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/capability.h>
  17 #include <linux/fs.h>
  18 #include <linux/jbd.h>
  19 #include <linux/ext3_fs.h>
  20 #include <linux/ext3_jbd.h>
  21 #include <linux/quotaops.h>
  22 #include <linux/buffer_head.h>
  23 #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 offset;
  49         struct ext3_group_desc * desc;
  50         struct ext3_sb_info *sbi = EXT3_SB(sb);
  51
  52         if (block_group >= sbi->s_groups_count) {
  53                 ext3_error (sb, "ext3_get_group_desc",
  54                             "block_group >= groups_count - "
  55                             "block_group = %d, groups_count = %lu",
  56                             block_group, sbi->s_groups_count);
  57
  58                 return NULL;
  59         }
  60         smp_rmb();
  61
  62         group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb);
  63         offset = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1);
  64         if (!sbi->s_group_desc[group_desc]) {
  65                 ext3_error (sb, "ext3_get_group_desc",
  66                             "Group descriptor not loaded - "
  67                             "block_group = %d, group_desc = %lu, desc = %lu",
  68                              block_group, group_desc, offset);
  69                 return NULL;
  70         }
  71
  72         desc = (struct ext3_group_desc *) sbi->s_group_desc[group_desc]->b_data;
  73         if (bh)
  74                 *bh = sbi->s_group_desc[group_desc];
  75         return desc + offset;
  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         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 void ext3_init_block_alloc_info(struct inode *inode)
 265 {
 266         struct ext3_inode_info *ei = EXT3_I(inode);
 267         struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
 268         struct super_block *sb = inode->i_sb;
 269
 270         block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
 271         if (block_i) {
 272                 struct ext3_reserve_window_node *rsv = &block_i->rsv_window_node;
 273
 274                 rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 275                 rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 276
 277                 /*
 278                  * if filesystem is mounted with NORESERVATION, the goal
 279                  * reservation window size is set to zero to indicate
 280                  * block reservation is off
 281                  */
 282                 if (!test_opt(sb, RESERVATION))
 283                         rsv->rsv_goal_size = 0;
 284                 else
 285                         rsv->rsv_goal_size = EXT3_DEFAULT_RESERVE_BLOCKS;
 286                 rsv->rsv_alloc_hit = 0;
 287                 block_i->last_alloc_logical_block = 0;
 288                 block_i->last_alloc_physical_block = 0;
 289         }
 290         ei->i_block_alloc_info = block_i;
 291 }
 292
 293 void ext3_discard_reservation(struct inode *inode)
 294 {
 295         struct ext3_inode_info *ei = EXT3_I(inode);
 296         struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
 297         struct ext3_reserve_window_node *rsv;
 298         spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
 299
 300         if (!block_i)
 301                 return;
 302
 303         rsv = &block_i->rsv_window_node;
 304         if (!rsv_is_empty(&rsv->rsv_window)) {
 305                 spin_lock(rsv_lock);
 306                 if (!rsv_is_empty(&rsv->rsv_window))
 307                         rsv_window_remove(inode->i_sb, rsv);
 308                 spin_unlock(rsv_lock);
 309         }
 310 }
 311
 312 /* Free given blocks, update quota and i_blocks field */
 313 void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,
 314                          unsigned long block, unsigned long count,
 315                          int *pdquot_freed_blocks)
 316 {
 317         struct buffer_head *bitmap_bh = NULL;
 318         struct buffer_head *gd_bh;
 319         unsigned long block_group;
 320         unsigned long bit;
 321         unsigned long i;
 322         unsigned long overflow;
 323         struct ext3_group_desc * desc;
 324         struct ext3_super_block * es;
 325         struct ext3_sb_info *sbi;
 326         int err = 0, ret;
 327         unsigned group_freed;
 328
 329         *pdquot_freed_blocks = 0;
 330         sbi = EXT3_SB(sb);
 331         es = sbi->s_es;
 332         if (block < le32_to_cpu(es->s_first_data_block) ||
 333             block + count < block ||
 334             block + count > le32_to_cpu(es->s_blocks_count)) {
 335                 ext3_error (sb, "ext3_free_blocks",
 336                             "Freeing blocks not in datazone - "
 337                             "block = %lu, count = %lu", block, count);
 338                 goto error_return;
 339         }
 340
 341         ext3_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
 342
 343 do_more:
 344         overflow = 0;
 345         block_group = (block - le32_to_cpu(es->s_first_data_block)) /
 346                       EXT3_BLOCKS_PER_GROUP(sb);
 347         bit = (block - le32_to_cpu(es->s_first_data_block)) %
 348                       EXT3_BLOCKS_PER_GROUP(sb);
 349         /*
 350          * Check to see if we are freeing blocks across a group
 351          * boundary.
 352          */
 353         if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
 354                 overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
 355                 count -= overflow;
 356         }
 357         brelse(bitmap_bh);
 358         bitmap_bh = read_block_bitmap(sb, block_group);
 359         if (!bitmap_bh)
 360                 goto error_return;
 361         desc = ext3_get_group_desc (sb, block_group, &gd_bh);
 362         if (!desc)
 363                 goto error_return;
 364
 365         if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
 366             in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
 367             in_range (block, le32_to_cpu(desc->bg_inode_table),
 368                       sbi->s_itb_per_group) ||
 369             in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
 370                       sbi->s_itb_per_group))
 371                 ext3_error (sb, "ext3_free_blocks",
 372                             "Freeing blocks in system zones - "
 373                             "Block = %lu, count = %lu",
 374                             block, count);
 375
 376         /*
 377          * We are about to start releasing blocks in the bitmap,
 378          * so we need undo access.
 379          */
 380         /* @@@ check errors */
 381         BUFFER_TRACE(bitmap_bh, "getting undo access");
 382         err = ext3_journal_get_undo_access(handle, bitmap_bh);
 383         if (err)
 384                 goto error_return;
 385
 386         /*
 387          * We are about to modify some metadata.  Call the journal APIs
 388          * to unshare ->b_data if a currently-committing transaction is
 389          * using it
 390          */
 391         BUFFER_TRACE(gd_bh, "get_write_access");
 392         err = ext3_journal_get_write_access(handle, gd_bh);
 393         if (err)
 394                 goto error_return;
 395
 396         jbd_lock_bh_state(bitmap_bh);
 397
 398         for (i = 0, group_freed = 0; i < count; i++) {
 399                 /*
 400                  * An HJ special.  This is expensive...
 401                  */
 402 #ifdef CONFIG_JBD_DEBUG
 403                 jbd_unlock_bh_state(bitmap_bh);
 404                 {
 405                         struct buffer_head *debug_bh;
 406                         debug_bh = sb_find_get_block(sb, block + i);
 407                         if (debug_bh) {
 408                                 BUFFER_TRACE(debug_bh, "Deleted!");
 409                                 if (!bh2jh(bitmap_bh)->b_committed_data)
 410                                         BUFFER_TRACE(debug_bh,
 411                                                 "No commited data in bitmap");
 412                                 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
 413                                 __brelse(debug_bh);
 414                         }
 415                 }
 416                 jbd_lock_bh_state(bitmap_bh);
 417 #endif
 418                 if (need_resched()) {
 419                         jbd_unlock_bh_state(bitmap_bh);
 420                         cond_resched();
 421                         jbd_lock_bh_state(bitmap_bh);
 422                 }
 423                 /* @@@ This prevents newly-allocated data from being
 424                  * freed and then reallocated within the same
 425                  * transaction.
 426                  *
 427                  * Ideally we would want to allow that to happen, but to
 428                  * do so requires making journal_forget() capable of
 429                  * revoking the queued write of a data block, which
 430                  * implies blocking on the journal lock.  *forget()
 431                  * cannot block due to truncate races.
 432                  *
 433                  * Eventually we can fix this by making journal_forget()
 434                  * return a status indicating whether or not it was able
 435                  * to revoke the buffer.  On successful revoke, it is
 436                  * safe not to set the allocation bit in the committed
 437                  * bitmap, because we know that there is no outstanding
 438                  * activity on the buffer any more and so it is safe to
 439                  * reallocate it.
 440                  */
 441                 BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
 442                 J_ASSERT_BH(bitmap_bh,
 443                                 bh2jh(bitmap_bh)->b_committed_data != NULL);
 444                 ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
 445                                 bh2jh(bitmap_bh)->b_committed_data);
 446
 447                 /*
 448                  * We clear the bit in the bitmap after setting the committed
 449                  * data bit, because this is the reverse order to that which
 450                  * the allocator uses.
 451                  */
 452                 BUFFER_TRACE(bitmap_bh, "clear bit");
 453                 if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 454                                                 bit + i, bitmap_bh->b_data)) {
 455                         jbd_unlock_bh_state(bitmap_bh);
 456                         ext3_error(sb, __FUNCTION__,
 457                                 "bit already cleared for block %lu", block + i);
 458                         jbd_lock_bh_state(bitmap_bh);
 459                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
 460                 } else {
 461                         group_freed++;
 462                 }
 463         }
 464         jbd_unlock_bh_state(bitmap_bh);
 465
 466         spin_lock(sb_bgl_lock(sbi, block_group));
 467         desc->bg_free_blocks_count =
 468                 cpu_to_le16(le16_to_cpu(desc->bg_free_blocks_count) +
 469                         group_freed);
 470         spin_unlock(sb_bgl_lock(sbi, block_group));
 471         percpu_counter_mod(&sbi->s_freeblocks_counter, count);
 472
 473         /* We dirtied the bitmap block */
 474         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
 475         err = ext3_journal_dirty_metadata(handle, bitmap_bh);
 476
 477         /* And the group descriptor block */
 478         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
 479         ret = ext3_journal_dirty_metadata(handle, gd_bh);
 480         if (!err) err = ret;
 481         *pdquot_freed_blocks += group_freed;
 482
 483         if (overflow && !err) {
 484                 block += count;
 485                 count = overflow;
 486                 goto do_more;
 487         }
 488         sb->s_dirt = 1;
 489 error_return:
 490         brelse(bitmap_bh);
 491         ext3_std_error(sb, err);
 492         return;
 493 }
 494
 495 /* Free given blocks, update quota and i_blocks field */
 496 void ext3_free_blocks(handle_t *handle, struct inode *inode,
 497                         unsigned long block, unsigned long count)
 498 {
 499         struct super_block * sb;
 500         int dquot_freed_blocks;
 501
 502         sb = inode->i_sb;
 503         if (!sb) {
 504                 printk ("ext3_free_blocks: nonexistent device");
 505                 return;
 506         }
 507         ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
 508         if (dquot_freed_blocks) {
 509                 DLIMIT_FREE_BLOCK(inode, dquot_freed_blocks);
 510                 DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
 511         }
 512         return;
 513 }
 514
 515 /*
 516  * For ext3 allocations, we must not reuse any blocks which are
 517  * allocated in the bitmap buffer's "last committed data" copy.  This
 518  * prevents deletes from freeing up the page for reuse until we have
 519  * committed the delete transaction.
 520  *
 521  * If we didn't do this, then deleting something and reallocating it as
 522  * data would allow the old block to be overwritten before the
 523  * transaction committed (because we force data to disk before commit).
 524  * This would lead to corruption if we crashed between overwriting the
 525  * data and committing the delete.
 526  *
 527  * @@@ We may want to make this allocation behaviour conditional on
 528  * data-writes at some point, and disable it for metadata allocations or
 529  * sync-data inodes.
 530  */
 531 static int ext3_test_allocatable(int nr, struct buffer_head *bh)
 532 {
 533         int ret;
 534         struct journal_head *jh = bh2jh(bh);
 535
 536         if (ext3_test_bit(nr, bh->b_data))
 537                 return 0;
 538
 539         jbd_lock_bh_state(bh);
 540         if (!jh->b_committed_data)
 541                 ret = 1;
 542         else
 543                 ret = !ext3_test_bit(nr, jh->b_committed_data);
 544         jbd_unlock_bh_state(bh);
 545         return ret;
 546 }
 547
 548 static int
 549 bitmap_search_next_usable_block(int start, struct buffer_head *bh,
 550                                         int maxblocks)
 551 {
 552         int next;
 553         struct journal_head *jh = bh2jh(bh);
 554
 555         /*
 556          * The bitmap search --- search forward alternately through the actual
 557          * bitmap and the last-committed copy until we find a bit free in
 558          * both
 559          */
 560         while (start < maxblocks) {
 561                 next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
 562                 if (next >= maxblocks)
 563                         return -1;
 564                 if (ext3_test_allocatable(next, bh))
 565                         return next;
 566                 jbd_lock_bh_state(bh);
 567                 if (jh->b_committed_data)
 568                         start = ext3_find_next_zero_bit(jh->b_committed_data,
 569                                                         maxblocks, next);
 570                 jbd_unlock_bh_state(bh);
 571         }
 572         return -1;
 573 }
 574
 575 /*
 576  * Find an allocatable block in a bitmap.  We honour both the bitmap and
 577  * its last-committed copy (if that exists), and perform the "most
 578  * appropriate allocation" algorithm of looking for a free block near
 579  * the initial goal; then for a free byte somewhere in the bitmap; then
 580  * for any free bit in the bitmap.
 581  */
 582 static int
 583 find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
 584 {
 585         int here, next;
 586         char *p, *r;
 587
 588         if (start > 0) {
 589                 /*
 590                  * The goal was occupied; search forward for a free
 591                  * block within the next XX blocks.
 592                  *
 593                  * end_goal is more or less random, but it has to be
 594                  * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the
 595                  * next 64-bit boundary is simple..
 596                  */
 597                 int end_goal = (start + 63) & ~63;
 598                 if (end_goal > maxblocks)
 599                         end_goal = maxblocks;
 600                 here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
 601                 if (here < end_goal && ext3_test_allocatable(here, bh))
 602                         return here;
 603                 ext3_debug("Bit not found near goal\n");
 604         }
 605
 606         here = start;
 607         if (here < 0)
 608                 here = 0;
 609
 610         p = ((char *)bh->b_data) + (here >> 3);
 611         r = memscan(p, 0, (maxblocks - here + 7) >> 3);
 612         next = (r - ((char *)bh->b_data)) << 3;
 613
 614         if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))
 615                 return next;
 616
 617         /*
 618          * The bitmap search --- search forward alternately through the actual
 619          * bitmap and the last-committed copy until we find a bit free in
 620          * both
 621          */
 622         here = bitmap_search_next_usable_block(here, bh, maxblocks);
 623         return here;
 624 }
 625
 626 /*
 627  * We think we can allocate this block in this bitmap.  Try to set the bit.
 628  * If that succeeds then check that nobody has allocated and then freed the
 629  * block since we saw that is was not marked in b_committed_data.  If it _was_
 630  * allocated and freed then clear the bit in the bitmap again and return
 631  * zero (failure).
 632  */
 633 static inline int
 634 claim_block(spinlock_t *lock, int block, struct buffer_head *bh)
 635 {
 636         struct journal_head *jh = bh2jh(bh);
 637         int ret;
 638
 639         if (ext3_set_bit_atomic(lock, block, bh->b_data))
 640                 return 0;
 641         jbd_lock_bh_state(bh);
 642         if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) {
 643                 ext3_clear_bit_atomic(lock, block, bh->b_data);
 644                 ret = 0;
 645         } else {
 646                 ret = 1;
 647         }
 648         jbd_unlock_bh_state(bh);
 649         return ret;
 650 }
 651
 652 /*
 653  * If we failed to allocate the desired block then we may end up crossing to a
 654  * new bitmap.  In that case we must release write access to the old one via
 655  * ext3_journal_release_buffer(), else we'll run out of credits.
 656  */
 657 static int
 658 ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
 659                         struct buffer_head *bitmap_bh, int goal,
 660                         unsigned long *count, struct ext3_reserve_window *my_rsv)
 661 {
 662         int group_first_block, start, end;
 663         unsigned long num = 0;
 664
 665         /* we do allocation within the reservation window if we have a window */
 666         if (my_rsv) {
 667                 group_first_block =
 668                         le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
 669                         group * EXT3_BLOCKS_PER_GROUP(sb);
 670                 if (my_rsv->_rsv_start >= group_first_block)
 671                         start = my_rsv->_rsv_start - group_first_block;
 672                 else
 673                         /* reservation window cross group boundary */
 674                         start = 0;
 675                 end = my_rsv->_rsv_end - group_first_block + 1;
 676                 if (end > EXT3_BLOCKS_PER_GROUP(sb))
 677                         /* reservation window crosses group boundary */
 678                         end = EXT3_BLOCKS_PER_GROUP(sb);
 679                 if ((start <= goal) && (goal < end))
 680                         start = goal;
 681                 else
 682                         goal = -1;
 683         } else {
 684                 if (goal > 0)
 685                         start = goal;
 686                 else
 687                         start = 0;
 688                 end = EXT3_BLOCKS_PER_GROUP(sb);
 689         }
 690
 691         BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
 692
 693 repeat:
 694         if (goal < 0 || !ext3_test_allocatable(goal, bitmap_bh)) {
 695                 goal = find_next_usable_block(start, bitmap_bh, end);
 696                 if (goal < 0)
 697                         goto fail_access;
 698                 if (!my_rsv) {
 699                         int i;
 700
 701                         for (i = 0; i < 7 && goal > start &&
 702                                         ext3_test_allocatable(goal - 1,
 703                                                                 bitmap_bh);
 704                                         i++, goal--)
 705                                 ;
 706                 }
 707         }
 708         start = goal;
 709
 710         if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group), goal, bitmap_bh)) {
 711                 /*
 712                  * The block was allocated by another thread, or it was
 713                  * allocated and then freed by another thread
 714                  */
 715                 start++;
 716                 goal++;
 717                 if (start >= end)
 718                         goto fail_access;
 719                 goto repeat;
 720         }
 721         num++;
 722         goal++;
 723         while (num < *count && goal < end
 724                 && ext3_test_allocatable(goal, bitmap_bh)
 725                 && claim_block(sb_bgl_lock(EXT3_SB(sb), group), goal, bitmap_bh)) {
 726                 num++;
 727                 goal++;
 728         }
 729         *count = num;
 730         return goal - num;
 731 fail_access:
 732         *count = num;
 733         return -1;
 734 }
 735
 736 /**
 737  *      find_next_reservable_window():
 738  *              find a reservable space within the given range.
 739  *              It does not allocate the reservation window for now:
 740  *              alloc_new_reservation() will do the work later.
 741  *
 742  *      @search_head: the head of the searching list;
 743  *              This is not necessarily the list head of the whole filesystem
 744  *
 745  *              We have both head and start_block to assist the search
 746  *              for the reservable space. The list starts from head,
 747  *              but we will shift to the place where start_block is,
 748  *              then start from there, when looking for a reservable space.
 749  *
 750  *      @size: the target new reservation window size
 751  *
 752  *      @group_first_block: the first block we consider to start
 753  *                      the real search from
 754  *
 755  *      @last_block:
 756  *              the maximum block number that our goal reservable space
 757  *              could start from. This is normally the last block in this
 758  *              group. The search will end when we found the start of next
 759  *              possible reservable space is out of this boundary.
 760  *              This could handle the cross boundary reservation window
 761  *              request.
 762  *
 763  *      basically we search from the given range, rather than the whole
 764  *      reservation double linked list, (start_block, last_block)
 765  *      to find a free region that is of my size and has not
 766  *      been reserved.
 767  *
 768  */
 769 static int find_next_reservable_window(
 770                                 struct ext3_reserve_window_node *search_head,
 771                                 struct ext3_reserve_window_node *my_rsv,
 772                                 struct super_block * sb, int start_block,
 773                                 int last_block)
 774 {
 775         struct rb_node *next;
 776         struct ext3_reserve_window_node *rsv, *prev;
 777         int cur;
 778         int size = my_rsv->rsv_goal_size;
 779
 780         /* TODO: make the start of the reservation window byte-aligned */
 781         /* cur = *start_block & ~7;*/
 782         cur = start_block;
 783         rsv = search_head;
 784         if (!rsv)
 785                 return -1;
 786
 787         while (1) {
 788                 if (cur <= rsv->rsv_end)
 789                         cur = rsv->rsv_end + 1;
 790
 791                 /* TODO?
 792                  * in the case we could not find a reservable space
 793                  * that is what is expected, during the re-search, we could
 794                  * remember what's the largest reservable space we could have
 795                  * and return that one.
 796                  *
 797                  * For now it will fail if we could not find the reservable
 798                  * space with expected-size (or more)...
 799                  */
 800                 if (cur > last_block)
 801                         return -1;              /* fail */
 802
 803                 prev = rsv;
 804                 next = rb_next(&rsv->rsv_node);
 805                 rsv = list_entry(next,struct ext3_reserve_window_node,rsv_node);
 806
 807                 /*
 808                  * Reached the last reservation, we can just append to the
 809                  * previous one.
 810                  */
 811                 if (!next)
 812                         break;
 813
 814                 if (cur + size <= rsv->rsv_start) {
 815                         /*
 816                          * Found a reserveable space big enough.  We could
 817                          * have a reservation across the group boundary here
 818                          */
 819                         break;
 820                 }
 821         }
 822         /*
 823          * we come here either :
 824          * when we reach the end of the whole list,
 825          * and there is empty reservable space after last entry in the list.
 826          * append it to the end of the list.
 827          *
 828          * or we found one reservable space in the middle of the list,
 829          * return the reservation window that we could append to.
 830          * succeed.
 831          */
 832
 833         if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
 834                 rsv_window_remove(sb, my_rsv);
 835
 836         /*
 837          * Let's book the whole avaliable window for now.  We will check the
 838          * disk bitmap later and then, if there are free blocks then we adjust
 839          * the window size if it's larger than requested.
 840          * Otherwise, we will remove this node from the tree next time
 841          * call find_next_reservable_window.
 842          */
 843         my_rsv->rsv_start = cur;
 844         my_rsv->rsv_end = cur + size - 1;
 845         my_rsv->rsv_alloc_hit = 0;
 846
 847         if (prev != my_rsv)
 848                 ext3_rsv_window_add(sb, my_rsv);
 849
 850         return 0;
 851 }
 852
 853 /**
 854  *      alloc_new_reservation()--allocate a new reservation window
 855  *
 856  *              To make a new reservation, we search part of the filesystem
 857  *              reservation list (the list that inside the group). We try to
 858  *              allocate a new reservation window near the allocation goal,
 859  *              or the beginning of the group, if there is no goal.
 860  *
 861  *              We first find a reservable space after the goal, then from
 862  *              there, we check the bitmap for the first free block after
 863  *              it. If there is no free block until the end of group, then the
 864  *              whole group is full, we failed. Otherwise, check if the free
 865  *              block is inside the expected reservable space, if so, we
 866  *              succeed.
 867  *              If the first free block is outside the reservable space, then
 868  *              start from the first free block, we search for next available
 869  *              space, and go on.
 870  *
 871  *      on succeed, a new reservation will be found and inserted into the list
 872  *      It contains at least one free block, and it does not overlap with other
 873  *      reservation windows.
 874  *
 875  *      failed: we failed to find a reservation window in this group
 876  *
 877  *      @rsv: the reservation
 878  *
 879  *      @goal: The goal (group-relative).  It is where the search for a
 880  *              free reservable space should start from.
 881  *              if we have a goal(goal >0 ), then start from there,
 882  *              no goal(goal = -1), we start from the first block
 883  *              of the group.
 884  *
 885  *      @sb: the super block
 886  *      @group: the group we are trying to allocate in
 887  *      @bitmap_bh: the block group block bitmap
 888  *
 889  */
 890 static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
 891                 int goal, struct super_block *sb,
 892                 unsigned int group, struct buffer_head *bitmap_bh)
 893 {
 894         struct ext3_reserve_window_node *search_head;
 895         int group_first_block, group_end_block, start_block;
 896         int first_free_block;
 897         struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
 898         unsigned long size;
 899         int ret;
 900         spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
 901
 902         group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
 903                                 group * EXT3_BLOCKS_PER_GROUP(sb);
 904         group_end_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
 905
 906         if (goal < 0)
 907                 start_block = group_first_block;
 908         else
 909                 start_block = goal + group_first_block;
 910
 911         size = my_rsv->rsv_goal_size;
 912
 913         if (!rsv_is_empty(&my_rsv->rsv_window)) {
 914                 /*
 915                  * if the old reservation is cross group boundary
 916                  * and if the goal is inside the old reservation window,
 917                  * we will come here when we just failed to allocate from
 918                  * the first part of the window. We still have another part
 919                  * that belongs to the next group. In this case, there is no
 920                  * point to discard our window and try to allocate a new one
 921                  * in this group(which will fail). we should
 922                  * keep the reservation window, just simply move on.
 923                  *
 924                  * Maybe we could shift the start block of the reservation
 925                  * window to the first block of next group.
 926                  */
 927
 928                 if ((my_rsv->rsv_start <= group_end_block) &&
 929                                 (my_rsv->rsv_end > group_end_block) &&
 930                                 (start_block >= my_rsv->rsv_start))
 931                         return -1;
 932
 933                 if ((my_rsv->rsv_alloc_hit >
 934                      (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
 935                         /*
 936                          * if we previously allocation hit ration is greater than half
 937                          * we double the size of reservation window next time
 938                          * otherwise keep the same
 939                          */
 940                         size = size * 2;
 941                         if (size > EXT3_MAX_RESERVE_BLOCKS)
 942                                 size = EXT3_MAX_RESERVE_BLOCKS;
 943                         my_rsv->rsv_goal_size= size;
 944                 }
 945         }
 946
 947         spin_lock(rsv_lock);
 948         /*
 949          * shift the search start to the window near the goal block
 950          */
 951         search_head = search_reserve_window(fs_rsv_root, start_block);
 952
 953         /*
 954          * find_next_reservable_window() simply finds a reservable window
 955          * inside the given range(start_block, group_end_block).
 956          *
 957          * To make sure the reservation window has a free bit inside it, we
 958          * need to check the bitmap after we found a reservable window.
 959          */
 960 retry:
 961         ret = find_next_reservable_window(search_head, my_rsv, sb,
 962                                                 start_block, group_end_block);
 963
 964         if (ret == -1) {
 965                 if (!rsv_is_empty(&my_rsv->rsv_window))
 966                         rsv_window_remove(sb, my_rsv);
 967                 spin_unlock(rsv_lock);
 968                 return -1;
 969         }
 970
 971         /*
 972          * On success, find_next_reservable_window() returns the
 973          * reservation window where there is a reservable space after it.
 974          * Before we reserve this reservable space, we need
 975          * to make sure there is at least a free block inside this region.
 976          *
 977          * searching the first free bit on the block bitmap and copy of
 978          * last committed bitmap alternatively, until we found a allocatable
 979          * block. Search start from the start block of the reservable space
 980          * we just found.
 981          */
 982         spin_unlock(rsv_lock);
 983         first_free_block = bitmap_search_next_usable_block(
 984                         my_rsv->rsv_start - group_first_block,
 985                         bitmap_bh, group_end_block - group_first_block + 1);
 986
 987         if (first_free_block < 0) {
 988                 /*
 989                  * no free block left on the bitmap, no point
 990                  * to reserve the space. return failed.
 991                  */
 992                 spin_lock(rsv_lock);
 993                 if (!rsv_is_empty(&my_rsv->rsv_window))
 994                         rsv_window_remove(sb, my_rsv);
 995                 spin_unlock(rsv_lock);
 996                 return -1;              /* failed */
 997         }
 998
 999         start_block = first_free_block + group_first_block;
1000         /*
1001          * check if the first free block is within the
1002          * free space we just reserved
1003          */
1004         if (start_block >= my_rsv->rsv_start && start_block < my_rsv->rsv_end)
1005                 return 0;               /* success */
1006         /*
1007          * if the first free bit we found is out of the reservable space
1008          * continue search for next reservable space,
1009          * start from where the free block is,
1010          * we also shift the list head to where we stopped last time
1011          */
1012         search_head = my_rsv;
1013         spin_lock(rsv_lock);
1014         goto retry;
1015 }
1016
1017 static void try_to_extend_reservation(struct ext3_reserve_window_node *my_rsv,
1018                         struct super_block *sb, int size)
1019 {
1020         struct ext3_reserve_window_node *next_rsv;
1021         struct rb_node *next;
1022         spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1023
1024         if (!spin_trylock(rsv_lock))
1025                 return;
1026
1027         next = rb_next(&my_rsv->rsv_node);
1028
1029         if (!next)
1030                 my_rsv->rsv_end += size;
1031         else {
1032                 next_rsv = list_entry(next, struct ext3_reserve_window_node, rsv_node);
1033
1034                 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1035                         my_rsv->rsv_end += size;
1036                 else
1037                         my_rsv->rsv_end = next_rsv->rsv_start - 1;
1038         }
1039         spin_unlock(rsv_lock);
1040 }
1041
1042 /*
1043  * This is the main function used to allocate a new block and its reservation
1044  * window.
1045  *
1046  * Each time when a new block allocation is need, first try to allocate from
1047  * its own reservation.  If it does not have a reservation window, instead of
1048  * looking for a free bit on bitmap first, then look up the reservation list to
1049  * see if it is inside somebody else's reservation window, we try to allocate a
1050  * reservation window for it starting from the goal first. Then do the block
1051  * allocation within the reservation window.
1052  *
1053  * This will avoid keeping on searching the reservation list again and
1054  * again when somebody is looking for a free block (without
1055  * reservation), and there are lots of free blocks, but they are all
1056  * being reserved.
1057  *
1058  * We use a sorted double linked list for the per-filesystem reservation list.
1059  * The insert, remove and find a free space(non-reserved) operations for the
1060  * sorted double linked list should be fast.
1061  *
1062  */
1063 static int
1064 ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
1065                         unsigned int group, struct buffer_head *bitmap_bh,
1066                         int goal, struct ext3_reserve_window_node * my_rsv,
1067                         unsigned long *count, int *errp)
1068 {
1069         unsigned long group_first_block;
1070         int ret = 0;
1071         int fatal;
1072         unsigned long num = *count;
1073
1074         *errp = 0;
1075
1076         /*
1077          * Make sure we use undo access for the bitmap, because it is critical
1078          * that we do the frozen_data COW on bitmap buffers in all cases even
1079          * if the buffer is in BJ_Forget state in the committing transaction.
1080          */
1081         BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1082         fatal = ext3_journal_get_undo_access(handle, bitmap_bh);
1083         if (fatal) {
1084                 *errp = fatal;
1085                 return -1;
1086         }
1087
1088         /*
1089          * we don't deal with reservation when
1090          * filesystem is mounted without reservation
1091          * or the file is not a regular file
1092          * or last attempt to allocate a block with reservation turned on failed
1093          */
1094         if (my_rsv == NULL ) {
1095                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh,
1096                                                 goal, count, NULL);
1097                 goto out;
1098         }
1099         /*
1100          * goal is a group relative block number (if there is a goal)
1101          * 0 < goal < EXT3_BLOCKS_PER_GROUP(sb)
1102          * first block is a filesystem wide block number
1103          * first block is the block number of the first block in this group
1104          */
1105         group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
1106                         group * EXT3_BLOCKS_PER_GROUP(sb);
1107
1108         /*
1109          * Basically we will allocate a new block from inode's reservation
1110          * window.
1111          *
1112          * We need to allocate a new reservation window, if:
1113          * a) inode does not have a reservation window; or
1114          * b) last attempt to allocate a block from existing reservation
1115          *    failed; or
1116          * c) we come here with a goal and with a reservation window
1117          *
1118          * We do not need to allocate a new reservation window if we come here
1119          * at the beginning with a goal and the goal is inside the window, or
1120          * we don't have a goal but already have a reservation window.
1121          * then we could go to allocate from the reservation window directly.
1122          */
1123         while (1) {
1124                 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1125                         !goal_in_my_reservation(&my_rsv->rsv_window, goal, group, sb)) {
1126                         if (my_rsv->rsv_goal_size < *count)
1127                                 my_rsv->rsv_goal_size = *count;
1128                         ret = alloc_new_reservation(my_rsv, goal, sb,
1129                                                         group, bitmap_bh);
1130                         if (ret < 0)
1131                                 break;                  /* failed */
1132
1133                         if (!goal_in_my_reservation(&my_rsv->rsv_window, goal, group, sb))
1134                                 goal = -1;
1135                 } else if (goal > 0 && (my_rsv->rsv_end-goal+1) < *count)
1136                         try_to_extend_reservation(my_rsv, sb,
1137                                         *count-my_rsv->rsv_end + goal - 1);
1138
1139                 if ((my_rsv->rsv_start >= group_first_block + EXT3_BLOCKS_PER_GROUP(sb))
1140                     || (my_rsv->rsv_end < group_first_block))
1141                         BUG();
1142                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal,
1143                                            &num, &my_rsv->rsv_window);
1144                 if (ret >= 0) {
1145                         my_rsv->rsv_alloc_hit += num;
1146                         *count = num;
1147                         break;                          /* succeed */
1148                 }
1149                 num = *count;
1150         }
1151 out:
1152         if (ret >= 0) {
1153                 BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1154                                         "bitmap block");
1155                 fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
1156                 if (fatal) {
1157                         *errp = fatal;
1158                         return -1;
1159                 }
1160                 return ret;
1161         }
1162
1163         BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1164         ext3_journal_release_buffer(handle, bitmap_bh);
1165         return ret;
1166 }
1167
1168 static int ext3_has_free_blocks(struct super_block *sb)
1169 {
1170         struct ext3_sb_info *sbi = EXT3_SB(sb);
1171         int free_blocks, root_blocks, cond;
1172
1173         free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1174         root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1175
1176         vxdprintk(VXD_CBIT(dlim, 3),
1177                 "ext3_has_free_blocks(%p): free=%u, root=%u",
1178                 sb, free_blocks, root_blocks);
1179
1180         DLIMIT_ADJUST_BLOCK(sb, vx_current_xid(), &free_blocks, &root_blocks);
1181
1182         cond = (free_blocks < root_blocks + 1 &&
1183                 !capable(CAP_SYS_RESOURCE) &&
1184                 sbi->s_resuid != current->fsuid &&
1185                 (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid)));
1186
1187         vxdprintk(VXD_CBIT(dlim, 3),
1188                 "ext3_has_free_blocks(%p): %u<%u+1, %c, %u!=%u r=%d",
1189                 sb, free_blocks, root_blocks,
1190                 !capable(CAP_SYS_RESOURCE)?'1':'0',
1191                 sbi->s_resuid, current->fsuid, cond?0:1);
1192
1193         return (cond ? 0 : 1);
1194 }
1195
1196 /*
1197  * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
1198  * it is profitable to retry the operation, this function will wait
1199  * for the current or commiting transaction to complete, and then
1200  * return TRUE.
1201  */
1202 int ext3_should_retry_alloc(struct super_block *sb, int *retries)
1203 {
1204         if (!ext3_has_free_blocks(sb) || (*retries)++ > 3)
1205                 return 0;
1206
1207         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1208
1209         return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
1210 }
1211
1212 /*
1213  * ext3_new_block uses a goal block to assist allocation.  If the goal is
1214  * free, or there is a free block within 32 blocks of the goal, that block
1215  * is allocated.  Otherwise a forward search is made for a free block; within
1216  * each block group the search first looks for an entire free byte in the block
1217  * bitmap, and then for any free bit if that fails.
1218  * This function also updates quota and i_blocks field.
1219  */
1220 int ext3_new_blocks(handle_t *handle, struct inode *inode,
1221                         unsigned long goal, unsigned long *count, int *errp)
1222 {
1223         struct buffer_head *bitmap_bh = NULL;
1224         struct buffer_head *gdp_bh;
1225         int group_no;
1226         int goal_group;
1227         int ret_block;
1228         int bgi;                        /* blockgroup iteration index */
1229         int target_block;
1230         int fatal = 0, err;
1231         int performed_allocation = 0;
1232         int free_blocks;
1233         struct super_block *sb;
1234         struct ext3_group_desc *gdp;
1235         struct ext3_super_block *es;
1236         struct ext3_sb_info *sbi;
1237         struct ext3_reserve_window_node *my_rsv = NULL;
1238         struct ext3_block_alloc_info *block_i;
1239         unsigned short windowsz = 0;
1240 #ifdef EXT3FS_DEBUG
1241         static int goal_hits, goal_attempts;
1242 #endif
1243         unsigned long ngroups;
1244         unsigned long num = *count;
1245
1246         *errp = -ENOSPC;
1247         sb = inode->i_sb;
1248         if (!sb) {
1249                 printk("ext3_new_block: nonexistent device");
1250                 return 0;
1251         }
1252
1253         /*
1254          * Check quota for allocation of this block.
1255          */
1256         if (DQUOT_ALLOC_BLOCK(inode, num)) {
1257                 *errp = -EDQUOT;
1258                 return 0;
1259         }
1260         if (DLIMIT_ALLOC_BLOCK(inode, 1))
1261             goto out_dlimit;
1262
1263         sbi = EXT3_SB(sb);
1264         es = EXT3_SB(sb)->s_es;
1265         ext3_debug("goal=%lu.\n", goal);
1266         /*
1267          * Allocate a block from reservation only when
1268          * filesystem is mounted with reservation(default,-o reservation), and
1269          * it's a regular file, and
1270          * the desired window size is greater than 0 (One could use ioctl
1271          * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
1272          * reservation on that particular file)
1273          */
1274         block_i = EXT3_I(inode)->i_block_alloc_info;
1275         if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
1276                 my_rsv = &block_i->rsv_window_node;
1277
1278         if (!ext3_has_free_blocks(sb)) {
1279                 *errp = -ENOSPC;
1280                 goto out;
1281         }
1282
1283         /*
1284          * First, test whether the goal block is free.
1285          */
1286         if (goal < le32_to_cpu(es->s_first_data_block) ||
1287             goal >= le32_to_cpu(es->s_blocks_count))
1288                 goal = le32_to_cpu(es->s_first_data_block);
1289         group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1290                         EXT3_BLOCKS_PER_GROUP(sb);
1291         gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1292         if (!gdp)
1293                 goto io_error;
1294
1295         goal_group = group_no;
1296 retry:
1297         free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1298         /*
1299          * if there is not enough free blocks to make a new resevation
1300          * turn off reservation for this allocation
1301          */
1302         if (my_rsv && (free_blocks < windowsz)
1303                 && (rsv_is_empty(&my_rsv->rsv_window)))
1304                 my_rsv = NULL;
1305
1306         if (free_blocks > 0) {
1307                 ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) %
1308                                 EXT3_BLOCKS_PER_GROUP(sb));
1309                 bitmap_bh = read_block_bitmap(sb, group_no);
1310                 if (!bitmap_bh)
1311                         goto io_error;
1312                 ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
1313                                         bitmap_bh, ret_block, my_rsv, &num, &fatal);
1314                 if (fatal)
1315                         goto out;
1316                 if (ret_block >= 0)
1317                         goto allocated;
1318         }
1319
1320         ngroups = EXT3_SB(sb)->s_groups_count;
1321         smp_rmb();
1322
1323         /*
1324          * Now search the rest of the groups.  We assume that
1325          * i and gdp correctly point to the last group visited.
1326          */
1327         for (bgi = 0; bgi < ngroups; bgi++) {
1328                 group_no++;
1329                 if (group_no >= ngroups)
1330                         group_no = 0;
1331                 gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1332                 if (!gdp) {
1333                         *errp = -EIO;
1334                         goto out;
1335                 }
1336                 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1337                 /*
1338                  * skip this group if the number of
1339                  * free blocks is less than half of the reservation
1340                  * window size.
1341                  */
1342                 if (free_blocks <= (windowsz/2))
1343                         continue;
1344
1345                 brelse(bitmap_bh);
1346                 bitmap_bh = read_block_bitmap(sb, group_no);
1347                 if (!bitmap_bh)
1348                         goto io_error;
1349                 ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
1350                                         bitmap_bh, -1, my_rsv, &num, &fatal);
1351                 if (fatal)
1352                         goto out;
1353                 if (ret_block >= 0)
1354                         goto allocated;
1355         }
1356         /*
1357          * We may end up a bogus ealier ENOSPC error due to
1358          * filesystem is "full" of reservations, but
1359          * there maybe indeed free blocks avaliable on disk
1360          * In this case, we just forget about the reservations
1361          * just do block allocation as without reservations.
1362          */
1363         if (my_rsv) {
1364                 my_rsv = NULL;
1365                 group_no = goal_group;
1366                 goto retry;
1367         }
1368         /* No space left on the device */
1369         *errp = -ENOSPC;
1370         goto out;
1371
1372 allocated:
1373
1374         ext3_debug("using block group %d(%d)\n",
1375                         group_no, gdp->bg_free_blocks_count);
1376
1377         BUFFER_TRACE(gdp_bh, "get_write_access");
1378         fatal = ext3_journal_get_write_access(handle, gdp_bh);
1379         if (fatal)
1380                 goto out;
1381
1382         target_block = ret_block + group_no * EXT3_BLOCKS_PER_GROUP(sb)
1383                                 + le32_to_cpu(es->s_first_data_block);
1384
1385         if (in_range(le32_to_cpu(gdp->bg_block_bitmap), target_block, num) ||
1386             in_range(le32_to_cpu(gdp->bg_inode_bitmap), target_block, num) ||
1387             in_range(target_block, le32_to_cpu(gdp->bg_inode_table),
1388                       EXT3_SB(sb)->s_itb_per_group) ||
1389             in_range(target_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1390                       EXT3_SB(sb)->s_itb_per_group))
1391                 ext3_error(sb, "ext3_new_block",
1392                             "Allocating block in system zone - "
1393                             "blocks from %u, length %lu", target_block, num);
1394
1395         performed_allocation = 1;
1396
1397 #ifdef CONFIG_JBD_DEBUG
1398         {
1399                 struct buffer_head *debug_bh;
1400
1401                 /* Record bitmap buffer state in the newly allocated block */
1402                 debug_bh = sb_find_get_block(sb, target_block);
1403                 if (debug_bh) {
1404                         BUFFER_TRACE(debug_bh, "state when allocated");
1405                         BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1406                         brelse(debug_bh);
1407                 }
1408         }
1409         jbd_lock_bh_state(bitmap_bh);
1410         spin_lock(sb_bgl_lock(sbi, group_no));
1411         if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1412                 int i;
1413
1414                 for (i = 0; i < num; i++) {
1415                         if (ext3_test_bit(ret_block,
1416                                         bh2jh(bitmap_bh)->b_committed_data)) {
1417                                 printk("%s: block was unexpectedly set in "
1418                                         "b_committed_data\n", __FUNCTION__);
1419                         }
1420                 }
1421         }
1422         ext3_debug("found bit %d\n", ret_block);
1423         spin_unlock(sb_bgl_lock(sbi, group_no));
1424         jbd_unlock_bh_state(bitmap_bh);
1425 #endif
1426
1427         /* ret_block was blockgroup-relative.  Now it becomes fs-relative */
1428         ret_block = target_block;
1429
1430         if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1431                 ext3_error(sb, "ext3_new_block",
1432                             "block(%d) >= blocks count(%d) - "
1433                             "block_group = %d, es == %p ", ret_block,
1434                         le32_to_cpu(es->s_blocks_count), group_no, es);
1435                 goto out;
1436         }
1437
1438         /*
1439          * It is up to the caller to add the new buffer to a journal
1440          * list of some description.  We don't know in advance whether
1441          * the caller wants to use it as metadata or data.
1442          */
1443         ext3_debug("allocating block %d. Goal hits %d of %d.\n",
1444                         ret_block, goal_hits, goal_attempts);
1445
1446         spin_lock(sb_bgl_lock(sbi, group_no));
1447         gdp->bg_free_blocks_count =
1448                         cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) - num);
1449         spin_unlock(sb_bgl_lock(sbi, group_no));
1450         percpu_counter_mod(&sbi->s_freeblocks_counter, -num);
1451
1452         BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1453         err = ext3_journal_dirty_metadata(handle, gdp_bh);
1454         if (!fatal)
1455                 fatal = err;
1456
1457         sb->s_dirt = 1;
1458         if (fatal)
1459                 goto out;
1460
1461         *errp = 0;
1462         brelse(bitmap_bh);
1463         DQUOT_FREE_BLOCK(inode, *count-num);
1464         *count = num;
1465         return ret_block;
1466
1467 io_error:
1468         *errp = -EIO;
1469 out:
1470         if (!performed_allocation)
1471                 DLIMIT_FREE_BLOCK(inode, 1);
1472 out_dlimit:
1473         if (fatal) {
1474                 *errp = fatal;
1475                 ext3_std_error(sb, fatal);
1476         }
1477         /*
1478          * Undo the block allocation
1479          */
1480         if (!performed_allocation)
1481                 DQUOT_FREE_BLOCK(inode, *count);
1482         brelse(bitmap_bh);
1483         return 0;
1484 }
1485
1486 int ext3_new_block(handle_t *handle, struct inode *inode,
1487                         unsigned long goal, int *errp)
1488 {
1489         unsigned long count = 1;
1490
1491         return ext3_new_blocks(handle, inode, goal, &count, errp);
1492 }
1493
1494 unsigned long ext3_count_free_blocks(struct super_block *sb)
1495 {
1496         unsigned long desc_count;
1497         struct ext3_group_desc *gdp;
1498         int i;
1499         unsigned long ngroups = EXT3_SB(sb)->s_groups_count;
1500 #ifdef EXT3FS_DEBUG
1501         struct ext3_super_block *es;
1502         unsigned long bitmap_count, x;
1503         struct buffer_head *bitmap_bh = NULL;
1504
1505         es = EXT3_SB(sb)->s_es;
1506         desc_count = 0;
1507         bitmap_count = 0;
1508         gdp = NULL;
1509
1510         smp_rmb();
1511         for (i = 0; i < ngroups; i++) {
1512                 gdp = ext3_get_group_desc(sb, i, NULL);
1513                 if (!gdp)
1514                         continue;
1515                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1516                 brelse(bitmap_bh);
1517                 bitmap_bh = read_block_bitmap(sb, i);
1518                 if (bitmap_bh == NULL)
1519                         continue;
1520
1521                 x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1522                 printk("group %d: stored = %d, counted = %lu\n",
1523                         i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1524                 bitmap_count += x;
1525         }
1526         brelse(bitmap_bh);
1527         printk("ext3_count_free_blocks: stored = %u, computed = %lu, %lu\n",
1528                le32_to_cpu(es->s_free_blocks_count), desc_count, bitmap_count);
1529         return bitmap_count;
1530 #else
1531         desc_count = 0;
1532         smp_rmb();
1533         for (i = 0; i < ngroups; i++) {
1534                 gdp = ext3_get_group_desc(sb, i, NULL);
1535                 if (!gdp)
1536                         continue;
1537                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1538         }
1539
1540         return desc_count;
1541 #endif
1542 }
1543
1544 static inline int
1545 block_in_use(unsigned long block, struct super_block *sb, unsigned char *map)
1546 {
1547         return ext3_test_bit ((block -
1548                 le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) %
1549                          EXT3_BLOCKS_PER_GROUP(sb), map);
1550 }
1551
1552 static inline int test_root(int a, int b)
1553 {
1554         int num = b;
1555
1556         while (a > num)
1557                 num *= b;
1558         return num == a;
1559 }
1560
1561 static int ext3_group_sparse(int group)
1562 {
1563         if (group <= 1)
1564                 return 1;
1565         if (!(group & 1))
1566                 return 0;
1567         return (test_root(group, 7) || test_root(group, 5) ||
1568                 test_root(group, 3));
1569 }
1570
1571 /**
1572  *      ext3_bg_has_super - number of blocks used by the superblock in group
1573  *      @sb: superblock for filesystem
1574  *      @group: group number to check
1575  *
1576  *      Return the number of blocks used by the superblock (primary or backup)
1577  *      in this group.  Currently this will be only 0 or 1.
1578  */
1579 int ext3_bg_has_super(struct super_block *sb, int group)
1580 {
1581         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
1582                                 EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1583                         !ext3_group_sparse(group))
1584                 return 0;
1585         return 1;
1586 }
1587
1588 static unsigned long ext3_bg_num_gdb_meta(struct super_block *sb, int group)
1589 {
1590         unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1591         unsigned long first = metagroup * EXT3_DESC_PER_BLOCK(sb);
1592         unsigned long last = first + EXT3_DESC_PER_BLOCK(sb) - 1;
1593
1594         if (group == first || group == first + 1 || group == last)
1595                 return 1;
1596         return 0;
1597 }
1598
1599 static unsigned long ext3_bg_num_gdb_nometa(struct super_block *sb, int group)
1600 {
1601         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
1602                                 EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1603                         !ext3_group_sparse(group))
1604                 return 0;
1605         return EXT3_SB(sb)->s_gdb_count;
1606 }
1607
1608 /**
1609  *      ext3_bg_num_gdb - number of blocks used by the group table in group
1610  *      @sb: superblock for filesystem
1611  *      @group: group number to check
1612  *
1613  *      Return the number of blocks used by the group descriptor table
1614  *      (primary or backup) in this group.  In the future there may be a
1615  *      different number of descriptor blocks in each group.
1616  */
1617 unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
1618 {
1619         unsigned long first_meta_bg =
1620                         le32_to_cpu(EXT3_SB(sb)->s_es->s_first_meta_bg);
1621         unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1622
1623         if (!EXT3_HAS_INCOMPAT_FEATURE(sb,EXT3_FEATURE_INCOMPAT_META_BG) ||
1624                         metagroup < first_meta_bg)
1625                 return ext3_bg_num_gdb_nometa(sb,group);
1626
1627         return ext3_bg_num_gdb_meta(sb,group);
1628
1629 }