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_dlimit.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_read_super).
  37  */
  38
  39
  40 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
  41
  42 struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
  43                                              unsigned int block_group,
  44                                              struct buffer_head ** bh)
  45 {
  46         unsigned long group_desc;
  47         unsigned long desc;
  48         struct ext3_group_desc * gdp;
  49
  50         if (block_group >= EXT3_SB(sb)->s_groups_count) {
  51                 ext3_error (sb, "ext3_get_group_desc",
  52                             "block_group >= groups_count - "
  53                             "block_group = %d, groups_count = %lu",
  54                             block_group, EXT3_SB(sb)->s_groups_count);
  55
  56                 return NULL;
  57         }
  58         smp_rmb();
  59
  60         group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb);
  61         desc = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1);
  62         if (!EXT3_SB(sb)->s_group_desc[group_desc]) {
  63                 ext3_error (sb, "ext3_get_group_desc",
  64                             "Group descriptor not loaded - "
  65                             "block_group = %d, group_desc = %lu, desc = %lu",
  66                              block_group, group_desc, desc);
  67                 return NULL;
  68         }
  69
  70         gdp = (struct ext3_group_desc *)
  71               EXT3_SB(sb)->s_group_desc[group_desc]->b_data;
  72         if (bh)
  73                 *bh = EXT3_SB(sb)->s_group_desc[group_desc];
  74         return gdp + desc;
  75 }
  76
  77 /*
  78  * Read the bitmap for a given block_group, reading into the specified
  79  * slot in the superblock's bitmap cache.
  80  *
  81  * Return buffer_head on success or NULL in case of failure.
  82  */
  83 static struct buffer_head *
  84 read_block_bitmap(struct super_block *sb, unsigned int block_group)
  85 {
  86         struct ext3_group_desc * desc;
  87         struct buffer_head * bh = NULL;
  88
  89         desc = ext3_get_group_desc (sb, block_group, NULL);
  90         if (!desc)
  91                 goto error_out;
  92         bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
  93         if (!bh)
  94                 ext3_error (sb, "read_block_bitmap",
  95                             "Cannot read block bitmap - "
  96                             "block_group = %d, block_bitmap = %u",
  97                             block_group, le32_to_cpu(desc->bg_block_bitmap));
  98 error_out:
  99         return bh;
 100 }
 101 /*
 102  * The reservation window structure operations
 103  * --------------------------------------------
 104  * Operations include:
 105  * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
 106  *
 107  * We use sorted double linked list for the per-filesystem reservation
 108  * window list. (like in vm_region).
 109  *
 110  * Initially, we keep those small operations in the abstract functions,
 111  * so later if we need a better searching tree than double linked-list,
 112  * we could easily switch to that without changing too much
 113  * code.
 114  */
 115 #if 0
 116 static void __rsv_window_dump(struct rb_root *root, int verbose,
 117                               const char *fn)
 118 {
 119         struct rb_node *n;
 120         struct ext3_reserve_window_node *rsv, *prev;
 121         int bad;
 122
 123 restart:
 124         n = rb_first(root);
 125         bad = 0;
 126         prev = NULL;
 127
 128         printk("Block Allocation Reservation Windows Map (%s):\n", fn);
 129         while (n) {
 130                 rsv = list_entry(n, struct ext3_reserve_window_node, rsv_node);
 131                 if (verbose)
 132                         printk("reservation window 0x%p "
 133                                "start:  %d, end:  %d\n",
 134                                rsv, rsv->rsv_start, rsv->rsv_end);
 135                 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
 136                         printk("Bad reservation %p (start >= end)\n",
 137                                rsv);
 138                         bad = 1;
 139                 }
 140                 if (prev && prev->rsv_end >= rsv->rsv_start) {
 141                         printk("Bad reservation %p (prev->end >= start)\n",
 142                                rsv);
 143                         bad = 1;
 144                 }
 145                 if (bad) {
 146                         if (!verbose) {
 147                                 printk("Restarting reservation walk in verbose mode\n");
 148                                 verbose = 1;
 149                                 goto restart;
 150                         }
 151                 }
 152                 n = rb_next(n);
 153                 prev = rsv;
 154         }
 155         printk("Window map complete.\n");
 156         if (bad)
 157                 BUG();
 158 }
 159 #define rsv_window_dump(root, verbose) \
 160         __rsv_window_dump((root), (verbose), __FUNCTION__)
 161 #else
 162 #define rsv_window_dump(root, verbose) do {} while (0)
 163 #endif
 164
 165 static int
 166 goal_in_my_reservation(struct ext3_reserve_window *rsv, int goal,
 167                         unsigned int group, struct super_block * sb)
 168 {
 169         unsigned long group_first_block, group_last_block;
 170
 171         group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
 172                                 group * EXT3_BLOCKS_PER_GROUP(sb);
 173         group_last_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
 174
 175         if ((rsv->_rsv_start > group_last_block) ||
 176             (rsv->_rsv_end < group_first_block))
 177                 return 0;
 178         if ((goal >= 0) && ((goal + group_first_block < rsv->_rsv_start)
 179                 || (goal + group_first_block > rsv->_rsv_end)))
 180                 return 0;
 181         return 1;
 182 }
 183
 184 /*
 185  * Find the reserved window which includes the goal, or the previous one
 186  * if the goal is not in any window.
 187  * Returns NULL if there are no windows or if all windows start after the goal.
 188  */
 189 static struct ext3_reserve_window_node *
 190 search_reserve_window(struct rb_root *root, unsigned long goal)
 191 {
 192         struct rb_node *n = root->rb_node;
 193         struct ext3_reserve_window_node *rsv;
 194
 195         if (!n)
 196                 return NULL;
 197
 198         do {
 199                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 200
 201                 if (goal < rsv->rsv_start)
 202                         n = n->rb_left;
 203                 else if (goal > rsv->rsv_end)
 204                         n = n->rb_right;
 205                 else
 206                         return rsv;
 207         } while (n);
 208         /*
 209          * We've fallen off the end of the tree: the goal wasn't inside
 210          * any particular node.  OK, the previous node must be to one
 211          * side of the interval containing the goal.  If it's the RHS,
 212          * we need to back up one.
 213          */
 214         if (rsv->rsv_start > goal) {
 215                 n = rb_prev(&rsv->rsv_node);
 216                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 217         }
 218         return rsv;
 219 }
 220
 221 void ext3_rsv_window_add(struct super_block *sb,
 222                     struct ext3_reserve_window_node *rsv)
 223 {
 224         struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root;
 225         struct rb_node *node = &rsv->rsv_node;
 226         unsigned int start = rsv->rsv_start;
 227
 228         struct rb_node ** p = &root->rb_node;
 229         struct rb_node * parent = NULL;
 230         struct ext3_reserve_window_node *this;
 231
 232         while (*p)
 233         {
 234                 parent = *p;
 235                 this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node);
 236
 237                 if (start < this->rsv_start)
 238                         p = &(*p)->rb_left;
 239                 else if (start > this->rsv_end)
 240                         p = &(*p)->rb_right;
 241                 else
 242                         BUG();
 243         }
 244
 245         rb_link_node(node, parent, p);
 246         rb_insert_color(node, root);
 247 }
 248
 249 static void rsv_window_remove(struct super_block *sb,
 250                               struct ext3_reserve_window_node *rsv)
 251 {
 252         rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 253         rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 254         atomic_set(&rsv->rsv_alloc_hit, 0);
 255         rb_erase(&rsv->rsv_node, &EXT3_SB(sb)->s_rsv_window_root);
 256 }
 257
 258 static inline int rsv_is_empty(struct ext3_reserve_window *rsv)
 259 {
 260         /* a valid reservation end block could not be 0 */
 261         return (rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED);
 262 }
 263
 264 void ext3_discard_reservation(struct inode *inode)
 265 {
 266         struct ext3_inode_info *ei = EXT3_I(inode);
 267         struct ext3_reserve_window_node *rsv = &ei->i_rsv_window;
 268         spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
 269
 270         if (!rsv_is_empty(&rsv->rsv_window)) {
 271                 spin_lock(rsv_lock);
 272                 rsv_window_remove(inode->i_sb, rsv);
 273                 spin_unlock(rsv_lock);
 274         }
 275 }
 276
 277 /* Free given blocks, update quota and i_blocks field */
 278 void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,
 279                          unsigned long block, unsigned long count,
 280                          int *pdquot_freed_blocks)
 281 {
 282         struct buffer_head *bitmap_bh = NULL;
 283         struct buffer_head *gd_bh;
 284         unsigned long block_group;
 285         unsigned long bit;
 286         unsigned long i;
 287         unsigned long overflow;
 288         struct ext3_group_desc * gdp;
 289         struct ext3_super_block * es;
 290         struct ext3_sb_info *sbi;
 291         int err = 0, ret;
 292
 293         *pdquot_freed_blocks = 0;
 294         sbi = EXT3_SB(sb);
 295         es = EXT3_SB(sb)->s_es;
 296         if (block < le32_to_cpu(es->s_first_data_block) ||
 297             block + count < block ||
 298             block + count > le32_to_cpu(es->s_blocks_count)) {
 299                 ext3_error (sb, "ext3_free_blocks",
 300                             "Freeing blocks not in datazone - "
 301                             "block = %lu, count = %lu", block, count);
 302                 goto error_return;
 303         }
 304
 305         ext3_debug ("freeing block %lu\n", block);
 306
 307 do_more:
 308         overflow = 0;
 309         block_group = (block - le32_to_cpu(es->s_first_data_block)) /
 310                       EXT3_BLOCKS_PER_GROUP(sb);
 311         bit = (block - le32_to_cpu(es->s_first_data_block)) %
 312                       EXT3_BLOCKS_PER_GROUP(sb);
 313         /*
 314          * Check to see if we are freeing blocks across a group
 315          * boundary.
 316          */
 317         if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
 318                 overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
 319                 count -= overflow;
 320         }
 321         brelse(bitmap_bh);
 322         bitmap_bh = read_block_bitmap(sb, block_group);
 323         if (!bitmap_bh)
 324                 goto error_return;
 325         gdp = ext3_get_group_desc (sb, block_group, &gd_bh);
 326         if (!gdp)
 327                 goto error_return;
 328
 329         if (in_range (le32_to_cpu(gdp->bg_block_bitmap), block, count) ||
 330             in_range (le32_to_cpu(gdp->bg_inode_bitmap), block, count) ||
 331             in_range (block, le32_to_cpu(gdp->bg_inode_table),
 332                       EXT3_SB(sb)->s_itb_per_group) ||
 333             in_range (block + count - 1, le32_to_cpu(gdp->bg_inode_table),
 334                       EXT3_SB(sb)->s_itb_per_group))
 335                 ext3_error (sb, "ext3_free_blocks",
 336                             "Freeing blocks in system zones - "
 337                             "Block = %lu, count = %lu",
 338                             block, count);
 339
 340         /*
 341          * We are about to start releasing blocks in the bitmap,
 342          * so we need undo access.
 343          */
 344         /* @@@ check errors */
 345         BUFFER_TRACE(bitmap_bh, "getting undo access");
 346         err = ext3_journal_get_undo_access(handle, bitmap_bh, NULL);
 347         if (err)
 348                 goto error_return;
 349
 350         /*
 351          * We are about to modify some metadata.  Call the journal APIs
 352          * to unshare ->b_data if a currently-committing transaction is
 353          * using it
 354          */
 355         BUFFER_TRACE(gd_bh, "get_write_access");
 356         err = ext3_journal_get_write_access(handle, gd_bh);
 357         if (err)
 358                 goto error_return;
 359
 360         jbd_lock_bh_state(bitmap_bh);
 361
 362         for (i = 0; i < count; i++) {
 363                 /*
 364                  * An HJ special.  This is expensive...
 365                  */
 366 #ifdef CONFIG_JBD_DEBUG
 367                 jbd_unlock_bh_state(bitmap_bh);
 368                 {
 369                         struct buffer_head *debug_bh;
 370                         debug_bh = sb_find_get_block(sb, block + i);
 371                         if (debug_bh) {
 372                                 BUFFER_TRACE(debug_bh, "Deleted!");
 373                                 if (!bh2jh(bitmap_bh)->b_committed_data)
 374                                         BUFFER_TRACE(debug_bh,
 375                                                 "No commited data in bitmap");
 376                                 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
 377                                 __brelse(debug_bh);
 378                         }
 379                 }
 380                 jbd_lock_bh_state(bitmap_bh);
 381 #endif
 382                 if (need_resched()) {
 383                         jbd_unlock_bh_state(bitmap_bh);
 384                         cond_resched();
 385                         jbd_lock_bh_state(bitmap_bh);
 386                 }
 387                 /* @@@ This prevents newly-allocated data from being
 388                  * freed and then reallocated within the same
 389                  * transaction.
 390                  *
 391                  * Ideally we would want to allow that to happen, but to
 392                  * do so requires making journal_forget() capable of
 393                  * revoking the queued write of a data block, which
 394                  * implies blocking on the journal lock.  *forget()
 395                  * cannot block due to truncate races.
 396                  *
 397                  * Eventually we can fix this by making journal_forget()
 398                  * return a status indicating whether or not it was able
 399                  * to revoke the buffer.  On successful revoke, it is
 400                  * safe not to set the allocation bit in the committed
 401                  * bitmap, because we know that there is no outstanding
 402                  * activity on the buffer any more and so it is safe to
 403                  * reallocate it.
 404                  */
 405                 BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
 406                 J_ASSERT_BH(bitmap_bh,
 407                                 bh2jh(bitmap_bh)->b_committed_data != NULL);
 408                 ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
 409                                 bh2jh(bitmap_bh)->b_committed_data);
 410
 411                 /*
 412                  * We clear the bit in the bitmap after setting the committed
 413                  * data bit, because this is the reverse order to that which
 414                  * the allocator uses.
 415                  */
 416                 BUFFER_TRACE(bitmap_bh, "clear bit");
 417                 if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 418                                                 bit + i, bitmap_bh->b_data)) {
 419                         jbd_unlock_bh_state(bitmap_bh);
 420                         ext3_error(sb, __FUNCTION__,
 421                                 "bit already cleared for block %lu", block + i);
 422                         jbd_lock_bh_state(bitmap_bh);
 423                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
 424                 } else {
 425                         (*pdquot_freed_blocks)++;
 426                 }
 427         }
 428         jbd_unlock_bh_state(bitmap_bh);
 429
 430         spin_lock(sb_bgl_lock(sbi, block_group));
 431         gdp->bg_free_blocks_count =
 432                 cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) +
 433                         *pdquot_freed_blocks);
 434         spin_unlock(sb_bgl_lock(sbi, block_group));
 435         percpu_counter_mod(&sbi->s_freeblocks_counter, count);
 436
 437         /* We dirtied the bitmap block */
 438         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
 439         err = ext3_journal_dirty_metadata(handle, bitmap_bh);
 440
 441         /* And the group descriptor block */
 442         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
 443         ret = ext3_journal_dirty_metadata(handle, gd_bh);
 444         if (!err) err = ret;
 445
 446         if (overflow && !err) {
 447                 block += count;
 448                 count = overflow;
 449                 goto do_more;
 450         }
 451         sb->s_dirt = 1;
 452 error_return:
 453         brelse(bitmap_bh);
 454         ext3_std_error(sb, err);
 455         return;
 456 }
 457
 458 /* Free given blocks, update quota and i_blocks field */
 459 void ext3_free_blocks(handle_t *handle, struct inode *inode,
 460                         unsigned long block, unsigned long count)
 461 {
 462         struct super_block * sb;
 463         int dquot_freed_blocks;
 464
 465         sb = inode->i_sb;
 466         if (!sb) {
 467                 printk ("ext3_free_blocks: nonexistent device");
 468                 return;
 469         }
 470         ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
 471         if (dquot_freed_blocks) {
 472                 DLIMIT_FREE_BLOCK(sb, inode->i_xid, dquot_freed_blocks);
 473                 DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
 474         }
 475         return;
 476 }
 477
 478 /*
 479  * For ext3 allocations, we must not reuse any blocks which are
 480  * allocated in the bitmap buffer's "last committed data" copy.  This
 481  * prevents deletes from freeing up the page for reuse until we have
 482  * committed the delete transaction.
 483  *
 484  * If we didn't do this, then deleting something and reallocating it as
 485  * data would allow the old block to be overwritten before the
 486  * transaction committed (because we force data to disk before commit).
 487  * This would lead to corruption if we crashed between overwriting the
 488  * data and committing the delete.
 489  *
 490  * @@@ We may want to make this allocation behaviour conditional on
 491  * data-writes at some point, and disable it for metadata allocations or
 492  * sync-data inodes.
 493  */
 494 static int ext3_test_allocatable(int nr, struct buffer_head *bh)
 495 {
 496         int ret;
 497         struct journal_head *jh = bh2jh(bh);
 498
 499         if (ext3_test_bit(nr, bh->b_data))
 500                 return 0;
 501
 502         jbd_lock_bh_state(bh);
 503         if (!jh->b_committed_data)
 504                 ret = 1;
 505         else
 506                 ret = !ext3_test_bit(nr, jh->b_committed_data);
 507         jbd_unlock_bh_state(bh);
 508         return ret;
 509 }
 510
 511 static int
 512 bitmap_search_next_usable_block(int start, struct buffer_head *bh,
 513                                         int maxblocks)
 514 {
 515         int next;
 516         struct journal_head *jh = bh2jh(bh);
 517
 518         /*
 519          * The bitmap search --- search forward alternately through the actual
 520          * bitmap and the last-committed copy until we find a bit free in
 521          * both
 522          */
 523         while (start < maxblocks) {
 524                 next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
 525                 if (next >= maxblocks)
 526                         return -1;
 527                 if (ext3_test_allocatable(next, bh))
 528                         return next;
 529                 jbd_lock_bh_state(bh);
 530                 if (jh->b_committed_data)
 531                         start = ext3_find_next_zero_bit(jh->b_committed_data,
 532                                                         maxblocks, next);
 533                 jbd_unlock_bh_state(bh);
 534         }
 535         return -1;
 536 }
 537
 538 /*
 539  * Find an allocatable block in a bitmap.  We honour both the bitmap and
 540  * its last-committed copy (if that exists), and perform the "most
 541  * appropriate allocation" algorithm of looking for a free block near
 542  * the initial goal; then for a free byte somewhere in the bitmap; then
 543  * for any free bit in the bitmap.
 544  */
 545 static int
 546 find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
 547 {
 548         int here, next;
 549         char *p, *r;
 550
 551         if (start > 0) {
 552                 /*
 553                  * The goal was occupied; search forward for a free
 554                  * block within the next XX blocks.
 555                  *
 556                  * end_goal is more or less random, but it has to be
 557                  * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the
 558                  * next 64-bit boundary is simple..
 559                  */
 560                 int end_goal = (start + 63) & ~63;
 561                 if (end_goal > maxblocks)
 562                         end_goal = maxblocks;
 563                 here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
 564                 if (here < end_goal && ext3_test_allocatable(here, bh))
 565                         return here;
 566                 ext3_debug("Bit not found near goal\n");
 567         }
 568
 569         here = start;
 570         if (here < 0)
 571                 here = 0;
 572
 573         p = ((char *)bh->b_data) + (here >> 3);
 574         r = memscan(p, 0, (maxblocks - here + 7) >> 3);
 575         next = (r - ((char *)bh->b_data)) << 3;
 576
 577         if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))
 578                 return next;
 579
 580         /*
 581          * The bitmap search --- search forward alternately through the actual
 582          * bitmap and the last-committed copy until we find a bit free in
 583          * both
 584          */
 585         here = bitmap_search_next_usable_block(here, bh, maxblocks);
 586         return here;
 587 }
 588
 589 /*
 590  * We think we can allocate this block in this bitmap.  Try to set the bit.
 591  * If that succeeds then check that nobody has allocated and then freed the
 592  * block since we saw that is was not marked in b_committed_data.  If it _was_
 593  * allocated and freed then clear the bit in the bitmap again and return
 594  * zero (failure).
 595  */
 596 static inline int
 597 claim_block(spinlock_t *lock, int block, struct buffer_head *bh)
 598 {
 599         struct journal_head *jh = bh2jh(bh);
 600         int ret;
 601
 602         if (ext3_set_bit_atomic(lock, block, bh->b_data))
 603                 return 0;
 604         jbd_lock_bh_state(bh);
 605         if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) {
 606                 ext3_clear_bit_atomic(lock, block, bh->b_data);
 607                 ret = 0;
 608         } else {
 609                 ret = 1;
 610         }
 611         jbd_unlock_bh_state(bh);
 612         return ret;
 613 }
 614
 615 /*
 616  * If we failed to allocate the desired block then we may end up crossing to a
 617  * new bitmap.  In that case we must release write access to the old one via
 618  * ext3_journal_release_buffer(), else we'll run out of credits.
 619  */
 620 static int
 621 ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
 622         struct buffer_head *bitmap_bh, int goal, struct ext3_reserve_window *my_rsv)
 623 {
 624         int group_first_block, start, end;
 625
 626         /* we do allocation within the reservation window if we have a window */
 627         if (my_rsv) {
 628                 group_first_block =
 629                         le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
 630                         group * EXT3_BLOCKS_PER_GROUP(sb);
 631                 if (my_rsv->_rsv_start >= group_first_block)
 632                         start = my_rsv->_rsv_start - group_first_block;
 633                 else
 634                         /* reservation window cross group boundary */
 635                         start = 0;
 636                 end = my_rsv->_rsv_end - group_first_block + 1;
 637                 if (end > EXT3_BLOCKS_PER_GROUP(sb))
 638                         /* reservation window crosses group boundary */
 639                         end = EXT3_BLOCKS_PER_GROUP(sb);
 640                 if ((start <= goal) && (goal < end))
 641                         start = goal;
 642                 else
 643                         goal = -1;
 644         } else {
 645                 if (goal > 0)
 646                         start = goal;
 647                 else
 648                         start = 0;
 649                 end = EXT3_BLOCKS_PER_GROUP(sb);
 650         }
 651
 652         BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
 653
 654 repeat:
 655         if (goal < 0 || !ext3_test_allocatable(goal, bitmap_bh)) {
 656                 goal = find_next_usable_block(start, bitmap_bh, end);
 657                 if (goal < 0)
 658                         goto fail_access;
 659                 if (!my_rsv) {
 660                         int i;
 661
 662                         for (i = 0; i < 7 && goal > start &&
 663                                         ext3_test_allocatable(goal - 1,
 664                                                                 bitmap_bh);
 665                                         i++, goal--)
 666                                 ;
 667                 }
 668         }
 669         start = goal;
 670
 671         if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group), goal, bitmap_bh)) {
 672                 /*
 673                  * The block was allocated by another thread, or it was
 674                  * allocated and then freed by another thread
 675                  */
 676                 start++;
 677                 goal++;
 678                 if (start >= end)
 679                         goto fail_access;
 680                 goto repeat;
 681         }
 682         return goal;
 683 fail_access:
 684         return -1;
 685 }
 686
 687 /**
 688  *      find_next_reservable_window():
 689  *              find a reservable space within the given range.
 690  *              It does not allocate the reservation window for now:
 691  *              alloc_new_reservation() will do the work later.
 692  *
 693  *      @search_head: the head of the searching list;
 694  *              This is not necessarily the list head of the whole filesystem
 695  *
 696  *              We have both head and start_block to assist the search
 697  *              for the reservable space. The list starts from head,
 698  *              but we will shift to the place where start_block is,
 699  *              then start from there, when looking for a reservable space.
 700  *
 701  *      @size: the target new reservation window size
 702  *
 703  *      @group_first_block: the first block we consider to start
 704  *                      the real search from
 705  *
 706  *      @last_block:
 707  *              the maximum block number that our goal reservable space
 708  *              could start from. This is normally the last block in this
 709  *              group. The search will end when we found the start of next
 710  *              possible reservable space is out of this boundary.
 711  *              This could handle the cross boundary reservation window
 712  *              request.
 713  *
 714  *      basically we search from the given range, rather than the whole
 715  *      reservation double linked list, (start_block, last_block)
 716  *      to find a free region that is of my size and has not
 717  *      been reserved.
 718  *
 719  *      on succeed, it returns the reservation window to be appended to.
 720  *      failed, return NULL.
 721  */
 722 static struct ext3_reserve_window_node *find_next_reservable_window(
 723                                 struct ext3_reserve_window_node *search_head,
 724                                 unsigned long size, int *start_block,
 725                                 int last_block)
 726 {
 727         struct rb_node *next;
 728         struct ext3_reserve_window_node *rsv, *prev;
 729         int cur;
 730
 731         /* TODO: make the start of the reservation window byte-aligned */
 732         /* cur = *start_block & ~7;*/
 733         cur = *start_block;
 734         rsv = search_head;
 735         if (!rsv)
 736                 return NULL;
 737
 738         while (1) {
 739                 if (cur <= rsv->rsv_end)
 740                         cur = rsv->rsv_end + 1;
 741
 742                 /* TODO?
 743                  * in the case we could not find a reservable space
 744                  * that is what is expected, during the re-search, we could
 745                  * remember what's the largest reservable space we could have
 746                  * and return that one.
 747                  *
 748                  * For now it will fail if we could not find the reservable
 749                  * space with expected-size (or more)...
 750                  */
 751                 if (cur > last_block)
 752                         return NULL;            /* fail */
 753
 754                 prev = rsv;
 755                 next = rb_next(&rsv->rsv_node);
 756                 rsv = list_entry(next, struct ext3_reserve_window_node, rsv_node);
 757
 758                 /*
 759                  * Reached the last reservation, we can just append to the
 760                  * previous one.
 761                  */
 762                 if (!next)
 763                         break;
 764
 765                 if (cur + size <= rsv->rsv_start) {
 766                         /*
 767                          * Found a reserveable space big enough.  We could
 768                          * have a reservation across the group boundary here
 769                          */
 770                         break;
 771                 }
 772         }
 773         /*
 774          * we come here either :
 775          * when we reach the end of the whole list,
 776          * and there is empty reservable space after last entry in the list.
 777          * append it to the end of the list.
 778          *
 779          * or we found one reservable space in the middle of the list,
 780          * return the reservation window that we could append to.
 781          * succeed.
 782          */
 783         *start_block = cur;
 784         return prev;
 785 }
 786
 787 /**
 788  *      alloc_new_reservation()--allocate a new reservation window
 789  *
 790  *              To make a new reservation, we search part of the filesystem
 791  *              reservation list (the list that inside the group). We try to
 792  *              allocate a new reservation window near the allocation goal,
 793  *              or the beginning of the group, if there is no goal.
 794  *
 795  *              We first find a reservable space after the goal, then from
 796  *              there, we check the bitmap for the first free block after
 797  *              it. If there is no free block until the end of group, then the
 798  *              whole group is full, we failed. Otherwise, check if the free
 799  *              block is inside the expected reservable space, if so, we
 800  *              succeed.
 801  *              If the first free block is outside the reservable space, then
 802  *              start from the first free block, we search for next available
 803  *              space, and go on.
 804  *
 805  *      on succeed, a new reservation will be found and inserted into the list
 806  *      It contains at least one free block, and it does not overlap with other
 807  *      reservation windows.
 808  *
 809  *      failed: we failed to find a reservation window in this group
 810  *
 811  *      @rsv: the reservation
 812  *
 813  *      @goal: The goal (group-relative).  It is where the search for a
 814  *              free reservable space should start from.
 815  *              if we have a goal(goal >0 ), then start from there,
 816  *              no goal(goal = -1), we start from the first block
 817  *              of the group.
 818  *
 819  *      @sb: the super block
 820  *      @group: the group we are trying to allocate in
 821  *      @bitmap_bh: the block group block bitmap
 822  */
 823 static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
 824                 int goal, struct super_block *sb,
 825                 unsigned int group, struct buffer_head *bitmap_bh)
 826 {
 827         struct ext3_reserve_window_node *search_head;
 828         int group_first_block, group_end_block, start_block;
 829         int first_free_block;
 830         int reservable_space_start;
 831         struct ext3_reserve_window_node *prev_rsv;
 832         struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
 833         unsigned long size;
 834
 835         group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
 836                                 group * EXT3_BLOCKS_PER_GROUP(sb);
 837         group_end_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
 838
 839         if (goal < 0)
 840                 start_block = group_first_block;
 841         else
 842                 start_block = goal + group_first_block;
 843
 844         size = atomic_read(&my_rsv->rsv_goal_size);
 845         if (!rsv_is_empty(&my_rsv->rsv_window)) {
 846                 /*
 847                  * if the old reservation is cross group boundary
 848                  * and if the goal is inside the old reservation window,
 849                  * we will come here when we just failed to allocate from
 850                  * the first part of the window. We still have another part
 851                  * that belongs to the next group. In this case, there is no
 852                  * point to discard our window and try to allocate a new one
 853                  * in this group(which will fail). we should
 854                  * keep the reservation window, just simply move on.
 855                  *
 856                  * Maybe we could shift the start block of the reservation
 857                  * window to the first block of next group.
 858                  */
 859
 860                 if ((my_rsv->rsv_start <= group_end_block) &&
 861                                 (my_rsv->rsv_end > group_end_block) &&
 862                                 (start_block >= my_rsv->rsv_start))
 863                         return -1;
 864
 865                 if ((atomic_read(&my_rsv->rsv_alloc_hit) >
 866                      (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
 867                         /*
 868                          * if we previously allocation hit ration is greater than half
 869                          * we double the size of reservation window next time
 870                          * otherwise keep the same
 871                          */
 872                         size = size * 2;
 873                         if (size > EXT3_MAX_RESERVE_BLOCKS)
 874                                 size = EXT3_MAX_RESERVE_BLOCKS;
 875                         atomic_set(&my_rsv->rsv_goal_size, size);
 876                 }
 877         }
 878         /*
 879          * shift the search start to the window near the goal block
 880          */
 881         search_head = search_reserve_window(fs_rsv_root, start_block);
 882
 883         /*
 884          * find_next_reservable_window() simply finds a reservable window
 885          * inside the given range(start_block, group_end_block).
 886          *
 887          * To make sure the reservation window has a free bit inside it, we
 888          * need to check the bitmap after we found a reservable window.
 889          */
 890 retry:
 891         prev_rsv = find_next_reservable_window(search_head, size,
 892                                                 &start_block, group_end_block);
 893         if (prev_rsv == NULL)
 894                 goto failed;
 895         reservable_space_start = start_block;
 896         /*
 897          * On success, find_next_reservable_window() returns the
 898          * reservation window where there is a reservable space after it.
 899          * Before we reserve this reservable space, we need
 900          * to make sure there is at least a free block inside this region.
 901          *
 902          * searching the first free bit on the block bitmap and copy of
 903          * last committed bitmap alternatively, until we found a allocatable
 904          * block. Search start from the start block of the reservable space
 905          * we just found.
 906          */
 907         first_free_block = bitmap_search_next_usable_block(
 908                         reservable_space_start - group_first_block,
 909                         bitmap_bh, group_end_block - group_first_block + 1);
 910
 911         if (first_free_block < 0) {
 912                 /*
 913                  * no free block left on the bitmap, no point
 914                  * to reserve the space. return failed.
 915                  */
 916                 goto failed;
 917         }
 918         start_block = first_free_block + group_first_block;
 919         /*
 920          * check if the first free block is within the
 921          * free space we just found
 922          */
 923         if ((start_block >= reservable_space_start) &&
 924           (start_block < reservable_space_start + size))
 925                 goto found_rsv_window;
 926         /*
 927          * if the first free bit we found is out of the reservable space
 928          * this means there is no free block on the reservable space
 929          * we should continue search for next reservable space,
 930          * start from where the free block is,
 931          * we also shift the list head to where we stopped last time
 932          */
 933         search_head = prev_rsv;
 934         goto retry;
 935
 936 found_rsv_window:
 937         /*
 938          * great! the reservable space contains some free blocks.
 939          * if the search returns that we should add the new
 940          * window just next to where the old window, we don't
 941          * need to remove the old window first then add it to the
 942          * same place, just update the new start and new end.
 943          */
 944         if (my_rsv != prev_rsv)  {
 945                 if (!rsv_is_empty(&my_rsv->rsv_window))
 946                         rsv_window_remove(sb, my_rsv);
 947         }
 948         my_rsv->rsv_start = reservable_space_start;
 949         my_rsv->rsv_end = my_rsv->rsv_start + size - 1;
 950         atomic_set(&my_rsv->rsv_alloc_hit, 0);
 951         if (my_rsv != prev_rsv)  {
 952                 ext3_rsv_window_add(sb, my_rsv);
 953         }
 954         return 0;               /* succeed */
 955 failed:
 956         /*
 957          * failed to find a new reservation window in the current
 958          * group, remove the current(stale) reservation window
 959          * if there is any
 960          */
 961         if (!rsv_is_empty(&my_rsv->rsv_window))
 962                 rsv_window_remove(sb, my_rsv);
 963         return -1;              /* failed */
 964 }
 965
 966 /*
 967  * This is the main function used to allocate a new block and its reservation
 968  * window.
 969  *
 970  * Each time when a new block allocation is need, first try to allocate from
 971  * its own reservation.  If it does not have a reservation window, instead of
 972  * looking for a free bit on bitmap first, then look up the reservation list to
 973  * see if it is inside somebody else's reservation window, we try to allocate a
 974  * reservation window for it starting from the goal first. Then do the block
 975  * allocation within the reservation window.
 976  *
 977  * This will avoid keeping on searching the reservation list again and
 978  * again when someboday is looking for a free block (without
 979  * reservation), and there are lots of free blocks, but they are all
 980  * being reserved.
 981  *
 982  * We use a sorted double linked list for the per-filesystem reservation list.
 983  * The insert, remove and find a free space(non-reserved) operations for the
 984  * sorted double linked list should be fast.
 985  *
 986  */
 987 static int
 988 ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
 989                         unsigned int group, struct buffer_head *bitmap_bh,
 990                         int goal, struct ext3_reserve_window_node * my_rsv,
 991                         int *errp)
 992 {
 993         spinlock_t *rsv_lock;
 994         unsigned long group_first_block;
 995         int ret = 0;
 996         int fatal;
 997         int credits = 0;
 998
 999         *errp = 0;
1000
1001         /*
1002          * Make sure we use undo access for the bitmap, because it is critical
1003          * that we do the frozen_data COW on bitmap buffers in all cases even
1004          * if the buffer is in BJ_Forget state in the committing transaction.
1005          */
1006         BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1007         fatal = ext3_journal_get_undo_access(handle, bitmap_bh, &credits);
1008         if (fatal) {
1009                 *errp = fatal;
1010                 return -1;
1011         }
1012
1013         /*
1014          * we don't deal with reservation when
1015          * filesystem is mounted without reservation
1016          * or the file is not a regular file
1017          * or last attempt to allocate a block with reservation turned on failed
1018          */
1019         if (my_rsv == NULL ) {
1020                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal, NULL);
1021                 goto out;
1022         }
1023         rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1024         /*
1025          * goal is a group relative block number (if there is a goal)
1026          * 0 < goal < EXT3_BLOCKS_PER_GROUP(sb)
1027          * first block is a filesystem wide block number
1028          * first block is the block number of the first block in this group
1029          */
1030         group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
1031                         group * EXT3_BLOCKS_PER_GROUP(sb);
1032
1033         /*
1034          * Basically we will allocate a new block from inode's reservation
1035          * window.
1036          *
1037          * We need to allocate a new reservation window, if:
1038          * a) inode does not have a reservation window; or
1039          * b) last attempt to allocate a block from existing reservation
1040          *    failed; or
1041          * c) we come here with a goal and with a reservation window
1042          *
1043          * We do not need to allocate a new reservation window if we come here
1044          * at the beginning with a goal and the goal is inside the window, or
1045          * we don't have a goal but already have a reservation window.
1046          * then we could go to allocate from the reservation window directly.
1047          */
1048         while (1) {
1049                 struct ext3_reserve_window rsv_copy;
1050                 unsigned int seq;
1051
1052                 do {
1053                         seq = read_seqbegin(&my_rsv->rsv_seqlock);
1054                         rsv_copy._rsv_start = my_rsv->rsv_start;
1055                         rsv_copy._rsv_end = my_rsv->rsv_end;
1056                 } while (read_seqretry(&my_rsv->rsv_seqlock, seq));
1057
1058                 if (rsv_is_empty(&rsv_copy) || (ret < 0) ||
1059                         !goal_in_my_reservation(&rsv_copy, goal, group, sb)) {
1060                         spin_lock(rsv_lock);
1061                         write_seqlock(&my_rsv->rsv_seqlock);
1062                         ret = alloc_new_reservation(my_rsv, goal, sb,
1063                                                         group, bitmap_bh);
1064                         rsv_copy._rsv_start = my_rsv->rsv_start;
1065                         rsv_copy._rsv_end = my_rsv->rsv_end;
1066                         write_sequnlock(&my_rsv->rsv_seqlock);
1067                         spin_unlock(rsv_lock);
1068                         if (ret < 0)
1069                                 break;                  /* failed */
1070
1071                         if (!goal_in_my_reservation(&rsv_copy, goal, group, sb))
1072                                 goal = -1;
1073                 }
1074                 if ((rsv_copy._rsv_start >= group_first_block + EXT3_BLOCKS_PER_GROUP(sb))
1075                     || (rsv_copy._rsv_end < group_first_block))
1076                         BUG();
1077                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal,
1078                                            &rsv_copy);
1079                 if (ret >= 0) {
1080                         if (!read_seqretry(&my_rsv->rsv_seqlock, seq))
1081                                 atomic_inc(&my_rsv->rsv_alloc_hit);
1082                         break;                          /* succeed */
1083                 }
1084         }
1085 out:
1086         if (ret >= 0) {
1087                 BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1088                                         "bitmap block");
1089                 fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
1090                 if (fatal) {
1091                         *errp = fatal;
1092                         return -1;
1093                 }
1094                 return ret;
1095         }
1096
1097         BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1098         ext3_journal_release_buffer(handle, bitmap_bh, credits);
1099         return ret;
1100 }
1101
1102 static int ext3_has_free_blocks(struct super_block *sb)
1103 {
1104         struct ext3_sb_info *sbi = EXT3_SB(sb);
1105         int free_blocks, root_blocks, cond;
1106
1107         free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1108         root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1109
1110         vxdprintk(VXD_CBIT(dlim, 3),
1111                 "ext3_has_free_blocks(%p): free=%u, root=%u",
1112                 sb, free_blocks, root_blocks);
1113
1114         DLIMIT_ADJUST_BLOCK(sb, vx_current_xid(), &free_blocks, &root_blocks);
1115
1116         cond = (free_blocks < root_blocks + 1 &&
1117                 !capable(CAP_SYS_RESOURCE) &&
1118                 sbi->s_resuid != current->fsuid &&
1119                 (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid)));
1120
1121         vxdprintk(VXD_CBIT(dlim, 3),
1122                 "ext3_has_free_blocks(%p): %u<%u+1, %c, %u!=%u r=%d",
1123                 sb, free_blocks, root_blocks,
1124                 !capable(CAP_SYS_RESOURCE)?'1':'0',
1125                 sbi->s_resuid, current->fsuid, cond?0:1);
1126
1127         return (cond ? 0 : 1);
1128 }
1129
1130 /*
1131  * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
1132  * it is profitable to retry the operation, this function will wait
1133  * for the current or commiting transaction to complete, and then
1134  * return TRUE.
1135  */
1136 int ext3_should_retry_alloc(struct super_block *sb, int *retries)
1137 {
1138         if (!ext3_has_free_blocks(sb) || (*retries)++ > 3)
1139                 return 0;
1140
1141         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1142
1143         return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
1144 }
1145
1146 /*
1147  * ext3_new_block uses a goal block to assist allocation.  If the goal is
1148  * free, or there is a free block within 32 blocks of the goal, that block
1149  * is allocated.  Otherwise a forward search is made for a free block; within
1150  * each block group the search first looks for an entire free byte in the block
1151  * bitmap, and then for any free bit if that fails.
1152  * This function also updates quota and i_blocks field.
1153  */
1154 int ext3_new_block(handle_t *handle, struct inode *inode,
1155                         unsigned long goal, int *errp)
1156 {
1157         struct buffer_head *bitmap_bh = NULL;
1158         struct buffer_head *gdp_bh;
1159         int group_no;
1160         int goal_group;
1161         int ret_block;
1162         int bgi;                        /* blockgroup iteration index */
1163         int target_block;
1164         int fatal = 0, err;
1165         int performed_allocation = 0;
1166         int free_blocks;
1167         struct super_block *sb;
1168         struct ext3_group_desc *gdp;
1169         struct ext3_super_block *es;
1170         struct ext3_sb_info *sbi;
1171         struct ext3_reserve_window_node *my_rsv = NULL;
1172         struct ext3_reserve_window_node *rsv = &EXT3_I(inode)->i_rsv_window;
1173         unsigned short windowsz = 0;
1174 #ifdef EXT3FS_DEBUG
1175         static int goal_hits, goal_attempts;
1176 #endif
1177         unsigned long ngroups;
1178
1179         *errp = -ENOSPC;
1180         sb = inode->i_sb;
1181         if (!sb) {
1182                 printk("ext3_new_block: nonexistent device");
1183                 return 0;
1184         }
1185
1186         /*
1187          * Check quota for allocation of this block.
1188          */
1189         if (DQUOT_ALLOC_BLOCK(inode, 1)) {
1190                 *errp = -EDQUOT;
1191                 return 0;
1192         }
1193         if (DLIMIT_ALLOC_BLOCK(sb, inode->i_xid, 1))
1194                 goto out_dlimit;
1195
1196         sbi = EXT3_SB(sb);
1197         es = EXT3_SB(sb)->s_es;
1198         ext3_debug("goal=%lu.\n", goal);
1199         /*
1200          * Allocate a block from reservation only when
1201          * filesystem is mounted with reservation(default,-o reservation), and
1202          * it's a regular file, and
1203          * the desired window size is greater than 0 (One could use ioctl
1204          * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
1205          * reservation on that particular file)
1206          */
1207         windowsz = atomic_read(&rsv->rsv_goal_size);
1208         if (test_opt(sb, RESERVATION) &&
1209                 S_ISREG(inode->i_mode) && (windowsz > 0))
1210                 my_rsv = rsv;
1211         if (!ext3_has_free_blocks(sb)) {
1212                 *errp = -ENOSPC;
1213                 goto out;
1214         }
1215
1216         /*
1217          * First, test whether the goal block is free.
1218          */
1219         if (goal < le32_to_cpu(es->s_first_data_block) ||
1220             goal >= le32_to_cpu(es->s_blocks_count))
1221                 goal = le32_to_cpu(es->s_first_data_block);
1222         group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1223                         EXT3_BLOCKS_PER_GROUP(sb);
1224         gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1225         if (!gdp)
1226                 goto io_error;
1227
1228         goal_group = group_no;
1229 retry:
1230         free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1231         if (free_blocks > 0) {
1232                 ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) %
1233                                 EXT3_BLOCKS_PER_GROUP(sb));
1234                 bitmap_bh = read_block_bitmap(sb, group_no);
1235                 if (!bitmap_bh)
1236                         goto io_error;
1237                 ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
1238                                         bitmap_bh, ret_block, my_rsv, &fatal);
1239                 if (fatal)
1240                         goto out;
1241                 if (ret_block >= 0)
1242                         goto allocated;
1243         }
1244
1245         ngroups = EXT3_SB(sb)->s_groups_count;
1246         smp_rmb();
1247
1248         /*
1249          * Now search the rest of the groups.  We assume that
1250          * i and gdp correctly point to the last group visited.
1251          */
1252         for (bgi = 0; bgi < ngroups; bgi++) {
1253                 group_no++;
1254                 if (group_no >= ngroups)
1255                         group_no = 0;
1256                 gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1257                 if (!gdp) {
1258                         *errp = -EIO;
1259                         goto out;
1260                 }
1261                 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1262                 /*
1263                  * skip this group if the number of
1264                  * free blocks is less than half of the reservation
1265                  * window size.
1266                  */
1267                 if (free_blocks <= (windowsz/2))
1268                         continue;
1269
1270                 brelse(bitmap_bh);
1271                 bitmap_bh = read_block_bitmap(sb, group_no);
1272                 if (!bitmap_bh)
1273                         goto io_error;
1274                 ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
1275                                         bitmap_bh, -1, my_rsv, &fatal);
1276                 if (fatal)
1277                         goto out;
1278                 if (ret_block >= 0)
1279                         goto allocated;
1280         }
1281         /*
1282          * We may end up a bogus ealier ENOSPC error due to
1283          * filesystem is "full" of reservations, but
1284          * there maybe indeed free blocks avaliable on disk
1285          * In this case, we just forget about the reservations
1286          * just do block allocation as without reservations.
1287          */
1288         if (my_rsv) {
1289                 my_rsv = NULL;
1290                 group_no = goal_group;
1291                 goto retry;
1292         }
1293         /* No space left on the device */
1294         *errp = -ENOSPC;
1295         goto out;
1296
1297 allocated:
1298
1299         ext3_debug("using block group %d(%d)\n",
1300                         group_no, gdp->bg_free_blocks_count);
1301
1302         BUFFER_TRACE(gdp_bh, "get_write_access");
1303         fatal = ext3_journal_get_write_access(handle, gdp_bh);
1304         if (fatal)
1305                 goto out;
1306
1307         target_block = ret_block + group_no * EXT3_BLOCKS_PER_GROUP(sb)
1308                                 + le32_to_cpu(es->s_first_data_block);
1309
1310         if (target_block == le32_to_cpu(gdp->bg_block_bitmap) ||
1311             target_block == le32_to_cpu(gdp->bg_inode_bitmap) ||
1312             in_range(target_block, le32_to_cpu(gdp->bg_inode_table),
1313                       EXT3_SB(sb)->s_itb_per_group))
1314                 ext3_error(sb, "ext3_new_block",
1315                             "Allocating block in system zone - "
1316                             "block = %u", target_block);
1317
1318         performed_allocation = 1;
1319
1320 #ifdef CONFIG_JBD_DEBUG
1321         {
1322                 struct buffer_head *debug_bh;
1323
1324                 /* Record bitmap buffer state in the newly allocated block */
1325                 debug_bh = sb_find_get_block(sb, target_block);
1326                 if (debug_bh) {
1327                         BUFFER_TRACE(debug_bh, "state when allocated");
1328                         BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1329                         brelse(debug_bh);
1330                 }
1331         }
1332         jbd_lock_bh_state(bitmap_bh);
1333         spin_lock(sb_bgl_lock(sbi, group_no));
1334         if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1335                 if (ext3_test_bit(ret_block,
1336                                 bh2jh(bitmap_bh)->b_committed_data)) {
1337                         printk("%s: block was unexpectedly set in "
1338                                 "b_committed_data\n", __FUNCTION__);
1339                 }
1340         }
1341         ext3_debug("found bit %d\n", ret_block);
1342         spin_unlock(sb_bgl_lock(sbi, group_no));
1343         jbd_unlock_bh_state(bitmap_bh);
1344 #endif
1345
1346         /* ret_block was blockgroup-relative.  Now it becomes fs-relative */
1347         ret_block = target_block;
1348
1349         if (ret_block >= le32_to_cpu(es->s_blocks_count)) {
1350                 ext3_error(sb, "ext3_new_block",
1351                             "block(%d) >= blocks count(%d) - "
1352                             "block_group = %d, es == %p ", ret_block,
1353                         le32_to_cpu(es->s_blocks_count), group_no, es);
1354                 goto out;
1355         }
1356
1357         /*
1358          * It is up to the caller to add the new buffer to a journal
1359          * list of some description.  We don't know in advance whether
1360          * the caller wants to use it as metadata or data.
1361          */
1362         ext3_debug("allocating block %d. Goal hits %d of %d.\n",
1363                         ret_block, goal_hits, goal_attempts);
1364
1365         spin_lock(sb_bgl_lock(sbi, group_no));
1366         gdp->bg_free_blocks_count =
1367                         cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) - 1);
1368         spin_unlock(sb_bgl_lock(sbi, group_no));
1369         percpu_counter_mod(&sbi->s_freeblocks_counter, -1);
1370
1371         BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1372         err = ext3_journal_dirty_metadata(handle, gdp_bh);
1373         if (!fatal)
1374                 fatal = err;
1375
1376         sb->s_dirt = 1;
1377         if (fatal)
1378                 goto out;
1379
1380         *errp = 0;
1381         brelse(bitmap_bh);
1382         return ret_block;
1383
1384 io_error:
1385         *errp = -EIO;
1386 out:
1387         if (!performed_allocation)
1388                 DLIMIT_FREE_BLOCK(sb, inode->i_xid, 1);
1389 out_dlimit:
1390         if (fatal) {
1391                 *errp = fatal;
1392                 ext3_std_error(sb, fatal);
1393         }
1394         /*
1395          * Undo the block allocation
1396          */
1397         if (!performed_allocation)
1398                 DQUOT_FREE_BLOCK(inode, 1);
1399         brelse(bitmap_bh);
1400         return 0;
1401 }
1402
1403 unsigned long ext3_count_free_blocks(struct super_block *sb)
1404 {
1405         unsigned long desc_count;
1406         struct ext3_group_desc *gdp;
1407         int i;
1408         unsigned long ngroups;
1409 #ifdef EXT3FS_DEBUG
1410         struct ext3_super_block *es;
1411         unsigned long bitmap_count, x;
1412         struct buffer_head *bitmap_bh = NULL;
1413
1414         lock_super(sb);
1415         es = EXT3_SB(sb)->s_es;
1416         desc_count = 0;
1417         bitmap_count = 0;
1418         gdp = NULL;
1419         for (i = 0; i < EXT3_SB(sb)->s_groups_count; i++) {
1420                 gdp = ext3_get_group_desc(sb, i, NULL);
1421                 if (!gdp)
1422                         continue;
1423                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1424                 brelse(bitmap_bh);
1425                 bitmap_bh = read_block_bitmap(sb, i);
1426                 if (bitmap_bh == NULL)
1427                         continue;
1428
1429                 x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1430                 printk("group %d: stored = %d, counted = %lu\n",
1431                         i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1432                 bitmap_count += x;
1433         }
1434         brelse(bitmap_bh);
1435         printk("ext3_count_free_blocks: stored = %u, computed = %lu, %lu\n",
1436                le32_to_cpu(es->s_free_blocks_count), desc_count, bitmap_count);
1437         unlock_super(sb);
1438         return bitmap_count;
1439 #else
1440         desc_count = 0;
1441         ngroups = EXT3_SB(sb)->s_groups_count;
1442         smp_rmb();
1443         for (i = 0; i < ngroups; i++) {
1444                 gdp = ext3_get_group_desc(sb, i, NULL);
1445                 if (!gdp)
1446                         continue;
1447                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1448         }
1449
1450         return desc_count;
1451 #endif
1452 }
1453
1454 static inline int block_in_use(unsigned long block,
1455                                 struct super_block * sb,
1456                                 unsigned char * map)
1457 {
1458         return ext3_test_bit ((block -
1459                 le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) %
1460                          EXT3_BLOCKS_PER_GROUP(sb), map);
1461 }
1462
1463 static inline int test_root(int a, int b)
1464 {
1465         int num = b;
1466
1467         while (a > num)
1468                 num *= b;
1469         return num == a;
1470 }
1471
1472 static int ext3_group_sparse(int group)
1473 {
1474         if (group <= 1)
1475                 return 1;
1476         return (test_root(group, 3) || test_root(group, 5) ||
1477                 test_root(group, 7));
1478 }
1479
1480 /**
1481  *      ext3_bg_has_super - number of blocks used by the superblock in group
1482  *      @sb: superblock for filesystem
1483  *      @group: group number to check
1484  *
1485  *      Return the number of blocks used by the superblock (primary or backup)
1486  *      in this group.  Currently this will be only 0 or 1.
1487  */
1488 int ext3_bg_has_super(struct super_block *sb, int group)
1489 {
1490         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1491             !ext3_group_sparse(group))
1492                 return 0;
1493         return 1;
1494 }
1495
1496 /**
1497  *      ext3_bg_num_gdb - number of blocks used by the group table in group
1498  *      @sb: superblock for filesystem
1499  *      @group: group number to check
1500  *
1501  *      Return the number of blocks used by the group descriptor table
1502  *      (primary or backup) in this group.  In the future there may be a
1503  *      different number of descriptor blocks in each group.
1504  */
1505 unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
1506 {
1507         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1508             !ext3_group_sparse(group))
1509                 return 0;
1510         return EXT3_SB(sb)->s_gdb_count;
1511 }
1512
1513 #ifdef CONFIG_EXT3_CHECK
1514 /* Called at mount-time, super-block is locked */
1515 void ext3_check_blocks_bitmap (struct super_block * sb)
1516 {
1517         struct ext3_super_block *es;
1518         unsigned long desc_count, bitmap_count, x, j;
1519         unsigned long desc_blocks;
1520         struct buffer_head *bitmap_bh = NULL;
1521         struct ext3_group_desc *gdp;
1522         int i;
1523
1524         es = EXT3_SB(sb)->s_es;
1525         desc_count = 0;
1526         bitmap_count = 0;
1527         gdp = NULL;
1528         for (i = 0; i < EXT3_SB(sb)->s_groups_count; i++) {
1529                 gdp = ext3_get_group_desc (sb, i, NULL);
1530                 if (!gdp)
1531                         continue;
1532                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1533                 brelse(bitmap_bh);
1534                 bitmap_bh = read_block_bitmap(sb, i);
1535                 if (bitmap_bh == NULL)
1536                         continue;
1537
1538                 if (ext3_bg_has_super(sb, i) &&
1539                                 !ext3_test_bit(0, bitmap_bh->b_data))
1540                         ext3_error(sb, __FUNCTION__,
1541                                    "Superblock in group %d is marked free", i);
1542
1543                 desc_blocks = ext3_bg_num_gdb(sb, i);
1544                 for (j = 0; j < desc_blocks; j++)
1545                         if (!ext3_test_bit(j + 1, bitmap_bh->b_data))
1546                                 ext3_error(sb, __FUNCTION__,
1547                                            "Descriptor block #%ld in group "
1548                                            "%d is marked free", j, i);
1549
1550                 if (!block_in_use (le32_to_cpu(gdp->bg_block_bitmap),
1551                                                 sb, bitmap_bh->b_data))
1552                         ext3_error (sb, "ext3_check_blocks_bitmap",
1553                                     "Block bitmap for group %d is marked free",
1554                                     i);
1555
1556                 if (!block_in_use (le32_to_cpu(gdp->bg_inode_bitmap),
1557                                                 sb, bitmap_bh->b_data))
1558                         ext3_error (sb, "ext3_check_blocks_bitmap",
1559                                     "Inode bitmap for group %d is marked free",
1560                                     i);
1561
1562                 for (j = 0; j < EXT3_SB(sb)->s_itb_per_group; j++)
1563                         if (!block_in_use (le32_to_cpu(gdp->bg_inode_table) + j,
1564                                                         sb, bitmap_bh->b_data))
1565                                 ext3_error (sb, "ext3_check_blocks_bitmap",
1566                                             "Block #%d of the inode table in "
1567                                             "group %d is marked free", j, i);
1568
1569                 x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1570                 if (le16_to_cpu(gdp->bg_free_blocks_count) != x)
1571                         ext3_error (sb, "ext3_check_blocks_bitmap",
1572                                     "Wrong free blocks count for group %d, "
1573                                     "stored = %d, counted = %lu", i,
1574                                     le16_to_cpu(gdp->bg_free_blocks_count), x);
1575                 bitmap_count += x;
1576         }
1577         brelse(bitmap_bh);
1578         if (le32_to_cpu(es->s_free_blocks_count) != bitmap_count)
1579                 ext3_error (sb, "ext3_check_blocks_bitmap",
1580                         "Wrong free blocks count in super block, "
1581                         "stored = %lu, counted = %lu",
1582                         (unsigned long)le32_to_cpu(es->s_free_blocks_count),
1583                         bitmap_count);
1584 }
1585 #endif