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 EXT4_BLOCKS_PER_GROUP(sb) / 8); 179 return; 180 } 181 memset(bh->b_data, 0, sb->s_blocksize); 182 183 bit_max = ext4_num_base_meta_clusters(sb, block_group); 184 for (bit = 0; bit < bit_max; bit++) 185 ext4_set_bit(bit, bh->b_data); 186 187 start = ext4_group_first_block_no(sb, block_group); 188 189 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) 190 flex_bg = 1; 191 192 /* Set bits for block and inode bitmaps, and inode table */ 193 tmp = ext4_block_bitmap(sb, gdp); 194 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) 195 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); 196 197 tmp = ext4_inode_bitmap(sb, gdp); 198 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) 199 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); 200 201 tmp = ext4_inode_table(sb, gdp); 202 for (; tmp < ext4_inode_table(sb, gdp) + 203 sbi->s_itb_per_group; tmp++) { 204 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group)) 205 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); 206 } 207 208 /* 209 * Also if the number of blocks within the group is less than 210 * the blocksize * 8 ( which is the size of bitmap ), set rest 211 * of the block bitmap to 1 212 */ 213 ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group), 214 sb->s_blocksize * 8, bh->b_data); 215 ext4_block_bitmap_csum_set(sb, block_group, gdp, bh, 216 EXT4_BLOCKS_PER_GROUP(sb) / 8); 217 ext4_group_desc_csum_set(sb, block_group, gdp); 218 } 219 220 /* Return the number of free blocks in a block group. It is used when 221 * the block bitmap is uninitialized, so we can't just count the bits 222 * in the bitmap. */ 223 unsigned ext4_free_clusters_after_init(struct super_block *sb, 224 ext4_group_t block_group, 225 struct ext4_group_desc *gdp) 226 { 227 return num_clusters_in_group(sb, block_group) - 228 ext4_num_overhead_clusters(sb, block_group, gdp); 229 } 230 231 /* 232 * The free blocks are managed by bitmaps. A file system contains several 233 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap 234 * block for inodes, N blocks for the inode table and data blocks. 235 * 236 * The file system contains group descriptors which are located after the 237 * super block. Each descriptor contains the number of the bitmap block and 238 * the free blocks count in the block. The descriptors are loaded in memory 239 * when a file system is mounted (see ext4_fill_super). 240 */ 241 242 /** 243 * ext4_get_group_desc() -- load group descriptor from disk 244 * @sb: super block 245 * @block_group: given block group 246 * @bh: pointer to the buffer head to store the block 247 * group descriptor 248 */ 249 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb, 250 ext4_group_t block_group, 251 struct buffer_head **bh) 252 { 253 unsigned int group_desc; 254 unsigned int offset; 255 ext4_group_t ngroups = ext4_get_groups_count(sb); 256 struct ext4_group_desc *desc; 257 struct ext4_sb_info *sbi = EXT4_SB(sb); 258 259 if (block_group >= ngroups) { 260 ext4_error(sb, "block_group >= groups_count - block_group = %u," 261 " groups_count = %u", block_group, ngroups); 262 263 return NULL; 264 } 265 266 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb); 267 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1); 268 if (!sbi->s_group_desc[group_desc]) { 269 ext4_error(sb, "Group descriptor not loaded - " 270 "block_group = %u, group_desc = %u, desc = %u", 271 block_group, group_desc, offset); 272 return NULL; 273 } 274 275 desc = (struct ext4_group_desc *)( 276 (__u8 *)sbi->s_group_desc[group_desc]->b_data + 277 offset * EXT4_DESC_SIZE(sb)); 278 if (bh) 279 *bh = sbi->s_group_desc[group_desc]; 280 return desc; 281 } 282 283 /* 284 * Return the block number which was discovered to be invalid, or 0 if 285 * the block bitmap is valid. 286 */ 287 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, 288 struct ext4_group_desc *desc, 289 unsigned int block_group, 290 struct buffer_head *bh) 291 { 292 ext4_grpblk_t offset; 293 ext4_grpblk_t next_zero_bit; 294 ext4_fsblk_t blk; 295 ext4_fsblk_t group_first_block; 296 297 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) { 298 /* with FLEX_BG, the inode/block bitmaps and itable 299 * blocks may not be in the group at all 300 * so the bitmap validation will be skipped for those groups 301 * or it has to also read the block group where the bitmaps 302 * are located to verify they are set. 303 */ 304 return 0; 305 } 306 group_first_block = ext4_group_first_block_no(sb, block_group); 307 308 /* check whether block bitmap block number is set */ 309 blk = ext4_block_bitmap(sb, desc); 310 offset = blk - group_first_block; 311 if (!ext4_test_bit(offset, bh->b_data)) 312 /* bad block bitmap */ 313 return blk; 314 315 /* check whether the inode bitmap block number is set */ 316 blk = ext4_inode_bitmap(sb, desc); 317 offset = blk - group_first_block; 318 if (!ext4_test_bit(offset, bh->b_data)) 319 /* bad block bitmap */ 320 return blk; 321 322 /* check whether the inode table block number is set */ 323 blk = ext4_inode_table(sb, desc); 324 offset = blk - group_first_block; 325 next_zero_bit = ext4_find_next_zero_bit(bh->b_data, 326 offset + EXT4_SB(sb)->s_itb_per_group, 327 offset); 328 if (next_zero_bit < offset + EXT4_SB(sb)->s_itb_per_group) 329 /* bad bitmap for inode tables */ 330 return blk; 331 return 0; 332 } 333 334 void ext4_validate_block_bitmap(struct super_block *sb, 335 struct ext4_group_desc *desc, 336 unsigned int block_group, 337 struct buffer_head *bh) 338 { 339 ext4_fsblk_t blk; 340 341 if (buffer_verified(bh)) 342 return; 343 344 ext4_lock_group(sb, block_group); 345 blk = ext4_valid_block_bitmap(sb, desc, block_group, bh); 346 if (unlikely(blk != 0)) { 347 ext4_unlock_group(sb, block_group); 348 ext4_error(sb, "bg %u: block %llu: invalid block bitmap", 349 block_group, blk); 350 return; 351 } 352 if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group, 353 desc, bh, EXT4_BLOCKS_PER_GROUP(sb) / 8))) { 354 ext4_unlock_group(sb, block_group); 355 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group); 356 return; 357 } 358 set_buffer_verified(bh); 359 ext4_unlock_group(sb, block_group); 360 } 361 362 /** 363 * ext4_read_block_bitmap() 364 * @sb: super block 365 * @block_group: given block group 366 * 367 * Read the bitmap for a given block_group,and validate the 368 * bits for block/inode/inode tables are set in the bitmaps 369 * 370 * Return buffer_head on success or NULL in case of failure. 371 */ 372 struct buffer_head * 373 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group) 374 { 375 struct ext4_group_desc *desc; 376 struct buffer_head *bh; 377 ext4_fsblk_t bitmap_blk; 378 379 desc = ext4_get_group_desc(sb, block_group, NULL); 380 if (!desc) 381 return NULL; 382 bitmap_blk = ext4_block_bitmap(sb, desc); 383 bh = sb_getblk(sb, bitmap_blk); 384 if (unlikely(!bh)) { 385 ext4_error(sb, "Cannot get buffer for block bitmap - " 386 "block_group = %u, block_bitmap = %llu", 387 block_group, bitmap_blk); 388 return NULL; 389 } 390 391 if (bitmap_uptodate(bh)) 392 goto verify; 393 394 lock_buffer(bh); 395 if (bitmap_uptodate(bh)) { 396 unlock_buffer(bh); 397 goto verify; 398 } 399 ext4_lock_group(sb, block_group); 400 if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) { 401 ext4_init_block_bitmap(sb, bh, block_group, desc); 402 set_bitmap_uptodate(bh); 403 set_buffer_uptodate(bh); 404 ext4_unlock_group(sb, block_group); 405 unlock_buffer(bh); 406 return bh; 407 } 408 ext4_unlock_group(sb, block_group); 409 if (buffer_uptodate(bh)) { 410 /* 411 * if not uninit if bh is uptodate, 412 * bitmap is also uptodate 413 */ 414 set_bitmap_uptodate(bh); 415 unlock_buffer(bh); 416 goto verify; 417 } 418 /* 419 * submit the buffer_head for reading 420 */ 421 set_buffer_new(bh); 422 trace_ext4_read_block_bitmap_load(sb, block_group); 423 bh->b_end_io = ext4_end_bitmap_read; 424 get_bh(bh); 425 submit_bh(READ, bh); 426 return bh; 427 verify: 428 ext4_validate_block_bitmap(sb, desc, block_group, bh); 429 return bh; 430 } 431 432 /* Returns 0 on success, 1 on error */ 433 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group, 434 struct buffer_head *bh) 435 { 436 struct ext4_group_desc *desc; 437 438 if (!buffer_new(bh)) 439 return 0; 440 desc = ext4_get_group_desc(sb, block_group, NULL); 441 if (!desc) 442 return 1; 443 wait_on_buffer(bh); 444 if (!buffer_uptodate(bh)) { 445 ext4_error(sb, "Cannot read block bitmap - " 446 "block_group = %u, block_bitmap = %llu", 447 block_group, (unsigned long long) bh->b_blocknr); 448 return 1; 449 } 450 clear_buffer_new(bh); 451 /* Panic or remount fs read-only if block bitmap is invalid */ 452 ext4_validate_block_bitmap(sb, desc, block_group, bh); 453 return 0; 454 } 455 456 struct buffer_head * 457 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group) 458 { 459 struct buffer_head *bh; 460 461 bh = ext4_read_block_bitmap_nowait(sb, block_group); 462 if (ext4_wait_block_bitmap(sb, block_group, bh)) { 463 put_bh(bh); 464 return NULL; 465 } 466 return bh; 467 } 468 469 /** 470 * ext4_has_free_clusters() 471 * @sbi: in-core super block structure. 472 * @nclusters: number of needed blocks 473 * @flags: flags from ext4_mb_new_blocks() 474 * 475 * Check if filesystem has nclusters free & available for allocation. 476 * On success return 1, return 0 on failure. 477 */ 478 static int ext4_has_free_clusters(struct ext4_sb_info *sbi, 479 s64 nclusters, unsigned int flags) 480 { 481 s64 free_clusters, dirty_clusters, root_clusters; 482 struct percpu_counter *fcc = &sbi->s_freeclusters_counter; 483 struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter; 484 485 free_clusters = percpu_counter_read_positive(fcc); 486 dirty_clusters = percpu_counter_read_positive(dcc); 487 root_clusters = EXT4_B2C(sbi, ext4_r_blocks_count(sbi->s_es)); 488 489 if (free_clusters - (nclusters + root_clusters + dirty_clusters) < 490 EXT4_FREECLUSTERS_WATERMARK) { 491 free_clusters = EXT4_C2B(sbi, percpu_counter_sum_positive(fcc)); 492 dirty_clusters = percpu_counter_sum_positive(dcc); 493 } 494 /* Check whether we have space after accounting for current 495 * dirty clusters & root reserved clusters. 496 */ 497 if (free_clusters >= ((root_clusters + nclusters) + dirty_clusters)) 498 return 1; 499 500 /* Hm, nope. Are (enough) root reserved clusters available? */ 501 if (uid_eq(sbi->s_resuid, current_fsuid()) || 502 (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) || 503 capable(CAP_SYS_RESOURCE) || 504 (flags & EXT4_MB_USE_ROOT_BLOCKS)) { 505 506 if (free_clusters >= (nclusters + dirty_clusters)) 507 return 1; 508 } 509 510 return 0; 511 } 512 513 int ext4_claim_free_clusters(struct ext4_sb_info *sbi, 514 s64 nclusters, unsigned int flags) 515 { 516 if (ext4_has_free_clusters(sbi, nclusters, flags)) { 517 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters); 518 return 0; 519 } else 520 return -ENOSPC; 521 } 522 523 /** 524 * ext4_should_retry_alloc() 525 * @sb: super block 526 * @retries number of attemps has been made 527 * 528 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if 529 * it is profitable to retry the operation, this function will wait 530 * for the current or committing transaction to complete, and then 531 * return TRUE. 532 * 533 * if the total number of retries exceed three times, return FALSE. 534 */ 535 int ext4_should_retry_alloc(struct super_block *sb, int *retries) 536 { 537 if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) || 538 (*retries)++ > 3 || 539 !EXT4_SB(sb)->s_journal) 540 return 0; 541 542 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id); 543 544 return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal); 545 } 546 547 /* 548 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks 549 * 550 * @handle: handle to this transaction 551 * @inode: file inode 552 * @goal: given target block(filesystem wide) 553 * @count: pointer to total number of clusters needed 554 * @errp: error code 555 * 556 * Return 1st allocated block number on success, *count stores total account 557 * error stores in errp pointer 558 */ 559 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode, 560 ext4_fsblk_t goal, unsigned int flags, 561 unsigned long *count, int *errp) 562 { 563 struct ext4_allocation_request ar; 564 ext4_fsblk_t ret; 565 566 memset(&ar, 0, sizeof(ar)); 567 /* Fill with neighbour allocated blocks */ 568 ar.inode = inode; 569 ar.goal = goal; 570 ar.len = count ? *count : 1; 571 ar.flags = flags; 572 573 ret = ext4_mb_new_blocks(handle, &ar, errp); 574 if (count) 575 *count = ar.len; 576 /* 577 * Account for the allocated meta blocks. We will never 578 * fail EDQUOT for metdata, but we do account for it. 579 */ 580 if (!(*errp) && 581 ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) { 582 spin_lock(&EXT4_I(inode)->i_block_reservation_lock); 583 EXT4_I(inode)->i_allocated_meta_blocks += ar.len; 584 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); 585 dquot_alloc_block_nofail(inode, 586 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len)); 587 } 588 return ret; 589 } 590 591 /** 592 * ext4_count_free_clusters() -- count filesystem free clusters 593 * @sb: superblock 594 * 595 * Adds up the number of free clusters from each block group. 596 */ 597 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb) 598 { 599 ext4_fsblk_t desc_count; 600 struct ext4_group_desc *gdp; 601 ext4_group_t i; 602 ext4_group_t ngroups = ext4_get_groups_count(sb); 603 #ifdef EXT4FS_DEBUG 604 struct ext4_super_block *es; 605 ext4_fsblk_t bitmap_count; 606 unsigned int x; 607 struct buffer_head *bitmap_bh = NULL; 608 609 es = EXT4_SB(sb)->s_es; 610 desc_count = 0; 611 bitmap_count = 0; 612 gdp = NULL; 613 614 for (i = 0; i < ngroups; i++) { 615 gdp = ext4_get_group_desc(sb, i, NULL); 616 if (!gdp) 617 continue; 618 desc_count += ext4_free_group_clusters(sb, gdp); 619 brelse(bitmap_bh); 620 bitmap_bh = ext4_read_block_bitmap(sb, i); 621 if (bitmap_bh == NULL) 622 continue; 623 624 x = ext4_count_free(bitmap_bh->b_data, 625 EXT4_BLOCKS_PER_GROUP(sb) / 8); 626 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n", 627 i, ext4_free_group_clusters(sb, gdp), x); 628 bitmap_count += x; 629 } 630 brelse(bitmap_bh); 631 printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu" 632 ", computed = %llu, %llu\n", 633 EXT4_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)), 634 desc_count, bitmap_count); 635 return bitmap_count; 636 #else 637 desc_count = 0; 638 for (i = 0; i < ngroups; i++) { 639 gdp = ext4_get_group_desc(sb, i, NULL); 640 if (!gdp) 641 continue; 642 desc_count += ext4_free_group_clusters(sb, gdp); 643 } 644 645 return desc_count; 646 #endif 647 } 648 649 static inline int test_root(ext4_group_t a, int b) 650 { 651 int num = b; 652 653 while (a > num) 654 num *= b; 655 return num == a; 656 } 657 658 static int ext4_group_sparse(ext4_group_t group) 659 { 660 if (group <= 1) 661 return 1; 662 if (!(group & 1)) 663 return 0; 664 return (test_root(group, 7) || test_root(group, 5) || 665 test_root(group, 3)); 666 } 667 668 /** 669 * ext4_bg_has_super - number of blocks used by the superblock in group 670 * @sb: superblock for filesystem 671 * @group: group number to check 672 * 673 * Return the number of blocks used by the superblock (primary or backup) 674 * in this group. Currently this will be only 0 or 1. 675 */ 676 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group) 677 { 678 if (EXT4_HAS_RO_COMPAT_FEATURE(sb, 679 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) && 680 !ext4_group_sparse(group)) 681 return 0; 682 return 1; 683 } 684 685 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb, 686 ext4_group_t group) 687 { 688 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb); 689 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb); 690 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1; 691 692 if (group == first || group == first + 1 || group == last) 693 return 1; 694 return 0; 695 } 696 697 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb, 698 ext4_group_t group) 699 { 700 if (!ext4_bg_has_super(sb, group)) 701 return 0; 702 703 if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG)) 704 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg); 705 else 706 return EXT4_SB(sb)->s_gdb_count; 707 } 708 709 /** 710 * ext4_bg_num_gdb - number of blocks used by the group table in group 711 * @sb: superblock for filesystem 712 * @group: group number to check 713 * 714 * Return the number of blocks used by the group descriptor table 715 * (primary or backup) in this group. In the future there may be a 716 * different number of descriptor blocks in each group. 717 */ 718 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group) 719 { 720 unsigned long first_meta_bg = 721 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg); 722 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb); 723 724 if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) || 725 metagroup < first_meta_bg) 726 return ext4_bg_num_gdb_nometa(sb, group); 727 728 return ext4_bg_num_gdb_meta(sb,group); 729 730 } 731 732 /* 733 * This function returns the number of file system metadata clusters at 734 * the beginning of a block group, including the reserved gdt blocks. 735 */ 736 static unsigned ext4_num_base_meta_clusters(struct super_block *sb, 737 ext4_group_t block_group) 738 { 739 struct ext4_sb_info *sbi = EXT4_SB(sb); 740 unsigned num; 741 742 /* Check for superblock and gdt backups in this group */ 743 num = ext4_bg_has_super(sb, block_group); 744 745 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) || 746 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) * 747 sbi->s_desc_per_block) { 748 if (num) { 749 num += ext4_bg_num_gdb(sb, block_group); 750 num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks); 751 } 752 } else { /* For META_BG_BLOCK_GROUPS */ 753 num += ext4_bg_num_gdb(sb, block_group); 754 } 755 return EXT4_NUM_B2C(sbi, num); 756 } 757 /** 758 * ext4_inode_to_goal_block - return a hint for block allocation 759 * @inode: inode for block allocation 760 * 761 * Return the ideal location to start allocating blocks for a 762 * newly created inode. 763 */ 764 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode) 765 { 766 struct ext4_inode_info *ei = EXT4_I(inode); 767 ext4_group_t block_group; 768 ext4_grpblk_t colour; 769 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb)); 770 ext4_fsblk_t bg_start; 771 ext4_fsblk_t last_block; 772 773 block_group = ei->i_block_group; 774 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) { 775 /* 776 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME 777 * block groups per flexgroup, reserve the first block 778 * group for directories and special files. Regular 779 * files will start at the second block group. This 780 * tends to speed up directory access and improves 781 * fsck times. 782 */ 783 block_group &= ~(flex_size-1); 784 if (S_ISREG(inode->i_mode)) 785 block_group++; 786 } 787 bg_start = ext4_group_first_block_no(inode->i_sb, block_group); 788 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1; 789 790 /* 791 * If we are doing delayed allocation, we don't need take 792 * colour into account. 793 */ 794 if (test_opt(inode->i_sb, DELALLOC)) 795 return bg_start; 796 797 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block) 798 colour = (current->pid % 16) * 799 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16); 800 else 801 colour = (current->pid % 16) * ((last_block - bg_start) / 16); 802 return bg_start + colour; 803 } 804 805