fs/btrfs/free-space-cache.c

   1 /*
   2  * Copyright (C) 2008 Red Hat.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/pagemap.h>
  20 #include <linux/sched.h>
  21 #include <linux/slab.h>
  22 #include <linux/math64.h>
  23 #include "ctree.h"
  24 #include "free-space-cache.h"
  25 #include "transaction.h"
  26 #include "disk-io.h"
  27
  28 #define BITS_PER_BITMAP         (PAGE_CACHE_SIZE * 8)
  29 #define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
  30
  31 struct inode *lookup_free_space_inode(struct btrfs_root *root,
  32                                       struct btrfs_block_group_cache
  33                                       *block_group, struct btrfs_path *path)
  34 {
  35         struct btrfs_key key;
  36         struct btrfs_key location;
  37         struct btrfs_disk_key disk_key;
  38         struct btrfs_free_space_header *header;
  39         struct extent_buffer *leaf;
  40         struct inode *inode = NULL;
  41         int ret;
  42
  43         spin_lock(&block_group->lock);
  44         if (block_group->inode)
  45                 inode = igrab(block_group->inode);
  46         spin_unlock(&block_group->lock);
  47         if (inode)
  48                 return inode;
  49
  50         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
  51         key.offset = block_group->key.objectid;
  52         key.type = 0;
  53
  54         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  55         if (ret < 0)
  56                 return ERR_PTR(ret);
  57         if (ret > 0) {
  58                 btrfs_release_path(root, path);
  59                 return ERR_PTR(-ENOENT);
  60         }
  61
  62         leaf = path->nodes[0];
  63         header = btrfs_item_ptr(leaf, path->slots[0],
  64                                 struct btrfs_free_space_header);
  65         btrfs_free_space_key(leaf, header, &disk_key);
  66         btrfs_disk_key_to_cpu(&location, &disk_key);
  67         btrfs_release_path(root, path);
  68
  69         inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
  70         if (!inode)
  71                 return ERR_PTR(-ENOENT);
  72         if (IS_ERR(inode))
  73                 return inode;
  74         if (is_bad_inode(inode)) {
  75                 iput(inode);
  76                 return ERR_PTR(-ENOENT);
  77         }
  78
  79         spin_lock(&block_group->lock);
  80         if (!root->fs_info->closing) {
  81                 block_group->inode = igrab(inode);
  82                 block_group->iref = 1;
  83         }
  84         spin_unlock(&block_group->lock);
  85
  86         return inode;
  87 }
  88
  89 int create_free_space_inode(struct btrfs_root *root,
  90                             struct btrfs_trans_handle *trans,
  91                             struct btrfs_block_group_cache *block_group,
  92                             struct btrfs_path *path)
  93 {
  94         struct btrfs_key key;
  95         struct btrfs_disk_key disk_key;
  96         struct btrfs_free_space_header *header;
  97         struct btrfs_inode_item *inode_item;
  98         struct extent_buffer *leaf;
  99         u64 objectid;
 100         int ret;
 101
 102         ret = btrfs_find_free_objectid(trans, root, 0, &objectid);
 103         if (ret < 0)
 104                 return ret;
 105
 106         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
 107         if (ret)
 108                 return ret;
 109
 110         leaf = path->nodes[0];
 111         inode_item = btrfs_item_ptr(leaf, path->slots[0],
 112                                     struct btrfs_inode_item);
 113         btrfs_item_key(leaf, &disk_key, path->slots[0]);
 114         memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
 115                              sizeof(*inode_item));
 116         btrfs_set_inode_generation(leaf, inode_item, trans->transid);
 117         btrfs_set_inode_size(leaf, inode_item, 0);
 118         btrfs_set_inode_nbytes(leaf, inode_item, 0);
 119         btrfs_set_inode_uid(leaf, inode_item, 0);
 120         btrfs_set_inode_gid(leaf, inode_item, 0);
 121         btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
 122         btrfs_set_inode_flags(leaf, inode_item, BTRFS_INODE_NOCOMPRESS |
 123                               BTRFS_INODE_PREALLOC | BTRFS_INODE_NODATASUM);
 124         btrfs_set_inode_nlink(leaf, inode_item, 1);
 125         btrfs_set_inode_transid(leaf, inode_item, trans->transid);
 126         btrfs_set_inode_block_group(leaf, inode_item,
 127                                     block_group->key.objectid);
 128         btrfs_mark_buffer_dirty(leaf);
 129         btrfs_release_path(root, path);
 130
 131         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 132         key.offset = block_group->key.objectid;
 133         key.type = 0;
 134
 135         ret = btrfs_insert_empty_item(trans, root, path, &key,
 136                                       sizeof(struct btrfs_free_space_header));
 137         if (ret < 0) {
 138                 btrfs_release_path(root, path);
 139                 return ret;
 140         }
 141         leaf = path->nodes[0];
 142         header = btrfs_item_ptr(leaf, path->slots[0],
 143                                 struct btrfs_free_space_header);
 144         memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
 145         btrfs_set_free_space_key(leaf, header, &disk_key);
 146         btrfs_mark_buffer_dirty(leaf);
 147         btrfs_release_path(root, path);
 148
 149         return 0;
 150 }
 151
 152 int btrfs_truncate_free_space_cache(struct btrfs_root *root,
 153                                     struct btrfs_trans_handle *trans,
 154                                     struct btrfs_path *path,
 155                                     struct inode *inode)
 156 {
 157         loff_t oldsize;
 158         int ret = 0;
 159
 160         trans->block_rsv = root->orphan_block_rsv;
 161         ret = btrfs_block_rsv_check(trans, root,
 162                                     root->orphan_block_rsv,
 163                                     0, 5);
 164         if (ret)
 165                 return ret;
 166
 167         oldsize = i_size_read(inode);
 168         btrfs_i_size_write(inode, 0);
 169         truncate_pagecache(inode, oldsize, 0);
 170
 171         /*
 172          * We don't need an orphan item because truncating the free space cache
 173          * will never be split across transactions.
 174          */
 175         ret = btrfs_truncate_inode_items(trans, root, inode,
 176                                          0, BTRFS_EXTENT_DATA_KEY);
 177         if (ret) {
 178                 WARN_ON(1);
 179                 return ret;
 180         }
 181
 182         return btrfs_update_inode(trans, root, inode);
 183 }
 184
 185 static inline unsigned long offset_to_bit(u64 bitmap_start, u64 sectorsize,
 186                                           u64 offset)
 187 {
 188         BUG_ON(offset < bitmap_start);
 189         offset -= bitmap_start;
 190         return (unsigned long)(div64_u64(offset, sectorsize));
 191 }
 192
 193 static inline unsigned long bytes_to_bits(u64 bytes, u64 sectorsize)
 194 {
 195         return (unsigned long)(div64_u64(bytes, sectorsize));
 196 }
 197
 198 static inline u64 offset_to_bitmap(struct btrfs_block_group_cache *block_group,
 199                                    u64 offset)
 200 {
 201         u64 bitmap_start;
 202         u64 bytes_per_bitmap;
 203
 204         bytes_per_bitmap = BITS_PER_BITMAP * block_group->sectorsize;
 205         bitmap_start = offset - block_group->key.objectid;
 206         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
 207         bitmap_start *= bytes_per_bitmap;
 208         bitmap_start += block_group->key.objectid;
 209
 210         return bitmap_start;
 211 }
 212
 213 static int tree_insert_offset(struct rb_root *root, u64 offset,
 214                               struct rb_node *node, int bitmap)
 215 {
 216         struct rb_node **p = &root->rb_node;
 217         struct rb_node *parent = NULL;
 218         struct btrfs_free_space *info;
 219
 220         while (*p) {
 221                 parent = *p;
 222                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
 223
 224                 if (offset < info->offset) {
 225                         p = &(*p)->rb_left;
 226                 } else if (offset > info->offset) {
 227                         p = &(*p)->rb_right;
 228                 } else {
 229                         /*
 230                          * we could have a bitmap entry and an extent entry
 231                          * share the same offset.  If this is the case, we want
 232                          * the extent entry to always be found first if we do a
 233                          * linear search through the tree, since we want to have
 234                          * the quickest allocation time, and allocating from an
 235                          * extent is faster than allocating from a bitmap.  So
 236                          * if we're inserting a bitmap and we find an entry at
 237                          * this offset, we want to go right, or after this entry
 238                          * logically.  If we are inserting an extent and we've
 239                          * found a bitmap, we want to go left, or before
 240                          * logically.
 241                          */
 242                         if (bitmap) {
 243                                 WARN_ON(info->bitmap);
 244                                 p = &(*p)->rb_right;
 245                         } else {
 246                                 WARN_ON(!info->bitmap);
 247                                 p = &(*p)->rb_left;
 248                         }
 249                 }
 250         }
 251
 252         rb_link_node(node, parent, p);
 253         rb_insert_color(node, root);
 254
 255         return 0;
 256 }
 257
 258 /*
 259  * searches the tree for the given offset.
 260  *
 261  * fuzzy - If this is set, then we are trying to make an allocation, and we just
 262  * want a section that has at least bytes size and comes at or after the given
 263  * offset.
 264  */
 265 static struct btrfs_free_space *
 266 tree_search_offset(struct btrfs_block_group_cache *block_group,
 267                    u64 offset, int bitmap_only, int fuzzy)
 268 {
 269         struct rb_node *n = block_group->free_space_offset.rb_node;
 270         struct btrfs_free_space *entry, *prev = NULL;
 271
 272         /* find entry that is closest to the 'offset' */
 273         while (1) {
 274                 if (!n) {
 275                         entry = NULL;
 276                         break;
 277                 }
 278
 279                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
 280                 prev = entry;
 281
 282                 if (offset < entry->offset)
 283                         n = n->rb_left;
 284                 else if (offset > entry->offset)
 285                         n = n->rb_right;
 286                 else
 287                         break;
 288         }
 289
 290         if (bitmap_only) {
 291                 if (!entry)
 292                         return NULL;
 293                 if (entry->bitmap)
 294                         return entry;
 295
 296                 /*
 297                  * bitmap entry and extent entry may share same offset,
 298                  * in that case, bitmap entry comes after extent entry.
 299                  */
 300                 n = rb_next(n);
 301                 if (!n)
 302                         return NULL;
 303                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
 304                 if (entry->offset != offset)
 305                         return NULL;
 306
 307                 WARN_ON(!entry->bitmap);
 308                 return entry;
 309         } else if (entry) {
 310                 if (entry->bitmap) {
 311                         /*
 312                          * if previous extent entry covers the offset,
 313                          * we should return it instead of the bitmap entry
 314                          */
 315                         n = &entry->offset_index;
 316                         while (1) {
 317                                 n = rb_prev(n);
 318                                 if (!n)
 319                                         break;
 320                                 prev = rb_entry(n, struct btrfs_free_space,
 321                                                 offset_index);
 322                                 if (!prev->bitmap) {
 323                                         if (prev->offset + prev->bytes > offset)
 324                                                 entry = prev;
 325                                         break;
 326                                 }
 327                         }
 328                 }
 329                 return entry;
 330         }
 331
 332         if (!prev)
 333                 return NULL;
 334
 335         /* find last entry before the 'offset' */
 336         entry = prev;
 337         if (entry->offset > offset) {
 338                 n = rb_prev(&entry->offset_index);
 339                 if (n) {
 340                         entry = rb_entry(n, struct btrfs_free_space,
 341                                         offset_index);
 342                         BUG_ON(entry->offset > offset);
 343                 } else {
 344                         if (fuzzy)
 345                                 return entry;
 346                         else
 347                                 return NULL;
 348                 }
 349         }
 350
 351         if (entry->bitmap) {
 352                 n = &entry->offset_index;
 353                 while (1) {
 354                         n = rb_prev(n);
 355                         if (!n)
 356                                 break;
 357                         prev = rb_entry(n, struct btrfs_free_space,
 358                                         offset_index);
 359                         if (!prev->bitmap) {
 360                                 if (prev->offset + prev->bytes > offset)
 361                                         return prev;
 362                                 break;
 363                         }
 364                 }
 365                 if (entry->offset + BITS_PER_BITMAP *
 366                     block_group->sectorsize > offset)
 367                         return entry;
 368         } else if (entry->offset + entry->bytes > offset)
 369                 return entry;
 370
 371         if (!fuzzy)
 372                 return NULL;
 373
 374         while (1) {
 375                 if (entry->bitmap) {
 376                         if (entry->offset + BITS_PER_BITMAP *
 377                             block_group->sectorsize > offset)
 378                                 break;
 379                 } else {
 380                         if (entry->offset + entry->bytes > offset)
 381                                 break;
 382                 }
 383
 384                 n = rb_next(&entry->offset_index);
 385                 if (!n)
 386                         return NULL;
 387                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
 388         }
 389         return entry;
 390 }
 391
 392 static void unlink_free_space(struct btrfs_block_group_cache *block_group,
 393                               struct btrfs_free_space *info)
 394 {
 395         rb_erase(&info->offset_index, &block_group->free_space_offset);
 396         block_group->free_extents--;
 397         block_group->free_space -= info->bytes;
 398 }
 399
 400 static int link_free_space(struct btrfs_block_group_cache *block_group,
 401                            struct btrfs_free_space *info)
 402 {
 403         int ret = 0;
 404
 405         BUG_ON(!info->bitmap && !info->bytes);
 406         ret = tree_insert_offset(&block_group->free_space_offset, info->offset,
 407                                  &info->offset_index, (info->bitmap != NULL));
 408         if (ret)
 409                 return ret;
 410
 411         block_group->free_space += info->bytes;
 412         block_group->free_extents++;
 413         return ret;
 414 }
 415
 416 static void recalculate_thresholds(struct btrfs_block_group_cache *block_group)
 417 {
 418         u64 max_bytes;
 419         u64 bitmap_bytes;
 420         u64 extent_bytes;
 421
 422         /*
 423          * The goal is to keep the total amount of memory used per 1gb of space
 424          * at or below 32k, so we need to adjust how much memory we allow to be
 425          * used by extent based free space tracking
 426          */
 427         max_bytes = MAX_CACHE_BYTES_PER_GIG *
 428                 (div64_u64(block_group->key.offset, 1024 * 1024 * 1024));
 429
 430         /*
 431          * we want to account for 1 more bitmap than what we have so we can make
 432          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
 433          * we add more bitmaps.
 434          */
 435         bitmap_bytes = (block_group->total_bitmaps + 1) * PAGE_CACHE_SIZE;
 436
 437         if (bitmap_bytes >= max_bytes) {
 438                 block_group->extents_thresh = 0;
 439                 return;
 440         }
 441
 442         /*
 443          * we want the extent entry threshold to always be at most 1/2 the maxw
 444          * bytes we can have, or whatever is less than that.
 445          */
 446         extent_bytes = max_bytes - bitmap_bytes;
 447         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
 448
 449         block_group->extents_thresh =
 450                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
 451 }
 452
 453 static void bitmap_clear_bits(struct btrfs_block_group_cache *block_group,
 454                               struct btrfs_free_space *info, u64 offset,
 455                               u64 bytes)
 456 {
 457         unsigned long start, end;
 458         unsigned long i;
 459
 460         start = offset_to_bit(info->offset, block_group->sectorsize, offset);
 461         end = start + bytes_to_bits(bytes, block_group->sectorsize);
 462         BUG_ON(end > BITS_PER_BITMAP);
 463
 464         for (i = start; i < end; i++)
 465                 clear_bit(i, info->bitmap);
 466
 467         info->bytes -= bytes;
 468         block_group->free_space -= bytes;
 469 }
 470
 471 static void bitmap_set_bits(struct btrfs_block_group_cache *block_group,
 472                             struct btrfs_free_space *info, u64 offset,
 473                             u64 bytes)
 474 {
 475         unsigned long start, end;
 476         unsigned long i;
 477
 478         start = offset_to_bit(info->offset, block_group->sectorsize, offset);
 479         end = start + bytes_to_bits(bytes, block_group->sectorsize);
 480         BUG_ON(end > BITS_PER_BITMAP);
 481
 482         for (i = start; i < end; i++)
 483                 set_bit(i, info->bitmap);
 484
 485         info->bytes += bytes;
 486         block_group->free_space += bytes;
 487 }
 488
 489 static int search_bitmap(struct btrfs_block_group_cache *block_group,
 490                          struct btrfs_free_space *bitmap_info, u64 *offset,
 491                          u64 *bytes)
 492 {
 493         unsigned long found_bits = 0;
 494         unsigned long bits, i;
 495         unsigned long next_zero;
 496
 497         i = offset_to_bit(bitmap_info->offset, block_group->sectorsize,
 498                           max_t(u64, *offset, bitmap_info->offset));
 499         bits = bytes_to_bits(*bytes, block_group->sectorsize);
 500
 501         for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
 502              i < BITS_PER_BITMAP;
 503              i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
 504                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
 505                                                BITS_PER_BITMAP, i);
 506                 if ((next_zero - i) >= bits) {
 507                         found_bits = next_zero - i;
 508                         break;
 509                 }
 510                 i = next_zero;
 511         }
 512
 513         if (found_bits) {
 514                 *offset = (u64)(i * block_group->sectorsize) +
 515                         bitmap_info->offset;
 516                 *bytes = (u64)(found_bits) * block_group->sectorsize;
 517                 return 0;
 518         }
 519
 520         return -1;
 521 }
 522
 523 static struct btrfs_free_space *find_free_space(struct btrfs_block_group_cache
 524                                                 *block_group, u64 *offset,
 525                                                 u64 *bytes, int debug)
 526 {
 527         struct btrfs_free_space *entry;
 528         struct rb_node *node;
 529         int ret;
 530
 531         if (!block_group->free_space_offset.rb_node)
 532                 return NULL;
 533
 534         entry = tree_search_offset(block_group,
 535                                    offset_to_bitmap(block_group, *offset),
 536                                    0, 1);
 537         if (!entry)
 538                 return NULL;
 539
 540         for (node = &entry->offset_index; node; node = rb_next(node)) {
 541                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
 542                 if (entry->bytes < *bytes)
 543                         continue;
 544
 545                 if (entry->bitmap) {
 546                         ret = search_bitmap(block_group, entry, offset, bytes);
 547                         if (!ret)
 548                                 return entry;
 549                         continue;
 550                 }
 551
 552                 *offset = entry->offset;
 553                 *bytes = entry->bytes;
 554                 return entry;
 555         }
 556
 557         return NULL;
 558 }
 559
 560 static void add_new_bitmap(struct btrfs_block_group_cache *block_group,
 561                            struct btrfs_free_space *info, u64 offset)
 562 {
 563         u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
 564         int max_bitmaps = (int)div64_u64(block_group->key.offset +
 565                                          bytes_per_bg - 1, bytes_per_bg);
 566         BUG_ON(block_group->total_bitmaps >= max_bitmaps);
 567
 568         info->offset = offset_to_bitmap(block_group, offset);
 569         info->bytes = 0;
 570         link_free_space(block_group, info);
 571         block_group->total_bitmaps++;
 572
 573         recalculate_thresholds(block_group);
 574 }
 575
 576 static noinline int remove_from_bitmap(struct btrfs_block_group_cache *block_group,
 577                               struct btrfs_free_space *bitmap_info,
 578                               u64 *offset, u64 *bytes)
 579 {
 580         u64 end;
 581         u64 search_start, search_bytes;
 582         int ret;
 583
 584 again:
 585         end = bitmap_info->offset +
 586                 (u64)(BITS_PER_BITMAP * block_group->sectorsize) - 1;
 587
 588         /*
 589          * XXX - this can go away after a few releases.
 590          *
 591          * since the only user of btrfs_remove_free_space is the tree logging
 592          * stuff, and the only way to test that is under crash conditions, we
 593          * want to have this debug stuff here just in case somethings not
 594          * working.  Search the bitmap for the space we are trying to use to
 595          * make sure its actually there.  If its not there then we need to stop
 596          * because something has gone wrong.
 597          */
 598         search_start = *offset;
 599         search_bytes = *bytes;
 600         ret = search_bitmap(block_group, bitmap_info, &search_start,
 601                             &search_bytes);
 602         BUG_ON(ret < 0 || search_start != *offset);
 603
 604         if (*offset > bitmap_info->offset && *offset + *bytes > end) {
 605                 bitmap_clear_bits(block_group, bitmap_info, *offset,
 606                                   end - *offset + 1);
 607                 *bytes -= end - *offset + 1;
 608                 *offset = end + 1;
 609         } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
 610                 bitmap_clear_bits(block_group, bitmap_info, *offset, *bytes);
 611                 *bytes = 0;
 612         }
 613
 614         if (*bytes) {
 615                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
 616                 if (!bitmap_info->bytes) {
 617                         unlink_free_space(block_group, bitmap_info);
 618                         kfree(bitmap_info->bitmap);
 619                         kfree(bitmap_info);
 620                         block_group->total_bitmaps--;
 621                         recalculate_thresholds(block_group);
 622                 }
 623
 624                 /*
 625                  * no entry after this bitmap, but we still have bytes to
 626                  * remove, so something has gone wrong.
 627                  */
 628                 if (!next)
 629                         return -EINVAL;
 630
 631                 bitmap_info = rb_entry(next, struct btrfs_free_space,
 632                                        offset_index);
 633
 634                 /*
 635                  * if the next entry isn't a bitmap we need to return to let the
 636                  * extent stuff do its work.
 637                  */
 638                 if (!bitmap_info->bitmap)
 639                         return -EAGAIN;
 640
 641                 /*
 642                  * Ok the next item is a bitmap, but it may not actually hold
 643                  * the information for the rest of this free space stuff, so
 644                  * look for it, and if we don't find it return so we can try
 645                  * everything over again.
 646                  */
 647                 search_start = *offset;
 648                 search_bytes = *bytes;
 649                 ret = search_bitmap(block_group, bitmap_info, &search_start,
 650                                     &search_bytes);
 651                 if (ret < 0 || search_start != *offset)
 652                         return -EAGAIN;
 653
 654                 goto again;
 655         } else if (!bitmap_info->bytes) {
 656                 unlink_free_space(block_group, bitmap_info);
 657                 kfree(bitmap_info->bitmap);
 658                 kfree(bitmap_info);
 659                 block_group->total_bitmaps--;
 660                 recalculate_thresholds(block_group);
 661         }
 662
 663         return 0;
 664 }
 665
 666 static int insert_into_bitmap(struct btrfs_block_group_cache *block_group,
 667                               struct btrfs_free_space *info)
 668 {
 669         struct btrfs_free_space *bitmap_info;
 670         int added = 0;
 671         u64 bytes, offset, end;
 672         int ret;
 673
 674         /*
 675          * If we are below the extents threshold then we can add this as an
 676          * extent, and don't have to deal with the bitmap
 677          */
 678         if (block_group->free_extents < block_group->extents_thresh &&
 679             info->bytes > block_group->sectorsize * 4)
 680                 return 0;
 681
 682         /*
 683          * some block groups are so tiny they can't be enveloped by a bitmap, so
 684          * don't even bother to create a bitmap for this
 685          */
 686         if (BITS_PER_BITMAP * block_group->sectorsize >
 687             block_group->key.offset)
 688                 return 0;
 689
 690         bytes = info->bytes;
 691         offset = info->offset;
 692
 693 again:
 694         bitmap_info = tree_search_offset(block_group,
 695                                          offset_to_bitmap(block_group, offset),
 696                                          1, 0);
 697         if (!bitmap_info) {
 698                 BUG_ON(added);
 699                 goto new_bitmap;
 700         }
 701
 702         end = bitmap_info->offset +
 703                 (u64)(BITS_PER_BITMAP * block_group->sectorsize);
 704
 705         if (offset >= bitmap_info->offset && offset + bytes > end) {
 706                 bitmap_set_bits(block_group, bitmap_info, offset,
 707                                 end - offset);
 708                 bytes -= end - offset;
 709                 offset = end;
 710                 added = 0;
 711         } else if (offset >= bitmap_info->offset && offset + bytes <= end) {
 712                 bitmap_set_bits(block_group, bitmap_info, offset, bytes);
 713                 bytes = 0;
 714         } else {
 715                 BUG();
 716         }
 717
 718         if (!bytes) {
 719                 ret = 1;
 720                 goto out;
 721         } else
 722                 goto again;
 723
 724 new_bitmap:
 725         if (info && info->bitmap) {
 726                 add_new_bitmap(block_group, info, offset);
 727                 added = 1;
 728                 info = NULL;
 729                 goto again;
 730         } else {
 731                 spin_unlock(&block_group->tree_lock);
 732
 733                 /* no pre-allocated info, allocate a new one */
 734                 if (!info) {
 735                         info = kzalloc(sizeof(struct btrfs_free_space),
 736                                        GFP_NOFS);
 737                         if (!info) {
 738                                 spin_lock(&block_group->tree_lock);
 739                                 ret = -ENOMEM;
 740                                 goto out;
 741                         }
 742                 }
 743
 744                 /* allocate the bitmap */
 745                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
 746                 spin_lock(&block_group->tree_lock);
 747                 if (!info->bitmap) {
 748                         ret = -ENOMEM;
 749                         goto out;
 750                 }
 751                 goto again;
 752         }
 753
 754 out:
 755         if (info) {
 756                 if (info->bitmap)
 757                         kfree(info->bitmap);
 758                 kfree(info);
 759         }
 760
 761         return ret;
 762 }
 763
 764 int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
 765                          u64 offset, u64 bytes)
 766 {
 767         struct btrfs_free_space *right_info = NULL;
 768         struct btrfs_free_space *left_info = NULL;
 769         struct btrfs_free_space *info = NULL;
 770         int ret = 0;
 771
 772         info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
 773         if (!info)
 774                 return -ENOMEM;
 775
 776         info->offset = offset;
 777         info->bytes = bytes;
 778
 779         spin_lock(&block_group->tree_lock);
 780
 781         /*
 782          * first we want to see if there is free space adjacent to the range we
 783          * are adding, if there is remove that struct and add a new one to
 784          * cover the entire range
 785          */
 786         right_info = tree_search_offset(block_group, offset + bytes, 0, 0);
 787         if (right_info && rb_prev(&right_info->offset_index))
 788                 left_info = rb_entry(rb_prev(&right_info->offset_index),
 789                                      struct btrfs_free_space, offset_index);
 790         else
 791                 left_info = tree_search_offset(block_group, offset - 1, 0, 0);
 792
 793         /*
 794          * If there was no extent directly to the left or right of this new
 795          * extent then we know we're going to have to allocate a new extent, so
 796          * before we do that see if we need to drop this into a bitmap
 797          */
 798         if ((!left_info || left_info->bitmap) &&
 799             (!right_info || right_info->bitmap)) {
 800                 ret = insert_into_bitmap(block_group, info);
 801
 802                 if (ret < 0) {
 803                         goto out;
 804                 } else if (ret) {
 805                         ret = 0;
 806                         goto out;
 807                 }
 808         }
 809
 810         if (right_info && !right_info->bitmap) {
 811                 unlink_free_space(block_group, right_info);
 812                 info->bytes += right_info->bytes;
 813                 kfree(right_info);
 814         }
 815
 816         if (left_info && !left_info->bitmap &&
 817             left_info->offset + left_info->bytes == offset) {
 818                 unlink_free_space(block_group, left_info);
 819                 info->offset = left_info->offset;
 820                 info->bytes += left_info->bytes;
 821                 kfree(left_info);
 822         }
 823
 824         ret = link_free_space(block_group, info);
 825         if (ret)
 826                 kfree(info);
 827 out:
 828         spin_unlock(&block_group->tree_lock);
 829
 830         if (ret) {
 831                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
 832                 BUG_ON(ret == -EEXIST);
 833         }
 834
 835         return ret;
 836 }
 837
 838 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
 839                             u64 offset, u64 bytes)
 840 {
 841         struct btrfs_free_space *info;
 842         struct btrfs_free_space *next_info = NULL;
 843         int ret = 0;
 844
 845         spin_lock(&block_group->tree_lock);
 846
 847 again:
 848         info = tree_search_offset(block_group, offset, 0, 0);
 849         if (!info) {
 850                 /*
 851                  * oops didn't find an extent that matched the space we wanted
 852                  * to remove, look for a bitmap instead
 853                  */
 854                 info = tree_search_offset(block_group,
 855                                           offset_to_bitmap(block_group, offset),
 856                                           1, 0);
 857                 if (!info) {
 858                         WARN_ON(1);
 859                         goto out_lock;
 860                 }
 861         }
 862
 863         if (info->bytes < bytes && rb_next(&info->offset_index)) {
 864                 u64 end;
 865                 next_info = rb_entry(rb_next(&info->offset_index),
 866                                              struct btrfs_free_space,
 867                                              offset_index);
 868
 869                 if (next_info->bitmap)
 870                         end = next_info->offset + BITS_PER_BITMAP *
 871                                 block_group->sectorsize - 1;
 872                 else
 873                         end = next_info->offset + next_info->bytes;
 874
 875                 if (next_info->bytes < bytes ||
 876                     next_info->offset > offset || offset > end) {
 877                         printk(KERN_CRIT "Found free space at %llu, size %llu,"
 878                               " trying to use %llu\n",
 879                               (unsigned long long)info->offset,
 880                               (unsigned long long)info->bytes,
 881                               (unsigned long long)bytes);
 882                         WARN_ON(1);
 883                         ret = -EINVAL;
 884                         goto out_lock;
 885                 }
 886
 887                 info = next_info;
 888         }
 889
 890         if (info->bytes == bytes) {
 891                 unlink_free_space(block_group, info);
 892                 if (info->bitmap) {
 893                         kfree(info->bitmap);
 894                         block_group->total_bitmaps--;
 895                 }
 896                 kfree(info);
 897                 goto out_lock;
 898         }
 899
 900         if (!info->bitmap && info->offset == offset) {
 901                 unlink_free_space(block_group, info);
 902                 info->offset += bytes;
 903                 info->bytes -= bytes;
 904                 link_free_space(block_group, info);
 905                 goto out_lock;
 906         }
 907
 908         if (!info->bitmap && info->offset <= offset &&
 909             info->offset + info->bytes >= offset + bytes) {
 910                 u64 old_start = info->offset;
 911                 /*
 912                  * we're freeing space in the middle of the info,
 913                  * this can happen during tree log replay
 914                  *
 915                  * first unlink the old info and then
 916                  * insert it again after the hole we're creating
 917                  */
 918                 unlink_free_space(block_group, info);
 919                 if (offset + bytes < info->offset + info->bytes) {
 920                         u64 old_end = info->offset + info->bytes;
 921
 922                         info->offset = offset + bytes;
 923                         info->bytes = old_end - info->offset;
 924                         ret = link_free_space(block_group, info);
 925                         WARN_ON(ret);
 926                         if (ret)
 927                                 goto out_lock;
 928                 } else {
 929                         /* the hole we're creating ends at the end
 930                          * of the info struct, just free the info
 931                          */
 932                         kfree(info);
 933                 }
 934                 spin_unlock(&block_group->tree_lock);
 935
 936                 /* step two, insert a new info struct to cover
 937                  * anything before the hole
 938                  */
 939                 ret = btrfs_add_free_space(block_group, old_start,
 940                                            offset - old_start);
 941                 WARN_ON(ret);
 942                 goto out;
 943         }
 944
 945         ret = remove_from_bitmap(block_group, info, &offset, &bytes);
 946         if (ret == -EAGAIN)
 947                 goto again;
 948         BUG_ON(ret);
 949 out_lock:
 950         spin_unlock(&block_group->tree_lock);
 951 out:
 952         return ret;
 953 }
 954
 955 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
 956                            u64 bytes)
 957 {
 958         struct btrfs_free_space *info;
 959         struct rb_node *n;
 960         int count = 0;
 961
 962         for (n = rb_first(&block_group->free_space_offset); n; n = rb_next(n)) {
 963                 info = rb_entry(n, struct btrfs_free_space, offset_index);
 964                 if (info->bytes >= bytes)
 965                         count++;
 966                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
 967                        (unsigned long long)info->offset,
 968                        (unsigned long long)info->bytes,
 969                        (info->bitmap) ? "yes" : "no");
 970         }
 971         printk(KERN_INFO "block group has cluster?: %s\n",
 972                list_empty(&block_group->cluster_list) ? "no" : "yes");
 973         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
 974                "\n", count);
 975 }
 976
 977 u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group)
 978 {
 979         struct btrfs_free_space *info;
 980         struct rb_node *n;
 981         u64 ret = 0;
 982
 983         for (n = rb_first(&block_group->free_space_offset); n;
 984              n = rb_next(n)) {
 985                 info = rb_entry(n, struct btrfs_free_space, offset_index);
 986                 ret += info->bytes;
 987         }
 988
 989         return ret;
 990 }
 991
 992 /*
 993  * for a given cluster, put all of its extents back into the free
 994  * space cache.  If the block group passed doesn't match the block group
 995  * pointed to by the cluster, someone else raced in and freed the
 996  * cluster already.  In that case, we just return without changing anything
 997  */
 998 static int
 999 __btrfs_return_cluster_to_free_space(
1000                              struct btrfs_block_group_cache *block_group,
1001                              struct btrfs_free_cluster *cluster)
1002 {
1003         struct btrfs_free_space *entry;
1004         struct rb_node *node;
1005         bool bitmap;
1006
1007         spin_lock(&cluster->lock);
1008         if (cluster->block_group != block_group)
1009                 goto out;
1010
1011         bitmap = cluster->points_to_bitmap;
1012         cluster->block_group = NULL;
1013         cluster->window_start = 0;
1014         list_del_init(&cluster->block_group_list);
1015         cluster->points_to_bitmap = false;
1016
1017         if (bitmap)
1018                 goto out;
1019
1020         node = rb_first(&cluster->root);
1021         while (node) {
1022                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1023                 node = rb_next(&entry->offset_index);
1024                 rb_erase(&entry->offset_index, &cluster->root);
1025                 BUG_ON(entry->bitmap);
1026                 tree_insert_offset(&block_group->free_space_offset,
1027                                    entry->offset, &entry->offset_index, 0);
1028         }
1029         cluster->root = RB_ROOT;
1030
1031 out:
1032         spin_unlock(&cluster->lock);
1033         btrfs_put_block_group(block_group);
1034         return 0;
1035 }
1036
1037 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
1038 {
1039         struct btrfs_free_space *info;
1040         struct rb_node *node;
1041         struct btrfs_free_cluster *cluster;
1042         struct list_head *head;
1043
1044         spin_lock(&block_group->tree_lock);
1045         while ((head = block_group->cluster_list.next) !=
1046                &block_group->cluster_list) {
1047                 cluster = list_entry(head, struct btrfs_free_cluster,
1048                                      block_group_list);
1049
1050                 WARN_ON(cluster->block_group != block_group);
1051                 __btrfs_return_cluster_to_free_space(block_group, cluster);
1052                 if (need_resched()) {
1053                         spin_unlock(&block_group->tree_lock);
1054                         cond_resched();
1055                         spin_lock(&block_group->tree_lock);
1056                 }
1057         }
1058
1059         while ((node = rb_last(&block_group->free_space_offset)) != NULL) {
1060                 info = rb_entry(node, struct btrfs_free_space, offset_index);
1061                 unlink_free_space(block_group, info);
1062                 if (info->bitmap)
1063                         kfree(info->bitmap);
1064                 kfree(info);
1065                 if (need_resched()) {
1066                         spin_unlock(&block_group->tree_lock);
1067                         cond_resched();
1068                         spin_lock(&block_group->tree_lock);
1069                 }
1070         }
1071
1072         spin_unlock(&block_group->tree_lock);
1073 }
1074
1075 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
1076                                u64 offset, u64 bytes, u64 empty_size)
1077 {
1078         struct btrfs_free_space *entry = NULL;
1079         u64 bytes_search = bytes + empty_size;
1080         u64 ret = 0;
1081
1082         spin_lock(&block_group->tree_lock);
1083         entry = find_free_space(block_group, &offset, &bytes_search, 0);
1084         if (!entry)
1085                 goto out;
1086
1087         ret = offset;
1088         if (entry->bitmap) {
1089                 bitmap_clear_bits(block_group, entry, offset, bytes);
1090                 if (!entry->bytes) {
1091                         unlink_free_space(block_group, entry);
1092                         kfree(entry->bitmap);
1093                         kfree(entry);
1094                         block_group->total_bitmaps--;
1095                         recalculate_thresholds(block_group);
1096                 }
1097         } else {
1098                 unlink_free_space(block_group, entry);
1099                 entry->offset += bytes;
1100                 entry->bytes -= bytes;
1101                 if (!entry->bytes)
1102                         kfree(entry);
1103                 else
1104                         link_free_space(block_group, entry);
1105         }
1106
1107 out:
1108         spin_unlock(&block_group->tree_lock);
1109
1110         return ret;
1111 }
1112
1113 /*
1114  * given a cluster, put all of its extents back into the free space
1115  * cache.  If a block group is passed, this function will only free
1116  * a cluster that belongs to the passed block group.
1117  *
1118  * Otherwise, it'll get a reference on the block group pointed to by the
1119  * cluster and remove the cluster from it.
1120  */
1121 int btrfs_return_cluster_to_free_space(
1122                                struct btrfs_block_group_cache *block_group,
1123                                struct btrfs_free_cluster *cluster)
1124 {
1125         int ret;
1126
1127         /* first, get a safe pointer to the block group */
1128         spin_lock(&cluster->lock);
1129         if (!block_group) {
1130                 block_group = cluster->block_group;
1131                 if (!block_group) {
1132                         spin_unlock(&cluster->lock);
1133                         return 0;
1134                 }
1135         } else if (cluster->block_group != block_group) {
1136                 /* someone else has already freed it don't redo their work */
1137                 spin_unlock(&cluster->lock);
1138                 return 0;
1139         }
1140         atomic_inc(&block_group->count);
1141         spin_unlock(&cluster->lock);
1142
1143         /* now return any extents the cluster had on it */
1144         spin_lock(&block_group->tree_lock);
1145         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
1146         spin_unlock(&block_group->tree_lock);
1147
1148         /* finally drop our ref */
1149         btrfs_put_block_group(block_group);
1150         return ret;
1151 }
1152
1153 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
1154                                    struct btrfs_free_cluster *cluster,
1155                                    u64 bytes, u64 min_start)
1156 {
1157         struct btrfs_free_space *entry;
1158         int err;
1159         u64 search_start = cluster->window_start;
1160         u64 search_bytes = bytes;
1161         u64 ret = 0;
1162
1163         spin_lock(&block_group->tree_lock);
1164         spin_lock(&cluster->lock);
1165
1166         if (!cluster->points_to_bitmap)
1167                 goto out;
1168
1169         if (cluster->block_group != block_group)
1170                 goto out;
1171
1172         /*
1173          * search_start is the beginning of the bitmap, but at some point it may
1174          * be a good idea to point to the actual start of the free area in the
1175          * bitmap, so do the offset_to_bitmap trick anyway, and set bitmap_only
1176          * to 1 to make sure we get the bitmap entry
1177          */
1178         entry = tree_search_offset(block_group,
1179                                    offset_to_bitmap(block_group, search_start),
1180                                    1, 0);
1181         if (!entry || !entry->bitmap)
1182                 goto out;
1183
1184         search_start = min_start;
1185         search_bytes = bytes;
1186
1187         err = search_bitmap(block_group, entry, &search_start,
1188                             &search_bytes);
1189         if (err)
1190                 goto out;
1191
1192         ret = search_start;
1193         bitmap_clear_bits(block_group, entry, ret, bytes);
1194 out:
1195         spin_unlock(&cluster->lock);
1196         spin_unlock(&block_group->tree_lock);
1197
1198         return ret;
1199 }
1200
1201 /*
1202  * given a cluster, try to allocate 'bytes' from it, returns 0
1203  * if it couldn't find anything suitably large, or a logical disk offset
1204  * if things worked out
1205  */
1206 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
1207                              struct btrfs_free_cluster *cluster, u64 bytes,
1208                              u64 min_start)
1209 {
1210         struct btrfs_free_space *entry = NULL;
1211         struct rb_node *node;
1212         u64 ret = 0;
1213
1214         if (cluster->points_to_bitmap)
1215                 return btrfs_alloc_from_bitmap(block_group, cluster, bytes,
1216                                                min_start);
1217
1218         spin_lock(&cluster->lock);
1219         if (bytes > cluster->max_size)
1220                 goto out;
1221
1222         if (cluster->block_group != block_group)
1223                 goto out;
1224
1225         node = rb_first(&cluster->root);
1226         if (!node)
1227                 goto out;
1228
1229         entry = rb_entry(node, struct btrfs_free_space, offset_index);
1230
1231         while(1) {
1232                 if (entry->bytes < bytes || entry->offset < min_start) {
1233                         struct rb_node *node;
1234
1235                         node = rb_next(&entry->offset_index);
1236                         if (!node)
1237                                 break;
1238                         entry = rb_entry(node, struct btrfs_free_space,
1239                                          offset_index);
1240                         continue;
1241                 }
1242                 ret = entry->offset;
1243
1244                 entry->offset += bytes;
1245                 entry->bytes -= bytes;
1246
1247                 if (entry->bytes == 0) {
1248                         rb_erase(&entry->offset_index, &cluster->root);
1249                         kfree(entry);
1250                 }
1251                 break;
1252         }
1253 out:
1254         spin_unlock(&cluster->lock);
1255
1256         return ret;
1257 }
1258
1259 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
1260                                 struct btrfs_free_space *entry,
1261                                 struct btrfs_free_cluster *cluster,
1262                                 u64 offset, u64 bytes, u64 min_bytes)
1263 {
1264         unsigned long next_zero;
1265         unsigned long i;
1266         unsigned long search_bits;
1267         unsigned long total_bits;
1268         unsigned long found_bits;
1269         unsigned long start = 0;
1270         unsigned long total_found = 0;
1271         bool found = false;
1272
1273         i = offset_to_bit(entry->offset, block_group->sectorsize,
1274                           max_t(u64, offset, entry->offset));
1275         search_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
1276         total_bits = bytes_to_bits(bytes, block_group->sectorsize);
1277
1278 again:
1279         found_bits = 0;
1280         for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
1281              i < BITS_PER_BITMAP;
1282              i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
1283                 next_zero = find_next_zero_bit(entry->bitmap,
1284                                                BITS_PER_BITMAP, i);
1285                 if (next_zero - i >= search_bits) {
1286                         found_bits = next_zero - i;
1287                         break;
1288                 }
1289                 i = next_zero;
1290         }
1291
1292         if (!found_bits)
1293                 return -1;
1294
1295         if (!found) {
1296                 start = i;
1297                 found = true;
1298         }
1299
1300         total_found += found_bits;
1301
1302         if (cluster->max_size < found_bits * block_group->sectorsize)
1303                 cluster->max_size = found_bits * block_group->sectorsize;
1304
1305         if (total_found < total_bits) {
1306                 i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero);
1307                 if (i - start > total_bits * 2) {
1308                         total_found = 0;
1309                         cluster->max_size = 0;
1310                         found = false;
1311                 }
1312                 goto again;
1313         }
1314
1315         cluster->window_start = start * block_group->sectorsize +
1316                 entry->offset;
1317         cluster->points_to_bitmap = true;
1318
1319         return 0;
1320 }
1321
1322 /*
1323  * here we try to find a cluster of blocks in a block group.  The goal
1324  * is to find at least bytes free and up to empty_size + bytes free.
1325  * We might not find them all in one contiguous area.
1326  *
1327  * returns zero and sets up cluster if things worked out, otherwise
1328  * it returns -enospc
1329  */
1330 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
1331                              struct btrfs_root *root,
1332                              struct btrfs_block_group_cache *block_group,
1333                              struct btrfs_free_cluster *cluster,
1334                              u64 offset, u64 bytes, u64 empty_size)
1335 {
1336         struct btrfs_free_space *entry = NULL;
1337         struct rb_node *node;
1338         struct btrfs_free_space *next;
1339         struct btrfs_free_space *last = NULL;
1340         u64 min_bytes;
1341         u64 window_start;
1342         u64 window_free;
1343         u64 max_extent = 0;
1344         bool found_bitmap = false;
1345         int ret;
1346
1347         /* for metadata, allow allocates with more holes */
1348         if (btrfs_test_opt(root, SSD_SPREAD)) {
1349                 min_bytes = bytes + empty_size;
1350         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
1351                 /*
1352                  * we want to do larger allocations when we are
1353                  * flushing out the delayed refs, it helps prevent
1354                  * making more work as we go along.
1355                  */
1356                 if (trans->transaction->delayed_refs.flushing)
1357                         min_bytes = max(bytes, (bytes + empty_size) >> 1);
1358                 else
1359                         min_bytes = max(bytes, (bytes + empty_size) >> 4);
1360         } else
1361                 min_bytes = max(bytes, (bytes + empty_size) >> 2);
1362
1363         spin_lock(&block_group->tree_lock);
1364         spin_lock(&cluster->lock);
1365
1366         /* someone already found a cluster, hooray */
1367         if (cluster->block_group) {
1368                 ret = 0;
1369                 goto out;
1370         }
1371 again:
1372         entry = tree_search_offset(block_group, offset, found_bitmap, 1);
1373         if (!entry) {
1374                 ret = -ENOSPC;
1375                 goto out;
1376         }
1377
1378         /*
1379          * If found_bitmap is true, we exhausted our search for extent entries,
1380          * and we just want to search all of the bitmaps that we can find, and
1381          * ignore any extent entries we find.
1382          */
1383         while (entry->bitmap || found_bitmap ||
1384                (!entry->bitmap && entry->bytes < min_bytes)) {
1385                 struct rb_node *node = rb_next(&entry->offset_index);
1386
1387                 if (entry->bitmap && entry->bytes > bytes + empty_size) {
1388                         ret = btrfs_bitmap_cluster(block_group, entry, cluster,
1389                                                    offset, bytes + empty_size,
1390                                                    min_bytes);
1391                         if (!ret)
1392                                 goto got_it;
1393                 }
1394
1395                 if (!node) {
1396                         ret = -ENOSPC;
1397                         goto out;
1398                 }
1399                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1400         }
1401
1402         /*
1403          * We already searched all the extent entries from the passed in offset
1404          * to the end and didn't find enough space for the cluster, and we also
1405          * didn't find any bitmaps that met our criteria, just go ahead and exit
1406          */
1407         if (found_bitmap) {
1408                 ret = -ENOSPC;
1409                 goto out;
1410         }
1411
1412         cluster->points_to_bitmap = false;
1413         window_start = entry->offset;
1414         window_free = entry->bytes;
1415         last = entry;
1416         max_extent = entry->bytes;
1417
1418         while (1) {
1419                 /* out window is just right, lets fill it */
1420                 if (window_free >= bytes + empty_size)
1421                         break;
1422
1423                 node = rb_next(&last->offset_index);
1424                 if (!node) {
1425                         if (found_bitmap)
1426                                 goto again;
1427                         ret = -ENOSPC;
1428                         goto out;
1429                 }
1430                 next = rb_entry(node, struct btrfs_free_space, offset_index);
1431
1432                 /*
1433                  * we found a bitmap, so if this search doesn't result in a
1434                  * cluster, we know to go and search again for the bitmaps and
1435                  * start looking for space there
1436                  */
1437                 if (next->bitmap) {
1438                         if (!found_bitmap)
1439                                 offset = next->offset;
1440                         found_bitmap = true;
1441                         last = next;
1442                         continue;
1443                 }
1444
1445                 /*
1446                  * we haven't filled the empty size and the window is
1447                  * very large.  reset and try again
1448                  */
1449                 if (next->offset - (last->offset + last->bytes) > 128 * 1024 ||
1450                     next->offset - window_start > (bytes + empty_size) * 2) {
1451                         entry = next;
1452                         window_start = entry->offset;
1453                         window_free = entry->bytes;
1454                         last = entry;
1455                         max_extent = entry->bytes;
1456                 } else {
1457                         last = next;
1458                         window_free += next->bytes;
1459                         if (entry->bytes > max_extent)
1460                                 max_extent = entry->bytes;
1461                 }
1462         }
1463
1464         cluster->window_start = entry->offset;
1465
1466         /*
1467          * now we've found our entries, pull them out of the free space
1468          * cache and put them into the cluster rbtree
1469          *
1470          * The cluster includes an rbtree, but only uses the offset index
1471          * of each free space cache entry.
1472          */
1473         while (1) {
1474                 node = rb_next(&entry->offset_index);
1475                 if (entry->bitmap && node) {
1476                         entry = rb_entry(node, struct btrfs_free_space,
1477                                          offset_index);
1478                         continue;
1479                 } else if (entry->bitmap && !node) {
1480                         break;
1481                 }
1482
1483                 rb_erase(&entry->offset_index, &block_group->free_space_offset);
1484                 ret = tree_insert_offset(&cluster->root, entry->offset,
1485                                          &entry->offset_index, 0);
1486                 BUG_ON(ret);
1487
1488                 if (!node || entry == last)
1489                         break;
1490
1491                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1492         }
1493
1494         cluster->max_size = max_extent;
1495 got_it:
1496         ret = 0;
1497         atomic_inc(&block_group->count);
1498         list_add_tail(&cluster->block_group_list, &block_group->cluster_list);
1499         cluster->block_group = block_group;
1500 out:
1501         spin_unlock(&cluster->lock);
1502         spin_unlock(&block_group->tree_lock);
1503
1504         return ret;
1505 }
1506
1507 /*
1508  * simple code to zero out a cluster
1509  */
1510 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
1511 {
1512         spin_lock_init(&cluster->lock);
1513         spin_lock_init(&cluster->refill_lock);
1514         cluster->root = RB_ROOT;
1515         cluster->max_size = 0;
1516         cluster->points_to_bitmap = false;
1517         INIT_LIST_HEAD(&cluster->block_group_list);
1518         cluster->block_group = NULL;
1519 }
1520