1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/fs/ext4/balloc.c 4 * 5 * Copyright (C) 1992, 1993, 1994, 1995 6 * Remy Card (card@masi.ibp.fr) 7 * Laboratoire MASI - Institut Blaise Pascal 8 * Universite Pierre et Marie Curie (Paris VI) 9 * 10 * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 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/time.h> 16 #include <linux/capability.h> 17 #include <linux/fs.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 block group number for a given block number 34 */ 35 ext4_group_t ext4_get_group_number(struct super_block *sb, 36 ext4_fsblk_t block) 37 { 38 ext4_group_t group; 39 40 if (test_opt2(sb, STD_GROUP_SIZE)) 41 group = (block - 42 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >> 43 (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3); 44 else 45 ext4_get_group_no_and_offset(sb, block, &group, NULL); 46 return group; 47 } 48 49 /* 50 * Calculate the block group number and offset into the block/cluster 51 * allocation bitmap, given a block number 52 */ 53 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr, 54 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp) 55 { 56 struct ext4_super_block *es = EXT4_SB(sb)->s_es; 57 ext4_grpblk_t offset; 58 59 blocknr = blocknr - le32_to_cpu(es->s_first_data_block); 60 offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >> 61 EXT4_SB(sb)->s_cluster_bits; 62 if (offsetp) 63 *offsetp = offset; 64 if (blockgrpp) 65 *blockgrpp = blocknr; 66 67 } 68 69 /* 70 * Check whether the 'block' lives within the 'block_group'. Returns 1 if so 71 * and 0 otherwise. 72 */ 73 static inline int ext4_block_in_group(struct super_block *sb, 74 ext4_fsblk_t block, 75 ext4_group_t block_group) 76 { 77 ext4_group_t actual_group; 78 79 actual_group = ext4_get_group_number(sb, block); 80 return (actual_group == block_group) ? 1 : 0; 81 } 82 83 /* Return the number of clusters used for file system metadata; this 84 * represents the overhead needed by the file system. 85 */ 86 static unsigned ext4_num_overhead_clusters(struct super_block *sb, 87 ext4_group_t block_group, 88 struct ext4_group_desc *gdp) 89 { 90 unsigned num_clusters; 91 int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c; 92 ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group); 93 ext4_fsblk_t itbl_blk; 94 struct ext4_sb_info *sbi = EXT4_SB(sb); 95 96 /* This is the number of clusters used by the superblock, 97 * block group descriptors, and reserved block group 98 * descriptor blocks */ 99 num_clusters = ext4_num_base_meta_clusters(sb, block_group); 100 101 /* 102 * For the allocation bitmaps and inode table, we first need 103 * to check to see if the block is in the block group. If it 104 * is, then check to see if the cluster is already accounted 105 * for in the clusters used for the base metadata cluster, or 106 * if we can increment the base metadata cluster to include 107 * that block. Otherwise, we will have to track the cluster 108 * used for the allocation bitmap or inode table explicitly. 109 * Normally all of these blocks are contiguous, so the special 110 * case handling shouldn't be necessary except for *very* 111 * unusual file system layouts. 112 */ 113 if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) { 114 block_cluster = EXT4_B2C(sbi, 115 ext4_block_bitmap(sb, gdp) - start); 116 if (block_cluster < num_clusters) 117 block_cluster = -1; 118 else if (block_cluster == num_clusters) { 119 num_clusters++; 120 block_cluster = -1; 121 } 122 } 123 124 if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) { 125 inode_cluster = EXT4_B2C(sbi, 126 ext4_inode_bitmap(sb, gdp) - start); 127 if (inode_cluster < num_clusters) 128 inode_cluster = -1; 129 else if (inode_cluster == num_clusters) { 130 num_clusters++; 131 inode_cluster = -1; 132 } 133 } 134 135 itbl_blk = ext4_inode_table(sb, gdp); 136 for (i = 0; i < sbi->s_itb_per_group; i++) { 137 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) { 138 c = EXT4_B2C(sbi, itbl_blk + i - start); 139 if ((c < num_clusters) || (c == inode_cluster) || 140 (c == block_cluster) || (c == itbl_cluster)) 141 continue; 142 if (c == num_clusters) { 143 num_clusters++; 144 continue; 145 } 146 num_clusters++; 147 itbl_cluster = c; 148 } 149 } 150 151 if (block_cluster != -1) 152 num_clusters++; 153 if (inode_cluster != -1) 154 num_clusters++; 155 156 return num_clusters; 157 } 158 159 static unsigned int num_clusters_in_group(struct super_block *sb, 160 ext4_group_t block_group) 161 { 162 unsigned int blocks; 163 164 if (block_group == ext4_get_groups_count(sb) - 1) { 165 /* 166 * Even though mke2fs always initializes the first and 167 * last group, just in case some other tool was used, 168 * we need to make sure we calculate the right free 169 * blocks. 170 */ 171 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) - 172 ext4_group_first_block_no(sb, block_group); 173 } else 174 blocks = EXT4_BLOCKS_PER_GROUP(sb); 175 return EXT4_NUM_B2C(EXT4_SB(sb), blocks); 176 } 177 178 /* Initializes an uninitialized block bitmap */ 179 static int ext4_init_block_bitmap(struct super_block *sb, 180 struct buffer_head *bh, 181 ext4_group_t block_group, 182 struct ext4_group_desc *gdp) 183 { 184 unsigned int bit, bit_max; 185 struct ext4_sb_info *sbi = EXT4_SB(sb); 186 ext4_fsblk_t start, tmp; 187 188 ASSERT(buffer_locked(bh)); 189 190 /* If checksum is bad mark all blocks used to prevent allocation 191 * essentially implementing a per-group read-only flag. */ 192 if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) { 193 ext4_mark_group_bitmap_corrupted(sb, block_group, 194 EXT4_GROUP_INFO_BBITMAP_CORRUPT | 195 EXT4_GROUP_INFO_IBITMAP_CORRUPT); 196 return -EFSBADCRC; 197 } 198 memset(bh->b_data, 0, sb->s_blocksize); 199 200 bit_max = ext4_num_base_meta_clusters(sb, block_group); 201 if ((bit_max >> 3) >= bh->b_size) 202 return -EFSCORRUPTED; 203 204 for (bit = 0; bit < bit_max; bit++) 205 ext4_set_bit(bit, bh->b_data); 206 207 start = ext4_group_first_block_no(sb, block_group); 208 209 /* Set bits for block and inode bitmaps, and inode table */ 210 tmp = ext4_block_bitmap(sb, gdp); 211 if (ext4_block_in_group(sb, tmp, block_group)) 212 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); 213 214 tmp = ext4_inode_bitmap(sb, gdp); 215 if (ext4_block_in_group(sb, tmp, block_group)) 216 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); 217 218 tmp = ext4_inode_table(sb, gdp); 219 for (; tmp < ext4_inode_table(sb, gdp) + 220 sbi->s_itb_per_group; tmp++) { 221 if (ext4_block_in_group(sb, tmp, block_group)) 222 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data); 223 } 224 225 /* 226 * Also if the number of blocks within the group is less than 227 * the blocksize * 8 ( which is the size of bitmap ), set rest 228 * of the block bitmap to 1 229 */ 230 ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group), 231 sb->s_blocksize * 8, bh->b_data); 232 return 0; 233 } 234 235 /* Return the number of free blocks in a block group. It is used when 236 * the block bitmap is uninitialized, so we can't just count the bits 237 * in the bitmap. */ 238 unsigned ext4_free_clusters_after_init(struct super_block *sb, 239 ext4_group_t block_group, 240 struct ext4_group_desc *gdp) 241 { 242 return num_clusters_in_group(sb, block_group) - 243 ext4_num_overhead_clusters(sb, block_group, gdp); 244 } 245 246 /* 247 * The free blocks are managed by bitmaps. A file system contains several 248 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap 249 * block for inodes, N blocks for the inode table and data blocks. 250 * 251 * The file system contains group descriptors which are located after the 252 * super block. Each descriptor contains the number of the bitmap block and 253 * the free blocks count in the block. The descriptors are loaded in memory 254 * when a file system is mounted (see ext4_fill_super). 255 */ 256 257 /** 258 * ext4_get_group_desc() -- load group descriptor from disk 259 * @sb: super block 260 * @block_group: given block group 261 * @bh: pointer to the buffer head to store the block 262 * group descriptor 263 */ 264 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb, 265 ext4_group_t block_group, 266 struct buffer_head **bh) 267 { 268 unsigned int group_desc; 269 unsigned int offset; 270 ext4_group_t ngroups = ext4_get_groups_count(sb); 271 struct ext4_group_desc *desc; 272 struct ext4_sb_info *sbi = EXT4_SB(sb); 273 struct buffer_head *bh_p; 274 275 if (block_group >= ngroups) { 276 ext4_error(sb, "block_group >= groups_count - block_group = %u," 277 " groups_count = %u", block_group, ngroups); 278 279 return NULL; 280 } 281 282 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb); 283 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1); 284 bh_p = sbi_array_rcu_deref(sbi, s_group_desc, group_desc); 285 /* 286 * sbi_array_rcu_deref returns with rcu unlocked, this is ok since 287 * the pointer being dereferenced won't be dereferenced again. By 288 * looking at the usage in add_new_gdb() the value isn't modified, 289 * just the pointer, and so it remains valid. 290 */ 291 if (!bh_p) { 292 ext4_error(sb, "Group descriptor not loaded - " 293 "block_group = %u, group_desc = %u, desc = %u", 294 block_group, group_desc, offset); 295 return NULL; 296 } 297 298 desc = (struct ext4_group_desc *)( 299 (__u8 *)bh_p->b_data + 300 offset * EXT4_DESC_SIZE(sb)); 301 if (bh) 302 *bh = bh_p; 303 return desc; 304 } 305 306 /* 307 * Return the block number which was discovered to be invalid, or 0 if 308 * the block bitmap is valid. 309 */ 310 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb, 311 struct ext4_group_desc *desc, 312 ext4_group_t block_group, 313 struct buffer_head *bh) 314 { 315 struct ext4_sb_info *sbi = EXT4_SB(sb); 316 ext4_grpblk_t offset; 317 ext4_grpblk_t next_zero_bit; 318 ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb); 319 ext4_fsblk_t blk; 320 ext4_fsblk_t group_first_block; 321 322 if (ext4_has_feature_flex_bg(sb)) { 323 /* with FLEX_BG, the inode/block bitmaps and itable 324 * blocks may not be in the group at all 325 * so the bitmap validation will be skipped for those groups 326 * or it has to also read the block group where the bitmaps 327 * are located to verify they are set. 328 */ 329 return 0; 330 } 331 group_first_block = ext4_group_first_block_no(sb, block_group); 332 333 /* check whether block bitmap block number is set */ 334 blk = ext4_block_bitmap(sb, desc); 335 offset = blk - group_first_block; 336 if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || 337 !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) 338 /* bad block bitmap */ 339 return blk; 340 341 /* check whether the inode bitmap block number is set */ 342 blk = ext4_inode_bitmap(sb, desc); 343 offset = blk - group_first_block; 344 if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || 345 !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data)) 346 /* bad block bitmap */ 347 return blk; 348 349 /* check whether the inode table block number is set */ 350 blk = ext4_inode_table(sb, desc); 351 offset = blk - group_first_block; 352 if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit || 353 EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= max_bit) 354 return blk; 355 next_zero_bit = ext4_find_next_zero_bit(bh->b_data, 356 EXT4_B2C(sbi, offset + sbi->s_itb_per_group), 357 EXT4_B2C(sbi, offset)); 358 if (next_zero_bit < 359 EXT4_B2C(sbi, offset + sbi->s_itb_per_group)) 360 /* bad bitmap for inode tables */ 361 return blk; 362 return 0; 363 } 364 365 static int ext4_validate_block_bitmap(struct super_block *sb, 366 struct ext4_group_desc *desc, 367 ext4_group_t block_group, 368 struct buffer_head *bh) 369 { 370 ext4_fsblk_t blk; 371 struct ext4_group_info *grp; 372 373 if (EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY) 374 return 0; 375 376 grp = ext4_get_group_info(sb, block_group); 377 378 if (buffer_verified(bh)) 379 return 0; 380 if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp)) 381 return -EFSCORRUPTED; 382 383 ext4_lock_group(sb, block_group); 384 if (buffer_verified(bh)) 385 goto verified; 386 if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group, 387 desc, bh) || 388 ext4_simulate_fail(sb, EXT4_SIM_BBITMAP_CRC))) { 389 ext4_unlock_group(sb, block_group); 390 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group); 391 ext4_mark_group_bitmap_corrupted(sb, block_group, 392 EXT4_GROUP_INFO_BBITMAP_CORRUPT); 393 return -EFSBADCRC; 394 } 395 blk = ext4_valid_block_bitmap(sb, desc, block_group, bh); 396 if (unlikely(blk != 0)) { 397 ext4_unlock_group(sb, block_group); 398 ext4_error(sb, "bg %u: block %llu: invalid block bitmap", 399 block_group, blk); 400 ext4_mark_group_bitmap_corrupted(sb, block_group, 401 EXT4_GROUP_INFO_BBITMAP_CORRUPT); 402 return -EFSCORRUPTED; 403 } 404 set_buffer_verified(bh); 405 verified: 406 ext4_unlock_group(sb, block_group); 407 return 0; 408 } 409 410 /** 411 * ext4_read_block_bitmap_nowait() 412 * @sb: super block 413 * @block_group: given block group 414 * 415 * Read the bitmap for a given block_group,and validate the 416 * bits for block/inode/inode tables are set in the bitmaps 417 * 418 * Return buffer_head on success or an ERR_PTR in case of failure. 419 */ 420 struct buffer_head * 421 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group, 422 bool ignore_locked) 423 { 424 struct ext4_group_desc *desc; 425 struct ext4_sb_info *sbi = EXT4_SB(sb); 426 struct buffer_head *bh; 427 ext4_fsblk_t bitmap_blk; 428 int err; 429 430 desc = ext4_get_group_desc(sb, block_group, NULL); 431 if (!desc) 432 return ERR_PTR(-EFSCORRUPTED); 433 bitmap_blk = ext4_block_bitmap(sb, desc); 434 if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) || 435 (bitmap_blk >= ext4_blocks_count(sbi->s_es))) { 436 ext4_error(sb, "Invalid block bitmap block %llu in " 437 "block_group %u", bitmap_blk, block_group); 438 ext4_mark_group_bitmap_corrupted(sb, block_group, 439 EXT4_GROUP_INFO_BBITMAP_CORRUPT); 440 return ERR_PTR(-EFSCORRUPTED); 441 } 442 bh = sb_getblk(sb, bitmap_blk); 443 if (unlikely(!bh)) { 444 ext4_warning(sb, "Cannot get buffer for block bitmap - " 445 "block_group = %u, block_bitmap = %llu", 446 block_group, bitmap_blk); 447 return ERR_PTR(-ENOMEM); 448 } 449 450 if (ignore_locked && buffer_locked(bh)) { 451 /* buffer under IO already, return if called for prefetching */ 452 put_bh(bh); 453 return NULL; 454 } 455 456 if (bitmap_uptodate(bh)) 457 goto verify; 458 459 lock_buffer(bh); 460 if (bitmap_uptodate(bh)) { 461 unlock_buffer(bh); 462 goto verify; 463 } 464 ext4_lock_group(sb, block_group); 465 if (ext4_has_group_desc_csum(sb) && 466 (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) { 467 if (block_group == 0) { 468 ext4_unlock_group(sb, block_group); 469 unlock_buffer(bh); 470 ext4_error(sb, "Block bitmap for bg 0 marked " 471 "uninitialized"); 472 err = -EFSCORRUPTED; 473 goto out; 474 } 475 err = ext4_init_block_bitmap(sb, bh, block_group, desc); 476 set_bitmap_uptodate(bh); 477 set_buffer_uptodate(bh); 478 set_buffer_verified(bh); 479 ext4_unlock_group(sb, block_group); 480 unlock_buffer(bh); 481 if (err) { 482 ext4_error(sb, "Failed to init block bitmap for group " 483 "%u: %d", block_group, err); 484 goto out; 485 } 486 goto verify; 487 } 488 ext4_unlock_group(sb, block_group); 489 if (buffer_uptodate(bh)) { 490 /* 491 * if not uninit if bh is uptodate, 492 * bitmap is also uptodate 493 */ 494 set_bitmap_uptodate(bh); 495 unlock_buffer(bh); 496 goto verify; 497 } 498 /* 499 * submit the buffer_head for reading 500 */ 501 set_buffer_new(bh); 502 trace_ext4_read_block_bitmap_load(sb, block_group, ignore_locked); 503 ext4_read_bh_nowait(bh, REQ_META | REQ_PRIO | 504 (ignore_locked ? REQ_RAHEAD : 0), 505 ext4_end_bitmap_read); 506 return bh; 507 verify: 508 err = ext4_validate_block_bitmap(sb, desc, block_group, bh); 509 if (err) 510 goto out; 511 return bh; 512 out: 513 put_bh(bh); 514 return ERR_PTR(err); 515 } 516 517 /* Returns 0 on success, -errno on error */ 518 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group, 519 struct buffer_head *bh) 520 { 521 struct ext4_group_desc *desc; 522 523 if (!buffer_new(bh)) 524 return 0; 525 desc = ext4_get_group_desc(sb, block_group, NULL); 526 if (!desc) 527 return -EFSCORRUPTED; 528 wait_on_buffer(bh); 529 ext4_simulate_fail_bh(sb, bh, EXT4_SIM_BBITMAP_EIO); 530 if (!buffer_uptodate(bh)) { 531 ext4_error_err(sb, EIO, "Cannot read block bitmap - " 532 "block_group = %u, block_bitmap = %llu", 533 block_group, (unsigned long long) bh->b_blocknr); 534 ext4_mark_group_bitmap_corrupted(sb, block_group, 535 EXT4_GROUP_INFO_BBITMAP_CORRUPT); 536 return -EIO; 537 } 538 clear_buffer_new(bh); 539 /* Panic or remount fs read-only if block bitmap is invalid */ 540 return ext4_validate_block_bitmap(sb, desc, block_group, bh); 541 } 542 543 struct buffer_head * 544 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group) 545 { 546 struct buffer_head *bh; 547 int err; 548 549 bh = ext4_read_block_bitmap_nowait(sb, block_group, false); 550 if (IS_ERR(bh)) 551 return bh; 552 err = ext4_wait_block_bitmap(sb, block_group, bh); 553 if (err) { 554 put_bh(bh); 555 return ERR_PTR(err); 556 } 557 return bh; 558 } 559 560 /** 561 * ext4_has_free_clusters() 562 * @sbi: in-core super block structure. 563 * @nclusters: number of needed blocks 564 * @flags: flags from ext4_mb_new_blocks() 565 * 566 * Check if filesystem has nclusters free & available for allocation. 567 * On success return 1, return 0 on failure. 568 */ 569 static int ext4_has_free_clusters(struct ext4_sb_info *sbi, 570 s64 nclusters, unsigned int flags) 571 { 572 s64 free_clusters, dirty_clusters, rsv, resv_clusters; 573 struct percpu_counter *fcc = &sbi->s_freeclusters_counter; 574 struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter; 575 576 free_clusters = percpu_counter_read_positive(fcc); 577 dirty_clusters = percpu_counter_read_positive(dcc); 578 resv_clusters = atomic64_read(&sbi->s_resv_clusters); 579 580 /* 581 * r_blocks_count should always be multiple of the cluster ratio so 582 * we are safe to do a plane bit shift only. 583 */ 584 rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) + 585 resv_clusters; 586 587 if (free_clusters - (nclusters + rsv + dirty_clusters) < 588 EXT4_FREECLUSTERS_WATERMARK) { 589 free_clusters = percpu_counter_sum_positive(fcc); 590 dirty_clusters = percpu_counter_sum_positive(dcc); 591 } 592 /* Check whether we have space after accounting for current 593 * dirty clusters & root reserved clusters. 594 */ 595 if (free_clusters >= (rsv + nclusters + dirty_clusters)) 596 return 1; 597 598 /* Hm, nope. Are (enough) root reserved clusters available? */ 599 if (uid_eq(sbi->s_resuid, current_fsuid()) || 600 (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) || 601 capable(CAP_SYS_RESOURCE) || 602 (flags & EXT4_MB_USE_ROOT_BLOCKS)) { 603 604 if (free_clusters >= (nclusters + dirty_clusters + 605 resv_clusters)) 606 return 1; 607 } 608 /* No free blocks. Let's see if we can dip into reserved pool */ 609 if (flags & EXT4_MB_USE_RESERVED) { 610 if (free_clusters >= (nclusters + dirty_clusters)) 611 return 1; 612 } 613 614 return 0; 615 } 616 617 int ext4_claim_free_clusters(struct ext4_sb_info *sbi, 618 s64 nclusters, unsigned int flags) 619 { 620 if (ext4_has_free_clusters(sbi, nclusters, flags)) { 621 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters); 622 return 0; 623 } else 624 return -ENOSPC; 625 } 626 627 /** 628 * ext4_should_retry_alloc() - check if a block allocation should be retried 629 * @sb: super block 630 * @retries: number of attemps has been made 631 * 632 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if 633 * it is profitable to retry the operation, this function will wait 634 * for the current or committing transaction to complete, and then 635 * return TRUE. We will only retry once. 636 */ 637 int ext4_should_retry_alloc(struct super_block *sb, int *retries) 638 { 639 if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) || 640 (*retries)++ > 1 || 641 !EXT4_SB(sb)->s_journal) 642 return 0; 643 644 smp_mb(); 645 if (EXT4_SB(sb)->s_mb_free_pending == 0) 646 return 0; 647 648 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id); 649 jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal); 650 return 1; 651 } 652 653 /* 654 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks 655 * 656 * @handle: handle to this transaction 657 * @inode: file inode 658 * @goal: given target block(filesystem wide) 659 * @count: pointer to total number of clusters needed 660 * @errp: error code 661 * 662 * Return 1st allocated block number on success, *count stores total account 663 * error stores in errp pointer 664 */ 665 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode, 666 ext4_fsblk_t goal, unsigned int flags, 667 unsigned long *count, int *errp) 668 { 669 struct ext4_allocation_request ar; 670 ext4_fsblk_t ret; 671 672 memset(&ar, 0, sizeof(ar)); 673 /* Fill with neighbour allocated blocks */ 674 ar.inode = inode; 675 ar.goal = goal; 676 ar.len = count ? *count : 1; 677 ar.flags = flags; 678 679 ret = ext4_mb_new_blocks(handle, &ar, errp); 680 if (count) 681 *count = ar.len; 682 /* 683 * Account for the allocated meta blocks. We will never 684 * fail EDQUOT for metdata, but we do account for it. 685 */ 686 if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) { 687 dquot_alloc_block_nofail(inode, 688 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len)); 689 } 690 return ret; 691 } 692 693 /** 694 * ext4_count_free_clusters() -- count filesystem free clusters 695 * @sb: superblock 696 * 697 * Adds up the number of free clusters from each block group. 698 */ 699 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb) 700 { 701 ext4_fsblk_t desc_count; 702 struct ext4_group_desc *gdp; 703 ext4_group_t i; 704 ext4_group_t ngroups = ext4_get_groups_count(sb); 705 struct ext4_group_info *grp; 706 #ifdef EXT4FS_DEBUG 707 struct ext4_super_block *es; 708 ext4_fsblk_t bitmap_count; 709 unsigned int x; 710 struct buffer_head *bitmap_bh = NULL; 711 712 es = EXT4_SB(sb)->s_es; 713 desc_count = 0; 714 bitmap_count = 0; 715 gdp = NULL; 716 717 for (i = 0; i < ngroups; i++) { 718 gdp = ext4_get_group_desc(sb, i, NULL); 719 if (!gdp) 720 continue; 721 grp = NULL; 722 if (EXT4_SB(sb)->s_group_info) 723 grp = ext4_get_group_info(sb, i); 724 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp)) 725 desc_count += ext4_free_group_clusters(sb, gdp); 726 brelse(bitmap_bh); 727 bitmap_bh = ext4_read_block_bitmap(sb, i); 728 if (IS_ERR(bitmap_bh)) { 729 bitmap_bh = NULL; 730 continue; 731 } 732 733 x = ext4_count_free(bitmap_bh->b_data, 734 EXT4_CLUSTERS_PER_GROUP(sb) / 8); 735 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n", 736 i, ext4_free_group_clusters(sb, gdp), x); 737 bitmap_count += x; 738 } 739 brelse(bitmap_bh); 740 printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu" 741 ", computed = %llu, %llu\n", 742 EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)), 743 desc_count, bitmap_count); 744 return bitmap_count; 745 #else 746 desc_count = 0; 747 for (i = 0; i < ngroups; i++) { 748 gdp = ext4_get_group_desc(sb, i, NULL); 749 if (!gdp) 750 continue; 751 grp = NULL; 752 if (EXT4_SB(sb)->s_group_info) 753 grp = ext4_get_group_info(sb, i); 754 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp)) 755 desc_count += ext4_free_group_clusters(sb, gdp); 756 } 757 758 return desc_count; 759 #endif 760 } 761 762 static inline int test_root(ext4_group_t a, int b) 763 { 764 while (1) { 765 if (a < b) 766 return 0; 767 if (a == b) 768 return 1; 769 if ((a % b) != 0) 770 return 0; 771 a = a / b; 772 } 773 } 774 775 /** 776 * ext4_bg_has_super - number of blocks used by the superblock in group 777 * @sb: superblock for filesystem 778 * @group: group number to check 779 * 780 * Return the number of blocks used by the superblock (primary or backup) 781 * in this group. Currently this will be only 0 or 1. 782 */ 783 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group) 784 { 785 struct ext4_super_block *es = EXT4_SB(sb)->s_es; 786 787 if (group == 0) 788 return 1; 789 if (ext4_has_feature_sparse_super2(sb)) { 790 if (group == le32_to_cpu(es->s_backup_bgs[0]) || 791 group == le32_to_cpu(es->s_backup_bgs[1])) 792 return 1; 793 return 0; 794 } 795 if ((group <= 1) || !ext4_has_feature_sparse_super(sb)) 796 return 1; 797 if (!(group & 1)) 798 return 0; 799 if (test_root(group, 3) || (test_root(group, 5)) || 800 test_root(group, 7)) 801 return 1; 802 803 return 0; 804 } 805 806 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb, 807 ext4_group_t group) 808 { 809 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb); 810 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb); 811 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1; 812 813 if (group == first || group == first + 1 || group == last) 814 return 1; 815 return 0; 816 } 817 818 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb, 819 ext4_group_t group) 820 { 821 if (!ext4_bg_has_super(sb, group)) 822 return 0; 823 824 if (ext4_has_feature_meta_bg(sb)) 825 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg); 826 else 827 return EXT4_SB(sb)->s_gdb_count; 828 } 829 830 /** 831 * ext4_bg_num_gdb - number of blocks used by the group table in group 832 * @sb: superblock for filesystem 833 * @group: group number to check 834 * 835 * Return the number of blocks used by the group descriptor table 836 * (primary or backup) in this group. In the future there may be a 837 * different number of descriptor blocks in each group. 838 */ 839 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group) 840 { 841 unsigned long first_meta_bg = 842 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg); 843 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb); 844 845 if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg) 846 return ext4_bg_num_gdb_nometa(sb, group); 847 848 return ext4_bg_num_gdb_meta(sb,group); 849 850 } 851 852 /* 853 * This function returns the number of file system metadata clusters at 854 * the beginning of a block group, including the reserved gdt blocks. 855 */ 856 static unsigned ext4_num_base_meta_clusters(struct super_block *sb, 857 ext4_group_t block_group) 858 { 859 struct ext4_sb_info *sbi = EXT4_SB(sb); 860 unsigned num; 861 862 /* Check for superblock and gdt backups in this group */ 863 num = ext4_bg_has_super(sb, block_group); 864 865 if (!ext4_has_feature_meta_bg(sb) || 866 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) * 867 sbi->s_desc_per_block) { 868 if (num) { 869 num += ext4_bg_num_gdb(sb, block_group); 870 num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks); 871 } 872 } else { /* For META_BG_BLOCK_GROUPS */ 873 num += ext4_bg_num_gdb(sb, block_group); 874 } 875 return EXT4_NUM_B2C(sbi, num); 876 } 877 /** 878 * ext4_inode_to_goal_block - return a hint for block allocation 879 * @inode: inode for block allocation 880 * 881 * Return the ideal location to start allocating blocks for a 882 * newly created inode. 883 */ 884 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode) 885 { 886 struct ext4_inode_info *ei = EXT4_I(inode); 887 ext4_group_t block_group; 888 ext4_grpblk_t colour; 889 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb)); 890 ext4_fsblk_t bg_start; 891 ext4_fsblk_t last_block; 892 893 block_group = ei->i_block_group; 894 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) { 895 /* 896 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME 897 * block groups per flexgroup, reserve the first block 898 * group for directories and special files. Regular 899 * files will start at the second block group. This 900 * tends to speed up directory access and improves 901 * fsck times. 902 */ 903 block_group &= ~(flex_size-1); 904 if (S_ISREG(inode->i_mode)) 905 block_group++; 906 } 907 bg_start = ext4_group_first_block_no(inode->i_sb, block_group); 908 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1; 909 910 /* 911 * If we are doing delayed allocation, we don't need take 912 * colour into account. 913 */ 914 if (test_opt(inode->i_sb, DELALLOC)) 915 return bg_start; 916 917 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block) 918 colour = (task_pid_nr(current) % 16) * 919 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16); 920 else 921 colour = (task_pid_nr(current) % 16) * 922 ((last_block - bg_start) / 16); 923 return bg_start + colour; 924 } 925 926