 #include "ext4_jbd2.h" 22 #include "mballoc.h" 23 24 #include <trace/events/ext4.h> 25 26 static unsigned ext4_num_base_meta_clusters(struct super_block *sb, 27 ext4_group_t block_group); 28 /* 29 * balloc.c contains the blocks allocation and deallocation routines 30 */ 31 32 /* 33 * Calculate the block group number and offset into the block/cluster 34 * allocation bitmap, given a block number 35 */ 36 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr, 37 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp) 38 { 39 struct ext4_super_block *es = EXT4_SB(sb)->s_es; 40 ext4_grpblk_t offset; 41 42 blocknr = blocknr - le32_to_cpu(es->s_first_data_block); 43 offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >> 44 EXT4_SB(sb)->s_cluster_bits; 45 if (offsetp) 46 *offsetp = offset; 47 if (blockgrpp) 48 *blockgrpp = blocknr; 49 50 } 51 52 static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block, 53 ext4_group_t block_group) 54 { 55 ext4_group_t actual_group; 56 ext4_get_group_no_and_offset(sb, block, &actual_group, NULL); 57 if (actual_group == block_group) 58 return 1; 59 return 0; 60 } 61 62 /* Return the number of clusters used for file system metadata; this 63 * represents the overhead needed by the file system. 64 */ 65 unsigned ext4_num_overhead_clusters(struct super_block *sb, 66 ext4_group_t block_group, 67 struct ext4_group_desc *gdp) 68 { 69 unsigned num_clusters; 70 int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c; 71 ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group); 72 ext4_fsblk_t itbl_blk; 73 struct ext4_sb_info *sbi = EXT4_SB(sb); 74 75 /* This is the number of clusters used by the superblock, 76 * block group descriptors, and reserved block group 77 * descriptor blocks */ 78 num_clusters = ext4_num_base_meta_clusters(sb, block_group); 79 80 /* 81 * For the allocation bitmaps and inode table, we first need 82 * to check to see if the block is in the block group. If it 83 * is, then check to see if the cluster is already accounted 84 * for in the clusters used for the base metadata cluster, or 85 * if we can increment the base metadata cluster to include 86 * that block. Otherwise, we will have to track the cluster 87 * used for the allocation bitmap or inode table explicitly. 88 * Normally all of these blocks are contiguous, so the special 89 * case handling shouldn't be necessary except for *very* 90 * unusual file system layouts. 91 */ 92 if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) { 93 block_cluster = EXT4_B2C(sbi, 94 ext4_block_bitmap(sb, gdp) - start); 95 if (block_cluster < num_clusters) 96 block_cluster = -1; 97 else if (block_cluster == num_clusters) { 98 num_clusters++; 99 block_cluster = -1; 100 } 101 } 102 103 if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) { 104 inode_cluster = EXT4_B2C(sbi, 105 ext4_inode_bitmap(sb, gdp) - start); 106 if (inode_cluster < num_clusters) 107 inode_cluster = -1; 108 else if (inode_cluster == num_clusters) { 109 num_clusters++; 110 inode_cluster = -1; 111 } 112 } 113 114 itbl_blk = ext4_inode_table(sb, gdp); 115 for (i = 0; i < sbi->s_itb_per_group; i++) { 116 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) { 117 c = EXT4_B2C(sbi, itbl_blk + i - start); 118 if ((c < num_clusters) || (c == inode_cluster) || 119 (c == block_cluster) || (c == itbl_cluster)) 120 continue; 121 if (c == num_clusters) { 122 num_clusters++; 123 continue; 124 } 125 num_clusters++; 126 itbl_cluster = c; 127 } 128 } 129 130 if (block_cluster != -1) 131 num_clusters++; 132 if (inode_cluster != -1) 133 num_clusters++; 134 135 return num_clusters; 136 } 137 138 static unsigned int num_clusters_in_group(struct super_block *sb, 139 ext4_group_t block_group) 140 { 141 unsigned int blocks; 142 143 if (block_group == ext4_get_groups_count(sb) - 1) { 144 /* 145 * Even though mke2fs always initializes the first and 146 * last group, just in case some other tool was used, 147 * we need to make sure we calculate the right free 148 * blocks. 149 */ 150 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) - 151 ext4_group_first_block_no(sb, block_group); 152 } else 153 blocks = EXT4_BLOCKS_PER_GROUP(sb); 154 return EXT4_NUM_B2C(EXT4_SB(sb), blocks); 155 } 156 157 /* Initializes an uninitialized block bitmap */ 158 void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh, 159 ext4_group_t block_group, 160 struct ext4_group_desc *gdp) 161 { 162 unsigned int bit, bit_max; 163 struct ext4_sb_info *sbi = EXT4_SB(sb); 164 ext4_fsblk_t start, tmp; 165 int flex_bg = 0; 166 167 J_ASSERT_BH(bh, buffer_locked(bh)); 168 169 /* If checksum is bad mark all blocks used to prevent allocation 170 * essentially implementing a per-group read-only flag. */ 171 if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) { 172 ext4_error(sb, "Checksum bad for group %u", block_group); 173 ext4_free_group_clusters_set(sb, gdp, 0); 174 ext4_free_inodes_set(sb, gdp, 0); 175 ext4_itable_unused_set(sb, gdp, 0); 176 memset(bh->b_data, 0xff, sb->s_blocksize); 177 ext4_block_bitmap_csum_set(sb, block_group, gdp, bh); 178 return; 179 } 180 memset(bh->b_data, 0, sb->s_blocksize); 181 182 bit_max = ext4_num_base_meta_clusters(sb, block_group); 183 for (bit = 0; bit < bit_max; bit++) 184 ext4_set_bit(bit, bh->b_data); 185 186 start = ext4_group_first_block_no(sb, block_group); 187 188 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) 189 flex_bg = 1; 190 191 /* Set bits for block and inode bitmaps, and inode table */ 192 tmp = ext4_block_bitmap(sb, gdp); 193 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) 194 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); 195 196 tmp = ext4_inode_bitmap(sb, gdp); 197 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) 198 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); 199 200 tmp = ext4_inode_table(sb, gdp); 201 for (; tmp < ext4_inode_table(sb, gdp) + 202 sbi->s_itb_per_group; tmp++) { 203 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) 204 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); 205 } 206 207 /* 208 * Also if the number of blocks within the group is less than 209 * the blocksize * 8 ( which is the size of bitmap ), set rest 210 * of the block bitmap to 1 211 */ 212 ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group), 213 sb->s_blocksize * 8, bh->b_data); 214 ext4_block_bitmap_csum_set(sb, block_group, gdp, bh); 215 ext4_group_desc_csum_set(sb, block_group, gdp); 216 } 217 218 /* Return the number of free blocks in a block group. It is used when 219 * the block bitmap is uninitialized, so we can't just count the bits 220 * in the bitmap. */ 221 unsigned ext4_free_clusters_after_init(struct super_block *sb, 222 ext4_group_t block_group, 223 struct ext4_group_desc *gdp) 224 { 225 return num_clusters_in_group(sb, block_group) - 226 ext4_num_overhead_clusters(sb, block_group, gdp); 227 } 228 229 /* 230 * The free blocks are managed by bitmaps. A file system contains several 231 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap 232 * block for inodes, N blocks for the inode table and data blocks. 233 * 234 * The file system contains group descriptors which are located after the 235 * super block. Each descriptor contains the number of the bitmap block and 236 * the free blocks count in the block. The descriptors are loaded in memory 237 * when a file system is mounted (see ext4_fill_super). 238 */ 239 240 /** 241 * ext4_get_group_desc() -- load group descriptor from disk 242 * @sb: super block 243 * @block_group: given block group 244 * @bh: pointer to the buffer head to store the block 245 * group descriptor 246 */ 247 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb, 248 ext4_group_t block_group, 249 struct buffer_head **bh) 250 { 251 unsigned int group_desc; 252 unsigned int offset; 253 ext4_group_t ngroups = ext4_get_groups_count(sb); 254 struct ext4_group_desc *desc; 255 struct ext4_sb_info *sbi = EXT4_SB(sb); 256 257 if (block_group >= ngroups) { 258 ext4_error(sb, "block_group >= groups_count - block_group = %u," 259 " groups_count = %u", block_group, ngroups); 260 261 return NULL; 262 } 263 264 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb); 265 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1); 266 if (!sbi->s_group_desc[group_desc]) { 267 ext4_error(sb, "Group descriptor not loaded - " 268 "block_group = %u, group_desc = %u, desc = %u", 269 block_group, group_desc, offset); 270 return NULL; 271 } 272 273 desc = (struct ext4_group_desc *)( 274 (__u8 *)sbi->s_group_desc[group_desc]->b_data + 275 offset * EXT4_DESC_SIZE(sb)); 276 if (bh) 277 *bh = sbi->s_group_desc[group_desc]; 278 return desc; 279 } 280 281 /* 282 * Return the block number which was discovered to be invalid, or 0 if 283 * the block bitmap is valid. 284 */ 285 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, 286 struct ext4_group_desc *desc, 287 unsigned int block_group, 288 struct buffer_head *bh) 289 { 290 ext4_grpblk_t offset; 291 ext4_grpblk_t next_zero_bit; 292 ext4_fsblk_t blk; 293 ext4_fsblk_t group_first_block; 294 295 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) { 296 /* with FLEX_BG, the inode/block bitmaps and itable 297 * blocks may not be in the group at all 298 * so the bitmap validation will be skipped for those groups 299 * or it has to also read the block group where the bitmaps 300 * are located to verify they are set. 301 */ 302 return 0; 303 } 304 group_first_block = ext4_group_first_block_no(sb, block_group); 305 306 /* check whether block bitmap block number is set */ 307 blk = ext4_block_bitmap(sb, desc); 308 offset = blk - group_first_block; 309 if (!ext4_test_bit(offset, bh->b_data)) 310 /* bad block bitmap */ 311 return blk; 312 313 /* check whether the inode bitmap block number is set */ 314 blk = ext4_inode_bitmap(sb, desc); 315 offset = blk - group_first_block; 316 if (!ext4_test_bit(offset, bh->b_data)) 317 /* bad block bitmap */ 318 return blk; 319 320 /* check whether the inode table block number is set */ 321 blk = ext4_inode_table(sb, desc); 322 offset = blk - group_first_block; 323 next_zero_bit = ext4_find_next_zero_bit(bh->b_data, 324 offset + EXT4_SB(sb)->s_itb_per_group, 325 offset); 326 if (next_zero_bit < offset + EXT4_SB(sb)->s_itb_per_group) 327 /* bad bitmap for inode tables */ 328 return blk; 329 return 0; 330 } 331 332 void ext4_validate_block_bitmap(struct super_block *sb, 333 struct ext4_group_desc *desc, 334 unsigned int block_group, 335 struct buffer_head *bh) 336 { 337 ext4_fsblk_t blk; 338 339 if (buffer_verified(bh)) 340 return; 341 342 ext4_lock_group(sb, block_group); 343 blk = ext4_valid_block_bitmap(sb, desc, block_group, bh); 344 if (unlikely(blk != 0)) { 345 ext4_unlock_group(sb, block_group); 346 ext4_error(sb, "bg %u: block %llu: invalid block bitmap", 347 block_group, blk); 348 return; 349 } 350 if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group, 351 desc, bh))) { 352 ext4_unlock_group(sb, block_group); 353 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group); 354 return; 355 } 356 set_buffer_verified(bh); 357 ext4_unlock_group(sb, block_group); 358 } 359 360 /** 361 * ext4_read_block_bitmap() 362 * @sb: super block 363 * @block_group: given block group 364 * 365 * Read the bitmap for a given block_group,and validate the 366 * bits for block/inode/inode tables are set in the bitmaps 367 * 368 * Return buffer_head on success or NULL in case of failure. 369 */ 370 struct buffer_head * 371 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group) 372 { 373 struct ext4_group_desc *desc; 374 struct buffer_head *bh; 375 ext4_fsblk_t bitmap_blk; 376 377 desc = ext4_get_group_desc(sb, block_group, NULL); 378 if (!desc) 379 return NULL; 380 bitmap_blk = ext4_block_bitmap(sb, desc); 381 bh = sb_getblk(sb, bitmap_blk); 382 if (unlikely(!bh)) { 383 ext4_error(sb, "Cannot get buffer for block bitmap - " 384 "block_group = %u, block_bitmap = %llu", 385 block_group, bitmap_blk); 386 return NULL; 387 } 388 389 if (bitmap_uptodate(bh)) 390 goto verify; 391 392 lock_buffer(bh); 393 if (bitmap_uptodate(bh)) { 394 unlock_buffer(bh); 395 goto verify; 396 } 397 ext4_lock_group(sb, block_group); 398 if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) { 399 ext4_init_block_bitmap(sb, bh, block_group, desc); 400 set_bitmap_uptodate(bh); 401 set_buffer_uptodate(bh); 402 ext4_unlock_group(sb, block_group); 403 unlock_buffer(bh); 404 return bh; 405 } 406 ext4_unlock_group(sb, block_group); 407 if (buffer_uptodate(bh)) { 408 /* 409 * if not uninit if bh is uptodate, 410 * bitmap is also uptodate 411 */ 412 set_bitmap_uptodate(bh); 413 unlock_buffer(bh); 414 goto verify; 415 } 416 /* 417 * submit the buffer_head for reading 418 */ 419 set_buffer_new(bh); 420 trace_ext4_read_block_bitmap_load(sb, block_group); 421 bh->b_end_io = ext4_end_bitmap_read; 422 get_bh(bh); 423 submit_bh(READ, bh); 424 return bh; 425 verify: 426 ext4_validate_block_bitmap(sb, desc, block_group, bh); 427 return bh; 428 } 429 430 /* Returns 0 on success, 1 on error */ 431 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group, 432 struct buffer_head *bh) 433 { 434 struct ext4_group_desc *desc; 435 436 if (!buffer_new(bh)) 437 return 0; 438 desc = ext4_get_group_desc(sb, block_group, NULL); 439 if (!desc) 440 return 1; 441 wait_on_buffer(bh); 442 if (!buffer_uptodate(bh)) { 443 ext4_error(sb, "Cannot read block bitmap - " 444 "block_group = %u, block_bitmap = %llu", 445 block_group, (unsigned long long) bh->b_blocknr); 446 return 1; 447 } 448 clear_buffer_new(bh); 449 /* Panic or remount fs read-only if block bitmap is invalid */ 450 ext4_validate_block_bitmap(sb, desc, block_group, bh); 451 return 0; 452 } 453 454 struct buffer_head * 455 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group) 456 { 457 struct buffer_head *bh; 458 459 bh = ext4_read_block_bitmap_nowait(sb, block_group); 460 if (ext4_wait_block_bitmap(sb, block_group, bh)) { 461 put_bh(bh); 462 return NULL; 463 } 464 return bh; 465 } 466 467 /** 468 * ext4_has_free_clusters() 469 * @sbi: in-core super block structure. 470 * @nclusters: number of needed blocks 471 * @flags: flags from ext4_mb_new_blocks() 472 * 473 * Check if filesystem has nclusters free & available for allocation. 474 * On success return 1, return 0 on failure. 475 */ 476 static int ext4_has_free_clusters(struct ext4_sb_info *sbi, 477 s64 nclusters, unsigned int flags) 478 { 479 s64 free_clusters, dirty_clusters, root_clusters; 480 struct percpu_counter *fcc = &sbi->s_freeclusters_counter; 481 struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter; 482 483 free_clusters = percpu_counter_read_positive(fcc); 484 dirty_clusters = percpu_counter_read_positive(dcc); 485 root_clusters = EXT4_B2C(sbi, ext4_r_blocks_count(sbi->s_es)); 486 487 if (free_clusters - (nclusters + root_clusters + dirty_clusters) < 488 EXT4_FREECLUSTERS_WATERMARK) { 489 free_clusters = EXT4_C2B(sbi, percpu_counter_sum_positive(fcc)); 490 dirty_clusters = percpu_counter_sum_positive(dcc); 491 } 492 /* Check whether we have space after accounting for current 493 * dirty clusters & root reserved clusters. 494 */ 495 if (free_clusters >= ((root_clusters + nclusters) + dirty_clusters)) 496 return 1; 497 498 /* Hm, nope. Are (enough) root reserved clusters available? */ 499 if (uid_eq(sbi->s_resuid, current_fsuid()) || 500 (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) || 501 capable(CAP_SYS_RESOURCE) || 502 (flags & EXT4_MB_USE_ROOT_BLOCKS)) { 503 504 if (free_clusters >= (nclusters + dirty_clusters)) 505 return 1; 506 } 507 508 return 0; 509 } 510 511 int ext4_claim_free_clusters(struct ext4_sb_info *sbi, 512 s64 nclusters, unsigned int flags) 513 { 514 if (ext4_has_free_clusters(sbi, nclusters, flags)) { 515 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters); 516 return 0; 517 } else 518 return -ENOSPC; 519 } 520 521 /** 522 * ext4_should_retry_alloc() 523 * @sb: super block 524 * @retries number of attemps has been made 525 * 526 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if 527 * it is profitable to retry the operation, this function will wait 528 * for the current or committing transaction to complete, and then 529 * return TRUE. 530 * 531 * if the total number of retries exceed three times, return FALSE. 532 */ 533 int ext4_should_retry_alloc(struct super_block *sb, int *retries) 534 { 535 if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) || 536 (*retries)++ > 3 || 537 !EXT4_SB(sb)->s_journal) 538 return 0; 539 540 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id); 541 542 return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal); 543 } 544 545 /* 546 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks 547 * 548 * @handle: handle to this transaction 549 * @inode: file inode 550 * @goal: given target block(filesystem wide) 551 * @count: pointer to total number of clusters needed 552 * @errp: error code 553 * 554 * Return 1st allocated block number on success, *count stores total account 555 * error stores in errp pointer 556 */ 557 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode, 558 ext4_fsblk_t goal, unsigned int flags, 559 unsigned long *count, int *errp) 560 { 561 struct ext4_allocation_request ar; 562 ext4_fsblk_t ret; 563 564 memset(&ar, 0, sizeof(ar)); 565 /* Fill with neighbour allocated blocks */ 566 ar.inode = inode; 567 ar.goal = goal; 568 ar.len = count ? *count : 1; 569 ar.flags = flags; 570 571 ret = ext4_mb_new_blocks(handle, &ar, errp); 572 if (count) 573 *count = ar.len; 574 /* 575 * Account for the allocated meta blocks. We will never 576 * fail EDQUOT for metdata, but we do account for it. 577 */ 578 if (!(*errp) && 579 ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) { 580 spin_lock(&EXT4_I(inode)->i_block_reservation_lock); 581 EXT4_I(inode)->i_allocated_meta_blocks += ar.len; 582 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); 583 dquot_alloc_block_nofail(inode, 584 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len)); 585 } 586 return ret; 587 } 588 589 /** 590 * ext4_count_free_clusters() -- count filesystem free clusters 591 * @sb: superblock 592 * 593 * Adds up the number of free clusters from each block group. 594 */ 595 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb) 596 { 597 ext4_fsblk_t desc_count; 598 struct ext4_group_desc *gdp; 599 ext4_group_t i; 600 ext4_group_t ngroups = ext4_get_groups_count(sb); 601 #ifdef EXT4FS_DEBUG 602 struct ext4_super_block *es; 603 ext4_fsblk_t bitmap_count; 604 unsigned int x; 605 struct buffer_head *bitmap_bh = NULL; 606 607 es = EXT4_SB(sb)->s_es; 608 desc_count = 0; 609 bitmap_count = 0; 610 gdp = NULL; 611 612 for (i = 0; i < ngroups; i++) { 613 gdp = ext4_get_group_desc(sb, i, NULL); 614 if (!gdp) 615 continue; 616 desc_count += ext4_free_group_clusters(sb, gdp); 617 brelse(bitmap_bh); 618 bitmap_bh = ext4_read_block_bitmap(sb, i); 619 if (bitmap_bh == NULL) 620 continue; 621 622 x = ext4_count_free(bitmap_bh->b_data, 623 EXT4_BLOCKS_PER_GROUP(sb) / 8); 624 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n", 625 i, ext4_free_group_clusters(sb, gdp), x); 626 bitmap_count += x; 627 } 628 brelse(bitmap_bh); 629 printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu" 630 ", computed = %llu, %llu\n", 631 EXT4_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)), 632 desc_count, bitmap_count); 633 return bitmap_count; 634 #else 635 desc_count = 0; 636 for (i = 0; i < ngroups; i++) { 637 gdp = ext4_get_group_desc(sb, i, NULL); 638 if (!gdp) 639 continue; 640 desc_count += ext4_free_group_clusters(sb, gdp); 641 } 642 643 return desc_count; 644 #endif 645 } 646 647 static inline int test_root(ext4_group_t a, int b) 648 { 649 int num = b; 650 651 while (a > num) 652 num *= b; 653 return num == a; 654 } 655 656 static int ext4_group_sparse(ext4_group_t group) 657 { 658 if (group <= 1) 659 return 1; 660 if (!(group & 1)) 661 return 0; 662 return (test_root(group, 7) || test_root(group, 5) || 663 test_root(group, 3)); 664 } 665 666 /** 667 * ext4_bg_has_super - number of blocks used by the superblock in group 668 * @sb: superblock for filesystem 669 * @group: group number to check 670 * 671 * Return the number of blocks used by the superblock (primary or backup) 672 * in this group. Currently this will be only 0 or 1. 673 */ 674 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group) 675 { 676 if (EXT4_HAS_RO_COMPAT_FEATURE(sb, 677 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) && 678 !ext4_group_sparse(group)) 679 return 0; 680 return 1; 681 } 682 683 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb, 684 ext4_group_t group) 685 { 686 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb); 687 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb); 688 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1; 689 690 if (group == first || group == first + 1 || group == last) 691 return 1; 692 return 0; 693 } 694 695 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb, 696 ext4_group_t group) 697 { 698 if (!ext4_bg_has_super(sb, group)) 699 return 0; 700 701 if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG)) 702 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg); 703 else 704 return EXT4_SB(sb)->s_gdb_count; 705 } 706 707 /** 708 * ext4_bg_num_gdb - number of blocks used by the group table in group 709 * @sb: superblock for filesystem 710 * @group: group number to check 711 * 712 * Return the number of blocks used by the group descriptor table 713 * (primary or backup) in this group. In the future there may be a 714 * different number of descriptor blocks in each group. 715 */ 716 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group) 717 { 718 unsigned long first_meta_bg = 719 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg); 720 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb); 721 722 if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) || 723 metagroup < first_meta_bg) 724 return ext4_bg_num_gdb_nometa(sb, group); 725 726 return ext4_bg_num_gdb_meta(sb,group); 727 728 } 729 730 /* 731 * This function returns the number of file system metadata clusters at 732 * the beginning of a block group, including the reserved gdt blocks. 733 */ 734 static unsigned ext4_num_base_meta_clusters(struct super_block *sb, 735 ext4_group_t block_group) 736 { 737 struct ext4_sb_info *sbi = EXT4_SB(sb); 738 unsigned num; 739 740 /* Check for superblock and gdt backups in this group */ 741 num = ext4_bg_has_super(sb, block_group); 742 743 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) || 744 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) * 745 sbi->s_desc_per_block) { 746 if (num) { 747 num += ext4_bg_num_gdb(sb, block_group); 748 num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks); 749 } 750 } else { /* For META_BG_BLOCK_GROUPS */ 751 num += ext4_bg_num_gdb(sb, block_group); 752 } 753 return EXT4_NUM_B2C(sbi, num); 754 } 755 /** 756 * ext4_inode_to_goal_block - return a hint for block allocation 757 * @inode: inode for block allocation 758 * 759 * Return the ideal location to start allocating blocks for a 760 * newly created inode. 761 */ 762 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode) 763 { 764 struct ext4_inode_info *ei = EXT4_I(inode); 765 ext4_group_t block_group; 766 ext4_grpblk_t colour; 767 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb)); 768 ext4_fsblk_t bg_start; 769 ext4_fsblk_t last_block; 770 771 block_group = ei->i_block_group; 772 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) { 773 /* 774 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME 775 * block groups per flexgroup, reserve the first block 776 * group for directories and special files. Regular 777 * files will start at the second block group. This 778 * tends to speed up directory access and improves 779 * fsck times. 780 */ 781 block_group &= ~(flex_size-1); 782 if (S_ISREG(inode->i_mode)) 783 block_group++; 784 } 785 bg_start = ext4_group_first_block_no(inode->i_sb, block_group); 786 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1; 787 788 /* 789 * If we are doing delayed allocation, we don't need take 790 * colour into account. 791 */ 792 if (test_opt(inode->i_sb, DELALLOC)) 793 return bg_start; 794 795 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block) 796 colour = (current->pid % 16) * 797 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16); 798 else 799 colour = (current->pid % 16) * ((last_block - bg_start) / 16); 800 return bg_start + colour; 801 } 802 803