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/config.h>
  15 #include <linux/time.h>
  16 #include <linux/fs.h>
  17 #include <linux/jbd.h>
  18 #include <linux/ext3_fs.h>
  19 #include <linux/ext3_jbd.h>
  20 #include <linux/quotaops.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/vs_base.h>
  23 #include <linux/vs_dlimit.h>
  24
  25 /*
  26  * balloc.c contains the blocks allocation and deallocation routines
  27  */
  28
  29 /*
  30  * The free blocks are managed by bitmaps.  A file system contains several
  31  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
  32  * block for inodes, N blocks for the inode table and data blocks.
  33  *
  34  * The file system contains group descriptors which are located after the
  35  * super block.  Each descriptor contains the number of the bitmap block and
  36  * the free blocks count in the block.  The descriptors are loaded in memory
  37  * when a file system is mounted (see ext3_read_super).
  38  */
  39
  40
  41 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
  42
  43 struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
  44                                              unsigned int block_group,
  45                                              struct buffer_head ** bh)
  46 {
  47         unsigned long group_desc;
  48         unsigned long desc;
  49         struct ext3_group_desc * gdp;
  50
  51         if (block_group >= EXT3_SB(sb)->s_groups_count) {
  52                 ext3_error (sb, "ext3_get_group_desc",
  53                             "block_group >= groups_count - "
  54                             "block_group = %d, groups_count = %lu",
  55                             block_group, EXT3_SB(sb)->s_groups_count);
  56
  57                 return NULL;
  58         }
  59         smp_rmb();
  60
  61         group_desc = block_group / EXT3_DESC_PER_BLOCK(sb);
  62         desc = block_group % EXT3_DESC_PER_BLOCK(sb);
  63         if (!EXT3_SB(sb)->s_group_desc[group_desc]) {
  64                 ext3_error (sb, "ext3_get_group_desc",
  65                             "Group descriptor not loaded - "
  66                             "block_group = %d, group_desc = %lu, desc = %lu",
  67                              block_group, group_desc, desc);
  68                 return NULL;
  69         }
  70
  71         gdp = (struct ext3_group_desc *)
  72               EXT3_SB(sb)->s_group_desc[group_desc]->b_data;
  73         if (bh)
  74                 *bh = EXT3_SB(sb)->s_group_desc[group_desc];
  75         return gdp + desc;
  76 }
  77
  78 /*
  79  * Read the bitmap for a given block_group, reading into the specified
  80  * slot in the superblock's bitmap cache.
  81  *
  82  * Return buffer_head on success or NULL in case of failure.
  83  */
  84 static struct buffer_head *
  85 read_block_bitmap(struct super_block *sb, unsigned int block_group)
  86 {
  87         struct ext3_group_desc * desc;
  88         struct buffer_head * bh = NULL;
  89
  90         desc = ext3_get_group_desc (sb, block_group, NULL);
  91         if (!desc)
  92                 goto error_out;
  93         bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
  94         if (!bh)
  95                 ext3_error (sb, "read_block_bitmap",
  96                             "Cannot read block bitmap - "
  97                             "block_group = %d, block_bitmap = %u",
  98                             block_group, le32_to_cpu(desc->bg_block_bitmap));
  99 error_out:
 100         return bh;
 101 }
 102 /*
 103  * The reservation window structure operations
 104  * --------------------------------------------
 105  * Operations include:
 106  * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
 107  *
 108  * We use sorted double linked list for the per-filesystem reservation
 109  * window list. (like in vm_region).
 110  *
 111  * Initially, we keep those small operations in the abstract functions,
 112  * so later if we need a better searching tree than double linked-list,
 113  * we could easily switch to that without changing too much
 114  * code.
 115  */
 116 #if 0
 117 static void __rsv_window_dump(struct rb_root *root, int verbose,
 118                               const char *fn)
 119 {
 120         struct rb_node *n;
 121         struct ext3_reserve_window_node *rsv, *prev;
 122         int bad;
 123
 124 restart:
 125         n = rb_first(root);
 126         bad = 0;
 127         prev = NULL;
 128
 129         printk("Block Allocation Reservation Windows Map (%s):\n", fn);
 130         while (n) {
 131                 rsv = list_entry(n, struct ext3_reserve_window_node, rsv_node);
 132                 if (verbose)
 133                         printk("reservation window 0x%p "
 134                                "start:  %d, end:  %d\n",
 135                                rsv, rsv->rsv_start, rsv->rsv_end);
 136                 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
 137                         printk("Bad reservation %p (start >= end)\n",
 138                                rsv);
 139                         bad = 1;
 140                 }
 141                 if (prev && prev->rsv_end >= rsv->rsv_start) {
 142                         printk("Bad reservation %p (prev->end >= start)\n",
 143                                rsv);
 144                         bad = 1;
 145                 }
 146                 if (bad) {
 147                         if (!verbose) {
 148                                 printk("Restarting reservation walk in verbose mode\n");
 149                                 verbose = 1;
 150                                 goto restart;
 151                         }
 152                 }
 153                 n = rb_next(n);
 154                 prev = rsv;
 155         }
 156         printk("Window map complete.\n");
 157         if (bad)
 158                 BUG();
 159 }
 160 #define rsv_window_dump(root, verbose) \
 161         __rsv_window_dump((root), (verbose), __FUNCTION__)
 162 #else
 163 #define rsv_window_dump(root, verbose) do {} while (0)
 164 #endif
 165
 166 static int
 167 goal_in_my_reservation(struct ext3_reserve_window *rsv, int goal,
 168                         unsigned int group, struct super_block * sb)
 169 {
 170         unsigned long group_first_block, group_last_block;
 171
 172         group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
 173                                 group * EXT3_BLOCKS_PER_GROUP(sb);
 174         group_last_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
 175
 176         if ((rsv->_rsv_start > group_last_block) ||
 177             (rsv->_rsv_end < group_first_block))
 178                 return 0;
 179         if ((goal >= 0) && ((goal + group_first_block < rsv->_rsv_start)
 180                 || (goal + group_first_block > rsv->_rsv_end)))
 181                 return 0;
 182         return 1;
 183 }
 184
 185 /*
 186  * Find the reserved window which includes the goal, or the previous one
 187  * if the goal is not in any window.
 188  * Returns NULL if there are no windows or if all windows start after the goal.
 189  */
 190 static struct ext3_reserve_window_node *
 191 search_reserve_window(struct rb_root *root, unsigned long goal)
 192 {
 193         struct rb_node *n = root->rb_node;
 194         struct ext3_reserve_window_node *rsv;
 195
 196         if (!n)
 197                 return NULL;
 198
 199         do {
 200                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 201
 202                 if (goal < rsv->rsv_start)
 203                         n = n->rb_left;
 204                 else if (goal > rsv->rsv_end)
 205                         n = n->rb_right;
 206                 else
 207                         return rsv;
 208         } while (n);
 209         /*
 210          * We've fallen off the end of the tree: the goal wasn't inside
 211          * any particular node.  OK, the previous node must be to one
 212          * side of the interval containing the goal.  If it's the RHS,
 213          * we need to back up one.
 214          */
 215         if (rsv->rsv_start > goal) {
 216                 n = rb_prev(&rsv->rsv_node);
 217                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 218         }
 219         return rsv;
 220 }
 221
 222 void ext3_rsv_window_add(struct super_block *sb,
 223                     struct ext3_reserve_window_node *rsv)
 224 {
 225         struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root;
 226         struct rb_node *node = &rsv->rsv_node;
 227         unsigned int start = rsv->rsv_start;
 228
 229         struct rb_node ** p = &root->rb_node;
 230         struct rb_node * parent = NULL;
 231         struct ext3_reserve_window_node *this;
 232
 233         while (*p)
 234         {
 235                 parent = *p;
 236                 this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node);
 237
 238                 if (start < this->rsv_start)
 239                         p = &(*p)->rb_left;
 240                 else if (start > this->rsv_end)
 241                         p = &(*p)->rb_right;
 242                 else
 243                         BUG();
 244         }
 245
 246         rb_link_node(node, parent, p);
 247         rb_insert_color(node, root);
 248 }
 249
 250 static void rsv_window_remove(struct super_block *sb,
 251                               struct ext3_reserve_window_node *rsv)
 252 {
 253         rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 254         rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 255         atomic_set(&rsv->rsv_alloc_hit, 0);
 256         rb_erase(&rsv->rsv_node, &EXT3_SB(sb)->s_rsv_window_root);
 257 }
 258
 259 static inline int rsv_is_empty(struct ext3_reserve_window *rsv)
 260 {
 261         /* a valid reservation end block could not be 0 */
 262         return (rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED);
 263 }
 264
 265 void ext3_discard_reservation(struct inode *inode)
 266 {
 267         struct ext3_inode_info *ei = EXT3_I(inode);
 268         struct ext3_reserve_window_node *rsv = &ei->i_rsv_window;
 269         spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
 270
 271         if (!rsv_is_empty(&rsv->rsv_window)) {
 272                 spin_lock(rsv_lock);
 273                 rsv_window_remove(inode->i_sb, rsv);
 274                 spin_unlock(rsv_lock);
 275         }
 276 }
 277
 278 /* Free given blocks, update quota and i_blocks field */
 279 void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,
 280                          unsigned long block, unsigned long count,
 281                          int *pdquot_freed_blocks)
 282 {
 283         struct buffer_head *bitmap_bh = NULL;
 284         struct buffer_head *gd_bh;
 285         unsigned long block_group;
 286         unsigned long bit;
 287         unsigned long i;
 288         unsigned long overflow;
 289         struct ext3_group_desc * gdp;
 290         struct ext3_super_block * es;
 291         struct ext3_sb_info *sbi;
 292         int err = 0, ret;
 293
 294         *pdquot_freed_blocks = 0;
 295         sbi = EXT3_SB(sb);
 296         es = EXT3_SB(sb)->s_es;
 297         if (block < le32_to_cpu(es->s_first_data_block) ||
 298             block + count < block ||
 299             block + count > le32_to_cpu(es->s_blocks_count)) {
 300                 ext3_error (sb, "ext3_free_blocks",
 301                             "Freeing blocks not in datazone - "
 302                             "block = %lu, count = %lu", block, count);
 303                 goto error_return;
 304         }
 305
 306         ext3_debug ("freeing block %lu\n", block);
 307
 308 do_more:
 309         overflow = 0;
 310         block_group = (block - le32_to_cpu(es->s_first_data_block)) /
 311                       EXT3_BLOCKS_PER_GROUP(sb);
 312         bit = (block - le32_to_cpu(es->s_first_data_block)) %
 313                       EXT3_BLOCKS_PER_GROUP(sb);
 314         /*
 315          * Check to see if we are freeing blocks across a group
 316          * boundary.
 317          */
 318         if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
 319                 overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
 320                 count -= overflow;
 321         }
 322         brelse(bitmap_bh);
 323         bitmap_bh = read_block_bitmap(sb, block_group);
 324         if (!bitmap_bh)
 325                 goto error_return;
 326         gdp = ext3_get_group_desc (sb, block_group, &gd_bh);
 327         if (!gdp)
 328                 goto error_return;
 329
 330         if (in_range (le32_to_cpu(gdp->bg_block_bitmap), block, count) ||
 331             in_range (le32_to_cpu(gdp->bg_inode_bitmap), block, count) ||
 332             in_range (block, le32_to_cpu(gdp->bg_inode_table),
 333                       EXT3_SB(sb)->s_itb_per_group) ||
 334             in_range (block + count - 1, le32_to_cpu(gdp->bg_inode_table),
 335                       EXT3_SB(sb)->s_itb_per_group))
 336                 ext3_error (sb, "ext3_free_blocks",
 337                             "Freeing blocks in system zones - "
 338                             "Block = %lu, count = %lu",
 339                             block, count);
 340
 341         /*
 342          * We are about to start releasing blocks in the bitmap,
 343          * so we need undo access.
 344          */
 345         /* @@@ check errors */
 346         BUFFER_TRACE(bitmap_bh, "getting undo access");
 347         err = ext3_journal_get_undo_access(handle, bitmap_bh, NULL);
 348         if (err)
 349                 goto error_return;
 350
 351         /*
 352          * We are about to modify some metadata.  Call the journal APIs
 353          * to unshare ->b_data if a currently-committing transaction is
 354          * using it
 355          */
 356         BUFFER_TRACE(gd_bh, "get_write_access");
 357         err = ext3_journal_get_write_access(handle, gd_bh);
 358         if (err)
 359                 goto error_return;
 360
 361         jbd_lock_bh_state(bitmap_bh);
 362
 363         for (i = 0; i < count; i++) {
 364                 /*
 365                  * An HJ special.  This is expensive...
 366                  */
 367 #ifdef CONFIG_JBD_DEBUG
 368                 jbd_unlock_bh_state(bitmap_bh);
 369                 {
 370                         struct buffer_head *debug_bh;
 371                         debug_bh = sb_find_get_block(sb, block + i);
 372                         if (debug_bh) {
 373                                 BUFFER_TRACE(debug_bh, "Deleted!");
 374                                 if (!bh2jh(bitmap_bh)->b_committed_data)
 375                                         BUFFER_TRACE(debug_bh,
 376                                                 "No commited data in bitmap");
 377                                 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
 378                                 __brelse(debug_bh);
 379                         }
 380                 }
 381                 jbd_lock_bh_state(bitmap_bh);
 382 #endif
 383                 /* @@@ This prevents newly-allocated data from being
 384                  * freed and then reallocated within the same
 385                  * transaction.
 386                  *
 387                  * Ideally we would want to allow that to happen, but to
 388                  * do so requires making journal_forget() capable of
 389                  * revoking the queued write of a data block, which
 390                  * implies blocking on the journal lock.  *forget()
 391                  * cannot block due to truncate races.
 392                  *
 393                  * Eventually we can fix this by making journal_forget()
 394                  * return a status indicating whether or not it was able
 395                  * to revoke the buffer.  On successful revoke, it is
 396                  * safe not to set the allocation bit in the committed
 397                  * bitmap, because we know that there is no outstanding
 398                  * activity on the buffer any more and so it is safe to
 399                  * reallocate it.
 400                  */
 401                 BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
 402                 J_ASSERT_BH(bitmap_bh,
 403                                 bh2jh(bitmap_bh)->b_committed_data != NULL);
 404                 ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
 405                                 bh2jh(bitmap_bh)->b_committed_data);
 406
 407                 /*
 408                  * We clear the bit in the bitmap after setting the committed
 409                  * data bit, because this is the reverse order to that which
 410                  * the allocator uses.
 411                  */
 412                 BUFFER_TRACE(bitmap_bh, "clear bit");
 413                 if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 414                                                 bit + i, bitmap_bh->b_data)) {
 415                         jbd_unlock_bh_state(bitmap_bh);
 416                         ext3_error(sb, __FUNCTION__,
 417                                 "bit already cleared for block %lu", block + i);
 418                         jbd_lock_bh_state(bitmap_bh);
 419                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
 420                 } else {
 421                         (*pdquot_freed_blocks)++;
 422                 }
 423         }
 424         jbd_unlock_bh_state(bitmap_bh);
 425
 426         spin_lock(sb_bgl_lock(sbi, block_group));
 427         gdp->bg_free_blocks_count =
 428                 cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) +
 429                         *pdquot_freed_blocks);
 430         spin_unlock(sb_bgl_lock(sbi, block_group));
 431         percpu_counter_mod(&sbi->s_freeblocks_counter, count);
 432
 433         /* We dirtied the bitmap block */
 434         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
 435         err = ext3_journal_dirty_metadata(handle, bitmap_bh);
 436
 437         /* And the group descriptor block */
 438         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
 439         ret = ext3_journal_dirty_metadata(handle, gd_bh);
 440         if (!err) err = ret;
 441
 442         if (overflow && !err) {
 443                 block += count;
 444                 count = overflow;
 445                 goto do_more;
 446         }
 447         sb->s_dirt = 1;
 448 error_return:
 449         brelse(bitmap_bh);
 450         ext3_std_error(sb, err);
 451         return;
 452 }
 453
 454 /* Free given blocks, update quota and i_blocks field */
 455 void ext3_free_blocks(handle_t *handle, struct inode *inode,
 456                         unsigned long block, unsigned long count)
 457 {
 458         struct super_block * sb;
 459         int dquot_freed_blocks;
 460
 461         sb = inode->i_sb;
 462         if (!sb) {
 463                 printk ("ext3_free_blocks: nonexistent device");
 464                 return;
 465         }
 466         ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
 467         if (dquot_freed_blocks) {
 468                 DLIMIT_FREE_BLOCK(sb, inode->i_xid, dquot_freed_blocks);
 469                 DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
 470         }
 471         return;
 472 }
 473
 474 /*
 475  * For ext3 allocations, we must not reuse any blocks which are
 476  * allocated in the bitmap buffer's "last committed data" copy.  This
 477  * prevents deletes from freeing up the page for reuse until we have
 478  * committed the delete transaction.
 479  *
 480  * If we didn't do this, then deleting something and reallocating it as
 481  * data would allow the old block to be overwritten before the
 482  * transaction committed (because we force data to disk before commit).
 483  * This would lead to corruption if we crashed between overwriting the
 484  * data and committing the delete.
 485  *
 486  * @@@ We may want to make this allocation behaviour conditional on
 487  * data-writes at some point, and disable it for metadata allocations or
 488  * sync-data inodes.
 489  */
 490 static int ext3_test_allocatable(int nr, struct buffer_head *bh)
 491 {
 492         int ret;
 493         struct journal_head *jh = bh2jh(bh);
 494
 495         if (ext3_test_bit(nr, bh->b_data))
 496                 return 0;
 497
 498         jbd_lock_bh_state(bh);
 499         if (!jh->b_committed_data)
 500                 ret = 1;
 501         else
 502                 ret = !ext3_test_bit(nr, jh->b_committed_data);
 503         jbd_unlock_bh_state(bh);
 504         return ret;
 505 }
 506
 507 static int
 508 bitmap_search_next_usable_block(int start, struct buffer_head *bh,
 509                                         int maxblocks)
 510 {
 511         int next;
 512         struct journal_head *jh = bh2jh(bh);
 513
 514         /*
 515          * The bitmap search --- search forward alternately through the actual
 516          * bitmap and the last-committed copy until we find a bit free in
 517          * both
 518          */
 519         while (start < maxblocks) {
 520                 next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
 521                 if (next >= maxblocks)
 522                         return -1;
 523                 if (ext3_test_allocatable(next, bh))
 524                         return next;
 525                 jbd_lock_bh_state(bh);
 526                 if (jh->b_committed_data)
 527                         start = ext3_find_next_zero_bit(jh->b_committed_data,
 528                                                         maxblocks, next);
 529                 jbd_unlock_bh_state(bh);
 530         }
 531         return -1;
 532 }
 533
 534 /*
 535  * Find an allocatable block in a bitmap.  We honour both the bitmap and
 536  * its last-committed copy (if that exists), and perform the "most
 537  * appropriate allocation" algorithm of looking for a free block near
 538  * the initial goal; then for a free byte somewhere in the bitmap; then
 539  * for any free bit in the bitmap.
 540  */
 541 static int
 542 find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
 543 {
 544         int here, next;
 545         char *p, *r;
 546
 547         if (start > 0) {
 548                 /*
 549                  * The goal was occupied; search forward for a free
 550                  * block within the next XX blocks.
 551                  *
 552                  * end_goal is more or less random, but it has to be
 553                  * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the
 554                  * next 64-bit boundary is simple..
 555                  */
 556                 int end_goal = (start + 63) & ~63;
 557                 if (end_goal > maxblocks)
 558                         end_goal = maxblocks;
 559                 here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
 560                 if (here < end_goal && ext3_test_allocatable(here, bh))
 561                         return here;
 562                 ext3_debug("Bit not found near goal\n");
 563         }
 564
 565         here = start;
 566         if (here < 0)
 567                 here = 0;
 568
 569         p = ((char *)bh->b_data) + (here >> 3);
 570         r = memscan(p, 0, (maxblocks - here + 7) >> 3);
 571         next = (r - ((char *)bh->b_data)) << 3;
 572
 573         if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))
 574                 return next;
 575
 576         /*
 577          * The bitmap search --- search forward alternately through the actual
 578          * bitmap and the last-committed copy until we find a bit free in
 579          * both
 580          */
 581         here = bitmap_search_next_usable_block(here, bh, maxblocks);
 582         return here;
 583 }
 584
 585 /*
 586  * We think we can allocate this block in this bitmap.  Try to set the bit.
 587  * If that succeeds then check that nobody has allocated and then freed the
 588  * block since we saw that is was not marked in b_committed_data.  If it _was_
 589  * allocated and freed then clear the bit in the bitmap again and return
 590  * zero (failure).
 591  */
 592 static inline int
 593 claim_block(spinlock_t *lock, int block, struct buffer_head *bh)
 594 {
 595         struct journal_head *jh = bh2jh(bh);
 596         int ret;
 597
 598         if (ext3_set_bit_atomic(lock, block, bh->b_data))
 599                 return 0;
 600         jbd_lock_bh_state(bh);
 601         if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) {
 602                 ext3_clear_bit_atomic(lock, block, bh->b_data);
 603                 ret = 0;
 604         } else {
 605                 ret = 1;
 606         }
 607         jbd_unlock_bh_state(bh);
 608         return ret;
 609 }
 610
 611 /*
 612  * If we failed to allocate the desired block then we may end up crossing to a
 613  * new bitmap.  In that case we must release write access to the old one via
 614  * ext3_journal_release_buffer(), else we'll run out of credits.
 615  */
 616 static int
 617 ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
 618         struct buffer_head *bitmap_bh, int goal, struct ext3_reserve_window *my_rsv)
 619 {
 620         int group_first_block, start, end;
 621
 622         /* we do allocation within the reservation window if we have a window */
 623         if (my_rsv) {
 624                 group_first_block =
 625                         le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
 626                         group * EXT3_BLOCKS_PER_GROUP(sb);
 627                 if (my_rsv->_rsv_start >= group_first_block)
 628                         start = my_rsv->_rsv_start - group_first_block;
 629                 else
 630                         /* reservation window cross group boundary */
 631                         start = 0;
 632                 end = my_rsv->_rsv_end - group_first_block + 1;
 633                 if (end > EXT3_BLOCKS_PER_GROUP(sb))
 634                         /* reservation window crosses group boundary */
 635                         end = EXT3_BLOCKS_PER_GROUP(sb);
 636                 if ((start <= goal) && (goal < end))
 637                         start = goal;
 638                 else
 639                         goal = -1;
 640         } else {
 641                 if (goal > 0)
 642                         start = goal;
 643                 else
 644                         start = 0;
 645                 end = EXT3_BLOCKS_PER_GROUP(sb);
 646         }
 647
 648         BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
 649
 650 repeat:
 651         if (goal < 0 || !ext3_test_allocatable(goal, bitmap_bh)) {
 652                 goal = find_next_usable_block(start, bitmap_bh, end);
 653                 if (goal < 0)
 654                         goto fail_access;
 655                 if (!my_rsv) {
 656                         int i;
 657
 658                         for (i = 0; i < 7 && goal > start &&
 659                                         ext3_test_allocatable(goal - 1,
 660                                                                 bitmap_bh);
 661                                         i++, goal--)
 662                                 ;
 663                 }
 664         }
 665         start = goal;
 666
 667         if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group), goal, bitmap_bh)) {
 668                 /*
 669                  * The block was allocated by another thread, or it was
 670                  * allocated and then freed by another thread
 671                  */
 672                 start++;
 673                 goal++;
 674                 if (start >= end)
 675                         goto fail_access;
 676                 goto repeat;
 677         }
 678         return goal;
 679 fail_access:
 680         return -1;
 681 }
 682
 683 /**
 684  *      find_next_reservable_window():
 685  *              find a reservable space within the given range.
 686  *              It does not allocate the reservation window for now:
 687  *              alloc_new_reservation() will do the work later.
 688  *
 689  *      @search_head: the head of the searching list;
 690  *              This is not necessarily the list head of the whole filesystem
 691  *
 692  *              We have both head and start_block to assist the search
 693  *              for the reservable space. The list starts from head,
 694  *              but we will shift to the place where start_block is,
 695  *              then start from there, when looking for a reservable space.
 696  *
 697  *      @size: the target new reservation window size
 698  *
 699  *      @group_first_block: the first block we consider to start
 700  *                      the real search from
 701  *
 702  *      @last_block:
 703  *              the maximum block number that our goal reservable space
 704  *              could start from. This is normally the last block in this
 705  *              group. The search will end when we found the start of next
 706  *              possible reservable space is out of this boundary.
 707  *              This could handle the cross boundary reservation window
 708  *              request.
 709  *
 710  *      basically we search from the given range, rather than the whole
 711  *      reservation double linked list, (start_block, last_block)
 712  *      to find a free region that is of my size and has not
 713  *      been reserved.
 714  *
 715  *      on succeed, it returns the reservation window to be appended to.
 716  *      failed, return NULL.
 717  */
 718 static struct ext3_reserve_window_node *find_next_reservable_window(
 719                                 struct ext3_reserve_window_node *search_head,
 720                                 unsigned long size, int *start_block,
 721                                 int last_block)
 722 {
 723         struct rb_node *next;
 724         struct ext3_reserve_window_node *rsv, *prev;
 725         int cur;
 726
 727         /* TODO: make the start of the reservation window byte-aligned */
 728         /* cur = *start_block & ~7;*/
 729         cur = *start_block;
 730         rsv = search_head;
 731         if (!rsv)
 732                 return NULL;
 733
 734         while (1) {
 735                 if (cur <= rsv->rsv_end)
 736                         cur = rsv->rsv_end + 1;
 737
 738                 /* TODO?
 739                  * in the case we could not find a reservable space
 740                  * that is what is expected, during the re-search, we could
 741                  * remember what's the largest reservable space we could have
 742                  * and return that one.
 743                  *
 744                  * For now it will fail if we could not find the reservable
 745                  * space with expected-size (or more)...
 746                  */
 747                 if (cur > last_block)
 748                         return NULL;            /* fail */
 749
 750                 prev = rsv;
 751                 next = rb_next(&rsv->rsv_node);
 752                 rsv = list_entry(next, struct ext3_reserve_window_node, rsv_node);
 753
 754                 /*
 755                  * Reached the last reservation, we can just append to the
 756                  * previous one.
 757                  */
 758                 if (!next)
 759                         break;
 760
 761                 if (cur + size <= rsv->rsv_start) {
 762                         /*
 763                          * Found a reserveable space big enough.  We could
 764                          * have a reservation across the group boundary here
 765                          */
 766                         break;
 767                 }
 768         }
 769         /*
 770          * we come here either :
 771          * when we reach the end of the whole list,
 772          * and there is empty reservable space after last entry in the list.
 773          * append it to the end of the list.
 774          *
 775          * or we found one reservable space in the middle of the list,
 776          * return the reservation window that we could append to.
 777          * succeed.
 778          */
 779         *start_block = cur;
 780         return prev;
 781 }
 782
 783 /**
 784  *      alloc_new_reservation()--allocate a new reservation window
 785  *
 786  *              To make a new reservation, we search part of the filesystem
 787  *              reservation list (the list that inside the group). We try to
 788  *              allocate a new reservation window near the allocation goal,
 789  *              or the beginning of the group, if there is no goal.
 790  *
 791  *              We first find a reservable space after the goal, then from
 792  *              there, we check the bitmap for the first free block after
 793  *              it. If there is no free block until the end of group, then the
 794  *              whole group is full, we failed. Otherwise, check if the free
 795  *              block is inside the expected reservable space, if so, we
 796  *              succeed.
 797  *              If the first free block is outside the reservable space, then
 798  *              start from the first free block, we search for next available
 799  *              space, and go on.
 800  *
 801  *      on succeed, a new reservation will be found and inserted into the list
 802  *      It contains at least one free block, and it does not overlap with other
 803  *      reservation windows.
 804  *
 805  *      failed: we failed to find a reservation window in this group
 806  *
 807  *      @rsv: the reservation
 808  *
 809  *      @goal: The goal (group-relative).  It is where the search for a
 810  *              free reservable space should start from.
 811  *              if we have a goal(goal >0 ), then start from there,
 812  *              no goal(goal = -1), we start from the first block
 813  *              of the group.
 814  *
 815  *      @sb: the super block
 816  *      @group: the group we are trying to allocate in
 817  *      @bitmap_bh: the block group block bitmap
 818  */
 819 static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
 820                 int goal, struct super_block *sb,
 821                 unsigned int group, struct buffer_head *bitmap_bh)
 822 {
 823         struct ext3_reserve_window_node *search_head;
 824         int group_first_block, group_end_block, start_block;
 825         int first_free_block;
 826         int reservable_space_start;
 827         struct ext3_reserve_window_node *prev_rsv;
 828         struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
 829         unsigned long size;
 830
 831         group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
 832                                 group * EXT3_BLOCKS_PER_GROUP(sb);
 833         group_end_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
 834
 835         if (goal < 0)
 836                 start_block = group_first_block;
 837         else
 838                 start_block = goal + group_first_block;
 839
 840         size = atomic_read(&my_rsv->rsv_goal_size);
 841         if (!rsv_is_empty(&my_rsv->rsv_window)) {
 842                 /*
 843                  * if the old reservation is cross group boundary
 844                  * and if the goal is inside the old reservation window,
 845                  * we will come here when we just failed to allocate from
 846                  * the first part of the window. We still have another part
 847                  * that belongs to the next group. In this case, there is no
 848                  * point to discard our window and try to allocate a new one
 849                  * in this group(which will fail). we should
 850                  * keep the reservation window, just simply move on.
 851                  *
 852                  * Maybe we could shift the start block of the reservation
 853                  * window to the first block of next group.
 854                  */
 855
 856                 if ((my_rsv->rsv_start <= group_end_block) &&
 857                                 (my_rsv->rsv_end > group_end_block) &&
 858                                 (start_block >= my_rsv->rsv_start))
 859                         return -1;
 860
 861                 if ((atomic_read(&my_rsv->rsv_alloc_hit) >
 862                      (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
 863                         /*
 864                          * if we previously allocation hit ration is greater than half
 865                          * we double the size of reservation window next time
 866                          * otherwise keep the same
 867                          */
 868                         size = size * 2;
 869                         if (size > EXT3_MAX_RESERVE_BLOCKS)
 870                                 size = EXT3_MAX_RESERVE_BLOCKS;
 871                         atomic_set(&my_rsv->rsv_goal_size, size);
 872                 }
 873         }
 874         /*
 875          * shift the search start to the window near the goal block
 876          */
 877         search_head = search_reserve_window(fs_rsv_root, start_block);
 878
 879         /*
 880          * find_next_reservable_window() simply finds a reservable window
 881          * inside the given range(start_block, group_end_block).
 882          *
 883          * To make sure the reservation window has a free bit inside it, we
 884          * need to check the bitmap after we found a reservable window.
 885          */
 886 retry:
 887         prev_rsv = find_next_reservable_window(search_head, size,
 888                                                 &start_block, group_end_block);
 889         if (prev_rsv == NULL)
 890                 goto failed;
 891         reservable_space_start = start_block;
 892         /*
 893          * On success, find_next_reservable_window() returns the
 894          * reservation window where there is a reservable space after it.
 895          * Before we reserve this reservable space, we need
 896          * to make sure there is at least a free block inside this region.
 897          *
 898          * searching the first free bit on the block bitmap and copy of
 899          * last committed bitmap alternatively, until we found a allocatable
 900          * block. Search start from the start block of the reservable space
 901          * we just found.
 902          */
 903         first_free_block = bitmap_search_next_usable_block(
 904                         reservable_space_start - group_first_block,
 905                         bitmap_bh, group_end_block - group_first_block + 1);
 906
 907         if (first_free_block < 0) {
 908                 /*
 909                  * no free block left on the bitmap, no point
 910                  * to reserve the space. return failed.
 911                  */
 912                 goto failed;
 913         }
 914         start_block = first_free_block + group_first_block;
 915         /*
 916          * check if the first free block is within the
 917          * free space we just found
 918          */
 919         if ((start_block >= reservable_space_start) &&
 920           (start_block < reservable_space_start + size))
 921                 goto found_rsv_window;
 922         /*
 923          * if the first free bit we found is out of the reservable space
 924          * this means there is no free block on the reservable space
 925          * we should continue search for next reservable space,
 926          * start from where the free block is,
 927          * we also shift the list head to where we stopped last time
 928          */
 929         search_head = prev_rsv;
 930         goto retry;
 931
 932 found_rsv_window:
 933         /*
 934          * great! the reservable space contains some free blocks.
 935          * if the search returns that we should add the new
 936          * window just next to where the old window, we don't
 937          * need to remove the old window first then add it to the
 938          * same place, just update the new start and new end.
 939          */
 940         if (my_rsv != prev_rsv)  {
 941                 if (!rsv_is_empty(&my_rsv->rsv_window))
 942                         rsv_window_remove(sb, my_rsv);
 943         }
 944         my_rsv->rsv_start = reservable_space_start;
 945         my_rsv->rsv_end = my_rsv->rsv_start + size - 1;
 946         atomic_set(&my_rsv->rsv_alloc_hit, 0);
 947         if (my_rsv != prev_rsv)  {
 948                 ext3_rsv_window_add(sb, my_rsv);
 949         }
 950         return 0;               /* succeed */
 951 failed:
 952         /*
 953          * failed to find a new reservation window in the current
 954          * group, remove the current(stale) reservation window
 955          * if there is any
 956          */
 957         if (!rsv_is_empty(&my_rsv->rsv_window))
 958                 rsv_window_remove(sb, my_rsv);
 959         return -1;              /* failed */
 960 }
 961
 962 /*
 963  * This is the main function used to allocate a new block and its reservation
 964  * window.
 965  *
 966  * Each time when a new block allocation is need, first try to allocate from
 967  * its own reservation.  If it does not have a reservation window, instead of
 968  * looking for a free bit on bitmap first, then look up the reservation list to
 969  * see if it is inside somebody else's reservation window, we try to allocate a
 970  * reservation window for it starting from the goal first. Then do the block
 971  * allocation within the reservation window.
 972  *
 973  * This will avoid keeping on searching the reservation list again and
 974  * again when someboday is looking for a free block (without
 975  * reservation), and there are lots of free blocks, but they are all
 976  * being reserved.
 977  *
 978  * We use a sorted double linked list for the per-filesystem reservation list.
 979  * The insert, remove and find a free space(non-reserved) operations for the
 980  * sorted double linked list should be fast.
 981  *
 982  */
 983 static int
 984 ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
 985                         unsigned int group, struct buffer_head *bitmap_bh,
 986                         int goal, struct ext3_reserve_window_node * my_rsv,
 987                         int *errp)
 988 {
 989         spinlock_t *rsv_lock;
 990         unsigned long group_first_block;
 991         int ret = 0;
 992         int fatal;
 993         int credits = 0;
 994
 995         *errp = 0;
 996
 997         /*
 998          * Make sure we use undo access for the bitmap, because it is critical
 999          * that we do the frozen_data COW on bitmap buffers in all cases even
1000          * if the buffer is in BJ_Forget state in the committing transaction.
1001          */
1002         BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1003         fatal = ext3_journal_get_undo_access(handle, bitmap_bh, &credits);
1004         if (fatal) {
1005                 *errp = fatal;
1006                 return -1;
1007         }
1008
1009         /*
1010          * we don't deal with reservation when
1011          * filesystem is mounted without reservation
1012          * or the file is not a regular file
1013          * or last attempt to allocate a block with reservation turned on failed
1014          */
1015         if (my_rsv == NULL ) {
1016                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal, NULL);
1017                 goto out;
1018         }
1019         rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1020         /*
1021          * goal is a group relative block number (if there is a goal)
1022          * 0 < goal < EXT3_BLOCKS_PER_GROUP(sb)
1023          * first block is a filesystem wide block number
1024          * first block is the block number of the first block in this group
1025          */
1026         group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
1027                         group * EXT3_BLOCKS_PER_GROUP(sb);
1028
1029         /*
1030          * Basically we will allocate a new block from inode's reservation
1031          * window.
1032          *
1033          * We need to allocate a new reservation window, if:
1034          * a) inode does not have a reservation window; or
1035          * b) last attempt to allocate a block from existing reservation
1036          *    failed; or
1037          * c) we come here with a goal and with a reservation window
1038          *
1039          * We do not need to allocate a new reservation window if we come here
1040          * at the beginning with a goal and the goal is inside the window, or
1041          * we don't have a goal but already have a reservation window.
1042          * then we could go to allocate from the reservation window directly.
1043          */
1044         while (1) {
1045                 struct ext3_reserve_window rsv_copy;
1046                 unsigned int seq;
1047
1048                 do {
1049                         seq = read_seqbegin(&my_rsv->rsv_seqlock);
1050                         rsv_copy._rsv_start = my_rsv->rsv_start;
1051                         rsv_copy._rsv_end = my_rsv->rsv_end;
1052                 } while (read_seqretry(&my_rsv->rsv_seqlock, seq));
1053
1054                 if (rsv_is_empty(&rsv_copy) || (ret < 0) ||
1055                         !goal_in_my_reservation(&rsv_copy, goal, group, sb)) {
1056                         spin_lock(rsv_lock);
1057                         write_seqlock(&my_rsv->rsv_seqlock);
1058                         ret = alloc_new_reservation(my_rsv, goal, sb,
1059                                                         group, bitmap_bh);
1060                         rsv_copy._rsv_start = my_rsv->rsv_start;
1061                         rsv_copy._rsv_end = my_rsv->rsv_end;
1062                         write_sequnlock(&my_rsv->rsv_seqlock);
1063                         spin_unlock(rsv_lock);
1064                         if (ret < 0)
1065                                 break;                  /* failed */
1066
1067                         if (!goal_in_my_reservation(&rsv_copy, goal, group, sb))
1068                                 goal = -1;
1069                 }
1070                 if ((rsv_copy._rsv_start >= group_first_block + EXT3_BLOCKS_PER_GROUP(sb))
1071                     || (rsv_copy._rsv_end < group_first_block))
1072                         BUG();
1073                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal,
1074                                            &rsv_copy);
1075                 if (ret >= 0) {
1076                         if (!read_seqretry(&my_rsv->rsv_seqlock, seq))
1077                                 atomic_inc(&my_rsv->rsv_alloc_hit);
1078                         break;                          /* succeed */
1079                 }
1080         }
1081 out:
1082         if (ret >= 0) {
1083                 BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1084                                         "bitmap block");
1085                 fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
1086                 if (fatal) {
1087                         *errp = fatal;
1088                         return -1;
1089                 }
1090                 return ret;
1091         }
1092
1093         BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1094         ext3_journal_release_buffer(handle, bitmap_bh, credits);
1095         return ret;
1096 }
1097
1098 static int ext3_has_free_blocks(struct super_block *sb)
1099 {
1100         struct ext3_sb_info *sbi = EXT3_SB(sb);
1101         int free_blocks, root_blocks, cond;
1102
1103         free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1104         root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1105
1106         vxdprintk(VXD_CBIT(dlim, 3),
1107                 "ext3_has_free_blocks(%p): free=%u, root=%u",
1108                 sb, free_blocks, root_blocks);
1109
1110         DLIMIT_ADJUST_BLOCK(sb, vx_current_xid(), &free_blocks, &root_blocks);
1111
1112         cond = (free_blocks < root_blocks + 1 &&
1113                 !capable(CAP_SYS_RESOURCE) &&
1114                 sbi->s_resuid != current->fsuid &&
1115                 (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid)));
1116
1117         vxdprintk(VXD_CBIT(dlim, 3),
1118                 "ext3_has_free_blocks(%p): %u<%u+1, %c, %u!=%u r=%d",
1119                 sb, free_blocks, root_blocks,
1120                 !capable(CAP_SYS_RESOURCE)?'1':'0',
1121                 sbi->s_resuid, current->fsuid, cond?0:1);
1122
1123         return (cond ? 0 : 1);
1124 }
1125
1126 /*
1127  * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
1128  * it is profitable to retry the operation, this function will wait
1129  * for the current or commiting transaction to complete, and then
1130  * return TRUE.
1131  */
1132 int ext3_should_retry_alloc(struct super_block *sb, int *retries)
1133 {
1134         if (!ext3_has_free_blocks(sb) || (*retries)++ > 3)
1135                 return 0;
1136
1137         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1138
1139         return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
1140 }
1141
1142 /*
1143  * ext3_new_block uses a goal block to assist allocation.  If the goal is
1144  * free, or there is a free block within 32 blocks of the goal, that block
1145  * is allocated.  Otherwise a forward search is made for a free block; within
1146  * each block group the search first looks for an entire free byte in the block
1147  * bitmap, and then for any free bit if that fails.
1148  * This function also updates quota and i_blocks field.
1149  */
1150 int ext3_new_block(handle_t *handle, struct inode *inode,
1151                         unsigned long goal, int *errp)
1152 {
1153         struct buffer_head *bitmap_bh = NULL;
1154         struct buffer_head *gdp_bh;
1155         int group_no;
1156         int goal_group;
1157         int ret_block;
1158         int bgi;                        /* blockgroup iteration index */
1159         int target_block;
1160         int fatal = 0, err;
1161         int performed_allocation = 0;
1162         int free_blocks;
1163         struct super_block *sb;
1164         struct ext3_group_desc *gdp;
1165         struct ext3_super_block *es;
1166         struct ext3_sb_info *sbi;
1167         struct ext3_reserve_window_node *my_rsv = NULL;
1168         struct ext3_reserve_window_node *rsv = &EXT3_I(inode)->i_rsv_window;
1169         unsigned short windowsz = 0;
1170 #ifdef EXT3FS_DEBUG
1171         static int goal_hits, goal_attempts;
1172 #endif
1173         unsigned long ngroups;
1174
1175         *errp = -ENOSPC;
1176         sb = inode->i_sb;
1177         if (!sb) {
1178                 printk("ext3_new_block: nonexistent device");
1179                 return 0;
1180         }
1181
1182         /*
1183          * Check quota for allocation of this block.
1184          */
1185         if (DQUOT_ALLOC_BLOCK(inode, 1)) {
1186                 *errp = -EDQUOT;
1187                 return 0;
1188         }
1189         if (DLIMIT_ALLOC_BLOCK(sb, inode->i_xid, 1))
1190                 goto out_dlimit;
1191
1192         sbi = EXT3_SB(sb);
1193         es = EXT3_SB(sb)->s_es;
1194         ext3_debug("goal=%lu.\n", goal);
1195         /*
1196          * Allocate a block from reservation only when
1197          * filesystem is mounted with reservation(default,-o reservation), and
1198          * it's a regular file, and
1199          * the desired window size is greater than 0 (One could use ioctl
1200          * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
1201          * reservation on that particular file)
1202          */
1203         windowsz = atomic_read(&rsv->rsv_goal_size);
1204         if (test_opt(sb, RESERVATION) &&
1205                 S_ISREG(inode->i_mode) && (windowsz > 0))
1206                 my_rsv = rsv;
1207         if (!ext3_has_free_blocks(sb)) {
1208                 *errp = -ENOSPC;
1209                 goto out;
1210         }
1211
1212         /*
1213          * First, test whether the goal block is free.
1214          */
1215         if (goal < le32_to_cpu(es->s_first_data_block) ||
1216             goal >= le32_to_cpu(es->s_blocks_count))
1217                 goal = le32_to_cpu(es->s_first_data_block);
1218         group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1219                         EXT3_BLOCKS_PER_GROUP(sb);
1220         gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1221         if (!gdp)
1222                 goto io_error;
1223
1224         goal_group = group_no;
1225 retry:
1226         free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1227         if (free_blocks > 0) {
1228                 ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) %
1229                                 EXT3_BLOCKS_PER_GROUP(sb));
1230                 bitmap_bh = read_block_bitmap(sb, group_no);
1231                 if (!bitmap_bh)
1232                         goto io_error;
1233                 ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
1234                                         bitmap_bh, ret_block, my_rsv, &fatal);
1235                 if (fatal)
1236                         goto out;
1237                 if (ret_block >= 0)
1238                         goto allocated;
1239         }
1240
1241         ngroups = EXT3_SB(sb)->s_groups_count;
1242         smp_rmb();
1243
1244         /*
1245          * Now search the rest of the groups.  We assume that
1246          * i and gdp correctly point to the last group visited.
1247          */
1248         for (bgi = 0; bgi < ngroups; bgi++) {
1249                 group_no++;
1250                 if (group_no >= ngroups)
1251                         group_no = 0;
1252                 gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1253                 if (!gdp) {
1254                         *errp = -EIO;
1255                         goto out;
1256                 }
1257                 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1258                 /*
1259                  * skip this group if the number of
1260                  * free blocks is less than half of the reservation
1261                  * window size.
1262                  */
1263                 if (free_blocks <= (windowsz/2))
1264                         continue;
1265
1266                 brelse(bitmap_bh);
1267                 bitmap_bh = read_block_bitmap(sb, group_no);
1268                 if (!bitmap_bh)
1269                         goto io_error;
1270                 ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
1271                                         bitmap_bh, -1, my_rsv, &fatal);
1272                 if (fatal)
1273                         goto out;
1274                 if (ret_block >= 0)
1275                         goto allocated;
1276         }
1277         /*
1278          * We may end up a bogus ealier ENOSPC error due to
1279          * filesystem is "full" of reservations, but
1280          * there maybe indeed free blocks avaliable on disk
1281          * In this case, we just forget about the reservations
1282          * just do block allocation as without reservations.
1283          */
1284         if (my_rsv) {
1285                 my_rsv = NULL;
1286                 group_no = goal_group;
1287                 goto retry;
1288         }
1289         /* No space left on the device */
1290         *errp = -ENOSPC;
1291         goto out;
1292
1293 allocated:
1294
1295         ext3_debug("using block group %d(%d)\n",
1296                         group_no, gdp->bg_free_blocks_count);
1297
1298         BUFFER_TRACE(gdp_bh, "get_write_access");
1299         fatal = ext3_journal_get_write_access(handle, gdp_bh);
1300         if (fatal)
1301                 goto out;
1302
1303         target_block = ret_block + group_no * EXT3_BLOCKS_PER_GROUP(sb)
1304                                 + le32_to_cpu(es->s_first_data_block);
1305
1306         if (target_block == le32_to_cpu(gdp->bg_block_bitmap) ||
1307             target_block == le32_to_cpu(gdp->bg_inode_bitmap) ||
1308             in_range(target_block, le32_to_cpu(gdp->bg_inode_table),
1309                       EXT3_SB(sb)->s_itb_per_group))
1310                 ext3_error(sb, "ext3_new_block",
1311                             "Allocating block in system zone - "
1312                             "block = %u", target_block);
1313
1314         performed_allocation = 1;
1315
1316 #ifdef CONFIG_JBD_DEBUG
1317         {
1318                 struct buffer_head *debug_bh;
1319
1320                 /* Record bitmap buffer state in the newly allocated block */
1321                 debug_bh = sb_find_get_block(sb, target_block);
1322                 if (debug_bh) {
1323                         BUFFER_TRACE(debug_bh, "state when allocated");
1324                         BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1325                         brelse(debug_bh);
1326                 }
1327         }
1328         jbd_lock_bh_state(bitmap_bh);
1329         spin_lock(sb_bgl_lock(sbi, group_no));
1330         if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1331                 if (ext3_test_bit(ret_block,
1332                                 bh2jh(bitmap_bh)->b_committed_data)) {
1333                         printk("%s: block was unexpectedly set in "
1334                                 "b_committed_data\n", __FUNCTION__);
1335                 }
1336         }
1337         ext3_debug("found bit %d\n", ret_block);
1338         spin_unlock(sb_bgl_lock(sbi, group_no));
1339         jbd_unlock_bh_state(bitmap_bh);
1340 #endif
1341
1342         /* ret_block was blockgroup-relative.  Now it becomes fs-relative */
1343         ret_block = target_block;
1344
1345         if (ret_block >= le32_to_cpu(es->s_blocks_count)) {
1346                 ext3_error(sb, "ext3_new_block",
1347                             "block(%d) >= blocks count(%d) - "
1348                             "block_group = %d, es == %p ", ret_block,
1349                         le32_to_cpu(es->s_blocks_count), group_no, es);
1350                 goto out;
1351         }
1352
1353         /*
1354          * It is up to the caller to add the new buffer to a journal
1355          * list of some description.  We don't know in advance whether
1356          * the caller wants to use it as metadata or data.
1357          */
1358         ext3_debug("allocating block %d. Goal hits %d of %d.\n",
1359                         ret_block, goal_hits, goal_attempts);
1360
1361         spin_lock(sb_bgl_lock(sbi, group_no));
1362         gdp->bg_free_blocks_count =
1363                         cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) - 1);
1364         spin_unlock(sb_bgl_lock(sbi, group_no));
1365         percpu_counter_mod(&sbi->s_freeblocks_counter, -1);
1366
1367         BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1368         err = ext3_journal_dirty_metadata(handle, gdp_bh);
1369         if (!fatal)
1370                 fatal = err;
1371
1372         sb->s_dirt = 1;
1373         if (fatal)
1374                 goto out;
1375
1376         *errp = 0;
1377         brelse(bitmap_bh);
1378         return ret_block;
1379
1380 io_error:
1381         *errp = -EIO;
1382 out:
1383         if (!performed_allocation)
1384                 DLIMIT_FREE_BLOCK(sb, inode->i_xid, 1);
1385 out_dlimit:
1386         if (fatal) {
1387                 *errp = fatal;
1388                 ext3_std_error(sb, fatal);
1389         }
1390         /*
1391          * Undo the block allocation
1392          */
1393         if (!performed_allocation)
1394                 DQUOT_FREE_BLOCK(inode, 1);
1395         brelse(bitmap_bh);
1396         return 0;
1397 }
1398
1399 unsigned long ext3_count_free_blocks(struct super_block *sb)
1400 {
1401         unsigned long desc_count;
1402         struct ext3_group_desc *gdp;
1403         int i;
1404         unsigned long ngroups;
1405 #ifdef EXT3FS_DEBUG
1406         struct ext3_super_block *es;
1407         unsigned long bitmap_count, x;
1408         struct buffer_head *bitmap_bh = NULL;
1409
1410         lock_super(sb);
1411         es = EXT3_SB(sb)->s_es;
1412         desc_count = 0;
1413         bitmap_count = 0;
1414         gdp = NULL;
1415         for (i = 0; i < EXT3_SB(sb)->s_groups_count; i++) {
1416                 gdp = ext3_get_group_desc(sb, i, NULL);
1417                 if (!gdp)
1418                         continue;
1419                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1420                 brelse(bitmap_bh);
1421                 bitmap_bh = read_block_bitmap(sb, i);
1422                 if (bitmap_bh == NULL)
1423                         continue;
1424
1425                 x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1426                 printk("group %d: stored = %d, counted = %lu\n",
1427                         i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1428                 bitmap_count += x;
1429         }
1430         brelse(bitmap_bh);
1431         printk("ext3_count_free_blocks: stored = %u, computed = %lu, %lu\n",
1432                le32_to_cpu(es->s_free_blocks_count), desc_count, bitmap_count);
1433         unlock_super(sb);
1434         return bitmap_count;
1435 #else
1436         desc_count = 0;
1437         ngroups = EXT3_SB(sb)->s_groups_count;
1438         smp_rmb();
1439         for (i = 0; i < ngroups; i++) {
1440                 gdp = ext3_get_group_desc(sb, i, NULL);
1441                 if (!gdp)
1442                         continue;
1443                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1444         }
1445
1446         return desc_count;
1447 #endif
1448 }
1449
1450 static inline int block_in_use(unsigned long block,
1451                                 struct super_block * sb,
1452                                 unsigned char * map)
1453 {
1454         return ext3_test_bit ((block -
1455                 le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) %
1456                          EXT3_BLOCKS_PER_GROUP(sb), map);
1457 }
1458
1459 static inline int test_root(int a, int b)
1460 {
1461         if (a == 0)
1462                 return 1;
1463         while (1) {
1464                 if (a == 1)
1465                         return 1;
1466                 if (a % b)
1467                         return 0;
1468                 a = a / b;
1469         }
1470 }
1471
1472 int ext3_group_sparse(int group)
1473 {
1474         return (test_root(group, 3) || test_root(group, 5) ||
1475                 test_root(group, 7));
1476 }
1477
1478 /**
1479  *      ext3_bg_has_super - number of blocks used by the superblock in group
1480  *      @sb: superblock for filesystem
1481  *      @group: group number to check
1482  *
1483  *      Return the number of blocks used by the superblock (primary or backup)
1484  *      in this group.  Currently this will be only 0 or 1.
1485  */
1486 int ext3_bg_has_super(struct super_block *sb, int group)
1487 {
1488         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1489             !ext3_group_sparse(group))
1490                 return 0;
1491         return 1;
1492 }
1493
1494 /**
1495  *      ext3_bg_num_gdb - number of blocks used by the group table in group
1496  *      @sb: superblock for filesystem
1497  *      @group: group number to check
1498  *
1499  *      Return the number of blocks used by the group descriptor table
1500  *      (primary or backup) in this group.  In the future there may be a
1501  *      different number of descriptor blocks in each group.
1502  */
1503 unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
1504 {
1505         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1506             !ext3_group_sparse(group))
1507                 return 0;
1508         return EXT3_SB(sb)->s_gdb_count;
1509 }
1510
1511 #ifdef CONFIG_EXT3_CHECK
1512 /* Called at mount-time, super-block is locked */
1513 void ext3_check_blocks_bitmap (struct super_block * sb)
1514 {
1515         struct ext3_super_block *es;
1516         unsigned long desc_count, bitmap_count, x, j;
1517         unsigned long desc_blocks;
1518         struct buffer_head *bitmap_bh = NULL;
1519         struct ext3_group_desc *gdp;
1520         int i;
1521
1522         es = EXT3_SB(sb)->s_es;
1523         desc_count = 0;
1524         bitmap_count = 0;
1525         gdp = NULL;
1526         for (i = 0; i < EXT3_SB(sb)->s_groups_count; i++) {
1527                 gdp = ext3_get_group_desc (sb, i, NULL);
1528                 if (!gdp)
1529                         continue;
1530                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1531                 brelse(bitmap_bh);
1532                 bitmap_bh = read_block_bitmap(sb, i);
1533                 if (bitmap_bh == NULL)
1534                         continue;
1535
1536                 if (ext3_bg_has_super(sb, i) &&
1537                                 !ext3_test_bit(0, bitmap_bh->b_data))
1538                         ext3_error(sb, __FUNCTION__,
1539                                    "Superblock in group %d is marked free", i);
1540
1541                 desc_blocks = ext3_bg_num_gdb(sb, i);
1542                 for (j = 0; j < desc_blocks; j++)
1543                         if (!ext3_test_bit(j + 1, bitmap_bh->b_data))
1544                                 ext3_error(sb, __FUNCTION__,
1545                                            "Descriptor block #%ld in group "
1546                                            "%d is marked free", j, i);
1547
1548                 if (!block_in_use (le32_to_cpu(gdp->bg_block_bitmap),
1549                                                 sb, bitmap_bh->b_data))
1550                         ext3_error (sb, "ext3_check_blocks_bitmap",
1551                                     "Block bitmap for group %d is marked free",
1552                                     i);
1553
1554                 if (!block_in_use (le32_to_cpu(gdp->bg_inode_bitmap),
1555                                                 sb, bitmap_bh->b_data))
1556                         ext3_error (sb, "ext3_check_blocks_bitmap",
1557                                     "Inode bitmap for group %d is marked free",
1558                                     i);
1559
1560                 for (j = 0; j < EXT3_SB(sb)->s_itb_per_group; j++)
1561                         if (!block_in_use (le32_to_cpu(gdp->bg_inode_table) + j,
1562                                                         sb, bitmap_bh->b_data))
1563                                 ext3_error (sb, "ext3_check_blocks_bitmap",
1564                                             "Block #%d of the inode table in "
1565                                             "group %d is marked free", j, i);
1566
1567                 x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1568                 if (le16_to_cpu(gdp->bg_free_blocks_count) != x)
1569                         ext3_error (sb, "ext3_check_blocks_bitmap",
1570                                     "Wrong free blocks count for group %d, "
1571                                     "stored = %d, counted = %lu", i,
1572                                     le16_to_cpu(gdp->bg_free_blocks_count), x);
1573                 bitmap_count += x;
1574         }
1575         brelse(bitmap_bh);
1576         if (le32_to_cpu(es->s_free_blocks_count) != bitmap_count)
1577                 ext3_error (sb, "ext3_check_blocks_bitmap",
1578                         "Wrong free blocks count in super block, "
1579                         "stored = %lu, counted = %lu",
1580                         (unsigned long)le32_to_cpu(es->s_free_blocks_count),
1581                         bitmap_count);
1582 }
1583 #endif