fs/ext3/balloc.c

   1 /*
   2  *  linux/fs/ext3/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/slab.h>
  18 #include <linux/jbd.h>
  19 #include <linux/ext3_fs.h>
  20 #include <linux/ext3_jbd.h>
  21 #include <linux/quotaops.h>
  22 #include <linux/buffer_head.h>
  23
  24 /*
  25  * balloc.c contains the blocks allocation and deallocation routines
  26  */
  27
  28 /*
  29  * The free blocks are managed by bitmaps.  A file system contains several
  30  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
  31  * block for inodes, N blocks for the inode table and data blocks.
  32  *
  33  * The file system contains group descriptors which are located after the
  34  * super block.  Each descriptor contains the number of the bitmap block and
  35  * the free blocks count in the block.  The descriptors are loaded in memory
  36  * when a file system is mounted (see ext3_fill_super).
  37  */
  38
  39
  40 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
  41
  42 /**
  43  * ext3_get_group_desc() -- load group descriptor from disk
  44  * @sb:                 super block
  45  * @block_group:        given block group
  46  * @bh:                 pointer to the buffer head to store the block
  47  *                      group descriptor
  48  */
  49 struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
  50                                              unsigned int block_group,
  51                                              struct buffer_head ** bh)
  52 {
  53         unsigned long group_desc;
  54         unsigned long offset;
  55         struct ext3_group_desc * desc;
  56         struct ext3_sb_info *sbi = EXT3_SB(sb);
  57
  58         if (block_group >= sbi->s_groups_count) {
  59                 ext3_error (sb, "ext3_get_group_desc",
  60                             "block_group >= groups_count - "
  61                             "block_group = %d, groups_count = %lu",
  62                             block_group, sbi->s_groups_count);
  63
  64                 return NULL;
  65         }
  66         smp_rmb();
  67
  68         group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb);
  69         offset = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1);
  70         if (!sbi->s_group_desc[group_desc]) {
  71                 ext3_error (sb, "ext3_get_group_desc",
  72                             "Group descriptor not loaded - "
  73                             "block_group = %d, group_desc = %lu, desc = %lu",
  74                              block_group, group_desc, offset);
  75                 return NULL;
  76         }
  77
  78         desc = (struct ext3_group_desc *) sbi->s_group_desc[group_desc]->b_data;
  79         if (bh)
  80                 *bh = sbi->s_group_desc[group_desc];
  81         return desc + offset;
  82 }
  83
  84 static int ext3_valid_block_bitmap(struct super_block *sb,
  85                                         struct ext3_group_desc *desc,
  86                                         unsigned int block_group,
  87                                         struct buffer_head *bh)
  88 {
  89         ext3_grpblk_t offset;
  90         ext3_grpblk_t next_zero_bit;
  91         ext3_fsblk_t bitmap_blk;
  92         ext3_fsblk_t group_first_block;
  93
  94         group_first_block = ext3_group_first_block_no(sb, block_group);
  95
  96         /* check whether block bitmap block number is set */
  97         bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
  98         offset = bitmap_blk - group_first_block;
  99         if (!ext3_test_bit(offset, bh->b_data))
 100                 /* bad block bitmap */
 101                 goto err_out;
 102
 103         /* check whether the inode bitmap block number is set */
 104         bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
 105         offset = bitmap_blk - group_first_block;
 106         if (!ext3_test_bit(offset, bh->b_data))
 107                 /* bad block bitmap */
 108                 goto err_out;
 109
 110         /* check whether the inode table block number is set */
 111         bitmap_blk = le32_to_cpu(desc->bg_inode_table);
 112         offset = bitmap_blk - group_first_block;
 113         next_zero_bit = ext3_find_next_zero_bit(bh->b_data,
 114                                 offset + EXT3_SB(sb)->s_itb_per_group,
 115                                 offset);
 116         if (next_zero_bit >= offset + EXT3_SB(sb)->s_itb_per_group)
 117                 /* good bitmap for inode tables */
 118                 return 1;
 119
 120 err_out:
 121         ext3_error(sb, __func__,
 122                         "Invalid block bitmap - "
 123                         "block_group = %d, block = %lu",
 124                         block_group, bitmap_blk);
 125         return 0;
 126 }
 127
 128 /**
 129  * read_block_bitmap()
 130  * @sb:                 super block
 131  * @block_group:        given block group
 132  *
 133  * Read the bitmap for a given block_group,and validate the
 134  * bits for block/inode/inode tables are set in the bitmaps
 135  *
 136  * Return buffer_head on success or NULL in case of failure.
 137  */
 138 static struct buffer_head *
 139 read_block_bitmap(struct super_block *sb, unsigned int block_group)
 140 {
 141         struct ext3_group_desc * desc;
 142         struct buffer_head * bh = NULL;
 143         ext3_fsblk_t bitmap_blk;
 144
 145         desc = ext3_get_group_desc(sb, block_group, NULL);
 146         if (!desc)
 147                 return NULL;
 148         bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
 149         bh = sb_getblk(sb, bitmap_blk);
 150         if (unlikely(!bh)) {
 151                 ext3_error(sb, __func__,
 152                             "Cannot read block bitmap - "
 153                             "block_group = %d, block_bitmap = %u",
 154                             block_group, le32_to_cpu(desc->bg_block_bitmap));
 155                 return NULL;
 156         }
 157         if (likely(bh_uptodate_or_lock(bh)))
 158                 return bh;
 159
 160         if (bh_submit_read(bh) < 0) {
 161                 brelse(bh);
 162                 ext3_error(sb, __func__,
 163                             "Cannot read block bitmap - "
 164                             "block_group = %d, block_bitmap = %u",
 165                             block_group, le32_to_cpu(desc->bg_block_bitmap));
 166                 return NULL;
 167         }
 168         ext3_valid_block_bitmap(sb, desc, block_group, bh);
 169         /*
 170          * file system mounted not to panic on error, continue with corrupt
 171          * bitmap
 172          */
 173         return bh;
 174 }
 175 /*
 176  * The reservation window structure operations
 177  * --------------------------------------------
 178  * Operations include:
 179  * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
 180  *
 181  * We use a red-black tree to represent per-filesystem reservation
 182  * windows.
 183  *
 184  */
 185
 186 /**
 187  * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
 188  * @rb_root:            root of per-filesystem reservation rb tree
 189  * @verbose:            verbose mode
 190  * @fn:                 function which wishes to dump the reservation map
 191  *
 192  * If verbose is turned on, it will print the whole block reservation
 193  * windows(start, end). Otherwise, it will only print out the "bad" windows,
 194  * those windows that overlap with their immediate neighbors.
 195  */
 196 #if 1
 197 static void __rsv_window_dump(struct rb_root *root, int verbose,
 198                               const char *fn)
 199 {
 200         struct rb_node *n;
 201         struct ext3_reserve_window_node *rsv, *prev;
 202         int bad;
 203
 204 restart:
 205         n = rb_first(root);
 206         bad = 0;
 207         prev = NULL;
 208
 209         printk("Block Allocation Reservation Windows Map (%s):\n", fn);
 210         while (n) {
 211                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 212                 if (verbose)
 213                         printk("reservation window 0x%p "
 214                                "start:  %lu, end:  %lu\n",
 215                                rsv, rsv->rsv_start, rsv->rsv_end);
 216                 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
 217                         printk("Bad reservation %p (start >= end)\n",
 218                                rsv);
 219                         bad = 1;
 220                 }
 221                 if (prev && prev->rsv_end >= rsv->rsv_start) {
 222                         printk("Bad reservation %p (prev->end >= start)\n",
 223                                rsv);
 224                         bad = 1;
 225                 }
 226                 if (bad) {
 227                         if (!verbose) {
 228                                 printk("Restarting reservation walk in verbose mode\n");
 229                                 verbose = 1;
 230                                 goto restart;
 231                         }
 232                 }
 233                 n = rb_next(n);
 234                 prev = rsv;
 235         }
 236         printk("Window map complete.\n");
 237         BUG_ON(bad);
 238 }
 239 #define rsv_window_dump(root, verbose) \
 240         __rsv_window_dump((root), (verbose), __func__)
 241 #else
 242 #define rsv_window_dump(root, verbose) do {} while (0)
 243 #endif
 244
 245 /**
 246  * goal_in_my_reservation()
 247  * @rsv:                inode's reservation window
 248  * @grp_goal:           given goal block relative to the allocation block group
 249  * @group:              the current allocation block group
 250  * @sb:                 filesystem super block
 251  *
 252  * Test if the given goal block (group relative) is within the file's
 253  * own block reservation window range.
 254  *
 255  * If the reservation window is outside the goal allocation group, return 0;
 256  * grp_goal (given goal block) could be -1, which means no specific
 257  * goal block. In this case, always return 1.
 258  * If the goal block is within the reservation window, return 1;
 259  * otherwise, return 0;
 260  */
 261 static int
 262 goal_in_my_reservation(struct ext3_reserve_window *rsv, ext3_grpblk_t grp_goal,
 263                         unsigned int group, struct super_block * sb)
 264 {
 265         ext3_fsblk_t group_first_block, group_last_block;
 266
 267         group_first_block = ext3_group_first_block_no(sb, group);
 268         group_last_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
 269
 270         if ((rsv->_rsv_start > group_last_block) ||
 271             (rsv->_rsv_end < group_first_block))
 272                 return 0;
 273         if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
 274                 || (grp_goal + group_first_block > rsv->_rsv_end)))
 275                 return 0;
 276         return 1;
 277 }
 278
 279 /**
 280  * search_reserve_window()
 281  * @rb_root:            root of reservation tree
 282  * @goal:               target allocation block
 283  *
 284  * Find the reserved window which includes the goal, or the previous one
 285  * if the goal is not in any window.
 286  * Returns NULL if there are no windows or if all windows start after the goal.
 287  */
 288 static struct ext3_reserve_window_node *
 289 search_reserve_window(struct rb_root *root, ext3_fsblk_t goal)
 290 {
 291         struct rb_node *n = root->rb_node;
 292         struct ext3_reserve_window_node *rsv;
 293
 294         if (!n)
 295                 return NULL;
 296
 297         do {
 298                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 299
 300                 if (goal < rsv->rsv_start)
 301                         n = n->rb_left;
 302                 else if (goal > rsv->rsv_end)
 303                         n = n->rb_right;
 304                 else
 305                         return rsv;
 306         } while (n);
 307         /*
 308          * We've fallen off the end of the tree: the goal wasn't inside
 309          * any particular node.  OK, the previous node must be to one
 310          * side of the interval containing the goal.  If it's the RHS,
 311          * we need to back up one.
 312          */
 313         if (rsv->rsv_start > goal) {
 314                 n = rb_prev(&rsv->rsv_node);
 315                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 316         }
 317         return rsv;
 318 }
 319
 320 /**
 321  * ext3_rsv_window_add() -- Insert a window to the block reservation rb tree.
 322  * @sb:                 super block
 323  * @rsv:                reservation window to add
 324  *
 325  * Must be called with rsv_lock hold.
 326  */
 327 void ext3_rsv_window_add(struct super_block *sb,
 328                     struct ext3_reserve_window_node *rsv)
 329 {
 330         struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root;
 331         struct rb_node *node = &rsv->rsv_node;
 332         ext3_fsblk_t start = rsv->rsv_start;
 333
 334         struct rb_node ** p = &root->rb_node;
 335         struct rb_node * parent = NULL;
 336         struct ext3_reserve_window_node *this;
 337
 338         while (*p)
 339         {
 340                 parent = *p;
 341                 this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node);
 342
 343                 if (start < this->rsv_start)
 344                         p = &(*p)->rb_left;
 345                 else if (start > this->rsv_end)
 346                         p = &(*p)->rb_right;
 347                 else {
 348                         rsv_window_dump(root, 1);
 349                         BUG();
 350                 }
 351         }
 352
 353         rb_link_node(node, parent, p);
 354         rb_insert_color(node, root);
 355 }
 356
 357 /**
 358  * ext3_rsv_window_remove() -- unlink a window from the reservation rb tree
 359  * @sb:                 super block
 360  * @rsv:                reservation window to remove
 361  *
 362  * Mark the block reservation window as not allocated, and unlink it
 363  * from the filesystem reservation window rb tree. Must be called with
 364  * rsv_lock hold.
 365  */
 366 static void rsv_window_remove(struct super_block *sb,
 367                               struct ext3_reserve_window_node *rsv)
 368 {
 369         rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 370         rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 371         rsv->rsv_alloc_hit = 0;
 372         rb_erase(&rsv->rsv_node, &EXT3_SB(sb)->s_rsv_window_root);
 373 }
 374
 375 /*
 376  * rsv_is_empty() -- Check if the reservation window is allocated.
 377  * @rsv:                given reservation window to check
 378  *
 379  * returns 1 if the end block is EXT3_RESERVE_WINDOW_NOT_ALLOCATED.
 380  */
 381 static inline int rsv_is_empty(struct ext3_reserve_window *rsv)
 382 {
 383         /* a valid reservation end block could not be 0 */
 384         return rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 385 }
 386
 387 /**
 388  * ext3_init_block_alloc_info()
 389  * @inode:              file inode structure
 390  *
 391  * Allocate and initialize the  reservation window structure, and
 392  * link the window to the ext3 inode structure at last
 393  *
 394  * The reservation window structure is only dynamically allocated
 395  * and linked to ext3 inode the first time the open file
 396  * needs a new block. So, before every ext3_new_block(s) call, for
 397  * regular files, we should check whether the reservation window
 398  * structure exists or not. In the latter case, this function is called.
 399  * Fail to do so will result in block reservation being turned off for that
 400  * open file.
 401  *
 402  * This function is called from ext3_get_blocks_handle(), also called
 403  * when setting the reservation window size through ioctl before the file
 404  * is open for write (needs block allocation).
 405  *
 406  * Needs truncate_mutex protection prior to call this function.
 407  */
 408 void ext3_init_block_alloc_info(struct inode *inode)
 409 {
 410         struct ext3_inode_info *ei = EXT3_I(inode);
 411         struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
 412         struct super_block *sb = inode->i_sb;
 413
 414         block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
 415         if (block_i) {
 416                 struct ext3_reserve_window_node *rsv = &block_i->rsv_window_node;
 417
 418                 rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 419                 rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 420
 421                 /*
 422                  * if filesystem is mounted with NORESERVATION, the goal
 423                  * reservation window size is set to zero to indicate
 424                  * block reservation is off
 425                  */
 426                 if (!test_opt(sb, RESERVATION))
 427                         rsv->rsv_goal_size = 0;
 428                 else
 429                         rsv->rsv_goal_size = EXT3_DEFAULT_RESERVE_BLOCKS;
 430                 rsv->rsv_alloc_hit = 0;
 431                 block_i->last_alloc_logical_block = 0;
 432                 block_i->last_alloc_physical_block = 0;
 433         }
 434         ei->i_block_alloc_info = block_i;
 435 }
 436
 437 /**
 438  * ext3_discard_reservation()
 439  * @inode:              inode
 440  *
 441  * Discard(free) block reservation window on last file close, or truncate
 442  * or at last iput().
 443  *
 444  * It is being called in three cases:
 445  *      ext3_release_file(): last writer close the file
 446  *      ext3_clear_inode(): last iput(), when nobody link to this file.
 447  *      ext3_truncate(): when the block indirect map is about to change.
 448  *
 449  */
 450 void ext3_discard_reservation(struct inode *inode)
 451 {
 452         struct ext3_inode_info *ei = EXT3_I(inode);
 453         struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
 454         struct ext3_reserve_window_node *rsv;
 455         spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
 456
 457         if (!block_i)
 458                 return;
 459
 460         rsv = &block_i->rsv_window_node;
 461         if (!rsv_is_empty(&rsv->rsv_window)) {
 462                 spin_lock(rsv_lock);
 463                 if (!rsv_is_empty(&rsv->rsv_window))
 464                         rsv_window_remove(inode->i_sb, rsv);
 465                 spin_unlock(rsv_lock);
 466         }
 467 }
 468
 469 /**
 470  * ext3_free_blocks_sb() -- Free given blocks and update quota
 471  * @handle:                     handle to this transaction
 472  * @sb:                         super block
 473  * @block:                      start physcial block to free
 474  * @count:                      number of blocks to free
 475  * @pdquot_freed_blocks:        pointer to quota
 476  */
 477 void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,
 478                          ext3_fsblk_t block, unsigned long count,
 479                          unsigned long *pdquot_freed_blocks)
 480 {
 481         struct buffer_head *bitmap_bh = NULL;
 482         struct buffer_head *gd_bh;
 483         unsigned long block_group;
 484         ext3_grpblk_t bit;
 485         unsigned long i;
 486         unsigned long overflow;
 487         struct ext3_group_desc * desc;
 488         struct ext3_super_block * es;
 489         struct ext3_sb_info *sbi;
 490         int err = 0, ret;
 491         ext3_grpblk_t group_freed;
 492
 493         *pdquot_freed_blocks = 0;
 494         sbi = EXT3_SB(sb);
 495         es = sbi->s_es;
 496         if (block < le32_to_cpu(es->s_first_data_block) ||
 497             block + count < block ||
 498             block + count > le32_to_cpu(es->s_blocks_count)) {
 499                 ext3_error (sb, "ext3_free_blocks",
 500                             "Freeing blocks not in datazone - "
 501                             "block = "E3FSBLK", count = %lu", block, count);
 502                 goto error_return;
 503         }
 504
 505         ext3_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
 506
 507 do_more:
 508         overflow = 0;
 509         block_group = (block - le32_to_cpu(es->s_first_data_block)) /
 510                       EXT3_BLOCKS_PER_GROUP(sb);
 511         bit = (block - le32_to_cpu(es->s_first_data_block)) %
 512                       EXT3_BLOCKS_PER_GROUP(sb);
 513         /*
 514          * Check to see if we are freeing blocks across a group
 515          * boundary.
 516          */
 517         if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
 518                 overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
 519                 count -= overflow;
 520         }
 521         brelse(bitmap_bh);
 522         bitmap_bh = read_block_bitmap(sb, block_group);
 523         if (!bitmap_bh)
 524                 goto error_return;
 525         desc = ext3_get_group_desc (sb, block_group, &gd_bh);
 526         if (!desc)
 527                 goto error_return;
 528
 529         if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
 530             in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
 531             in_range (block, le32_to_cpu(desc->bg_inode_table),
 532                       sbi->s_itb_per_group) ||
 533             in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
 534                       sbi->s_itb_per_group)) {
 535                 ext3_error (sb, "ext3_free_blocks",
 536                             "Freeing blocks in system zones - "
 537                             "Block = "E3FSBLK", count = %lu",
 538                             block, count);
 539                 goto error_return;
 540         }
 541
 542         /*
 543          * We are about to start releasing blocks in the bitmap,
 544          * so we need undo access.
 545          */
 546         /* @@@ check errors */
 547         BUFFER_TRACE(bitmap_bh, "getting undo access");
 548         err = ext3_journal_get_undo_access(handle, bitmap_bh);
 549         if (err)
 550                 goto error_return;
 551
 552         /*
 553          * We are about to modify some metadata.  Call the journal APIs
 554          * to unshare ->b_data if a currently-committing transaction is
 555          * using it
 556          */
 557         BUFFER_TRACE(gd_bh, "get_write_access");
 558         err = ext3_journal_get_write_access(handle, gd_bh);
 559         if (err)
 560                 goto error_return;
 561
 562         jbd_lock_bh_state(bitmap_bh);
 563
 564         for (i = 0, group_freed = 0; i < count; i++) {
 565                 /*
 566                  * An HJ special.  This is expensive...
 567                  */
 568 #ifdef CONFIG_JBD_DEBUG
 569                 jbd_unlock_bh_state(bitmap_bh);
 570                 {
 571                         struct buffer_head *debug_bh;
 572                         debug_bh = sb_find_get_block(sb, block + i);
 573                         if (debug_bh) {
 574                                 BUFFER_TRACE(debug_bh, "Deleted!");
 575                                 if (!bh2jh(bitmap_bh)->b_committed_data)
 576                                         BUFFER_TRACE(debug_bh,
 577                                                 "No commited data in bitmap");
 578                                 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
 579                                 __brelse(debug_bh);
 580                         }
 581                 }
 582                 jbd_lock_bh_state(bitmap_bh);
 583 #endif
 584                 if (need_resched()) {
 585                         jbd_unlock_bh_state(bitmap_bh);
 586                         cond_resched();
 587                         jbd_lock_bh_state(bitmap_bh);
 588                 }
 589                 /* @@@ This prevents newly-allocated data from being
 590                  * freed and then reallocated within the same
 591                  * transaction.
 592                  *
 593                  * Ideally we would want to allow that to happen, but to
 594                  * do so requires making journal_forget() capable of
 595                  * revoking the queued write of a data block, which
 596                  * implies blocking on the journal lock.  *forget()
 597                  * cannot block due to truncate races.
 598                  *
 599                  * Eventually we can fix this by making journal_forget()
 600                  * return a status indicating whether or not it was able
 601                  * to revoke the buffer.  On successful revoke, it is
 602                  * safe not to set the allocation bit in the committed
 603                  * bitmap, because we know that there is no outstanding
 604                  * activity on the buffer any more and so it is safe to
 605                  * reallocate it.
 606                  */
 607                 BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
 608                 J_ASSERT_BH(bitmap_bh,
 609                                 bh2jh(bitmap_bh)->b_committed_data != NULL);
 610                 ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
 611                                 bh2jh(bitmap_bh)->b_committed_data);
 612
 613                 /*
 614                  * We clear the bit in the bitmap after setting the committed
 615                  * data bit, because this is the reverse order to that which
 616                  * the allocator uses.
 617                  */
 618                 BUFFER_TRACE(bitmap_bh, "clear bit");
 619                 if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 620                                                 bit + i, bitmap_bh->b_data)) {
 621                         jbd_unlock_bh_state(bitmap_bh);
 622                         ext3_error(sb, __func__,
 623                                 "bit already cleared for block "E3FSBLK,
 624                                  block + i);
 625                         jbd_lock_bh_state(bitmap_bh);
 626                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
 627                 } else {
 628                         group_freed++;
 629                 }
 630         }
 631         jbd_unlock_bh_state(bitmap_bh);
 632
 633         spin_lock(sb_bgl_lock(sbi, block_group));
 634         le16_add_cpu(&desc->bg_free_blocks_count, group_freed);
 635         spin_unlock(sb_bgl_lock(sbi, block_group));
 636         percpu_counter_add(&sbi->s_freeblocks_counter, count);
 637
 638         /* We dirtied the bitmap block */
 639         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
 640         err = ext3_journal_dirty_metadata(handle, bitmap_bh);
 641
 642         /* And the group descriptor block */
 643         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
 644         ret = ext3_journal_dirty_metadata(handle, gd_bh);
 645         if (!err) err = ret;
 646         *pdquot_freed_blocks += group_freed;
 647
 648         if (overflow && !err) {
 649                 block += count;
 650                 count = overflow;
 651                 goto do_more;
 652         }
 653
 654 error_return:
 655         brelse(bitmap_bh);
 656         ext3_std_error(sb, err);
 657         return;
 658 }
 659
 660 /**
 661  * ext3_free_blocks() -- Free given blocks and update quota
 662  * @handle:             handle for this transaction
 663  * @inode:              inode
 664  * @block:              start physical block to free
 665  * @count:              number of blocks to count
 666  */
 667 void ext3_free_blocks(handle_t *handle, struct inode *inode,
 668                         ext3_fsblk_t block, unsigned long count)
 669 {
 670         struct super_block * sb;
 671         unsigned long dquot_freed_blocks;
 672
 673         sb = inode->i_sb;
 674         if (!sb) {
 675                 printk ("ext3_free_blocks: nonexistent device");
 676                 return;
 677         }
 678         ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
 679         if (dquot_freed_blocks)
 680                 dquot_free_block(inode, dquot_freed_blocks);
 681         return;
 682 }
 683
 684 /**
 685  * ext3_test_allocatable()
 686  * @nr:                 given allocation block group
 687  * @bh:                 bufferhead contains the bitmap of the given block group
 688  *
 689  * For ext3 allocations, we must not reuse any blocks which are
 690  * allocated in the bitmap buffer's "last committed data" copy.  This
 691  * prevents deletes from freeing up the page for reuse until we have
 692  * committed the delete transaction.
 693  *
 694  * If we didn't do this, then deleting something and reallocating it as
 695  * data would allow the old block to be overwritten before the
 696  * transaction committed (because we force data to disk before commit).
 697  * This would lead to corruption if we crashed between overwriting the
 698  * data and committing the delete.
 699  *
 700  * @@@ We may want to make this allocation behaviour conditional on
 701  * data-writes at some point, and disable it for metadata allocations or
 702  * sync-data inodes.
 703  */
 704 static int ext3_test_allocatable(ext3_grpblk_t nr, struct buffer_head *bh)
 705 {
 706         int ret;
 707         struct journal_head *jh = bh2jh(bh);
 708
 709         if (ext3_test_bit(nr, bh->b_data))
 710                 return 0;
 711
 712         jbd_lock_bh_state(bh);
 713         if (!jh->b_committed_data)
 714                 ret = 1;
 715         else
 716                 ret = !ext3_test_bit(nr, jh->b_committed_data);
 717         jbd_unlock_bh_state(bh);
 718         return ret;
 719 }
 720
 721 /**
 722  * bitmap_search_next_usable_block()
 723  * @start:              the starting block (group relative) of the search
 724  * @bh:                 bufferhead contains the block group bitmap
 725  * @maxblocks:          the ending block (group relative) of the reservation
 726  *
 727  * The bitmap search --- search forward alternately through the actual
 728  * bitmap on disk and the last-committed copy in journal, until we find a
 729  * bit free in both bitmaps.
 730  */
 731 static ext3_grpblk_t
 732 bitmap_search_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
 733                                         ext3_grpblk_t maxblocks)
 734 {
 735         ext3_grpblk_t next;
 736         struct journal_head *jh = bh2jh(bh);
 737
 738         while (start < maxblocks) {
 739                 next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
 740                 if (next >= maxblocks)
 741                         return -1;
 742                 if (ext3_test_allocatable(next, bh))
 743                         return next;
 744                 jbd_lock_bh_state(bh);
 745                 if (jh->b_committed_data)
 746                         start = ext3_find_next_zero_bit(jh->b_committed_data,
 747                                                         maxblocks, next);
 748                 jbd_unlock_bh_state(bh);
 749         }
 750         return -1;
 751 }
 752
 753 /**
 754  * find_next_usable_block()
 755  * @start:              the starting block (group relative) to find next
 756  *                      allocatable block in bitmap.
 757  * @bh:                 bufferhead contains the block group bitmap
 758  * @maxblocks:          the ending block (group relative) for the search
 759  *
 760  * Find an allocatable block in a bitmap.  We honor both the bitmap and
 761  * its last-committed copy (if that exists), and perform the "most
 762  * appropriate allocation" algorithm of looking for a free block near
 763  * the initial goal; then for a free byte somewhere in the bitmap; then
 764  * for any free bit in the bitmap.
 765  */
 766 static ext3_grpblk_t
 767 find_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
 768                         ext3_grpblk_t maxblocks)
 769 {
 770         ext3_grpblk_t here, next;
 771         char *p, *r;
 772
 773         if (start > 0) {
 774                 /*
 775                  * The goal was occupied; search forward for a free
 776                  * block within the next XX blocks.
 777                  *
 778                  * end_goal is more or less random, but it has to be
 779                  * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the
 780                  * next 64-bit boundary is simple..
 781                  */
 782                 ext3_grpblk_t end_goal = (start + 63) & ~63;
 783                 if (end_goal > maxblocks)
 784                         end_goal = maxblocks;
 785                 here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
 786                 if (here < end_goal && ext3_test_allocatable(here, bh))
 787                         return here;
 788                 ext3_debug("Bit not found near goal\n");
 789         }
 790
 791         here = start;
 792         if (here < 0)
 793                 here = 0;
 794
 795         p = ((char *)bh->b_data) + (here >> 3);
 796         r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
 797         next = (r - ((char *)bh->b_data)) << 3;
 798
 799         if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))
 800                 return next;
 801
 802         /*
 803          * The bitmap search --- search forward alternately through the actual
 804          * bitmap and the last-committed copy until we find a bit free in
 805          * both
 806          */
 807         here = bitmap_search_next_usable_block(here, bh, maxblocks);
 808         return here;
 809 }
 810
 811 /**
 812  * claim_block()
 813  * @block:              the free block (group relative) to allocate
 814  * @bh:                 the bufferhead containts the block group bitmap
 815  *
 816  * We think we can allocate this block in this bitmap.  Try to set the bit.
 817  * If that succeeds then check that nobody has allocated and then freed the
 818  * block since we saw that is was not marked in b_committed_data.  If it _was_
 819  * allocated and freed then clear the bit in the bitmap again and return
 820  * zero (failure).
 821  */
 822 static inline int
 823 claim_block(spinlock_t *lock, ext3_grpblk_t block, struct buffer_head *bh)
 824 {
 825         struct journal_head *jh = bh2jh(bh);
 826         int ret;
 827
 828         if (ext3_set_bit_atomic(lock, block, bh->b_data))
 829                 return 0;
 830         jbd_lock_bh_state(bh);
 831         if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) {
 832                 ext3_clear_bit_atomic(lock, block, bh->b_data);
 833                 ret = 0;
 834         } else {
 835                 ret = 1;
 836         }
 837         jbd_unlock_bh_state(bh);
 838         return ret;
 839 }
 840
 841 /**
 842  * ext3_try_to_allocate()
 843  * @sb:                 superblock
 844  * @handle:             handle to this transaction
 845  * @group:              given allocation block group
 846  * @bitmap_bh:          bufferhead holds the block bitmap
 847  * @grp_goal:           given target block within the group
 848  * @count:              target number of blocks to allocate
 849  * @my_rsv:             reservation window
 850  *
 851  * Attempt to allocate blocks within a give range. Set the range of allocation
 852  * first, then find the first free bit(s) from the bitmap (within the range),
 853  * and at last, allocate the blocks by claiming the found free bit as allocated.
 854  *
 855  * To set the range of this allocation:
 856  *      if there is a reservation window, only try to allocate block(s) from the
 857  *      file's own reservation window;
 858  *      Otherwise, the allocation range starts from the give goal block, ends at
 859  *      the block group's last block.
 860  *
 861  * If we failed to allocate the desired block then we may end up crossing to a
 862  * new bitmap.  In that case we must release write access to the old one via
 863  * ext3_journal_release_buffer(), else we'll run out of credits.
 864  */
 865 static ext3_grpblk_t
 866 ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
 867                         struct buffer_head *bitmap_bh, ext3_grpblk_t grp_goal,
 868                         unsigned long *count, struct ext3_reserve_window *my_rsv)
 869 {
 870         ext3_fsblk_t group_first_block;
 871         ext3_grpblk_t start, end;
 872         unsigned long num = 0;
 873
 874         /* we do allocation within the reservation window if we have a window */
 875         if (my_rsv) {
 876                 group_first_block = ext3_group_first_block_no(sb, group);
 877                 if (my_rsv->_rsv_start >= group_first_block)
 878                         start = my_rsv->_rsv_start - group_first_block;
 879                 else
 880                         /* reservation window cross group boundary */
 881                         start = 0;
 882                 end = my_rsv->_rsv_end - group_first_block + 1;
 883                 if (end > EXT3_BLOCKS_PER_GROUP(sb))
 884                         /* reservation window crosses group boundary */
 885                         end = EXT3_BLOCKS_PER_GROUP(sb);
 886                 if ((start <= grp_goal) && (grp_goal < end))
 887                         start = grp_goal;
 888                 else
 889                         grp_goal = -1;
 890         } else {
 891                 if (grp_goal > 0)
 892                         start = grp_goal;
 893                 else
 894                         start = 0;
 895                 end = EXT3_BLOCKS_PER_GROUP(sb);
 896         }
 897
 898         BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
 899
 900 repeat:
 901         if (grp_goal < 0 || !ext3_test_allocatable(grp_goal, bitmap_bh)) {
 902                 grp_goal = find_next_usable_block(start, bitmap_bh, end);
 903                 if (grp_goal < 0)
 904                         goto fail_access;
 905                 if (!my_rsv) {
 906                         int i;
 907
 908                         for (i = 0; i < 7 && grp_goal > start &&
 909                                         ext3_test_allocatable(grp_goal - 1,
 910                                                                 bitmap_bh);
 911                                         i++, grp_goal--)
 912                                 ;
 913                 }
 914         }
 915         start = grp_goal;
 916
 917         if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group),
 918                 grp_goal, bitmap_bh)) {
 919                 /*
 920                  * The block was allocated by another thread, or it was
 921                  * allocated and then freed by another thread
 922                  */
 923                 start++;
 924                 grp_goal++;
 925                 if (start >= end)
 926                         goto fail_access;
 927                 goto repeat;
 928         }
 929         num++;
 930         grp_goal++;
 931         while (num < *count && grp_goal < end
 932                 && ext3_test_allocatable(grp_goal, bitmap_bh)
 933                 && claim_block(sb_bgl_lock(EXT3_SB(sb), group),
 934                                 grp_goal, bitmap_bh)) {
 935                 num++;
 936                 grp_goal++;
 937         }
 938         *count = num;
 939         return grp_goal - num;
 940 fail_access:
 941         *count = num;
 942         return -1;
 943 }
 944
 945 /**
 946  *      find_next_reservable_window():
 947  *              find a reservable space within the given range.
 948  *              It does not allocate the reservation window for now:
 949  *              alloc_new_reservation() will do the work later.
 950  *
 951  *      @search_head: the head of the searching list;
 952  *              This is not necessarily the list head of the whole filesystem
 953  *
 954  *              We have both head and start_block to assist the search
 955  *              for the reservable space. The list starts from head,
 956  *              but we will shift to the place where start_block is,
 957  *              then start from there, when looking for a reservable space.
 958  *
 959  *      @size: the target new reservation window size
 960  *
 961  *      @group_first_block: the first block we consider to start
 962  *                      the real search from
 963  *
 964  *      @last_block:
 965  *              the maximum block number that our goal reservable space
 966  *              could start from. This is normally the last block in this
 967  *              group. The search will end when we found the start of next
 968  *              possible reservable space is out of this boundary.
 969  *              This could handle the cross boundary reservation window
 970  *              request.
 971  *
 972  *      basically we search from the given range, rather than the whole
 973  *      reservation double linked list, (start_block, last_block)
 974  *      to find a free region that is of my size and has not
 975  *      been reserved.
 976  *
 977  */
 978 static int find_next_reservable_window(
 979                                 struct ext3_reserve_window_node *search_head,
 980                                 struct ext3_reserve_window_node *my_rsv,
 981                                 struct super_block * sb,
 982                                 ext3_fsblk_t start_block,
 983                                 ext3_fsblk_t last_block)
 984 {
 985         struct rb_node *next;
 986         struct ext3_reserve_window_node *rsv, *prev;
 987         ext3_fsblk_t cur;
 988         int size = my_rsv->rsv_goal_size;
 989
 990         /* TODO: make the start of the reservation window byte-aligned */
 991         /* cur = *start_block & ~7;*/
 992         cur = start_block;
 993         rsv = search_head;
 994         if (!rsv)
 995                 return -1;
 996
 997         while (1) {
 998                 if (cur <= rsv->rsv_end)
 999                         cur = rsv->rsv_end + 1;
1000
1001                 /* TODO?
1002                  * in the case we could not find a reservable space
1003                  * that is what is expected, during the re-search, we could
1004                  * remember what's the largest reservable space we could have
1005                  * and return that one.
1006                  *
1007                  * For now it will fail if we could not find the reservable
1008                  * space with expected-size (or more)...
1009                  */
1010                 if (cur > last_block)
1011                         return -1;              /* fail */
1012
1013                 prev = rsv;
1014                 next = rb_next(&rsv->rsv_node);
1015                 rsv = rb_entry(next,struct ext3_reserve_window_node,rsv_node);
1016
1017                 /*
1018                  * Reached the last reservation, we can just append to the
1019                  * previous one.
1020                  */
1021                 if (!next)
1022                         break;
1023
1024                 if (cur + size <= rsv->rsv_start) {
1025                         /*
1026                          * Found a reserveable space big enough.  We could
1027                          * have a reservation across the group boundary here
1028                          */
1029                         break;
1030                 }
1031         }
1032         /*
1033          * we come here either :
1034          * when we reach the end of the whole list,
1035          * and there is empty reservable space after last entry in the list.
1036          * append it to the end of the list.
1037          *
1038          * or we found one reservable space in the middle of the list,
1039          * return the reservation window that we could append to.
1040          * succeed.
1041          */
1042
1043         if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
1044                 rsv_window_remove(sb, my_rsv);
1045
1046         /*
1047          * Let's book the whole avaliable window for now.  We will check the
1048          * disk bitmap later and then, if there are free blocks then we adjust
1049          * the window size if it's larger than requested.
1050          * Otherwise, we will remove this node from the tree next time
1051          * call find_next_reservable_window.
1052          */
1053         my_rsv->rsv_start = cur;
1054         my_rsv->rsv_end = cur + size - 1;
1055         my_rsv->rsv_alloc_hit = 0;
1056
1057         if (prev != my_rsv)
1058                 ext3_rsv_window_add(sb, my_rsv);
1059
1060         return 0;
1061 }
1062
1063 /**
1064  *      alloc_new_reservation()--allocate a new reservation window
1065  *
1066  *              To make a new reservation, we search part of the filesystem
1067  *              reservation list (the list that inside the group). We try to
1068  *              allocate a new reservation window near the allocation goal,
1069  *              or the beginning of the group, if there is no goal.
1070  *
1071  *              We first find a reservable space after the goal, then from
1072  *              there, we check the bitmap for the first free block after
1073  *              it. If there is no free block until the end of group, then the
1074  *              whole group is full, we failed. Otherwise, check if the free
1075  *              block is inside the expected reservable space, if so, we
1076  *              succeed.
1077  *              If the first free block is outside the reservable space, then
1078  *              start from the first free block, we search for next available
1079  *              space, and go on.
1080  *
1081  *      on succeed, a new reservation will be found and inserted into the list
1082  *      It contains at least one free block, and it does not overlap with other
1083  *      reservation windows.
1084  *
1085  *      failed: we failed to find a reservation window in this group
1086  *
1087  *      @rsv: the reservation
1088  *
1089  *      @grp_goal: The goal (group-relative).  It is where the search for a
1090  *              free reservable space should start from.
1091  *              if we have a grp_goal(grp_goal >0 ), then start from there,
1092  *              no grp_goal(grp_goal = -1), we start from the first block
1093  *              of the group.
1094  *
1095  *      @sb: the super block
1096  *      @group: the group we are trying to allocate in
1097  *      @bitmap_bh: the block group block bitmap
1098  *
1099  */
1100 static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
1101                 ext3_grpblk_t grp_goal, struct super_block *sb,
1102                 unsigned int group, struct buffer_head *bitmap_bh)
1103 {
1104         struct ext3_reserve_window_node *search_head;
1105         ext3_fsblk_t group_first_block, group_end_block, start_block;
1106         ext3_grpblk_t first_free_block;
1107         struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
1108         unsigned long size;
1109         int ret;
1110         spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1111
1112         group_first_block = ext3_group_first_block_no(sb, group);
1113         group_end_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
1114
1115         if (grp_goal < 0)
1116                 start_block = group_first_block;
1117         else
1118                 start_block = grp_goal + group_first_block;
1119
1120         size = my_rsv->rsv_goal_size;
1121
1122         if (!rsv_is_empty(&my_rsv->rsv_window)) {
1123                 /*
1124                  * if the old reservation is cross group boundary
1125                  * and if the goal is inside the old reservation window,
1126                  * we will come here when we just failed to allocate from
1127                  * the first part of the window. We still have another part
1128                  * that belongs to the next group. In this case, there is no
1129                  * point to discard our window and try to allocate a new one
1130                  * in this group(which will fail). we should
1131                  * keep the reservation window, just simply move on.
1132                  *
1133                  * Maybe we could shift the start block of the reservation
1134                  * window to the first block of next group.
1135                  */
1136
1137                 if ((my_rsv->rsv_start <= group_end_block) &&
1138                                 (my_rsv->rsv_end > group_end_block) &&
1139                                 (start_block >= my_rsv->rsv_start))
1140                         return -1;
1141
1142                 if ((my_rsv->rsv_alloc_hit >
1143                      (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
1144                         /*
1145                          * if the previously allocation hit ratio is
1146                          * greater than 1/2, then we double the size of
1147                          * the reservation window the next time,
1148                          * otherwise we keep the same size window
1149                          */
1150                         size = size * 2;
1151                         if (size > EXT3_MAX_RESERVE_BLOCKS)
1152                                 size = EXT3_MAX_RESERVE_BLOCKS;
1153                         my_rsv->rsv_goal_size= size;
1154                 }
1155         }
1156
1157         spin_lock(rsv_lock);
1158         /*
1159          * shift the search start to the window near the goal block
1160          */
1161         search_head = search_reserve_window(fs_rsv_root, start_block);
1162
1163         /*
1164          * find_next_reservable_window() simply finds a reservable window
1165          * inside the given range(start_block, group_end_block).
1166          *
1167          * To make sure the reservation window has a free bit inside it, we
1168          * need to check the bitmap after we found a reservable window.
1169          */
1170 retry:
1171         ret = find_next_reservable_window(search_head, my_rsv, sb,
1172                                                 start_block, group_end_block);
1173
1174         if (ret == -1) {
1175                 if (!rsv_is_empty(&my_rsv->rsv_window))
1176                         rsv_window_remove(sb, my_rsv);
1177                 spin_unlock(rsv_lock);
1178                 return -1;
1179         }
1180
1181         /*
1182          * On success, find_next_reservable_window() returns the
1183          * reservation window where there is a reservable space after it.
1184          * Before we reserve this reservable space, we need
1185          * to make sure there is at least a free block inside this region.
1186          *
1187          * searching the first free bit on the block bitmap and copy of
1188          * last committed bitmap alternatively, until we found a allocatable
1189          * block. Search start from the start block of the reservable space
1190          * we just found.
1191          */
1192         spin_unlock(rsv_lock);
1193         first_free_block = bitmap_search_next_usable_block(
1194                         my_rsv->rsv_start - group_first_block,
1195                         bitmap_bh, group_end_block - group_first_block + 1);
1196
1197         if (first_free_block < 0) {
1198                 /*
1199                  * no free block left on the bitmap, no point
1200                  * to reserve the space. return failed.
1201                  */
1202                 spin_lock(rsv_lock);
1203                 if (!rsv_is_empty(&my_rsv->rsv_window))
1204                         rsv_window_remove(sb, my_rsv);
1205                 spin_unlock(rsv_lock);
1206                 return -1;              /* failed */
1207         }
1208
1209         start_block = first_free_block + group_first_block;
1210         /*
1211          * check if the first free block is within the
1212          * free space we just reserved
1213          */
1214         if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
1215                 return 0;               /* success */
1216         /*
1217          * if the first free bit we found is out of the reservable space
1218          * continue search for next reservable space,
1219          * start from where the free block is,
1220          * we also shift the list head to where we stopped last time
1221          */
1222         search_head = my_rsv;
1223         spin_lock(rsv_lock);
1224         goto retry;
1225 }
1226
1227 /**
1228  * try_to_extend_reservation()
1229  * @my_rsv:             given reservation window
1230  * @sb:                 super block
1231  * @size:               the delta to extend
1232  *
1233  * Attempt to expand the reservation window large enough to have
1234  * required number of free blocks
1235  *
1236  * Since ext3_try_to_allocate() will always allocate blocks within
1237  * the reservation window range, if the window size is too small,
1238  * multiple blocks allocation has to stop at the end of the reservation
1239  * window. To make this more efficient, given the total number of
1240  * blocks needed and the current size of the window, we try to
1241  * expand the reservation window size if necessary on a best-effort
1242  * basis before ext3_new_blocks() tries to allocate blocks,
1243  */
1244 static void try_to_extend_reservation(struct ext3_reserve_window_node *my_rsv,
1245                         struct super_block *sb, int size)
1246 {
1247         struct ext3_reserve_window_node *next_rsv;
1248         struct rb_node *next;
1249         spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1250
1251         if (!spin_trylock(rsv_lock))
1252                 return;
1253
1254         next = rb_next(&my_rsv->rsv_node);
1255
1256         if (!next)
1257                 my_rsv->rsv_end += size;
1258         else {
1259                 next_rsv = rb_entry(next, struct ext3_reserve_window_node, rsv_node);
1260
1261                 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1262                         my_rsv->rsv_end += size;
1263                 else
1264                         my_rsv->rsv_end = next_rsv->rsv_start - 1;
1265         }
1266         spin_unlock(rsv_lock);
1267 }
1268
1269 /**
1270  * ext3_try_to_allocate_with_rsv()
1271  * @sb:                 superblock
1272  * @handle:             handle to this transaction
1273  * @group:              given allocation block group
1274  * @bitmap_bh:          bufferhead holds the block bitmap
1275  * @grp_goal:           given target block within the group
1276  * @count:              target number of blocks to allocate
1277  * @my_rsv:             reservation window
1278  * @errp:               pointer to store the error code
1279  *
1280  * This is the main function used to allocate a new block and its reservation
1281  * window.
1282  *
1283  * Each time when a new block allocation is need, first try to allocate from
1284  * its own reservation.  If it does not have a reservation window, instead of
1285  * looking for a free bit on bitmap first, then look up the reservation list to
1286  * see if it is inside somebody else's reservation window, we try to allocate a
1287  * reservation window for it starting from the goal first. Then do the block
1288  * allocation within the reservation window.
1289  *
1290  * This will avoid keeping on searching the reservation list again and
1291  * again when somebody is looking for a free block (without
1292  * reservation), and there are lots of free blocks, but they are all
1293  * being reserved.
1294  *
1295  * We use a red-black tree for the per-filesystem reservation list.
1296  *
1297  */
1298 static ext3_grpblk_t
1299 ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
1300                         unsigned int group, struct buffer_head *bitmap_bh,
1301                         ext3_grpblk_t grp_goal,
1302                         struct ext3_reserve_window_node * my_rsv,
1303                         unsigned long *count, int *errp)
1304 {
1305         ext3_fsblk_t group_first_block, group_last_block;
1306         ext3_grpblk_t ret = 0;
1307         int fatal;
1308         unsigned long num = *count;
1309
1310         *errp = 0;
1311
1312         /*
1313          * Make sure we use undo access for the bitmap, because it is critical
1314          * that we do the frozen_data COW on bitmap buffers in all cases even
1315          * if the buffer is in BJ_Forget state in the committing transaction.
1316          */
1317         BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1318         fatal = ext3_journal_get_undo_access(handle, bitmap_bh);
1319         if (fatal) {
1320                 *errp = fatal;
1321                 return -1;
1322         }
1323
1324         /*
1325          * we don't deal with reservation when
1326          * filesystem is mounted without reservation
1327          * or the file is not a regular file
1328          * or last attempt to allocate a block with reservation turned on failed
1329          */
1330         if (my_rsv == NULL ) {
1331                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh,
1332                                                 grp_goal, count, NULL);
1333                 goto out;
1334         }
1335         /*
1336          * grp_goal is a group relative block number (if there is a goal)
1337          * 0 <= grp_goal < EXT3_BLOCKS_PER_GROUP(sb)
1338          * first block is a filesystem wide block number
1339          * first block is the block number of the first block in this group
1340          */
1341         group_first_block = ext3_group_first_block_no(sb, group);
1342         group_last_block = group_first_block + (EXT3_BLOCKS_PER_GROUP(sb) - 1);
1343
1344         /*
1345          * Basically we will allocate a new block from inode's reservation
1346          * window.
1347          *
1348          * We need to allocate a new reservation window, if:
1349          * a) inode does not have a reservation window; or
1350          * b) last attempt to allocate a block from existing reservation
1351          *    failed; or
1352          * c) we come here with a goal and with a reservation window
1353          *
1354          * We do not need to allocate a new reservation window if we come here
1355          * at the beginning with a goal and the goal is inside the window, or
1356          * we don't have a goal but already have a reservation window.
1357          * then we could go to allocate from the reservation window directly.
1358          */
1359         while (1) {
1360                 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1361                         !goal_in_my_reservation(&my_rsv->rsv_window,
1362                                                 grp_goal, group, sb)) {
1363                         if (my_rsv->rsv_goal_size < *count)
1364                                 my_rsv->rsv_goal_size = *count;
1365                         ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1366                                                         group, bitmap_bh);
1367                         if (ret < 0)
1368                                 break;                  /* failed */
1369
1370                         if (!goal_in_my_reservation(&my_rsv->rsv_window,
1371                                                         grp_goal, group, sb))
1372                                 grp_goal = -1;
1373                 } else if (grp_goal >= 0) {
1374                         int curr = my_rsv->rsv_end -
1375                                         (grp_goal + group_first_block) + 1;
1376
1377                         if (curr < *count)
1378                                 try_to_extend_reservation(my_rsv, sb,
1379                                                         *count - curr);
1380                 }
1381
1382                 if ((my_rsv->rsv_start > group_last_block) ||
1383                                 (my_rsv->rsv_end < group_first_block)) {
1384                         rsv_window_dump(&EXT3_SB(sb)->s_rsv_window_root, 1);
1385                         BUG();
1386                 }
1387                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh,
1388                                            grp_goal, &num, &my_rsv->rsv_window);
1389                 if (ret >= 0) {
1390                         my_rsv->rsv_alloc_hit += num;
1391                         *count = num;
1392                         break;                          /* succeed */
1393                 }
1394                 num = *count;
1395         }
1396 out:
1397         if (ret >= 0) {
1398                 BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1399                                         "bitmap block");
1400                 fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
1401                 if (fatal) {
1402                         *errp = fatal;
1403                         return -1;
1404                 }
1405                 return ret;
1406         }
1407
1408         BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1409         ext3_journal_release_buffer(handle, bitmap_bh);
1410         return ret;
1411 }
1412
1413 /**
1414  * ext3_has_free_blocks()
1415  * @sbi:                in-core super block structure.
1416  *
1417  * Check if filesystem has at least 1 free block available for allocation.
1418  */
1419 static int ext3_has_free_blocks(struct ext3_sb_info *sbi)
1420 {
1421         ext3_fsblk_t free_blocks, root_blocks;
1422
1423         free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1424         root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1425         if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1426                 sbi->s_resuid != current_fsuid() &&
1427                 (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
1428                 return 0;
1429         }
1430         return 1;
1431 }
1432
1433 /**
1434  * ext3_should_retry_alloc()
1435  * @sb:                 super block
1436  * @retries             number of attemps has been made
1437  *
1438  * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
1439  * it is profitable to retry the operation, this function will wait
1440  * for the current or commiting transaction to complete, and then
1441  * return TRUE.
1442  *
1443  * if the total number of retries exceed three times, return FALSE.
1444  */
1445 int ext3_should_retry_alloc(struct super_block *sb, int *retries)
1446 {
1447         if (!ext3_has_free_blocks(EXT3_SB(sb)) || (*retries)++ > 3)
1448                 return 0;
1449
1450         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1451
1452         return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
1453 }
1454
1455 /**
1456  * ext3_new_blocks() -- core block(s) allocation function
1457  * @handle:             handle to this transaction
1458  * @inode:              file inode
1459  * @goal:               given target block(filesystem wide)
1460  * @count:              target number of blocks to allocate
1461  * @errp:               error code
1462  *
1463  * ext3_new_blocks uses a goal block to assist allocation.  It tries to
1464  * allocate block(s) from the block group contains the goal block first. If that
1465  * fails, it will try to allocate block(s) from other block groups without
1466  * any specific goal block.
1467  *
1468  */
1469 ext3_fsblk_t ext3_new_blocks(handle_t *handle, struct inode *inode,
1470                         ext3_fsblk_t goal, unsigned long *count, int *errp)
1471 {
1472         struct buffer_head *bitmap_bh = NULL;
1473         struct buffer_head *gdp_bh;
1474         int group_no;
1475         int goal_group;
1476         ext3_grpblk_t grp_target_blk;   /* blockgroup relative goal block */
1477         ext3_grpblk_t grp_alloc_blk;    /* blockgroup-relative allocated block*/
1478         ext3_fsblk_t ret_block;         /* filesyetem-wide allocated block */
1479         int bgi;                        /* blockgroup iteration index */
1480         int fatal = 0, err;
1481         int performed_allocation = 0;
1482         ext3_grpblk_t free_blocks;      /* number of free blocks in a group */
1483         struct super_block *sb;
1484         struct ext3_group_desc *gdp;
1485         struct ext3_super_block *es;
1486         struct ext3_sb_info *sbi;
1487         struct ext3_reserve_window_node *my_rsv = NULL;
1488         struct ext3_block_alloc_info *block_i;
1489         unsigned short windowsz = 0;
1490 #ifdef EXT3FS_DEBUG
1491         static int goal_hits, goal_attempts;
1492 #endif
1493         unsigned long ngroups;
1494         unsigned long num = *count;
1495
1496         *errp = -ENOSPC;
1497         sb = inode->i_sb;
1498         if (!sb) {
1499                 printk("ext3_new_block: nonexistent device");
1500                 return 0;
1501         }
1502
1503         /*
1504          * Check quota for allocation of this block.
1505          */
1506         err = dquot_alloc_block(inode, num);
1507         if (err) {
1508                 *errp = err;
1509                 return 0;
1510         }
1511
1512         sbi = EXT3_SB(sb);
1513         es = EXT3_SB(sb)->s_es;
1514         ext3_debug("goal=%lu.\n", goal);
1515         /*
1516          * Allocate a block from reservation only when
1517          * filesystem is mounted with reservation(default,-o reservation), and
1518          * it's a regular file, and
1519          * the desired window size is greater than 0 (One could use ioctl
1520          * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
1521          * reservation on that particular file)
1522          */
1523         block_i = EXT3_I(inode)->i_block_alloc_info;
1524         if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
1525                 my_rsv = &block_i->rsv_window_node;
1526
1527         if (!ext3_has_free_blocks(sbi)) {
1528                 *errp = -ENOSPC;
1529                 goto out;
1530         }
1531
1532         /*
1533          * First, test whether the goal block is free.
1534          */
1535         if (goal < le32_to_cpu(es->s_first_data_block) ||
1536             goal >= le32_to_cpu(es->s_blocks_count))
1537                 goal = le32_to_cpu(es->s_first_data_block);
1538         group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1539                         EXT3_BLOCKS_PER_GROUP(sb);
1540         goal_group = group_no;
1541 retry_alloc:
1542         gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1543         if (!gdp)
1544                 goto io_error;
1545
1546         free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1547         /*
1548          * if there is not enough free blocks to make a new resevation
1549          * turn off reservation for this allocation
1550          */
1551         if (my_rsv && (free_blocks < windowsz)
1552                 && (free_blocks > 0)
1553                 && (rsv_is_empty(&my_rsv->rsv_window)))
1554                 my_rsv = NULL;
1555
1556         if (free_blocks > 0) {
1557                 grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1558                                 EXT3_BLOCKS_PER_GROUP(sb));
1559                 bitmap_bh = read_block_bitmap(sb, group_no);
1560                 if (!bitmap_bh)
1561                         goto io_error;
1562                 grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
1563                                         group_no, bitmap_bh, grp_target_blk,
1564                                         my_rsv, &num, &fatal);
1565                 if (fatal)
1566                         goto out;
1567                 if (grp_alloc_blk >= 0)
1568                         goto allocated;
1569         }
1570
1571         ngroups = EXT3_SB(sb)->s_groups_count;
1572         smp_rmb();
1573
1574         /*
1575          * Now search the rest of the groups.  We assume that
1576          * group_no and gdp correctly point to the last group visited.
1577          */
1578         for (bgi = 0; bgi < ngroups; bgi++) {
1579                 group_no++;
1580                 if (group_no >= ngroups)
1581                         group_no = 0;
1582                 gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1583                 if (!gdp)
1584                         goto io_error;
1585                 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1586                 /*
1587                  * skip this group (and avoid loading bitmap) if there
1588                  * are no free blocks
1589                  */
1590                 if (!free_blocks)
1591                         continue;
1592                 /*
1593                  * skip this group if the number of
1594                  * free blocks is less than half of the reservation
1595                  * window size.
1596                  */
1597                 if (my_rsv && (free_blocks <= (windowsz/2)))
1598                         continue;
1599
1600                 brelse(bitmap_bh);
1601                 bitmap_bh = read_block_bitmap(sb, group_no);
1602                 if (!bitmap_bh)
1603                         goto io_error;
1604                 /*
1605                  * try to allocate block(s) from this group, without a goal(-1).
1606                  */
1607                 grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
1608                                         group_no, bitmap_bh, -1, my_rsv,
1609                                         &num, &fatal);
1610                 if (fatal)
1611                         goto out;
1612                 if (grp_alloc_blk >= 0)
1613                         goto allocated;
1614         }
1615         /*
1616          * We may end up a bogus ealier ENOSPC error due to
1617          * filesystem is "full" of reservations, but
1618          * there maybe indeed free blocks avaliable on disk
1619          * In this case, we just forget about the reservations
1620          * just do block allocation as without reservations.
1621          */
1622         if (my_rsv) {
1623                 my_rsv = NULL;
1624                 windowsz = 0;
1625                 group_no = goal_group;
1626                 goto retry_alloc;
1627         }
1628         /* No space left on the device */
1629         *errp = -ENOSPC;
1630         goto out;
1631
1632 allocated:
1633
1634         ext3_debug("using block group %d(%d)\n",
1635                         group_no, gdp->bg_free_blocks_count);
1636
1637         BUFFER_TRACE(gdp_bh, "get_write_access");
1638         fatal = ext3_journal_get_write_access(handle, gdp_bh);
1639         if (fatal)
1640                 goto out;
1641
1642         ret_block = grp_alloc_blk + ext3_group_first_block_no(sb, group_no);
1643
1644         if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1645             in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1646             in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1647                       EXT3_SB(sb)->s_itb_per_group) ||
1648             in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1649                       EXT3_SB(sb)->s_itb_per_group)) {
1650                 ext3_error(sb, "ext3_new_block",
1651                             "Allocating block in system zone - "
1652                             "blocks from "E3FSBLK", length %lu",
1653                              ret_block, num);
1654                 /*
1655                  * claim_block() marked the blocks we allocated as in use. So we
1656                  * may want to selectively mark some of the blocks as free.
1657                  */
1658                 goto retry_alloc;
1659         }
1660
1661         performed_allocation = 1;
1662
1663 #ifdef CONFIG_JBD_DEBUG
1664         {
1665                 struct buffer_head *debug_bh;
1666
1667                 /* Record bitmap buffer state in the newly allocated block */
1668                 debug_bh = sb_find_get_block(sb, ret_block);
1669                 if (debug_bh) {
1670                         BUFFER_TRACE(debug_bh, "state when allocated");
1671                         BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1672                         brelse(debug_bh);
1673                 }
1674         }
1675         jbd_lock_bh_state(bitmap_bh);
1676         spin_lock(sb_bgl_lock(sbi, group_no));
1677         if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1678                 int i;
1679
1680                 for (i = 0; i < num; i++) {
1681                         if (ext3_test_bit(grp_alloc_blk+i,
1682                                         bh2jh(bitmap_bh)->b_committed_data)) {
1683                                 printk("%s: block was unexpectedly set in "
1684                                         "b_committed_data\n", __func__);
1685                         }
1686                 }
1687         }
1688         ext3_debug("found bit %d\n", grp_alloc_blk);
1689         spin_unlock(sb_bgl_lock(sbi, group_no));
1690         jbd_unlock_bh_state(bitmap_bh);
1691 #endif
1692
1693         if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1694                 ext3_error(sb, "ext3_new_block",
1695                             "block("E3FSBLK") >= blocks count(%d) - "
1696                             "block_group = %d, es == %p ", ret_block,
1697                         le32_to_cpu(es->s_blocks_count), group_no, es);
1698                 goto out;
1699         }
1700
1701         /*
1702          * It is up to the caller to add the new buffer to a journal
1703          * list of some description.  We don't know in advance whether
1704          * the caller wants to use it as metadata or data.
1705          */
1706         ext3_debug("allocating block %lu. Goal hits %d of %d.\n",
1707                         ret_block, goal_hits, goal_attempts);
1708
1709         spin_lock(sb_bgl_lock(sbi, group_no));
1710         le16_add_cpu(&gdp->bg_free_blocks_count, -num);
1711         spin_unlock(sb_bgl_lock(sbi, group_no));
1712         percpu_counter_sub(&sbi->s_freeblocks_counter, num);
1713
1714         BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1715         err = ext3_journal_dirty_metadata(handle, gdp_bh);
1716         if (!fatal)
1717                 fatal = err;
1718
1719         if (fatal)
1720                 goto out;
1721
1722         *errp = 0;
1723         brelse(bitmap_bh);
1724         dquot_free_block(inode, *count-num);
1725         *count = num;
1726         return ret_block;
1727
1728 io_error:
1729         *errp = -EIO;
1730 out:
1731         if (fatal) {
1732                 *errp = fatal;
1733                 ext3_std_error(sb, fatal);
1734         }
1735         /*
1736          * Undo the block allocation
1737          */
1738         if (!performed_allocation)
1739                 dquot_free_block(inode, *count);
1740         brelse(bitmap_bh);
1741         return 0;
1742 }
1743
1744 ext3_fsblk_t ext3_new_block(handle_t *handle, struct inode *inode,
1745                         ext3_fsblk_t goal, int *errp)
1746 {
1747         unsigned long count = 1;
1748
1749         return ext3_new_blocks(handle, inode, goal, &count, errp);
1750 }
1751
1752 /**
1753  * ext3_count_free_blocks() -- count filesystem free blocks
1754  * @sb:         superblock
1755  *
1756  * Adds up the number of free blocks from each block group.
1757  */
1758 ext3_fsblk_t ext3_count_free_blocks(struct super_block *sb)
1759 {
1760         ext3_fsblk_t desc_count;
1761         struct ext3_group_desc *gdp;
1762         int i;
1763         unsigned long ngroups = EXT3_SB(sb)->s_groups_count;
1764 #ifdef EXT3FS_DEBUG
1765         struct ext3_super_block *es;
1766         ext3_fsblk_t bitmap_count;
1767         unsigned long x;
1768         struct buffer_head *bitmap_bh = NULL;
1769
1770         es = EXT3_SB(sb)->s_es;
1771         desc_count = 0;
1772         bitmap_count = 0;
1773         gdp = NULL;
1774
1775         smp_rmb();
1776         for (i = 0; i < ngroups; i++) {
1777                 gdp = ext3_get_group_desc(sb, i, NULL);
1778                 if (!gdp)
1779                         continue;
1780                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1781                 brelse(bitmap_bh);
1782                 bitmap_bh = read_block_bitmap(sb, i);
1783                 if (bitmap_bh == NULL)
1784                         continue;
1785
1786                 x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1787                 printk("group %d: stored = %d, counted = %lu\n",
1788                         i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1789                 bitmap_count += x;
1790         }
1791         brelse(bitmap_bh);
1792         printk("ext3_count_free_blocks: stored = "E3FSBLK
1793                 ", computed = "E3FSBLK", "E3FSBLK"\n",
1794                le32_to_cpu(es->s_free_blocks_count),
1795                 desc_count, bitmap_count);
1796         return bitmap_count;
1797 #else
1798         desc_count = 0;
1799         smp_rmb();
1800         for (i = 0; i < ngroups; i++) {
1801                 gdp = ext3_get_group_desc(sb, i, NULL);
1802                 if (!gdp)
1803                         continue;
1804                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1805         }
1806
1807         return desc_count;
1808 #endif
1809 }
1810
1811 static inline int test_root(int a, int b)
1812 {
1813         int num = b;
1814
1815         while (a > num)
1816                 num *= b;
1817         return num == a;
1818 }
1819
1820 static int ext3_group_sparse(int group)
1821 {
1822         if (group <= 1)
1823                 return 1;
1824         if (!(group & 1))
1825                 return 0;
1826         return (test_root(group, 7) || test_root(group, 5) ||
1827                 test_root(group, 3));
1828 }
1829
1830 /**
1831  *      ext3_bg_has_super - number of blocks used by the superblock in group
1832  *      @sb: superblock for filesystem
1833  *      @group: group number to check
1834  *
1835  *      Return the number of blocks used by the superblock (primary or backup)
1836  *      in this group.  Currently this will be only 0 or 1.
1837  */
1838 int ext3_bg_has_super(struct super_block *sb, int group)
1839 {
1840         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
1841                                 EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1842                         !ext3_group_sparse(group))
1843                 return 0;
1844         return 1;
1845 }
1846
1847 static unsigned long ext3_bg_num_gdb_meta(struct super_block *sb, int group)
1848 {
1849         unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1850         unsigned long first = metagroup * EXT3_DESC_PER_BLOCK(sb);
1851         unsigned long last = first + EXT3_DESC_PER_BLOCK(sb) - 1;
1852
1853         if (group == first || group == first + 1 || group == last)
1854                 return 1;
1855         return 0;
1856 }
1857
1858 static unsigned long ext3_bg_num_gdb_nometa(struct super_block *sb, int group)
1859 {
1860         return ext3_bg_has_super(sb, group) ? EXT3_SB(sb)->s_gdb_count : 0;
1861 }
1862
1863 /**
1864  *      ext3_bg_num_gdb - number of blocks used by the group table in group
1865  *      @sb: superblock for filesystem
1866  *      @group: group number to check
1867  *
1868  *      Return the number of blocks used by the group descriptor table
1869  *      (primary or backup) in this group.  In the future there may be a
1870  *      different number of descriptor blocks in each group.
1871  */
1872 unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
1873 {
1874         unsigned long first_meta_bg =
1875                         le32_to_cpu(EXT3_SB(sb)->s_es->s_first_meta_bg);
1876         unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1877
1878         if (!EXT3_HAS_INCOMPAT_FEATURE(sb,EXT3_FEATURE_INCOMPAT_META_BG) ||
1879                         metagroup < first_meta_bg)
1880                 return ext3_bg_num_gdb_nometa(sb,group);
1881
1882         return ext3_bg_num_gdb_meta(sb,group);
1883
1884 }