fs/ext4/balloc.c

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This source file includes following definitions.
ext4_get_group_number
ext4_get_group_no_and_offset
ext4_block_in_group
ext4_num_overhead_clusters
num_clusters_in_group
ext4_init_block_bitmap
ext4_free_clusters_after_init
ext4_get_group_desc
ext4_valid_block_bitmap
ext4_validate_block_bitmap
ext4_read_block_bitmap_nowait
ext4_wait_block_bitmap
ext4_read_block_bitmap
ext4_has_free_clusters
ext4_claim_free_clusters
ext4_should_retry_alloc
ext4_new_meta_blocks
ext4_count_free_clusters
test_root
ext4_bg_has_super
ext4_bg_num_gdb_meta
ext4_bg_num_gdb_nometa
ext4_bg_num_gdb
ext4_num_base_meta_clusters
ext4_inode_to_goal_block
   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         J_ASSERT_BH(bh, 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 = ext4_get_group_info(sb, block_group);
 372 
 373         if (buffer_verified(bh))
 374                 return 0;
 375         if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 376                 return -EFSCORRUPTED;
 377 
 378         ext4_lock_group(sb, block_group);
 379         if (buffer_verified(bh))
 380                 goto verified;
 381         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
 382                         desc, bh))) {
 383                 ext4_unlock_group(sb, block_group);
 384                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
 385                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 386                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 387                 return -EFSBADCRC;
 388         }
 389         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
 390         if (unlikely(blk != 0)) {
 391                 ext4_unlock_group(sb, block_group);
 392                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
 393                            block_group, blk);
 394                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 395                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 396                 return -EFSCORRUPTED;
 397         }
 398         set_buffer_verified(bh);
 399 verified:
 400         ext4_unlock_group(sb, block_group);
 401         return 0;
 402 }
 403 
 404 /**
 405  * ext4_read_block_bitmap_nowait()
 406  * @sb:                 super block
 407  * @block_group:        given block group
 408  *
 409  * Read the bitmap for a given block_group,and validate the
 410  * bits for block/inode/inode tables are set in the bitmaps
 411  *
 412  * Return buffer_head on success or NULL in case of failure.
 413  */
 414 struct buffer_head *
 415 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
 416 {
 417         struct ext4_group_desc *desc;
 418         struct ext4_sb_info *sbi = EXT4_SB(sb);
 419         struct buffer_head *bh;
 420         ext4_fsblk_t bitmap_blk;
 421         int err;
 422 
 423         desc = ext4_get_group_desc(sb, block_group, NULL);
 424         if (!desc)
 425                 return ERR_PTR(-EFSCORRUPTED);
 426         bitmap_blk = ext4_block_bitmap(sb, desc);
 427         if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
 428             (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
 429                 ext4_error(sb, "Invalid block bitmap block %llu in "
 430                            "block_group %u", bitmap_blk, block_group);
 431                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 432                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 433                 return ERR_PTR(-EFSCORRUPTED);
 434         }
 435         bh = sb_getblk(sb, bitmap_blk);
 436         if (unlikely(!bh)) {
 437                 ext4_warning(sb, "Cannot get buffer for block bitmap - "
 438                              "block_group = %u, block_bitmap = %llu",
 439                              block_group, bitmap_blk);
 440                 return ERR_PTR(-ENOMEM);
 441         }
 442 
 443         if (bitmap_uptodate(bh))
 444                 goto verify;
 445 
 446         lock_buffer(bh);
 447         if (bitmap_uptodate(bh)) {
 448                 unlock_buffer(bh);
 449                 goto verify;
 450         }
 451         ext4_lock_group(sb, block_group);
 452         if (ext4_has_group_desc_csum(sb) &&
 453             (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
 454                 if (block_group == 0) {
 455                         ext4_unlock_group(sb, block_group);
 456                         unlock_buffer(bh);
 457                         ext4_error(sb, "Block bitmap for bg 0 marked "
 458                                    "uninitialized");
 459                         err = -EFSCORRUPTED;
 460                         goto out;
 461                 }
 462                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
 463                 set_bitmap_uptodate(bh);
 464                 set_buffer_uptodate(bh);
 465                 set_buffer_verified(bh);
 466                 ext4_unlock_group(sb, block_group);
 467                 unlock_buffer(bh);
 468                 if (err) {
 469                         ext4_error(sb, "Failed to init block bitmap for group "
 470                                    "%u: %d", block_group, err);
 471                         goto out;
 472                 }
 473                 goto verify;
 474         }
 475         ext4_unlock_group(sb, block_group);
 476         if (buffer_uptodate(bh)) {
 477                 /*
 478                  * if not uninit if bh is uptodate,
 479                  * bitmap is also uptodate
 480                  */
 481                 set_bitmap_uptodate(bh);
 482                 unlock_buffer(bh);
 483                 goto verify;
 484         }
 485         /*
 486          * submit the buffer_head for reading
 487          */
 488         set_buffer_new(bh);
 489         trace_ext4_read_block_bitmap_load(sb, block_group);
 490         bh->b_end_io = ext4_end_bitmap_read;
 491         get_bh(bh);
 492         submit_bh(REQ_OP_READ, REQ_META | REQ_PRIO, bh);
 493         return bh;
 494 verify:
 495         err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
 496         if (err)
 497                 goto out;
 498         return bh;
 499 out:
 500         put_bh(bh);
 501         return ERR_PTR(err);
 502 }
 503 
 504 /* Returns 0 on success, 1 on error */
 505 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
 506                            struct buffer_head *bh)
 507 {
 508         struct ext4_group_desc *desc;
 509 
 510         if (!buffer_new(bh))
 511                 return 0;
 512         desc = ext4_get_group_desc(sb, block_group, NULL);
 513         if (!desc)
 514                 return -EFSCORRUPTED;
 515         wait_on_buffer(bh);
 516         if (!buffer_uptodate(bh)) {
 517                 ext4_error(sb, "Cannot read block bitmap - "
 518                            "block_group = %u, block_bitmap = %llu",
 519                            block_group, (unsigned long long) bh->b_blocknr);
 520                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 521                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 522                 return -EIO;
 523         }
 524         clear_buffer_new(bh);
 525         /* Panic or remount fs read-only if block bitmap is invalid */
 526         return ext4_validate_block_bitmap(sb, desc, block_group, bh);
 527 }
 528 
 529 struct buffer_head *
 530 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 531 {
 532         struct buffer_head *bh;
 533         int err;
 534 
 535         bh = ext4_read_block_bitmap_nowait(sb, block_group);
 536         if (IS_ERR(bh))
 537                 return bh;
 538         err = ext4_wait_block_bitmap(sb, block_group, bh);
 539         if (err) {
 540                 put_bh(bh);
 541                 return ERR_PTR(err);
 542         }
 543         return bh;
 544 }
 545 
 546 /**
 547  * ext4_has_free_clusters()
 548  * @sbi:        in-core super block structure.
 549  * @nclusters:  number of needed blocks
 550  * @flags:      flags from ext4_mb_new_blocks()
 551  *
 552  * Check if filesystem has nclusters free & available for allocation.
 553  * On success return 1, return 0 on failure.
 554  */
 555 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
 556                                   s64 nclusters, unsigned int flags)
 557 {
 558         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
 559         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
 560         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
 561 
 562         free_clusters  = percpu_counter_read_positive(fcc);
 563         dirty_clusters = percpu_counter_read_positive(dcc);
 564         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
 565 
 566         /*
 567          * r_blocks_count should always be multiple of the cluster ratio so
 568          * we are safe to do a plane bit shift only.
 569          */
 570         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
 571               resv_clusters;
 572 
 573         if (free_clusters - (nclusters + rsv + dirty_clusters) <
 574                                         EXT4_FREECLUSTERS_WATERMARK) {
 575                 free_clusters  = percpu_counter_sum_positive(fcc);
 576                 dirty_clusters = percpu_counter_sum_positive(dcc);
 577         }
 578         /* Check whether we have space after accounting for current
 579          * dirty clusters & root reserved clusters.
 580          */
 581         if (free_clusters >= (rsv + nclusters + dirty_clusters))
 582                 return 1;
 583 
 584         /* Hm, nope.  Are (enough) root reserved clusters available? */
 585         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
 586             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
 587             capable(CAP_SYS_RESOURCE) ||
 588             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
 589 
 590                 if (free_clusters >= (nclusters + dirty_clusters +
 591                                       resv_clusters))
 592                         return 1;
 593         }
 594         /* No free blocks. Let's see if we can dip into reserved pool */
 595         if (flags & EXT4_MB_USE_RESERVED) {
 596                 if (free_clusters >= (nclusters + dirty_clusters))
 597                         return 1;
 598         }
 599 
 600         return 0;
 601 }
 602 
 603 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 604                              s64 nclusters, unsigned int flags)
 605 {
 606         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
 607                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
 608                 return 0;
 609         } else
 610                 return -ENOSPC;
 611 }
 612 
 613 /**
 614  * ext4_should_retry_alloc() - check if a block allocation should be retried
 615  * @sb:                 super block
 616  * @retries:            number of attemps has been made
 617  *
 618  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
 619  * it is profitable to retry the operation, this function will wait
 620  * for the current or committing transaction to complete, and then
 621  * return TRUE.  We will only retry once.
 622  */
 623 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 624 {
 625         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
 626             (*retries)++ > 1 ||
 627             !EXT4_SB(sb)->s_journal)
 628                 return 0;
 629 
 630         smp_mb();
 631         if (EXT4_SB(sb)->s_mb_free_pending == 0)
 632                 return 0;
 633 
 634         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
 635         jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
 636         return 1;
 637 }
 638 
 639 /*
 640  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 641  *
 642  * @handle:             handle to this transaction
 643  * @inode:              file inode
 644  * @goal:               given target block(filesystem wide)
 645  * @count:              pointer to total number of clusters needed
 646  * @errp:               error code
 647  *
 648  * Return 1st allocated block number on success, *count stores total account
 649  * error stores in errp pointer
 650  */
 651 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 652                                   ext4_fsblk_t goal, unsigned int flags,
 653                                   unsigned long *count, int *errp)
 654 {
 655         struct ext4_allocation_request ar;
 656         ext4_fsblk_t ret;
 657 
 658         memset(&ar, 0, sizeof(ar));
 659         /* Fill with neighbour allocated blocks */
 660         ar.inode = inode;
 661         ar.goal = goal;
 662         ar.len = count ? *count : 1;
 663         ar.flags = flags;
 664 
 665         ret = ext4_mb_new_blocks(handle, &ar, errp);
 666         if (count)
 667                 *count = ar.len;
 668         /*
 669          * Account for the allocated meta blocks.  We will never
 670          * fail EDQUOT for metdata, but we do account for it.
 671          */
 672         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
 673                 dquot_alloc_block_nofail(inode,
 674                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
 675         }
 676         return ret;
 677 }
 678 
 679 /**
 680  * ext4_count_free_clusters() -- count filesystem free clusters
 681  * @sb:         superblock
 682  *
 683  * Adds up the number of free clusters from each block group.
 684  */
 685 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
 686 {
 687         ext4_fsblk_t desc_count;
 688         struct ext4_group_desc *gdp;
 689         ext4_group_t i;
 690         ext4_group_t ngroups = ext4_get_groups_count(sb);
 691         struct ext4_group_info *grp;
 692 #ifdef EXT4FS_DEBUG
 693         struct ext4_super_block *es;
 694         ext4_fsblk_t bitmap_count;
 695         unsigned int x;
 696         struct buffer_head *bitmap_bh = NULL;
 697 
 698         es = EXT4_SB(sb)->s_es;
 699         desc_count = 0;
 700         bitmap_count = 0;
 701         gdp = NULL;
 702 
 703         for (i = 0; i < ngroups; i++) {
 704                 gdp = ext4_get_group_desc(sb, i, NULL);
 705                 if (!gdp)
 706                         continue;
 707                 grp = NULL;
 708                 if (EXT4_SB(sb)->s_group_info)
 709                         grp = ext4_get_group_info(sb, i);
 710                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 711                         desc_count += ext4_free_group_clusters(sb, gdp);
 712                 brelse(bitmap_bh);
 713                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 714                 if (IS_ERR(bitmap_bh)) {
 715                         bitmap_bh = NULL;
 716                         continue;
 717                 }
 718 
 719                 x = ext4_count_free(bitmap_bh->b_data,
 720                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
 721                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 722                         i, ext4_free_group_clusters(sb, gdp), x);
 723                 bitmap_count += x;
 724         }
 725         brelse(bitmap_bh);
 726         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
 727                ", computed = %llu, %llu\n",
 728                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
 729                desc_count, bitmap_count);
 730         return bitmap_count;
 731 #else
 732         desc_count = 0;
 733         for (i = 0; i < ngroups; i++) {
 734                 gdp = ext4_get_group_desc(sb, i, NULL);
 735                 if (!gdp)
 736                         continue;
 737                 grp = NULL;
 738                 if (EXT4_SB(sb)->s_group_info)
 739                         grp = ext4_get_group_info(sb, i);
 740                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 741                         desc_count += ext4_free_group_clusters(sb, gdp);
 742         }
 743 
 744         return desc_count;
 745 #endif
 746 }
 747 
 748 static inline int test_root(ext4_group_t a, int b)
 749 {
 750         while (1) {
 751                 if (a < b)
 752                         return 0;
 753                 if (a == b)
 754                         return 1;
 755                 if ((a % b) != 0)
 756                         return 0;
 757                 a = a / b;
 758         }
 759 }
 760 
 761 /**
 762  *      ext4_bg_has_super - number of blocks used by the superblock in group
 763  *      @sb: superblock for filesystem
 764  *      @group: group number to check
 765  *
 766  *      Return the number of blocks used by the superblock (primary or backup)
 767  *      in this group.  Currently this will be only 0 or 1.
 768  */
 769 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 770 {
 771         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 772 
 773         if (group == 0)
 774                 return 1;
 775         if (ext4_has_feature_sparse_super2(sb)) {
 776                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
 777                     group == le32_to_cpu(es->s_backup_bgs[1]))
 778                         return 1;
 779                 return 0;
 780         }
 781         if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
 782                 return 1;
 783         if (!(group & 1))
 784                 return 0;
 785         if (test_root(group, 3) || (test_root(group, 5)) ||
 786             test_root(group, 7))
 787                 return 1;
 788 
 789         return 0;
 790 }
 791 
 792 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 793                                         ext4_group_t group)
 794 {
 795         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 796         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 797         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 798 
 799         if (group == first || group == first + 1 || group == last)
 800                 return 1;
 801         return 0;
 802 }
 803 
 804 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 805                                         ext4_group_t group)
 806 {
 807         if (!ext4_bg_has_super(sb, group))
 808                 return 0;
 809 
 810         if (ext4_has_feature_meta_bg(sb))
 811                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 812         else
 813                 return EXT4_SB(sb)->s_gdb_count;
 814 }
 815 
 816 /**
 817  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 818  *      @sb: superblock for filesystem
 819  *      @group: group number to check
 820  *
 821  *      Return the number of blocks used by the group descriptor table
 822  *      (primary or backup) in this group.  In the future there may be a
 823  *      different number of descriptor blocks in each group.
 824  */
 825 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 826 {
 827         unsigned long first_meta_bg =
 828                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 829         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 830 
 831         if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
 832                 return ext4_bg_num_gdb_nometa(sb, group);
 833 
 834         return ext4_bg_num_gdb_meta(sb,group);
 835 
 836 }
 837 
 838 /*
 839  * This function returns the number of file system metadata clusters at
 840  * the beginning of a block group, including the reserved gdt blocks.
 841  */
 842 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
 843                                      ext4_group_t block_group)
 844 {
 845         struct ext4_sb_info *sbi = EXT4_SB(sb);
 846         unsigned num;
 847 
 848         /* Check for superblock and gdt backups in this group */
 849         num = ext4_bg_has_super(sb, block_group);
 850 
 851         if (!ext4_has_feature_meta_bg(sb) ||
 852             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 853                           sbi->s_desc_per_block) {
 854                 if (num) {
 855                         num += ext4_bg_num_gdb(sb, block_group);
 856                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 857                 }
 858         } else { /* For META_BG_BLOCK_GROUPS */
 859                 num += ext4_bg_num_gdb(sb, block_group);
 860         }
 861         return EXT4_NUM_B2C(sbi, num);
 862 }
 863 /**
 864  *      ext4_inode_to_goal_block - return a hint for block allocation
 865  *      @inode: inode for block allocation
 866  *
 867  *      Return the ideal location to start allocating blocks for a
 868  *      newly created inode.
 869  */
 870 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
 871 {
 872         struct ext4_inode_info *ei = EXT4_I(inode);
 873         ext4_group_t block_group;
 874         ext4_grpblk_t colour;
 875         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 876         ext4_fsblk_t bg_start;
 877         ext4_fsblk_t last_block;
 878 
 879         block_group = ei->i_block_group;
 880         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
 881                 /*
 882                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
 883                  * block groups per flexgroup, reserve the first block
 884                  * group for directories and special files.  Regular
 885                  * files will start at the second block group.  This
 886                  * tends to speed up directory access and improves
 887                  * fsck times.
 888                  */
 889                 block_group &= ~(flex_size-1);
 890                 if (S_ISREG(inode->i_mode))
 891                         block_group++;
 892         }
 893         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
 894         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
 895 
 896         /*
 897          * If we are doing delayed allocation, we don't need take
 898          * colour into account.
 899          */
 900         if (test_opt(inode->i_sb, DELALLOC))
 901                 return bg_start;
 902 
 903         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
 904                 colour = (current->pid % 16) *
 905                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 906         else
 907                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
 908         return bg_start + colour;
 909 }
 910
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root/fs/ext4/balloc.c

DEFINITIONS
