fs/ext3/balloc.c

   1 /*
   2  *  linux/fs/ext3/balloc.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
  10  *  Big-endian to little-endian byte-swapping/bitmaps by
  11  *        David S. Miller (davem@caip.rutgers.edu), 1995
  12  */
  13
  14 #include <linux/time.h>
  15 #include <linux/capability.h>
  16 #include <linux/fs.h>
  17 #include <linux/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
  23 /*
  24  * balloc.c contains the blocks allocation and deallocation routines
  25  */
  26
  27 /*
  28  * The free blocks are managed by bitmaps.  A file system contains several
  29  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
  30  * block for inodes, N blocks for the inode table and data blocks.
  31  *
  32  * The file system contains group descriptors which are located after the
  33  * super block.  Each descriptor contains the number of the bitmap block and
  34  * the free blocks count in the block.  The descriptors are loaded in memory
  35  * when a file system is mounted (see ext3_read_super).
  36  */
  37
  38
  39 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
  40
  41 struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
  42                                              unsigned int block_group,
  43                                              struct buffer_head ** bh)
  44 {
  45         unsigned long group_desc;
  46         unsigned long offset;
  47         struct ext3_group_desc * desc;
  48         struct ext3_sb_info *sbi = EXT3_SB(sb);
  49
  50         if (block_group >= sbi->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, sbi->s_groups_count);
  55
  56                 return NULL;
  57         }
  58         smp_rmb();
  59
  60         group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb);
  61         offset = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1);
  62         if (!sbi->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, offset);
  67                 return NULL;
  68         }
  69
  70         desc = (struct ext3_group_desc *) sbi->s_group_desc[group_desc]->b_data;
  71         if (bh)
  72                 *bh = sbi->s_group_desc[group_desc];
  73         return desc + offset;
  74 }
  75
  76 /*
  77  * Read the bitmap for a given block_group, reading into the specified
  78  * slot in the superblock's bitmap cache.
  79  *
  80  * Return buffer_head on success or NULL in case of failure.
  81  */
  82 static struct buffer_head *
  83 read_block_bitmap(struct super_block *sb, unsigned int block_group)
  84 {
  85         struct ext3_group_desc * desc;
  86         struct buffer_head * bh = NULL;
  87
  88         desc = ext3_get_group_desc (sb, block_group, NULL);
  89         if (!desc)
  90                 goto error_out;
  91         bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
  92         if (!bh)
  93                 ext3_error (sb, "read_block_bitmap",
  94                             "Cannot read block bitmap - "
  95                             "block_group = %d, block_bitmap = %u",
  96                             block_group, le32_to_cpu(desc->bg_block_bitmap));
  97 error_out:
  98         return bh;
  99 }
 100 /*
 101  * The reservation window structure operations
 102  * --------------------------------------------
 103  * Operations include:
 104  * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
 105  *
 106  * We use sorted double linked list for the per-filesystem reservation
 107  * window list. (like in vm_region).
 108  *
 109  * Initially, we keep those small operations in the abstract functions,
 110  * so later if we need a better searching tree than double linked-list,
 111  * we could easily switch to that without changing too much
 112  * code.
 113  */
 114 #if 0
 115 static void __rsv_window_dump(struct rb_root *root, int verbose,
 116                               const char *fn)
 117 {
 118         struct rb_node *n;
 119         struct ext3_reserve_window_node *rsv, *prev;
 120         int bad;
 121
 122 restart:
 123         n = rb_first(root);
 124         bad = 0;
 125         prev = NULL;
 126
 127         printk("Block Allocation Reservation Windows Map (%s):\n", fn);
 128         while (n) {
 129                 rsv = list_entry(n, struct ext3_reserve_window_node, rsv_node);
 130                 if (verbose)
 131                         printk("reservation window 0x%p "
 132                                "start:  %d, end:  %d\n",
 133                                rsv, rsv->rsv_start, rsv->rsv_end);
 134                 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
 135                         printk("Bad reservation %p (start >= end)\n",
 136                                rsv);
 137                         bad = 1;
 138                 }
 139                 if (prev && prev->rsv_end >= rsv->rsv_start) {
 140                         printk("Bad reservation %p (prev->end >= start)\n",
 141                                rsv);
 142                         bad = 1;
 143                 }
 144                 if (bad) {
 145                         if (!verbose) {
 146                                 printk("Restarting reservation walk in verbose mode\n");
 147                                 verbose = 1;
 148                                 goto restart;
 149                         }
 150                 }
 151                 n = rb_next(n);
 152                 prev = rsv;
 153         }
 154         printk("Window map complete.\n");
 155         if (bad)
 156                 BUG();
 157 }
 158 #define rsv_window_dump(root, verbose) \
 159         __rsv_window_dump((root), (verbose), __FUNCTION__)
 160 #else
 161 #define rsv_window_dump(root, verbose) do {} while (0)
 162 #endif
 163
 164 static int
 165 goal_in_my_reservation(struct ext3_reserve_window *rsv, ext3_grpblk_t grp_goal,
 166                         unsigned int group, struct super_block * sb)
 167 {
 168         ext3_fsblk_t group_first_block, group_last_block;
 169
 170         group_first_block = ext3_group_first_block_no(sb, group);
 171         group_last_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
 172
 173         if ((rsv->_rsv_start > group_last_block) ||
 174             (rsv->_rsv_end < group_first_block))
 175                 return 0;
 176         if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
 177                 || (grp_goal + group_first_block > rsv->_rsv_end)))
 178                 return 0;
 179         return 1;
 180 }
 181
 182 /*
 183  * Find the reserved window which includes the goal, or the previous one
 184  * if the goal is not in any window.
 185  * Returns NULL if there are no windows or if all windows start after the goal.
 186  */
 187 static struct ext3_reserve_window_node *
 188 search_reserve_window(struct rb_root *root, ext3_fsblk_t goal)
 189 {
 190         struct rb_node *n = root->rb_node;
 191         struct ext3_reserve_window_node *rsv;
 192
 193         if (!n)
 194                 return NULL;
 195
 196         do {
 197                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 198
 199                 if (goal < rsv->rsv_start)
 200                         n = n->rb_left;
 201                 else if (goal > rsv->rsv_end)
 202                         n = n->rb_right;
 203                 else
 204                         return rsv;
 205         } while (n);
 206         /*
 207          * We've fallen off the end of the tree: the goal wasn't inside
 208          * any particular node.  OK, the previous node must be to one
 209          * side of the interval containing the goal.  If it's the RHS,
 210          * we need to back up one.
 211          */
 212         if (rsv->rsv_start > goal) {
 213                 n = rb_prev(&rsv->rsv_node);
 214                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
 215         }
 216         return rsv;
 217 }
 218
 219 void ext3_rsv_window_add(struct super_block *sb,
 220                     struct ext3_reserve_window_node *rsv)
 221 {
 222         struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root;
 223         struct rb_node *node = &rsv->rsv_node;
 224         ext3_fsblk_t start = rsv->rsv_start;
 225
 226         struct rb_node ** p = &root->rb_node;
 227         struct rb_node * parent = NULL;
 228         struct ext3_reserve_window_node *this;
 229
 230         while (*p)
 231         {
 232                 parent = *p;
 233                 this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node);
 234
 235                 if (start < this->rsv_start)
 236                         p = &(*p)->rb_left;
 237                 else if (start > this->rsv_end)
 238                         p = &(*p)->rb_right;
 239                 else
 240                         BUG();
 241         }
 242
 243         rb_link_node(node, parent, p);
 244         rb_insert_color(node, root);
 245 }
 246
 247 static void rsv_window_remove(struct super_block *sb,
 248                               struct ext3_reserve_window_node *rsv)
 249 {
 250         rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 251         rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 252         rsv->rsv_alloc_hit = 0;
 253         rb_erase(&rsv->rsv_node, &EXT3_SB(sb)->s_rsv_window_root);
 254 }
 255
 256 static inline int rsv_is_empty(struct ext3_reserve_window *rsv)
 257 {
 258         /* a valid reservation end block could not be 0 */
 259         return (rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED);
 260 }
 261 void ext3_init_block_alloc_info(struct inode *inode)
 262 {
 263         struct ext3_inode_info *ei = EXT3_I(inode);
 264         struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
 265         struct super_block *sb = inode->i_sb;
 266
 267         block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
 268         if (block_i) {
 269                 struct ext3_reserve_window_node *rsv = &block_i->rsv_window_node;
 270
 271                 rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 272                 rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
 273
 274                 /*
 275                  * if filesystem is mounted with NORESERVATION, the goal
 276                  * reservation window size is set to zero to indicate
 277                  * block reservation is off
 278                  */
 279                 if (!test_opt(sb, RESERVATION))
 280                         rsv->rsv_goal_size = 0;
 281                 else
 282                         rsv->rsv_goal_size = EXT3_DEFAULT_RESERVE_BLOCKS;
 283                 rsv->rsv_alloc_hit = 0;
 284                 block_i->last_alloc_logical_block = 0;
 285                 block_i->last_alloc_physical_block = 0;
 286         }
 287         ei->i_block_alloc_info = block_i;
 288 }
 289
 290 void ext3_discard_reservation(struct inode *inode)
 291 {
 292         struct ext3_inode_info *ei = EXT3_I(inode);
 293         struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
 294         struct ext3_reserve_window_node *rsv;
 295         spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
 296
 297         if (!block_i)
 298                 return;
 299
 300         rsv = &block_i->rsv_window_node;
 301         if (!rsv_is_empty(&rsv->rsv_window)) {
 302                 spin_lock(rsv_lock);
 303                 if (!rsv_is_empty(&rsv->rsv_window))
 304                         rsv_window_remove(inode->i_sb, rsv);
 305                 spin_unlock(rsv_lock);
 306         }
 307 }
 308
 309 /* Free given blocks, update quota and i_blocks field */
 310 void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,
 311                          ext3_fsblk_t block, unsigned long count,
 312                          unsigned long *pdquot_freed_blocks)
 313 {
 314         struct buffer_head *bitmap_bh = NULL;
 315         struct buffer_head *gd_bh;
 316         unsigned long block_group;
 317         ext3_grpblk_t bit;
 318         unsigned long i;
 319         unsigned long overflow;
 320         struct ext3_group_desc * desc;
 321         struct ext3_super_block * es;
 322         struct ext3_sb_info *sbi;
 323         int err = 0, ret;
 324         ext3_grpblk_t group_freed;
 325
 326         *pdquot_freed_blocks = 0;
 327         sbi = EXT3_SB(sb);
 328         es = sbi->s_es;
 329         if (block < le32_to_cpu(es->s_first_data_block) ||
 330             block + count < block ||
 331             block + count > le32_to_cpu(es->s_blocks_count)) {
 332                 ext3_error (sb, "ext3_free_blocks",
 333                             "Freeing blocks not in datazone - "
 334                             "block = "E3FSBLK", count = %lu", block, count);
 335                 goto error_return;
 336         }
 337
 338         ext3_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
 339
 340 do_more:
 341         overflow = 0;
 342         block_group = (block - le32_to_cpu(es->s_first_data_block)) /
 343                       EXT3_BLOCKS_PER_GROUP(sb);
 344         bit = (block - le32_to_cpu(es->s_first_data_block)) %
 345                       EXT3_BLOCKS_PER_GROUP(sb);
 346         /*
 347          * Check to see if we are freeing blocks across a group
 348          * boundary.
 349          */
 350         if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
 351                 overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
 352                 count -= overflow;
 353         }
 354         brelse(bitmap_bh);
 355         bitmap_bh = read_block_bitmap(sb, block_group);
 356         if (!bitmap_bh)
 357                 goto error_return;
 358         desc = ext3_get_group_desc (sb, block_group, &gd_bh);
 359         if (!desc)
 360                 goto error_return;
 361
 362         if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
 363             in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
 364             in_range (block, le32_to_cpu(desc->bg_inode_table),
 365                       sbi->s_itb_per_group) ||
 366             in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
 367                       sbi->s_itb_per_group))
 368                 ext3_error (sb, "ext3_free_blocks",
 369                             "Freeing blocks in system zones - "
 370                             "Block = "E3FSBLK", count = %lu",
 371                             block, count);
 372
 373         /*
 374          * We are about to start releasing blocks in the bitmap,
 375          * so we need undo access.
 376          */
 377         /* @@@ check errors */
 378         BUFFER_TRACE(bitmap_bh, "getting undo access");
 379         err = ext3_journal_get_undo_access(handle, bitmap_bh);
 380         if (err)
 381                 goto error_return;
 382
 383         /*
 384          * We are about to modify some metadata.  Call the journal APIs
 385          * to unshare ->b_data if a currently-committing transaction is
 386          * using it
 387          */
 388         BUFFER_TRACE(gd_bh, "get_write_access");
 389         err = ext3_journal_get_write_access(handle, gd_bh);
 390         if (err)
 391                 goto error_return;
 392
 393         jbd_lock_bh_state(bitmap_bh);
 394
 395         for (i = 0, group_freed = 0; i < count; i++) {
 396                 /*
 397                  * An HJ special.  This is expensive...
 398                  */
 399 #ifdef CONFIG_JBD_DEBUG
 400                 jbd_unlock_bh_state(bitmap_bh);
 401                 {
 402                         struct buffer_head *debug_bh;
 403                         debug_bh = sb_find_get_block(sb, block + i);
 404                         if (debug_bh) {
 405                                 BUFFER_TRACE(debug_bh, "Deleted!");
 406                                 if (!bh2jh(bitmap_bh)->b_committed_data)
 407                                         BUFFER_TRACE(debug_bh,
 408                                                 "No commited data in bitmap");
 409                                 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
 410                                 __brelse(debug_bh);
 411                         }
 412                 }
 413                 jbd_lock_bh_state(bitmap_bh);
 414 #endif
 415                 if (need_resched()) {
 416                         jbd_unlock_bh_state(bitmap_bh);
 417                         cond_resched();
 418                         jbd_lock_bh_state(bitmap_bh);
 419                 }
 420                 /* @@@ This prevents newly-allocated data from being
 421                  * freed and then reallocated within the same
 422                  * transaction.
 423                  *
 424                  * Ideally we would want to allow that to happen, but to
 425                  * do so requires making journal_forget() capable of
 426                  * revoking the queued write of a data block, which
 427                  * implies blocking on the journal lock.  *forget()
 428                  * cannot block due to truncate races.
 429                  *
 430                  * Eventually we can fix this by making journal_forget()
 431                  * return a status indicating whether or not it was able
 432                  * to revoke the buffer.  On successful revoke, it is
 433                  * safe not to set the allocation bit in the committed
 434                  * bitmap, because we know that there is no outstanding
 435                  * activity on the buffer any more and so it is safe to
 436                  * reallocate it.
 437                  */
 438                 BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
 439                 J_ASSERT_BH(bitmap_bh,
 440                                 bh2jh(bitmap_bh)->b_committed_data != NULL);
 441                 ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
 442                                 bh2jh(bitmap_bh)->b_committed_data);
 443
 444                 /*
 445                  * We clear the bit in the bitmap after setting the committed
 446                  * data bit, because this is the reverse order to that which
 447                  * the allocator uses.
 448                  */
 449                 BUFFER_TRACE(bitmap_bh, "clear bit");
 450                 if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 451                                                 bit + i, bitmap_bh->b_data)) {
 452                         jbd_unlock_bh_state(bitmap_bh);
 453                         ext3_error(sb, __FUNCTION__,
 454                                 "bit already cleared for block "E3FSBLK,
 455                                  block + i);
 456                         jbd_lock_bh_state(bitmap_bh);
 457                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
 458                 } else {
 459                         group_freed++;
 460                 }
 461         }
 462         jbd_unlock_bh_state(bitmap_bh);
 463
 464         spin_lock(sb_bgl_lock(sbi, block_group));
 465         desc->bg_free_blocks_count =
 466                 cpu_to_le16(le16_to_cpu(desc->bg_free_blocks_count) +
 467                         group_freed);
 468         spin_unlock(sb_bgl_lock(sbi, block_group));
 469         percpu_counter_mod(&sbi->s_freeblocks_counter, count);
 470
 471         /* We dirtied the bitmap block */
 472         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
 473         err = ext3_journal_dirty_metadata(handle, bitmap_bh);
 474
 475         /* And the group descriptor block */
 476         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
 477         ret = ext3_journal_dirty_metadata(handle, gd_bh);
 478         if (!err) err = ret;
 479         *pdquot_freed_blocks += group_freed;
 480
 481         if (overflow && !err) {
 482                 block += count;
 483                 count = overflow;
 484                 goto do_more;
 485         }
 486         sb->s_dirt = 1;
 487 error_return:
 488         brelse(bitmap_bh);
 489         ext3_std_error(sb, err);
 490         return;
 491 }
 492
 493 /* Free given blocks, update quota and i_blocks field */
 494 void ext3_free_blocks(handle_t *handle, struct inode *inode,
 495                         ext3_fsblk_t block, unsigned long count)
 496 {
 497         struct super_block * sb;
 498         unsigned long dquot_freed_blocks;
 499
 500         sb = inode->i_sb;
 501         if (!sb) {
 502                 printk ("ext3_free_blocks: nonexistent device");
 503                 return;
 504         }
 505         ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
 506         if (dquot_freed_blocks)
 507                 DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
 508         return;
 509 }
 510
 511 /*
 512  * For ext3 allocations, we must not reuse any blocks which are
 513  * allocated in the bitmap buffer's "last committed data" copy.  This
 514  * prevents deletes from freeing up the page for reuse until we have
 515  * committed the delete transaction.
 516  *
 517  * If we didn't do this, then deleting something and reallocating it as
 518  * data would allow the old block to be overwritten before the
 519  * transaction committed (because we force data to disk before commit).
 520  * This would lead to corruption if we crashed between overwriting the
 521  * data and committing the delete.
 522  *
 523  * @@@ We may want to make this allocation behaviour conditional on
 524  * data-writes at some point, and disable it for metadata allocations or
 525  * sync-data inodes.
 526  */
 527 static int ext3_test_allocatable(ext3_grpblk_t nr, struct buffer_head *bh)
 528 {
 529         int ret;
 530         struct journal_head *jh = bh2jh(bh);
 531
 532         if (ext3_test_bit(nr, bh->b_data))
 533                 return 0;
 534
 535         jbd_lock_bh_state(bh);
 536         if (!jh->b_committed_data)
 537                 ret = 1;
 538         else
 539                 ret = !ext3_test_bit(nr, jh->b_committed_data);
 540         jbd_unlock_bh_state(bh);
 541         return ret;
 542 }
 543
 544 static ext3_grpblk_t
 545 bitmap_search_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
 546                                         ext3_grpblk_t maxblocks)
 547 {
 548         ext3_grpblk_t next;
 549         struct journal_head *jh = bh2jh(bh);
 550
 551         /*
 552          * The bitmap search --- search forward alternately through the actual
 553          * bitmap and the last-committed copy until we find a bit free in
 554          * both
 555          */
 556         while (start < maxblocks) {
 557                 next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
 558                 if (next >= maxblocks)
 559                         return -1;
 560                 if (ext3_test_allocatable(next, bh))
 561                         return next;
 562                 jbd_lock_bh_state(bh);
 563                 if (jh->b_committed_data)
 564                         start = ext3_find_next_zero_bit(jh->b_committed_data,
 565                                                         maxblocks, next);
 566                 jbd_unlock_bh_state(bh);
 567         }
 568         return -1;
 569 }
 570
 571 /*
 572  * Find an allocatable block in a bitmap.  We honour both the bitmap and
 573  * its last-committed copy (if that exists), and perform the "most
 574  * appropriate allocation" algorithm of looking for a free block near
 575  * the initial goal; then for a free byte somewhere in the bitmap; then
 576  * for any free bit in the bitmap.
 577  */
 578 static ext3_grpblk_t
 579 find_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
 580                         ext3_grpblk_t maxblocks)
 581 {
 582         ext3_grpblk_t here, next;
 583         char *p, *r;
 584
 585         if (start > 0) {
 586                 /*
 587                  * The goal was occupied; search forward for a free
 588                  * block within the next XX blocks.
 589                  *
 590                  * end_goal is more or less random, but it has to be
 591                  * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the
 592                  * next 64-bit boundary is simple..
 593                  */
 594                 ext3_grpblk_t end_goal = (start + 63) & ~63;
 595                 if (end_goal > maxblocks)
 596                         end_goal = maxblocks;
 597                 here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
 598                 if (here < end_goal && ext3_test_allocatable(here, bh))
 599                         return here;
 600                 ext3_debug("Bit not found near goal\n");
 601         }
 602
 603         here = start;
 604         if (here < 0)
 605                 here = 0;
 606
 607         p = ((char *)bh->b_data) + (here >> 3);
 608         r = memscan(p, 0, (maxblocks - here + 7) >> 3);
 609         next = (r - ((char *)bh->b_data)) << 3;
 610
 611         if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))
 612                 return next;
 613
 614         /*
 615          * The bitmap search --- search forward alternately through the actual
 616          * bitmap and the last-committed copy until we find a bit free in
 617          * both
 618          */
 619         here = bitmap_search_next_usable_block(here, bh, maxblocks);
 620         return here;
 621 }
 622
 623 /*
 624  * We think we can allocate this block in this bitmap.  Try to set the bit.
 625  * If that succeeds then check that nobody has allocated and then freed the
 626  * block since we saw that is was not marked in b_committed_data.  If it _was_
 627  * allocated and freed then clear the bit in the bitmap again and return
 628  * zero (failure).
 629  */
 630 static inline int
 631 claim_block(spinlock_t *lock, ext3_grpblk_t block, struct buffer_head *bh)
 632 {
 633         struct journal_head *jh = bh2jh(bh);
 634         int ret;
 635
 636         if (ext3_set_bit_atomic(lock, block, bh->b_data))
 637                 return 0;
 638         jbd_lock_bh_state(bh);
 639         if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) {
 640                 ext3_clear_bit_atomic(lock, block, bh->b_data);
 641                 ret = 0;
 642         } else {
 643                 ret = 1;
 644         }
 645         jbd_unlock_bh_state(bh);
 646         return ret;
 647 }
 648
 649 /*
 650  * If we failed to allocate the desired block then we may end up crossing to a
 651  * new bitmap.  In that case we must release write access to the old one via
 652  * ext3_journal_release_buffer(), else we'll run out of credits.
 653  */
 654 static ext3_grpblk_t
 655 ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
 656                         struct buffer_head *bitmap_bh, ext3_grpblk_t grp_goal,
 657                         unsigned long *count, struct ext3_reserve_window *my_rsv)
 658 {
 659         ext3_fsblk_t group_first_block;
 660         ext3_grpblk_t start, end;
 661         unsigned long num = 0;
 662
 663         /* we do allocation within the reservation window if we have a window */
 664         if (my_rsv) {
 665                 group_first_block = ext3_group_first_block_no(sb, group);
 666                 if (my_rsv->_rsv_start >= group_first_block)
 667                         start = my_rsv->_rsv_start - group_first_block;
 668                 else
 669                         /* reservation window cross group boundary */
 670                         start = 0;
 671                 end = my_rsv->_rsv_end - group_first_block + 1;
 672                 if (end > EXT3_BLOCKS_PER_GROUP(sb))
 673                         /* reservation window crosses group boundary */
 674                         end = EXT3_BLOCKS_PER_GROUP(sb);
 675                 if ((start <= grp_goal) && (grp_goal < end))
 676                         start = grp_goal;
 677                 else
 678                         grp_goal = -1;
 679         } else {
 680                 if (grp_goal > 0)
 681                         start = grp_goal;
 682                 else
 683                         start = 0;
 684                 end = EXT3_BLOCKS_PER_GROUP(sb);
 685         }
 686
 687         BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
 688
 689 repeat:
 690         if (grp_goal < 0 || !ext3_test_allocatable(grp_goal, bitmap_bh)) {
 691                 grp_goal = find_next_usable_block(start, bitmap_bh, end);
 692                 if (grp_goal < 0)
 693                         goto fail_access;
 694                 if (!my_rsv) {
 695                         int i;
 696
 697                         for (i = 0; i < 7 && grp_goal > start &&
 698                                         ext3_test_allocatable(grp_goal - 1,
 699                                                                 bitmap_bh);
 700                                         i++, grp_goal--)
 701                                 ;
 702                 }
 703         }
 704         start = grp_goal;
 705
 706         if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group), grp_goal, bitmap_bh)) {
 707                 /*
 708                  * The block was allocated by another thread, or it was
 709                  * allocated and then freed by another thread
 710                  */
 711                 start++;
 712                 grp_goal++;
 713                 if (start >= end)
 714                         goto fail_access;
 715                 goto repeat;
 716         }
 717         num++;
 718         grp_goal++;
 719         while (num < *count && grp_goal < end
 720                 && ext3_test_allocatable(grp_goal, bitmap_bh)
 721                 && claim_block(sb_bgl_lock(EXT3_SB(sb), group), grp_goal, bitmap_bh)) {
 722                 num++;
 723                 grp_goal++;
 724         }
 725         *count = num;
 726         return grp_goal - num;
 727 fail_access:
 728         *count = num;
 729         return -1;
 730 }
 731
 732 /**
 733  *      find_next_reservable_window():
 734  *              find a reservable space within the given range.
 735  *              It does not allocate the reservation window for now:
 736  *              alloc_new_reservation() will do the work later.
 737  *
 738  *      @search_head: the head of the searching list;
 739  *              This is not necessarily the list head of the whole filesystem
 740  *
 741  *              We have both head and start_block to assist the search
 742  *              for the reservable space. The list starts from head,
 743  *              but we will shift to the place where start_block is,
 744  *              then start from there, when looking for a reservable space.
 745  *
 746  *      @size: the target new reservation window size
 747  *
 748  *      @group_first_block: the first block we consider to start
 749  *                      the real search from
 750  *
 751  *      @last_block:
 752  *              the maximum block number that our goal reservable space
 753  *              could start from. This is normally the last block in this
 754  *              group. The search will end when we found the start of next
 755  *              possible reservable space is out of this boundary.
 756  *              This could handle the cross boundary reservation window
 757  *              request.
 758  *
 759  *      basically we search from the given range, rather than the whole
 760  *      reservation double linked list, (start_block, last_block)
 761  *      to find a free region that is of my size and has not
 762  *      been reserved.
 763  *
 764  */
 765 static int find_next_reservable_window(
 766                                 struct ext3_reserve_window_node *search_head,
 767                                 struct ext3_reserve_window_node *my_rsv,
 768                                 struct super_block * sb,
 769                                 ext3_fsblk_t start_block,
 770                                 ext3_fsblk_t last_block)
 771 {
 772         struct rb_node *next;
 773         struct ext3_reserve_window_node *rsv, *prev;
 774         ext3_fsblk_t cur;
 775         int size = my_rsv->rsv_goal_size;
 776
 777         /* TODO: make the start of the reservation window byte-aligned */
 778         /* cur = *start_block & ~7;*/
 779         cur = start_block;
 780         rsv = search_head;
 781         if (!rsv)
 782                 return -1;
 783
 784         while (1) {
 785                 if (cur <= rsv->rsv_end)
 786                         cur = rsv->rsv_end + 1;
 787
 788                 /* TODO?
 789                  * in the case we could not find a reservable space
 790                  * that is what is expected, during the re-search, we could
 791                  * remember what's the largest reservable space we could have
 792                  * and return that one.
 793                  *
 794                  * For now it will fail if we could not find the reservable
 795                  * space with expected-size (or more)...
 796                  */
 797                 if (cur > last_block)
 798                         return -1;              /* fail */
 799
 800                 prev = rsv;
 801                 next = rb_next(&rsv->rsv_node);
 802                 rsv = list_entry(next,struct ext3_reserve_window_node,rsv_node);
 803
 804                 /*
 805                  * Reached the last reservation, we can just append to the
 806                  * previous one.
 807                  */
 808                 if (!next)
 809                         break;
 810
 811                 if (cur + size <= rsv->rsv_start) {
 812                         /*
 813                          * Found a reserveable space big enough.  We could
 814                          * have a reservation across the group boundary here
 815                          */
 816                         break;
 817                 }
 818         }
 819         /*
 820          * we come here either :
 821          * when we reach the end of the whole list,
 822          * and there is empty reservable space after last entry in the list.
 823          * append it to the end of the list.
 824          *
 825          * or we found one reservable space in the middle of the list,
 826          * return the reservation window that we could append to.
 827          * succeed.
 828          */
 829
 830         if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
 831                 rsv_window_remove(sb, my_rsv);
 832
 833         /*
 834          * Let's book the whole avaliable window for now.  We will check the
 835          * disk bitmap later and then, if there are free blocks then we adjust
 836          * the window size if it's larger than requested.
 837          * Otherwise, we will remove this node from the tree next time
 838          * call find_next_reservable_window.
 839          */
 840         my_rsv->rsv_start = cur;
 841         my_rsv->rsv_end = cur + size - 1;
 842         my_rsv->rsv_alloc_hit = 0;
 843
 844         if (prev != my_rsv)
 845                 ext3_rsv_window_add(sb, my_rsv);
 846
 847         return 0;
 848 }
 849
 850 /**
 851  *      alloc_new_reservation()--allocate a new reservation window
 852  *
 853  *              To make a new reservation, we search part of the filesystem
 854  *              reservation list (the list that inside the group). We try to
 855  *              allocate a new reservation window near the allocation goal,
 856  *              or the beginning of the group, if there is no goal.
 857  *
 858  *              We first find a reservable space after the goal, then from
 859  *              there, we check the bitmap for the first free block after
 860  *              it. If there is no free block until the end of group, then the
 861  *              whole group is full, we failed. Otherwise, check if the free
 862  *              block is inside the expected reservable space, if so, we
 863  *              succeed.
 864  *              If the first free block is outside the reservable space, then
 865  *              start from the first free block, we search for next available
 866  *              space, and go on.
 867  *
 868  *      on succeed, a new reservation will be found and inserted into the list
 869  *      It contains at least one free block, and it does not overlap with other
 870  *      reservation windows.
 871  *
 872  *      failed: we failed to find a reservation window in this group
 873  *
 874  *      @rsv: the reservation
 875  *
 876  *      @grp_goal: The goal (group-relative).  It is where the search for a
 877  *              free reservable space should start from.
 878  *              if we have a grp_goal(grp_goal >0 ), then start from there,
 879  *              no grp_goal(grp_goal = -1), we start from the first block
 880  *              of the group.
 881  *
 882  *      @sb: the super block
 883  *      @group: the group we are trying to allocate in
 884  *      @bitmap_bh: the block group block bitmap
 885  *
 886  */
 887 static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
 888                 ext3_grpblk_t grp_goal, struct super_block *sb,
 889                 unsigned int group, struct buffer_head *bitmap_bh)
 890 {
 891         struct ext3_reserve_window_node *search_head;
 892         ext3_fsblk_t group_first_block, group_end_block, start_block;
 893         ext3_grpblk_t first_free_block;
 894         struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
 895         unsigned long size;
 896         int ret;
 897         spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
 898
 899         group_first_block = ext3_group_first_block_no(sb, group);
 900         group_end_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
 901
 902         if (grp_goal < 0)
 903                 start_block = group_first_block;
 904         else
 905                 start_block = grp_goal + group_first_block;
 906
 907         size = my_rsv->rsv_goal_size;
 908
 909         if (!rsv_is_empty(&my_rsv->rsv_window)) {
 910                 /*
 911                  * if the old reservation is cross group boundary
 912                  * and if the goal is inside the old reservation window,
 913                  * we will come here when we just failed to allocate from
 914                  * the first part of the window. We still have another part
 915                  * that belongs to the next group. In this case, there is no
 916                  * point to discard our window and try to allocate a new one
 917                  * in this group(which will fail). we should
 918                  * keep the reservation window, just simply move on.
 919                  *
 920                  * Maybe we could shift the start block of the reservation
 921                  * window to the first block of next group.
 922                  */
 923
 924                 if ((my_rsv->rsv_start <= group_end_block) &&
 925                                 (my_rsv->rsv_end > group_end_block) &&
 926                                 (start_block >= my_rsv->rsv_start))
 927                         return -1;
 928
 929                 if ((my_rsv->rsv_alloc_hit >
 930                      (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
 931                         /*
 932                          * if we previously allocation hit ration is greater than half
 933                          * we double the size of reservation window next time
 934                          * otherwise keep the same
 935                          */
 936                         size = size * 2;
 937                         if (size > EXT3_MAX_RESERVE_BLOCKS)
 938                                 size = EXT3_MAX_RESERVE_BLOCKS;
 939                         my_rsv->rsv_goal_size= size;
 940                 }
 941         }
 942
 943         spin_lock(rsv_lock);
 944         /*
 945          * shift the search start to the window near the goal block
 946          */
 947         search_head = search_reserve_window(fs_rsv_root, start_block);
 948
 949         /*
 950          * find_next_reservable_window() simply finds a reservable window
 951          * inside the given range(start_block, group_end_block).
 952          *
 953          * To make sure the reservation window has a free bit inside it, we
 954          * need to check the bitmap after we found a reservable window.
 955          */
 956 retry:
 957         ret = find_next_reservable_window(search_head, my_rsv, sb,
 958                                                 start_block, group_end_block);
 959
 960         if (ret == -1) {
 961                 if (!rsv_is_empty(&my_rsv->rsv_window))
 962                         rsv_window_remove(sb, my_rsv);
 963                 spin_unlock(rsv_lock);
 964                 return -1;
 965         }
 966
 967         /*
 968          * On success, find_next_reservable_window() returns the
 969          * reservation window where there is a reservable space after it.
 970          * Before we reserve this reservable space, we need
 971          * to make sure there is at least a free block inside this region.
 972          *
 973          * searching the first free bit on the block bitmap and copy of
 974          * last committed bitmap alternatively, until we found a allocatable
 975          * block. Search start from the start block of the reservable space
 976          * we just found.
 977          */
 978         spin_unlock(rsv_lock);
 979         first_free_block = bitmap_search_next_usable_block(
 980                         my_rsv->rsv_start - group_first_block,
 981                         bitmap_bh, group_end_block - group_first_block + 1);
 982
 983         if (first_free_block < 0) {
 984                 /*
 985                  * no free block left on the bitmap, no point
 986                  * to reserve the space. return failed.
 987                  */
 988                 spin_lock(rsv_lock);
 989                 if (!rsv_is_empty(&my_rsv->rsv_window))
 990                         rsv_window_remove(sb, my_rsv);
 991                 spin_unlock(rsv_lock);
 992                 return -1;              /* failed */
 993         }
 994
 995         start_block = first_free_block + group_first_block;
 996         /*
 997          * check if the first free block is within the
 998          * free space we just reserved
 999          */
1000         if (start_block >= my_rsv->rsv_start && start_block < my_rsv->rsv_end)
1001                 return 0;               /* success */
1002         /*
1003          * if the first free bit we found is out of the reservable space
1004          * continue search for next reservable space,
1005          * start from where the free block is,
1006          * we also shift the list head to where we stopped last time
1007          */
1008         search_head = my_rsv;
1009         spin_lock(rsv_lock);
1010         goto retry;
1011 }
1012
1013 static void try_to_extend_reservation(struct ext3_reserve_window_node *my_rsv,
1014                         struct super_block *sb, int size)
1015 {
1016         struct ext3_reserve_window_node *next_rsv;
1017         struct rb_node *next;
1018         spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1019
1020         if (!spin_trylock(rsv_lock))
1021                 return;
1022
1023         next = rb_next(&my_rsv->rsv_node);
1024
1025         if (!next)
1026                 my_rsv->rsv_end += size;
1027         else {
1028                 next_rsv = list_entry(next, struct ext3_reserve_window_node, rsv_node);
1029
1030                 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1031                         my_rsv->rsv_end += size;
1032                 else
1033                         my_rsv->rsv_end = next_rsv->rsv_start - 1;
1034         }
1035         spin_unlock(rsv_lock);
1036 }
1037
1038 /*
1039  * This is the main function used to allocate a new block and its reservation
1040  * window.
1041  *
1042  * Each time when a new block allocation is need, first try to allocate from
1043  * its own reservation.  If it does not have a reservation window, instead of
1044  * looking for a free bit on bitmap first, then look up the reservation list to
1045  * see if it is inside somebody else's reservation window, we try to allocate a
1046  * reservation window for it starting from the goal first. Then do the block
1047  * allocation within the reservation window.
1048  *
1049  * This will avoid keeping on searching the reservation list again and
1050  * again when somebody is looking for a free block (without
1051  * reservation), and there are lots of free blocks, but they are all
1052  * being reserved.
1053  *
1054  * We use a sorted double linked list for the per-filesystem reservation list.
1055  * The insert, remove and find a free space(non-reserved) operations for the
1056  * sorted double linked list should be fast.
1057  *
1058  */
1059 static ext3_grpblk_t
1060 ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
1061                         unsigned int group, struct buffer_head *bitmap_bh,
1062                         ext3_grpblk_t grp_goal,
1063                         struct ext3_reserve_window_node * my_rsv,
1064                         unsigned long *count, int *errp)
1065 {
1066         ext3_fsblk_t group_first_block;
1067         ext3_grpblk_t ret = 0;
1068         int fatal;
1069         unsigned long num = *count;
1070
1071         *errp = 0;
1072
1073         /*
1074          * Make sure we use undo access for the bitmap, because it is critical
1075          * that we do the frozen_data COW on bitmap buffers in all cases even
1076          * if the buffer is in BJ_Forget state in the committing transaction.
1077          */
1078         BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1079         fatal = ext3_journal_get_undo_access(handle, bitmap_bh);
1080         if (fatal) {
1081                 *errp = fatal;
1082                 return -1;
1083         }
1084
1085         /*
1086          * we don't deal with reservation when
1087          * filesystem is mounted without reservation
1088          * or the file is not a regular file
1089          * or last attempt to allocate a block with reservation turned on failed
1090          */
1091         if (my_rsv == NULL ) {
1092                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh,
1093                                                 grp_goal, count, NULL);
1094                 goto out;
1095         }
1096         /*
1097          * grp_goal is a group relative block number (if there is a goal)
1098          * 0 < grp_goal < EXT3_BLOCKS_PER_GROUP(sb)
1099          * first block is a filesystem wide block number
1100          * first block is the block number of the first block in this group
1101          */
1102         group_first_block = ext3_group_first_block_no(sb, group);
1103
1104         /*
1105          * Basically we will allocate a new block from inode's reservation
1106          * window.
1107          *
1108          * We need to allocate a new reservation window, if:
1109          * a) inode does not have a reservation window; or
1110          * b) last attempt to allocate a block from existing reservation
1111          *    failed; or
1112          * c) we come here with a goal and with a reservation window
1113          *
1114          * We do not need to allocate a new reservation window if we come here
1115          * at the beginning with a goal and the goal is inside the window, or
1116          * we don't have a goal but already have a reservation window.
1117          * then we could go to allocate from the reservation window directly.
1118          */
1119         while (1) {
1120                 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1121                         !goal_in_my_reservation(&my_rsv->rsv_window, grp_goal, group, sb)) {
1122                         if (my_rsv->rsv_goal_size < *count)
1123                                 my_rsv->rsv_goal_size = *count;
1124                         ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1125                                                         group, bitmap_bh);
1126                         if (ret < 0)
1127                                 break;                  /* failed */
1128
1129                         if (!goal_in_my_reservation(&my_rsv->rsv_window, grp_goal, group, sb))
1130                                 grp_goal = -1;
1131                 } else if (grp_goal > 0 && (my_rsv->rsv_end-grp_goal+1) < *count)
1132                         try_to_extend_reservation(my_rsv, sb,
1133                                         *count-my_rsv->rsv_end + grp_goal - 1);
1134
1135                 if ((my_rsv->rsv_start >= group_first_block + EXT3_BLOCKS_PER_GROUP(sb))
1136                     || (my_rsv->rsv_end < group_first_block))
1137                         BUG();
1138                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, grp_goal,
1139                                            &num, &my_rsv->rsv_window);
1140                 if (ret >= 0) {
1141                         my_rsv->rsv_alloc_hit += num;
1142                         *count = num;
1143                         break;                          /* succeed */
1144                 }
1145                 num = *count;
1146         }
1147 out:
1148         if (ret >= 0) {
1149                 BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1150                                         "bitmap block");
1151                 fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
1152                 if (fatal) {
1153                         *errp = fatal;
1154                         return -1;
1155                 }
1156                 return ret;
1157         }
1158
1159         BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1160         ext3_journal_release_buffer(handle, bitmap_bh);
1161         return ret;
1162 }
1163
1164 static int ext3_has_free_blocks(struct ext3_sb_info *sbi)
1165 {
1166         ext3_fsblk_t free_blocks, root_blocks;
1167
1168         free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1169         root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1170         if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1171                 sbi->s_resuid != current->fsuid &&
1172                 (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
1173                 return 0;
1174         }
1175         return 1;
1176 }
1177
1178 /*
1179  * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
1180  * it is profitable to retry the operation, this function will wait
1181  * for the current or commiting transaction to complete, and then
1182  * return TRUE.
1183  */
1184 int ext3_should_retry_alloc(struct super_block *sb, int *retries)
1185 {
1186         if (!ext3_has_free_blocks(EXT3_SB(sb)) || (*retries)++ > 3)
1187                 return 0;
1188
1189         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1190
1191         return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
1192 }
1193
1194 /*
1195  * ext3_new_block uses a goal block to assist allocation.  If the goal is
1196  * free, or there is a free block within 32 blocks of the goal, that block
1197  * is allocated.  Otherwise a forward search is made for a free block; within
1198  * each block group the search first looks for an entire free byte in the block
1199  * bitmap, and then for any free bit if that fails.
1200  * This function also updates quota and i_blocks field.
1201  */
1202 ext3_fsblk_t ext3_new_blocks(handle_t *handle, struct inode *inode,
1203                         ext3_fsblk_t goal, unsigned long *count, int *errp)
1204 {
1205         struct buffer_head *bitmap_bh = NULL;
1206         struct buffer_head *gdp_bh;
1207         int group_no;
1208         int goal_group;
1209         ext3_grpblk_t grp_target_blk;   /* blockgroup relative goal block */
1210         ext3_grpblk_t grp_alloc_blk;    /* blockgroup-relative allocated block*/
1211         ext3_fsblk_t ret_block;         /* filesyetem-wide allocated block */
1212         int bgi;                        /* blockgroup iteration index */
1213         int fatal = 0, err;
1214         int performed_allocation = 0;
1215         ext3_grpblk_t free_blocks;      /* number of free blocks in a group */
1216         struct super_block *sb;
1217         struct ext3_group_desc *gdp;
1218         struct ext3_super_block *es;
1219         struct ext3_sb_info *sbi;
1220         struct ext3_reserve_window_node *my_rsv = NULL;
1221         struct ext3_block_alloc_info *block_i;
1222         unsigned short windowsz = 0;
1223 #ifdef EXT3FS_DEBUG
1224         static int goal_hits, goal_attempts;
1225 #endif
1226         unsigned long ngroups;
1227         unsigned long num = *count;
1228
1229         *errp = -ENOSPC;
1230         sb = inode->i_sb;
1231         if (!sb) {
1232                 printk("ext3_new_block: nonexistent device");
1233                 return 0;
1234         }
1235
1236         /*
1237          * Check quota for allocation of this block.
1238          */
1239         if (DQUOT_ALLOC_BLOCK(inode, num)) {
1240                 *errp = -EDQUOT;
1241                 return 0;
1242         }
1243
1244         sbi = EXT3_SB(sb);
1245         es = EXT3_SB(sb)->s_es;
1246         ext3_debug("goal=%lu.\n", goal);
1247         /*
1248          * Allocate a block from reservation only when
1249          * filesystem is mounted with reservation(default,-o reservation), and
1250          * it's a regular file, and
1251          * the desired window size is greater than 0 (One could use ioctl
1252          * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
1253          * reservation on that particular file)
1254          */
1255         block_i = EXT3_I(inode)->i_block_alloc_info;
1256         if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
1257                 my_rsv = &block_i->rsv_window_node;
1258
1259         if (!ext3_has_free_blocks(sbi)) {
1260                 *errp = -ENOSPC;
1261                 goto out;
1262         }
1263
1264         /*
1265          * First, test whether the goal block is free.
1266          */
1267         if (goal < le32_to_cpu(es->s_first_data_block) ||
1268             goal >= le32_to_cpu(es->s_blocks_count))
1269                 goal = le32_to_cpu(es->s_first_data_block);
1270         group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1271                         EXT3_BLOCKS_PER_GROUP(sb);
1272         goal_group = group_no;
1273 retry_alloc:
1274         gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1275         if (!gdp)
1276                 goto io_error;
1277
1278         free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1279         /*
1280          * if there is not enough free blocks to make a new resevation
1281          * turn off reservation for this allocation
1282          */
1283         if (my_rsv && (free_blocks < windowsz)
1284                 && (rsv_is_empty(&my_rsv->rsv_window)))
1285                 my_rsv = NULL;
1286
1287         if (free_blocks > 0) {
1288                 grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1289                                 EXT3_BLOCKS_PER_GROUP(sb));
1290                 bitmap_bh = read_block_bitmap(sb, group_no);
1291                 if (!bitmap_bh)
1292                         goto io_error;
1293                 grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
1294                                         group_no, bitmap_bh, grp_target_blk,
1295                                         my_rsv, &num, &fatal);
1296                 if (fatal)
1297                         goto out;
1298                 if (grp_alloc_blk >= 0)
1299                         goto allocated;
1300         }
1301
1302         ngroups = EXT3_SB(sb)->s_groups_count;
1303         smp_rmb();
1304
1305         /*
1306          * Now search the rest of the groups.  We assume that
1307          * i and gdp correctly point to the last group visited.
1308          */
1309         for (bgi = 0; bgi < ngroups; bgi++) {
1310                 group_no++;
1311                 if (group_no >= ngroups)
1312                         group_no = 0;
1313                 gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1314                 if (!gdp) {
1315                         *errp = -EIO;
1316                         goto out;
1317                 }
1318                 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1319                 /*
1320                  * skip this group if the number of
1321                  * free blocks is less than half of the reservation
1322                  * window size.
1323                  */
1324                 if (free_blocks <= (windowsz/2))
1325                         continue;
1326
1327                 brelse(bitmap_bh);
1328                 bitmap_bh = read_block_bitmap(sb, group_no);
1329                 if (!bitmap_bh)
1330                         goto io_error;
1331                 /*
1332                  * try to allocate block(s) from this group, without a goal(-1).
1333                  */
1334                 grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
1335                                         group_no, bitmap_bh, -1, my_rsv,
1336                                         &num, &fatal);
1337                 if (fatal)
1338                         goto out;
1339                 if (grp_alloc_blk >= 0)
1340                         goto allocated;
1341         }
1342         /*
1343          * We may end up a bogus ealier ENOSPC error due to
1344          * filesystem is "full" of reservations, but
1345          * there maybe indeed free blocks avaliable on disk
1346          * In this case, we just forget about the reservations
1347          * just do block allocation as without reservations.
1348          */
1349         if (my_rsv) {
1350                 my_rsv = NULL;
1351                 group_no = goal_group;
1352                 goto retry_alloc;
1353         }
1354         /* No space left on the device */
1355         *errp = -ENOSPC;
1356         goto out;
1357
1358 allocated:
1359
1360         ext3_debug("using block group %d(%d)\n",
1361                         group_no, gdp->bg_free_blocks_count);
1362
1363         BUFFER_TRACE(gdp_bh, "get_write_access");
1364         fatal = ext3_journal_get_write_access(handle, gdp_bh);
1365         if (fatal)
1366                 goto out;
1367
1368         ret_block = grp_alloc_blk + ext3_group_first_block_no(sb, group_no);
1369
1370         if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1371             in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1372             in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1373                       EXT3_SB(sb)->s_itb_per_group) ||
1374             in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1375                       EXT3_SB(sb)->s_itb_per_group))
1376                 ext3_error(sb, "ext3_new_block",
1377                             "Allocating block in system zone - "
1378                             "blocks from "E3FSBLK", length %lu",
1379                              ret_block, num);
1380
1381         performed_allocation = 1;
1382
1383 #ifdef CONFIG_JBD_DEBUG
1384         {
1385                 struct buffer_head *debug_bh;
1386
1387                 /* Record bitmap buffer state in the newly allocated block */
1388                 debug_bh = sb_find_get_block(sb, ret_block);
1389                 if (debug_bh) {
1390                         BUFFER_TRACE(debug_bh, "state when allocated");
1391                         BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1392                         brelse(debug_bh);
1393                 }
1394         }
1395         jbd_lock_bh_state(bitmap_bh);
1396         spin_lock(sb_bgl_lock(sbi, group_no));
1397         if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1398                 int i;
1399
1400                 for (i = 0; i < num; i++) {
1401                         if (ext3_test_bit(grp_alloc_blk+i,
1402                                         bh2jh(bitmap_bh)->b_committed_data)) {
1403                                 printk("%s: block was unexpectedly set in "
1404                                         "b_committed_data\n", __FUNCTION__);
1405                         }
1406                 }
1407         }
1408         ext3_debug("found bit %d\n", grp_alloc_blk);
1409         spin_unlock(sb_bgl_lock(sbi, group_no));
1410         jbd_unlock_bh_state(bitmap_bh);
1411 #endif
1412
1413         if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1414                 ext3_error(sb, "ext3_new_block",
1415                             "block("E3FSBLK") >= blocks count(%d) - "
1416                             "block_group = %d, es == %p ", ret_block,
1417                         le32_to_cpu(es->s_blocks_count), group_no, es);
1418                 goto out;
1419         }
1420
1421         /*
1422          * It is up to the caller to add the new buffer to a journal
1423          * list of some description.  We don't know in advance whether
1424          * the caller wants to use it as metadata or data.
1425          */
1426         ext3_debug("allocating block %lu. Goal hits %d of %d.\n",
1427                         ret_block, goal_hits, goal_attempts);
1428
1429         spin_lock(sb_bgl_lock(sbi, group_no));
1430         gdp->bg_free_blocks_count =
1431                         cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) - num);
1432         spin_unlock(sb_bgl_lock(sbi, group_no));
1433         percpu_counter_mod(&sbi->s_freeblocks_counter, -num);
1434
1435         BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1436         err = ext3_journal_dirty_metadata(handle, gdp_bh);
1437         if (!fatal)
1438                 fatal = err;
1439
1440         sb->s_dirt = 1;
1441         if (fatal)
1442                 goto out;
1443
1444         *errp = 0;
1445         brelse(bitmap_bh);
1446         DQUOT_FREE_BLOCK(inode, *count-num);
1447         *count = num;
1448         return ret_block;
1449
1450 io_error:
1451         *errp = -EIO;
1452 out:
1453         if (fatal) {
1454                 *errp = fatal;
1455                 ext3_std_error(sb, fatal);
1456         }
1457         /*
1458          * Undo the block allocation
1459          */
1460         if (!performed_allocation)
1461                 DQUOT_FREE_BLOCK(inode, *count);
1462         brelse(bitmap_bh);
1463         return 0;
1464 }
1465
1466 ext3_fsblk_t ext3_new_block(handle_t *handle, struct inode *inode,
1467                         ext3_fsblk_t goal, int *errp)
1468 {
1469         unsigned long count = 1;
1470
1471         return ext3_new_blocks(handle, inode, goal, &count, errp);
1472 }
1473
1474 ext3_fsblk_t ext3_count_free_blocks(struct super_block *sb)
1475 {
1476         ext3_fsblk_t desc_count;
1477         struct ext3_group_desc *gdp;
1478         int i;
1479         unsigned long ngroups = EXT3_SB(sb)->s_groups_count;
1480 #ifdef EXT3FS_DEBUG
1481         struct ext3_super_block *es;
1482         ext3_fsblk_t bitmap_count;
1483         unsigned long x;
1484         struct buffer_head *bitmap_bh = NULL;
1485
1486         es = EXT3_SB(sb)->s_es;
1487         desc_count = 0;
1488         bitmap_count = 0;
1489         gdp = NULL;
1490
1491         smp_rmb();
1492         for (i = 0; i < ngroups; i++) {
1493                 gdp = ext3_get_group_desc(sb, i, NULL);
1494                 if (!gdp)
1495                         continue;
1496                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1497                 brelse(bitmap_bh);
1498                 bitmap_bh = read_block_bitmap(sb, i);
1499                 if (bitmap_bh == NULL)
1500                         continue;
1501
1502                 x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1503                 printk("group %d: stored = %d, counted = %lu\n",
1504                         i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1505                 bitmap_count += x;
1506         }
1507         brelse(bitmap_bh);
1508         printk("ext3_count_free_blocks: stored = "E3FSBLK
1509                 ", computed = "E3FSBLK", "E3FSBLK"\n",
1510                le32_to_cpu(es->s_free_blocks_count),
1511                 desc_count, bitmap_count);
1512         return bitmap_count;
1513 #else
1514         desc_count = 0;
1515         smp_rmb();
1516         for (i = 0; i < ngroups; i++) {
1517                 gdp = ext3_get_group_desc(sb, i, NULL);
1518                 if (!gdp)
1519                         continue;
1520                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1521         }
1522
1523         return desc_count;
1524 #endif
1525 }
1526
1527 static inline int
1528 block_in_use(ext3_fsblk_t block, struct super_block *sb, unsigned char *map)
1529 {
1530         return ext3_test_bit ((block -
1531                 le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) %
1532                          EXT3_BLOCKS_PER_GROUP(sb), map);
1533 }
1534
1535 static inline int test_root(int a, int b)
1536 {
1537         int num = b;
1538
1539         while (a > num)
1540                 num *= b;
1541         return num == a;
1542 }
1543
1544 static int ext3_group_sparse(int group)
1545 {
1546         if (group <= 1)
1547                 return 1;
1548         if (!(group & 1))
1549                 return 0;
1550         return (test_root(group, 7) || test_root(group, 5) ||
1551                 test_root(group, 3));
1552 }
1553
1554 /**
1555  *      ext3_bg_has_super - number of blocks used by the superblock in group
1556  *      @sb: superblock for filesystem
1557  *      @group: group number to check
1558  *
1559  *      Return the number of blocks used by the superblock (primary or backup)
1560  *      in this group.  Currently this will be only 0 or 1.
1561  */
1562 int ext3_bg_has_super(struct super_block *sb, int group)
1563 {
1564         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
1565                                 EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1566                         !ext3_group_sparse(group))
1567                 return 0;
1568         return 1;
1569 }
1570
1571 static unsigned long ext3_bg_num_gdb_meta(struct super_block *sb, int group)
1572 {
1573         unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1574         unsigned long first = metagroup * EXT3_DESC_PER_BLOCK(sb);
1575         unsigned long last = first + EXT3_DESC_PER_BLOCK(sb) - 1;
1576
1577         if (group == first || group == first + 1 || group == last)
1578                 return 1;
1579         return 0;
1580 }
1581
1582 static unsigned long ext3_bg_num_gdb_nometa(struct super_block *sb, int group)
1583 {
1584         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
1585                                 EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1586                         !ext3_group_sparse(group))
1587                 return 0;
1588         return EXT3_SB(sb)->s_gdb_count;
1589 }
1590
1591 /**
1592  *      ext3_bg_num_gdb - number of blocks used by the group table in group
1593  *      @sb: superblock for filesystem
1594  *      @group: group number to check
1595  *
1596  *      Return the number of blocks used by the group descriptor table
1597  *      (primary or backup) in this group.  In the future there may be a
1598  *      different number of descriptor blocks in each group.
1599  */
1600 unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
1601 {
1602         unsigned long first_meta_bg =
1603                         le32_to_cpu(EXT3_SB(sb)->s_es->s_first_meta_bg);
1604         unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1605
1606         if (!EXT3_HAS_INCOMPAT_FEATURE(sb,EXT3_FEATURE_INCOMPAT_META_BG) ||
1607                         metagroup < first_meta_bg)
1608                 return ext3_bg_num_gdb_nometa(sb,group);
1609
1610         return ext3_bg_num_gdb_meta(sb,group);
1611
1612 }