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 static void recalculate_thresholds(struct btrfs_block_group_cache
  32                                    *block_group);
  33 static int link_free_space(struct btrfs_block_group_cache *block_group,
  34                            struct btrfs_free_space *info);
  35
  36 struct inode *lookup_free_space_inode(struct btrfs_root *root,
  37                                       struct btrfs_block_group_cache
  38                                       *block_group, struct btrfs_path *path)
  39 {
  40         struct btrfs_key key;
  41         struct btrfs_key location;
  42         struct btrfs_disk_key disk_key;
  43         struct btrfs_free_space_header *header;
  44         struct extent_buffer *leaf;
  45         struct inode *inode = NULL;
  46         int ret;
  47
  48         spin_lock(&block_group->lock);
  49         if (block_group->inode)
  50                 inode = igrab(block_group->inode);
  51         spin_unlock(&block_group->lock);
  52         if (inode)
  53                 return inode;
  54
  55         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
  56         key.offset = block_group->key.objectid;
  57         key.type = 0;
  58
  59         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  60         if (ret < 0)
  61                 return ERR_PTR(ret);
  62         if (ret > 0) {
  63                 btrfs_release_path(root, path);
  64                 return ERR_PTR(-ENOENT);
  65         }
  66
  67         leaf = path->nodes[0];
  68         header = btrfs_item_ptr(leaf, path->slots[0],
  69                                 struct btrfs_free_space_header);
  70         btrfs_free_space_key(leaf, header, &disk_key);
  71         btrfs_disk_key_to_cpu(&location, &disk_key);
  72         btrfs_release_path(root, path);
  73
  74         inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
  75         if (!inode)
  76                 return ERR_PTR(-ENOENT);
  77         if (IS_ERR(inode))
  78                 return inode;
  79         if (is_bad_inode(inode)) {
  80                 iput(inode);
  81                 return ERR_PTR(-ENOENT);
  82         }
  83
  84         spin_lock(&block_group->lock);
  85         if (!root->fs_info->closing) {
  86                 block_group->inode = igrab(inode);
  87                 block_group->iref = 1;
  88         }
  89         spin_unlock(&block_group->lock);
  90
  91         return inode;
  92 }
  93
  94 int create_free_space_inode(struct btrfs_root *root,
  95                             struct btrfs_trans_handle *trans,
  96                             struct btrfs_block_group_cache *block_group,
  97                             struct btrfs_path *path)
  98 {
  99         struct btrfs_key key;
 100         struct btrfs_disk_key disk_key;
 101         struct btrfs_free_space_header *header;
 102         struct btrfs_inode_item *inode_item;
 103         struct extent_buffer *leaf;
 104         u64 objectid;
 105         int ret;
 106
 107         ret = btrfs_find_free_objectid(trans, root, 0, &objectid);
 108         if (ret < 0)
 109                 return ret;
 110
 111         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
 112         if (ret)
 113                 return ret;
 114
 115         leaf = path->nodes[0];
 116         inode_item = btrfs_item_ptr(leaf, path->slots[0],
 117                                     struct btrfs_inode_item);
 118         btrfs_item_key(leaf, &disk_key, path->slots[0]);
 119         memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
 120                              sizeof(*inode_item));
 121         btrfs_set_inode_generation(leaf, inode_item, trans->transid);
 122         btrfs_set_inode_size(leaf, inode_item, 0);
 123         btrfs_set_inode_nbytes(leaf, inode_item, 0);
 124         btrfs_set_inode_uid(leaf, inode_item, 0);
 125         btrfs_set_inode_gid(leaf, inode_item, 0);
 126         btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
 127         btrfs_set_inode_flags(leaf, inode_item, BTRFS_INODE_NOCOMPRESS |
 128                               BTRFS_INODE_PREALLOC | BTRFS_INODE_NODATASUM);
 129         btrfs_set_inode_nlink(leaf, inode_item, 1);
 130         btrfs_set_inode_transid(leaf, inode_item, trans->transid);
 131         btrfs_set_inode_block_group(leaf, inode_item,
 132                                     block_group->key.objectid);
 133         btrfs_mark_buffer_dirty(leaf);
 134         btrfs_release_path(root, path);
 135
 136         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 137         key.offset = block_group->key.objectid;
 138         key.type = 0;
 139
 140         ret = btrfs_insert_empty_item(trans, root, path, &key,
 141                                       sizeof(struct btrfs_free_space_header));
 142         if (ret < 0) {
 143                 btrfs_release_path(root, path);
 144                 return ret;
 145         }
 146         leaf = path->nodes[0];
 147         header = btrfs_item_ptr(leaf, path->slots[0],
 148                                 struct btrfs_free_space_header);
 149         memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
 150         btrfs_set_free_space_key(leaf, header, &disk_key);
 151         btrfs_mark_buffer_dirty(leaf);
 152         btrfs_release_path(root, path);
 153
 154         return 0;
 155 }
 156
 157 int btrfs_truncate_free_space_cache(struct btrfs_root *root,
 158                                     struct btrfs_trans_handle *trans,
 159                                     struct btrfs_path *path,
 160                                     struct inode *inode)
 161 {
 162         loff_t oldsize;
 163         int ret = 0;
 164
 165         trans->block_rsv = root->orphan_block_rsv;
 166         ret = btrfs_block_rsv_check(trans, root,
 167                                     root->orphan_block_rsv,
 168                                     0, 5);
 169         if (ret)
 170                 return ret;
 171
 172         oldsize = i_size_read(inode);
 173         btrfs_i_size_write(inode, 0);
 174         truncate_pagecache(inode, oldsize, 0);
 175
 176         /*
 177          * We don't need an orphan item because truncating the free space cache
 178          * will never be split across transactions.
 179          */
 180         ret = btrfs_truncate_inode_items(trans, root, inode,
 181                                          0, BTRFS_EXTENT_DATA_KEY);
 182         if (ret) {
 183                 WARN_ON(1);
 184                 return ret;
 185         }
 186
 187         return btrfs_update_inode(trans, root, inode);
 188 }
 189
 190 static int readahead_cache(struct inode *inode)
 191 {
 192         struct file_ra_state *ra;
 193         unsigned long last_index;
 194
 195         ra = kzalloc(sizeof(*ra), GFP_NOFS);
 196         if (!ra)
 197                 return -ENOMEM;
 198
 199         file_ra_state_init(ra, inode->i_mapping);
 200         last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 201
 202         page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
 203
 204         kfree(ra);
 205
 206         return 0;
 207 }
 208
 209 int load_free_space_cache(struct btrfs_fs_info *fs_info,
 210                           struct btrfs_block_group_cache *block_group)
 211 {
 212         struct btrfs_root *root = fs_info->tree_root;
 213         struct inode *inode;
 214         struct btrfs_free_space_header *header;
 215         struct extent_buffer *leaf;
 216         struct page *page;
 217         struct btrfs_path *path;
 218         u32 *checksums = NULL, *crc;
 219         char *disk_crcs = NULL;
 220         struct btrfs_key key;
 221         struct list_head bitmaps;
 222         u64 num_entries;
 223         u64 num_bitmaps;
 224         u64 generation;
 225         u32 cur_crc = ~(u32)0;
 226         pgoff_t index = 0;
 227         unsigned long first_page_offset;
 228         int num_checksums;
 229         int ret = 0;
 230
 231         /*
 232          * If we're unmounting then just return, since this does a search on the
 233          * normal root and not the commit root and we could deadlock.
 234          */
 235         smp_mb();
 236         if (fs_info->closing)
 237                 return 0;
 238
 239         /*
 240          * If this block group has been marked to be cleared for one reason or
 241          * another then we can't trust the on disk cache, so just return.
 242          */
 243         spin_lock(&block_group->lock);
 244         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 245                 spin_unlock(&block_group->lock);
 246                 return 0;
 247         }
 248         spin_unlock(&block_group->lock);
 249
 250         INIT_LIST_HEAD(&bitmaps);
 251
 252         path = btrfs_alloc_path();
 253         if (!path)
 254                 return 0;
 255
 256         inode = lookup_free_space_inode(root, block_group, path);
 257         if (IS_ERR(inode)) {
 258                 btrfs_free_path(path);
 259                 return 0;
 260         }
 261
 262         /* Nothing in the space cache, goodbye */
 263         if (!i_size_read(inode)) {
 264                 btrfs_free_path(path);
 265                 goto out;
 266         }
 267
 268         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 269         key.offset = block_group->key.objectid;
 270         key.type = 0;
 271
 272         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 273         if (ret) {
 274                 btrfs_free_path(path);
 275                 goto out;
 276         }
 277
 278         leaf = path->nodes[0];
 279         header = btrfs_item_ptr(leaf, path->slots[0],
 280                                 struct btrfs_free_space_header);
 281         num_entries = btrfs_free_space_entries(leaf, header);
 282         num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
 283         generation = btrfs_free_space_generation(leaf, header);
 284         btrfs_free_path(path);
 285
 286         if (BTRFS_I(inode)->generation != generation) {
 287                 printk(KERN_ERR "btrfs: free space inode generation (%llu) did"
 288                        " not match free space cache generation (%llu) for "
 289                        "block group %llu\n",
 290                        (unsigned long long)BTRFS_I(inode)->generation,
 291                        (unsigned long long)generation,
 292                        (unsigned long long)block_group->key.objectid);
 293                 goto free_cache;
 294         }
 295
 296         if (!num_entries)
 297                 goto out;
 298
 299         /* Setup everything for doing checksumming */
 300         num_checksums = i_size_read(inode) / PAGE_CACHE_SIZE;
 301         checksums = crc = kzalloc(sizeof(u32) * num_checksums, GFP_NOFS);
 302         if (!checksums)
 303                 goto out;
 304         first_page_offset = (sizeof(u32) * num_checksums) + sizeof(u64);
 305         disk_crcs = kzalloc(first_page_offset, GFP_NOFS);
 306         if (!disk_crcs)
 307                 goto out;
 308
 309         ret = readahead_cache(inode);
 310         if (ret) {
 311                 ret = 0;
 312                 goto out;
 313         }
 314
 315         while (1) {
 316                 struct btrfs_free_space_entry *entry;
 317                 struct btrfs_free_space *e;
 318                 void *addr;
 319                 unsigned long offset = 0;
 320                 unsigned long start_offset = 0;
 321                 int need_loop = 0;
 322
 323                 if (!num_entries && !num_bitmaps)
 324                         break;
 325
 326                 if (index == 0) {
 327                         start_offset = first_page_offset;
 328                         offset = start_offset;
 329                 }
 330
 331                 page = grab_cache_page(inode->i_mapping, index);
 332                 if (!page) {
 333                         ret = 0;
 334                         goto free_cache;
 335                 }
 336
 337                 if (!PageUptodate(page)) {
 338                         btrfs_readpage(NULL, page);
 339                         lock_page(page);
 340                         if (!PageUptodate(page)) {
 341                                 unlock_page(page);
 342                                 page_cache_release(page);
 343                                 printk(KERN_ERR "btrfs: error reading free "
 344                                        "space cache: %llu\n",
 345                                        (unsigned long long)
 346                                        block_group->key.objectid);
 347                                 goto free_cache;
 348                         }
 349                 }
 350                 addr = kmap(page);
 351
 352                 if (index == 0) {
 353                         u64 *gen;
 354
 355                         memcpy(disk_crcs, addr, first_page_offset);
 356                         gen = addr + (sizeof(u32) * num_checksums);
 357                         if (*gen != BTRFS_I(inode)->generation) {
 358                                 printk(KERN_ERR "btrfs: space cache generation"
 359                                        " (%llu) does not match inode (%llu) "
 360                                        "for block group %llu\n",
 361                                        (unsigned long long)*gen,
 362                                        (unsigned long long)
 363                                        BTRFS_I(inode)->generation,
 364                                        (unsigned long long)
 365                                        block_group->key.objectid);
 366                                 kunmap(page);
 367                                 unlock_page(page);
 368                                 page_cache_release(page);
 369                                 goto free_cache;
 370                         }
 371                         crc = (u32 *)disk_crcs;
 372                 }
 373                 entry = addr + start_offset;
 374
 375                 /* First lets check our crc before we do anything fun */
 376                 cur_crc = ~(u32)0;
 377                 cur_crc = btrfs_csum_data(root, addr + start_offset, cur_crc,
 378                                           PAGE_CACHE_SIZE - start_offset);
 379                 btrfs_csum_final(cur_crc, (char *)&cur_crc);
 380                 if (cur_crc != *crc) {
 381                         printk(KERN_ERR "btrfs: crc mismatch for page %lu in "
 382                                "block group %llu\n", index,
 383                                (unsigned long long)block_group->key.objectid);
 384                         kunmap(page);
 385                         unlock_page(page);
 386                         page_cache_release(page);
 387                         goto free_cache;
 388                 }
 389                 crc++;
 390
 391                 while (1) {
 392                         if (!num_entries)
 393                                 break;
 394
 395                         need_loop = 1;
 396                         e = kmem_cache_zalloc(btrfs_free_space_cachep,
 397                                               GFP_NOFS);
 398                         if (!e) {
 399                                 kunmap(page);
 400                                 unlock_page(page);
 401                                 page_cache_release(page);
 402                                 goto free_cache;
 403                         }
 404
 405                         e->offset = le64_to_cpu(entry->offset);
 406                         e->bytes = le64_to_cpu(entry->bytes);
 407                         if (!e->bytes) {
 408                                 kunmap(page);
 409                                 kmem_cache_free(btrfs_free_space_cachep, e);
 410                                 unlock_page(page);
 411                                 page_cache_release(page);
 412                                 goto free_cache;
 413                         }
 414
 415                         if (entry->type == BTRFS_FREE_SPACE_EXTENT) {
 416                                 spin_lock(&block_group->tree_lock);
 417                                 ret = link_free_space(block_group, e);
 418                                 spin_unlock(&block_group->tree_lock);
 419                                 BUG_ON(ret);
 420                         } else {
 421                                 e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
 422                                 if (!e->bitmap) {
 423                                         kunmap(page);
 424                                         kmem_cache_free(
 425                                                 btrfs_free_space_cachep, e);
 426                                         unlock_page(page);
 427                                         page_cache_release(page);
 428                                         goto free_cache;
 429                                 }
 430                                 spin_lock(&block_group->tree_lock);
 431                                 ret = link_free_space(block_group, e);
 432                                 block_group->total_bitmaps++;
 433                                 recalculate_thresholds(block_group);
 434                                 spin_unlock(&block_group->tree_lock);
 435                                 list_add_tail(&e->list, &bitmaps);
 436                         }
 437
 438                         num_entries--;
 439                         offset += sizeof(struct btrfs_free_space_entry);
 440                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 441                             PAGE_CACHE_SIZE)
 442                                 break;
 443                         entry++;
 444                 }
 445
 446                 /*
 447                  * We read an entry out of this page, we need to move on to the
 448                  * next page.
 449                  */
 450                 if (need_loop) {
 451                         kunmap(page);
 452                         goto next;
 453                 }
 454
 455                 /*
 456                  * We add the bitmaps at the end of the entries in order that
 457                  * the bitmap entries are added to the cache.
 458                  */
 459                 e = list_entry(bitmaps.next, struct btrfs_free_space, list);
 460                 list_del_init(&e->list);
 461                 memcpy(e->bitmap, addr, PAGE_CACHE_SIZE);
 462                 kunmap(page);
 463                 num_bitmaps--;
 464 next:
 465                 unlock_page(page);
 466                 page_cache_release(page);
 467                 index++;
 468         }
 469
 470         ret = 1;
 471 out:
 472         kfree(checksums);
 473         kfree(disk_crcs);
 474         iput(inode);
 475         return ret;
 476
 477 free_cache:
 478         /* This cache is bogus, make sure it gets cleared */
 479         spin_lock(&block_group->lock);
 480         block_group->disk_cache_state = BTRFS_DC_CLEAR;
 481         spin_unlock(&block_group->lock);
 482         btrfs_remove_free_space_cache(block_group);
 483         goto out;
 484 }
 485
 486 int btrfs_write_out_cache(struct btrfs_root *root,
 487                           struct btrfs_trans_handle *trans,
 488                           struct btrfs_block_group_cache *block_group,
 489                           struct btrfs_path *path)
 490 {
 491         struct btrfs_free_space_header *header;
 492         struct extent_buffer *leaf;
 493         struct inode *inode;
 494         struct rb_node *node;
 495         struct list_head *pos, *n;
 496         struct page *page;
 497         struct extent_state *cached_state = NULL;
 498         struct list_head bitmap_list;
 499         struct btrfs_key key;
 500         u64 bytes = 0;
 501         u32 *crc, *checksums;
 502         pgoff_t index = 0, last_index = 0;
 503         unsigned long first_page_offset;
 504         int num_checksums;
 505         int entries = 0;
 506         int bitmaps = 0;
 507         int ret = 0;
 508
 509         root = root->fs_info->tree_root;
 510
 511         INIT_LIST_HEAD(&bitmap_list);
 512
 513         spin_lock(&block_group->lock);
 514         if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
 515                 spin_unlock(&block_group->lock);
 516                 return 0;
 517         }
 518         spin_unlock(&block_group->lock);
 519
 520         inode = lookup_free_space_inode(root, block_group, path);
 521         if (IS_ERR(inode))
 522                 return 0;
 523
 524         if (!i_size_read(inode)) {
 525                 iput(inode);
 526                 return 0;
 527         }
 528
 529         node = rb_first(&block_group->free_space_offset);
 530         if (!node) {
 531                 iput(inode);
 532                 return 0;
 533         }
 534
 535         last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 536         filemap_write_and_wait(inode->i_mapping);
 537         btrfs_wait_ordered_range(inode, inode->i_size &
 538                                  ~(root->sectorsize - 1), (u64)-1);
 539
 540         /* We need a checksum per page. */
 541         num_checksums = i_size_read(inode) / PAGE_CACHE_SIZE;
 542         crc = checksums  = kzalloc(sizeof(u32) * num_checksums, GFP_NOFS);
 543         if (!crc) {
 544                 iput(inode);
 545                 return 0;
 546         }
 547
 548         /* Since the first page has all of our checksums and our generation we
 549          * need to calculate the offset into the page that we can start writing
 550          * our entries.
 551          */
 552         first_page_offset = (sizeof(u32) * num_checksums) + sizeof(u64);
 553
 554         /*
 555          * Lock all pages first so we can lock the extent safely.
 556          *
 557          * NOTE: Because we hold the ref the entire time we're going to write to
 558          * the page find_get_page should never fail, so we don't do a check
 559          * after find_get_page at this point.  Just putting this here so people
 560          * know and don't freak out.
 561          */
 562         while (index <= last_index) {
 563                 page = grab_cache_page(inode->i_mapping, index);
 564                 if (!page) {
 565                         pgoff_t i = 0;
 566
 567                         while (i < index) {
 568                                 page = find_get_page(inode->i_mapping, i);
 569                                 unlock_page(page);
 570                                 page_cache_release(page);
 571                                 page_cache_release(page);
 572                                 i++;
 573                         }
 574                         goto out_free;
 575                 }
 576                 index++;
 577         }
 578
 579         index = 0;
 580         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
 581                          0, &cached_state, GFP_NOFS);
 582
 583         /* Write out the extent entries */
 584         do {
 585                 struct btrfs_free_space_entry *entry;
 586                 void *addr;
 587                 unsigned long offset = 0;
 588                 unsigned long start_offset = 0;
 589
 590                 if (index == 0) {
 591                         start_offset = first_page_offset;
 592                         offset = start_offset;
 593                 }
 594
 595                 page = find_get_page(inode->i_mapping, index);
 596
 597                 addr = kmap(page);
 598                 entry = addr + start_offset;
 599
 600                 memset(addr, 0, PAGE_CACHE_SIZE);
 601                 while (1) {
 602                         struct btrfs_free_space *e;
 603
 604                         e = rb_entry(node, struct btrfs_free_space, offset_index);
 605                         entries++;
 606
 607                         entry->offset = cpu_to_le64(e->offset);
 608                         entry->bytes = cpu_to_le64(e->bytes);
 609                         if (e->bitmap) {
 610                                 entry->type = BTRFS_FREE_SPACE_BITMAP;
 611                                 list_add_tail(&e->list, &bitmap_list);
 612                                 bitmaps++;
 613                         } else {
 614                                 entry->type = BTRFS_FREE_SPACE_EXTENT;
 615                         }
 616                         node = rb_next(node);
 617                         if (!node)
 618                                 break;
 619                         offset += sizeof(struct btrfs_free_space_entry);
 620                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 621                             PAGE_CACHE_SIZE)
 622                                 break;
 623                         entry++;
 624                 }
 625                 *crc = ~(u32)0;
 626                 *crc = btrfs_csum_data(root, addr + start_offset, *crc,
 627                                        PAGE_CACHE_SIZE - start_offset);
 628                 kunmap(page);
 629
 630                 btrfs_csum_final(*crc, (char *)crc);
 631                 crc++;
 632
 633                 bytes += PAGE_CACHE_SIZE;
 634
 635                 ClearPageChecked(page);
 636                 set_page_extent_mapped(page);
 637                 SetPageUptodate(page);
 638                 set_page_dirty(page);
 639
 640                 /*
 641                  * We need to release our reference we got for grab_cache_page,
 642                  * except for the first page which will hold our checksums, we
 643                  * do that below.
 644                  */
 645                 if (index != 0) {
 646                         unlock_page(page);
 647                         page_cache_release(page);
 648                 }
 649
 650                 page_cache_release(page);
 651
 652                 index++;
 653         } while (node);
 654
 655         /* Write out the bitmaps */
 656         list_for_each_safe(pos, n, &bitmap_list) {
 657                 void *addr;
 658                 struct btrfs_free_space *entry =
 659                         list_entry(pos, struct btrfs_free_space, list);
 660
 661                 page = find_get_page(inode->i_mapping, index);
 662
 663                 addr = kmap(page);
 664                 memcpy(addr, entry->bitmap, PAGE_CACHE_SIZE);
 665                 *crc = ~(u32)0;
 666                 *crc = btrfs_csum_data(root, addr, *crc, PAGE_CACHE_SIZE);
 667                 kunmap(page);
 668                 btrfs_csum_final(*crc, (char *)crc);
 669                 crc++;
 670                 bytes += PAGE_CACHE_SIZE;
 671
 672                 ClearPageChecked(page);
 673                 set_page_extent_mapped(page);
 674                 SetPageUptodate(page);
 675                 set_page_dirty(page);
 676                 unlock_page(page);
 677                 page_cache_release(page);
 678                 page_cache_release(page);
 679                 list_del_init(&entry->list);
 680                 index++;
 681         }
 682
 683         /* Zero out the rest of the pages just to make sure */
 684         while (index <= last_index) {
 685                 void *addr;
 686
 687                 page = find_get_page(inode->i_mapping, index);
 688
 689                 addr = kmap(page);
 690                 memset(addr, 0, PAGE_CACHE_SIZE);
 691                 kunmap(page);
 692                 ClearPageChecked(page);
 693                 set_page_extent_mapped(page);
 694                 SetPageUptodate(page);
 695                 set_page_dirty(page);
 696                 unlock_page(page);
 697                 page_cache_release(page);
 698                 page_cache_release(page);
 699                 bytes += PAGE_CACHE_SIZE;
 700                 index++;
 701         }
 702
 703         btrfs_set_extent_delalloc(inode, 0, bytes - 1, &cached_state);
 704
 705         /* Write the checksums and trans id to the first page */
 706         {
 707                 void *addr;
 708                 u64 *gen;
 709
 710                 page = find_get_page(inode->i_mapping, 0);
 711
 712                 addr = kmap(page);
 713                 memcpy(addr, checksums, sizeof(u32) * num_checksums);
 714                 gen = addr + (sizeof(u32) * num_checksums);
 715                 *gen = trans->transid;
 716                 kunmap(page);
 717                 ClearPageChecked(page);
 718                 set_page_extent_mapped(page);
 719                 SetPageUptodate(page);
 720                 set_page_dirty(page);
 721                 unlock_page(page);
 722                 page_cache_release(page);
 723                 page_cache_release(page);
 724         }
 725         BTRFS_I(inode)->generation = trans->transid;
 726
 727         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 728                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
 729
 730         filemap_write_and_wait(inode->i_mapping);
 731
 732         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 733         key.offset = block_group->key.objectid;
 734         key.type = 0;
 735
 736         ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
 737         if (ret < 0) {
 738                 ret = 0;
 739                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 740                                  EXTENT_DIRTY | EXTENT_DELALLOC |
 741                                  EXTENT_DO_ACCOUNTING, 0, 0, NULL, GFP_NOFS);
 742                 goto out_free;
 743         }
 744         leaf = path->nodes[0];
 745         if (ret > 0) {
 746                 struct btrfs_key found_key;
 747                 BUG_ON(!path->slots[0]);
 748                 path->slots[0]--;
 749                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 750                 if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
 751                     found_key.offset != block_group->key.objectid) {
 752                         ret = 0;
 753                         clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 754                                          EXTENT_DIRTY | EXTENT_DELALLOC |
 755                                          EXTENT_DO_ACCOUNTING, 0, 0, NULL,
 756                                          GFP_NOFS);
 757                         btrfs_release_path(root, path);
 758                         goto out_free;
 759                 }
 760         }
 761         header = btrfs_item_ptr(leaf, path->slots[0],
 762                                 struct btrfs_free_space_header);
 763         btrfs_set_free_space_entries(leaf, header, entries);
 764         btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
 765         btrfs_set_free_space_generation(leaf, header, trans->transid);
 766         btrfs_mark_buffer_dirty(leaf);
 767         btrfs_release_path(root, path);
 768
 769         ret = 1;
 770
 771 out_free:
 772         if (ret == 0) {
 773                 invalidate_inode_pages2_range(inode->i_mapping, 0, index);
 774                 spin_lock(&block_group->lock);
 775                 block_group->disk_cache_state = BTRFS_DC_ERROR;
 776                 spin_unlock(&block_group->lock);
 777                 BTRFS_I(inode)->generation = 0;
 778         }
 779         kfree(checksums);
 780         btrfs_update_inode(trans, root, inode);
 781         iput(inode);
 782         return ret;
 783 }
 784
 785 static inline unsigned long offset_to_bit(u64 bitmap_start, u64 sectorsize,
 786                                           u64 offset)
 787 {
 788         BUG_ON(offset < bitmap_start);
 789         offset -= bitmap_start;
 790         return (unsigned long)(div64_u64(offset, sectorsize));
 791 }
 792
 793 static inline unsigned long bytes_to_bits(u64 bytes, u64 sectorsize)
 794 {
 795         return (unsigned long)(div64_u64(bytes, sectorsize));
 796 }
 797
 798 static inline u64 offset_to_bitmap(struct btrfs_block_group_cache *block_group,
 799                                    u64 offset)
 800 {
 801         u64 bitmap_start;
 802         u64 bytes_per_bitmap;
 803
 804         bytes_per_bitmap = BITS_PER_BITMAP * block_group->sectorsize;
 805         bitmap_start = offset - block_group->key.objectid;
 806         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
 807         bitmap_start *= bytes_per_bitmap;
 808         bitmap_start += block_group->key.objectid;
 809
 810         return bitmap_start;
 811 }
 812
 813 static int tree_insert_offset(struct rb_root *root, u64 offset,
 814                               struct rb_node *node, int bitmap)
 815 {
 816         struct rb_node **p = &root->rb_node;
 817         struct rb_node *parent = NULL;
 818         struct btrfs_free_space *info;
 819
 820         while (*p) {
 821                 parent = *p;
 822                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
 823
 824                 if (offset < info->offset) {
 825                         p = &(*p)->rb_left;
 826                 } else if (offset > info->offset) {
 827                         p = &(*p)->rb_right;
 828                 } else {
 829                         /*
 830                          * we could have a bitmap entry and an extent entry
 831                          * share the same offset.  If this is the case, we want
 832                          * the extent entry to always be found first if we do a
 833                          * linear search through the tree, since we want to have
 834                          * the quickest allocation time, and allocating from an
 835                          * extent is faster than allocating from a bitmap.  So
 836                          * if we're inserting a bitmap and we find an entry at
 837                          * this offset, we want to go right, or after this entry
 838                          * logically.  If we are inserting an extent and we've
 839                          * found a bitmap, we want to go left, or before
 840                          * logically.
 841                          */
 842                         if (bitmap) {
 843                                 WARN_ON(info->bitmap);
 844                                 p = &(*p)->rb_right;
 845                         } else {
 846                                 WARN_ON(!info->bitmap);
 847                                 p = &(*p)->rb_left;
 848                         }
 849                 }
 850         }
 851
 852         rb_link_node(node, parent, p);
 853         rb_insert_color(node, root);
 854
 855         return 0;
 856 }
 857
 858 /*
 859  * searches the tree for the given offset.
 860  *
 861  * fuzzy - If this is set, then we are trying to make an allocation, and we just
 862  * want a section that has at least bytes size and comes at or after the given
 863  * offset.
 864  */
 865 static struct btrfs_free_space *
 866 tree_search_offset(struct btrfs_block_group_cache *block_group,
 867                    u64 offset, int bitmap_only, int fuzzy)
 868 {
 869         struct rb_node *n = block_group->free_space_offset.rb_node;
 870         struct btrfs_free_space *entry, *prev = NULL;
 871
 872         /* find entry that is closest to the 'offset' */
 873         while (1) {
 874                 if (!n) {
 875                         entry = NULL;
 876                         break;
 877                 }
 878
 879                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
 880                 prev = entry;
 881
 882                 if (offset < entry->offset)
 883                         n = n->rb_left;
 884                 else if (offset > entry->offset)
 885                         n = n->rb_right;
 886                 else
 887                         break;
 888         }
 889
 890         if (bitmap_only) {
 891                 if (!entry)
 892                         return NULL;
 893                 if (entry->bitmap)
 894                         return entry;
 895
 896                 /*
 897                  * bitmap entry and extent entry may share same offset,
 898                  * in that case, bitmap entry comes after extent entry.
 899                  */
 900                 n = rb_next(n);
 901                 if (!n)
 902                         return NULL;
 903                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
 904                 if (entry->offset != offset)
 905                         return NULL;
 906
 907                 WARN_ON(!entry->bitmap);
 908                 return entry;
 909         } else if (entry) {
 910                 if (entry->bitmap) {
 911                         /*
 912                          * if previous extent entry covers the offset,
 913                          * we should return it instead of the bitmap entry
 914                          */
 915                         n = &entry->offset_index;
 916                         while (1) {
 917                                 n = rb_prev(n);
 918                                 if (!n)
 919                                         break;
 920                                 prev = rb_entry(n, struct btrfs_free_space,
 921                                                 offset_index);
 922                                 if (!prev->bitmap) {
 923                                         if (prev->offset + prev->bytes > offset)
 924                                                 entry = prev;
 925                                         break;
 926                                 }
 927                         }
 928                 }
 929                 return entry;
 930         }
 931
 932         if (!prev)
 933                 return NULL;
 934
 935         /* find last entry before the 'offset' */
 936         entry = prev;
 937         if (entry->offset > offset) {
 938                 n = rb_prev(&entry->offset_index);
 939                 if (n) {
 940                         entry = rb_entry(n, struct btrfs_free_space,
 941                                         offset_index);
 942                         BUG_ON(entry->offset > offset);
 943                 } else {
 944                         if (fuzzy)
 945                                 return entry;
 946                         else
 947                                 return NULL;
 948                 }
 949         }
 950
 951         if (entry->bitmap) {
 952                 n = &entry->offset_index;
 953                 while (1) {
 954                         n = rb_prev(n);
 955                         if (!n)
 956                                 break;
 957                         prev = rb_entry(n, struct btrfs_free_space,
 958                                         offset_index);
 959                         if (!prev->bitmap) {
 960                                 if (prev->offset + prev->bytes > offset)
 961                                         return prev;
 962                                 break;
 963                         }
 964                 }
 965                 if (entry->offset + BITS_PER_BITMAP *
 966                     block_group->sectorsize > offset)
 967                         return entry;
 968         } else if (entry->offset + entry->bytes > offset)
 969                 return entry;
 970
 971         if (!fuzzy)
 972                 return NULL;
 973
 974         while (1) {
 975                 if (entry->bitmap) {
 976                         if (entry->offset + BITS_PER_BITMAP *
 977                             block_group->sectorsize > offset)
 978                                 break;
 979                 } else {
 980                         if (entry->offset + entry->bytes > offset)
 981                                 break;
 982                 }
 983
 984                 n = rb_next(&entry->offset_index);
 985                 if (!n)
 986                         return NULL;
 987                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
 988         }
 989         return entry;
 990 }
 991
 992 static inline void
 993 __unlink_free_space(struct btrfs_block_group_cache *block_group,
 994                     struct btrfs_free_space *info)
 995 {
 996         rb_erase(&info->offset_index, &block_group->free_space_offset);
 997         block_group->free_extents--;
 998 }
 999
1000 static void unlink_free_space(struct btrfs_block_group_cache *block_group,
1001                               struct btrfs_free_space *info)
1002 {
1003         __unlink_free_space(block_group, info);
1004         block_group->free_space -= info->bytes;
1005 }
1006
1007 static int link_free_space(struct btrfs_block_group_cache *block_group,
1008                            struct btrfs_free_space *info)
1009 {
1010         int ret = 0;
1011
1012         BUG_ON(!info->bitmap && !info->bytes);
1013         ret = tree_insert_offset(&block_group->free_space_offset, info->offset,
1014                                  &info->offset_index, (info->bitmap != NULL));
1015         if (ret)
1016                 return ret;
1017
1018         block_group->free_space += info->bytes;
1019         block_group->free_extents++;
1020         return ret;
1021 }
1022
1023 static void recalculate_thresholds(struct btrfs_block_group_cache *block_group)
1024 {
1025         u64 max_bytes;
1026         u64 bitmap_bytes;
1027         u64 extent_bytes;
1028         u64 size = block_group->key.offset;
1029
1030         /*
1031          * The goal is to keep the total amount of memory used per 1gb of space
1032          * at or below 32k, so we need to adjust how much memory we allow to be
1033          * used by extent based free space tracking
1034          */
1035         if (size < 1024 * 1024 * 1024)
1036                 max_bytes = MAX_CACHE_BYTES_PER_GIG;
1037         else
1038                 max_bytes = MAX_CACHE_BYTES_PER_GIG *
1039                         div64_u64(size, 1024 * 1024 * 1024);
1040
1041         /*
1042          * we want to account for 1 more bitmap than what we have so we can make
1043          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1044          * we add more bitmaps.
1045          */
1046         bitmap_bytes = (block_group->total_bitmaps + 1) * PAGE_CACHE_SIZE;
1047
1048         if (bitmap_bytes >= max_bytes) {
1049                 block_group->extents_thresh = 0;
1050                 return;
1051         }
1052
1053         /*
1054          * we want the extent entry threshold to always be at most 1/2 the maxw
1055          * bytes we can have, or whatever is less than that.
1056          */
1057         extent_bytes = max_bytes - bitmap_bytes;
1058         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
1059
1060         block_group->extents_thresh =
1061                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
1062 }
1063
1064 static void bitmap_clear_bits(struct btrfs_block_group_cache *block_group,
1065                               struct btrfs_free_space *info, u64 offset,
1066                               u64 bytes)
1067 {
1068         unsigned long start, end;
1069         unsigned long i;
1070
1071         start = offset_to_bit(info->offset, block_group->sectorsize, offset);
1072         end = start + bytes_to_bits(bytes, block_group->sectorsize);
1073         BUG_ON(end > BITS_PER_BITMAP);
1074
1075         for (i = start; i < end; i++)
1076                 clear_bit(i, info->bitmap);
1077
1078         info->bytes -= bytes;
1079         block_group->free_space -= bytes;
1080 }
1081
1082 static void bitmap_set_bits(struct btrfs_block_group_cache *block_group,
1083                             struct btrfs_free_space *info, u64 offset,
1084                             u64 bytes)
1085 {
1086         unsigned long start, end;
1087         unsigned long i;
1088
1089         start = offset_to_bit(info->offset, block_group->sectorsize, offset);
1090         end = start + bytes_to_bits(bytes, block_group->sectorsize);
1091         BUG_ON(end > BITS_PER_BITMAP);
1092
1093         for (i = start; i < end; i++)
1094                 set_bit(i, info->bitmap);
1095
1096         info->bytes += bytes;
1097         block_group->free_space += bytes;
1098 }
1099
1100 static int search_bitmap(struct btrfs_block_group_cache *block_group,
1101                          struct btrfs_free_space *bitmap_info, u64 *offset,
1102                          u64 *bytes)
1103 {
1104         unsigned long found_bits = 0;
1105         unsigned long bits, i;
1106         unsigned long next_zero;
1107
1108         i = offset_to_bit(bitmap_info->offset, block_group->sectorsize,
1109                           max_t(u64, *offset, bitmap_info->offset));
1110         bits = bytes_to_bits(*bytes, block_group->sectorsize);
1111
1112         for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
1113              i < BITS_PER_BITMAP;
1114              i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
1115                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
1116                                                BITS_PER_BITMAP, i);
1117                 if ((next_zero - i) >= bits) {
1118                         found_bits = next_zero - i;
1119                         break;
1120                 }
1121                 i = next_zero;
1122         }
1123
1124         if (found_bits) {
1125                 *offset = (u64)(i * block_group->sectorsize) +
1126                         bitmap_info->offset;
1127                 *bytes = (u64)(found_bits) * block_group->sectorsize;
1128                 return 0;
1129         }
1130
1131         return -1;
1132 }
1133
1134 static struct btrfs_free_space *find_free_space(struct btrfs_block_group_cache
1135                                                 *block_group, u64 *offset,
1136                                                 u64 *bytes, int debug)
1137 {
1138         struct btrfs_free_space *entry;
1139         struct rb_node *node;
1140         int ret;
1141
1142         if (!block_group->free_space_offset.rb_node)
1143                 return NULL;
1144
1145         entry = tree_search_offset(block_group,
1146                                    offset_to_bitmap(block_group, *offset),
1147                                    0, 1);
1148         if (!entry)
1149                 return NULL;
1150
1151         for (node = &entry->offset_index; node; node = rb_next(node)) {
1152                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1153                 if (entry->bytes < *bytes)
1154                         continue;
1155
1156                 if (entry->bitmap) {
1157                         ret = search_bitmap(block_group, entry, offset, bytes);
1158                         if (!ret)
1159                                 return entry;
1160                         continue;
1161                 }
1162
1163                 *offset = entry->offset;
1164                 *bytes = entry->bytes;
1165                 return entry;
1166         }
1167
1168         return NULL;
1169 }
1170
1171 static void add_new_bitmap(struct btrfs_block_group_cache *block_group,
1172                            struct btrfs_free_space *info, u64 offset)
1173 {
1174         u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
1175         int max_bitmaps = (int)div64_u64(block_group->key.offset +
1176                                          bytes_per_bg - 1, bytes_per_bg);
1177         BUG_ON(block_group->total_bitmaps >= max_bitmaps);
1178
1179         info->offset = offset_to_bitmap(block_group, offset);
1180         info->bytes = 0;
1181         link_free_space(block_group, info);
1182         block_group->total_bitmaps++;
1183
1184         recalculate_thresholds(block_group);
1185 }
1186
1187 static void free_bitmap(struct btrfs_block_group_cache *block_group,
1188                         struct btrfs_free_space *bitmap_info)
1189 {
1190         unlink_free_space(block_group, bitmap_info);
1191         kfree(bitmap_info->bitmap);
1192         kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1193         block_group->total_bitmaps--;
1194         recalculate_thresholds(block_group);
1195 }
1196
1197 static noinline int remove_from_bitmap(struct btrfs_block_group_cache *block_group,
1198                               struct btrfs_free_space *bitmap_info,
1199                               u64 *offset, u64 *bytes)
1200 {
1201         u64 end;
1202         u64 search_start, search_bytes;
1203         int ret;
1204
1205 again:
1206         end = bitmap_info->offset +
1207                 (u64)(BITS_PER_BITMAP * block_group->sectorsize) - 1;
1208
1209         /*
1210          * XXX - this can go away after a few releases.
1211          *
1212          * since the only user of btrfs_remove_free_space is the tree logging
1213          * stuff, and the only way to test that is under crash conditions, we
1214          * want to have this debug stuff here just in case somethings not
1215          * working.  Search the bitmap for the space we are trying to use to
1216          * make sure its actually there.  If its not there then we need to stop
1217          * because something has gone wrong.
1218          */
1219         search_start = *offset;
1220         search_bytes = *bytes;
1221         search_bytes = min(search_bytes, end - search_start + 1);
1222         ret = search_bitmap(block_group, bitmap_info, &search_start,
1223                             &search_bytes);
1224         BUG_ON(ret < 0 || search_start != *offset);
1225
1226         if (*offset > bitmap_info->offset && *offset + *bytes > end) {
1227                 bitmap_clear_bits(block_group, bitmap_info, *offset,
1228                                   end - *offset + 1);
1229                 *bytes -= end - *offset + 1;
1230                 *offset = end + 1;
1231         } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
1232                 bitmap_clear_bits(block_group, bitmap_info, *offset, *bytes);
1233                 *bytes = 0;
1234         }
1235
1236         if (*bytes) {
1237                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
1238                 if (!bitmap_info->bytes)
1239                         free_bitmap(block_group, bitmap_info);
1240
1241                 /*
1242                  * no entry after this bitmap, but we still have bytes to
1243                  * remove, so something has gone wrong.
1244                  */
1245                 if (!next)
1246                         return -EINVAL;
1247
1248                 bitmap_info = rb_entry(next, struct btrfs_free_space,
1249                                        offset_index);
1250
1251                 /*
1252                  * if the next entry isn't a bitmap we need to return to let the
1253                  * extent stuff do its work.
1254                  */
1255                 if (!bitmap_info->bitmap)
1256                         return -EAGAIN;
1257
1258                 /*
1259                  * Ok the next item is a bitmap, but it may not actually hold
1260                  * the information for the rest of this free space stuff, so
1261                  * look for it, and if we don't find it return so we can try
1262                  * everything over again.
1263                  */
1264                 search_start = *offset;
1265                 search_bytes = *bytes;
1266                 ret = search_bitmap(block_group, bitmap_info, &search_start,
1267                                     &search_bytes);
1268                 if (ret < 0 || search_start != *offset)
1269                         return -EAGAIN;
1270
1271                 goto again;
1272         } else if (!bitmap_info->bytes)
1273                 free_bitmap(block_group, bitmap_info);
1274
1275         return 0;
1276 }
1277
1278 static int insert_into_bitmap(struct btrfs_block_group_cache *block_group,
1279                               struct btrfs_free_space *info)
1280 {
1281         struct btrfs_free_space *bitmap_info;
1282         int added = 0;
1283         u64 bytes, offset, end;
1284         int ret;
1285
1286         /*
1287          * If we are below the extents threshold then we can add this as an
1288          * extent, and don't have to deal with the bitmap
1289          */
1290         if (block_group->free_extents < block_group->extents_thresh &&
1291             info->bytes > block_group->sectorsize * 4)
1292                 return 0;
1293
1294         /*
1295          * some block groups are so tiny they can't be enveloped by a bitmap, so
1296          * don't even bother to create a bitmap for this
1297          */
1298         if (BITS_PER_BITMAP * block_group->sectorsize >
1299             block_group->key.offset)
1300                 return 0;
1301
1302         bytes = info->bytes;
1303         offset = info->offset;
1304
1305 again:
1306         bitmap_info = tree_search_offset(block_group,
1307                                          offset_to_bitmap(block_group, offset),
1308                                          1, 0);
1309         if (!bitmap_info) {
1310                 BUG_ON(added);
1311                 goto new_bitmap;
1312         }
1313
1314         end = bitmap_info->offset +
1315                 (u64)(BITS_PER_BITMAP * block_group->sectorsize);
1316
1317         if (offset >= bitmap_info->offset && offset + bytes > end) {
1318                 bitmap_set_bits(block_group, bitmap_info, offset,
1319                                 end - offset);
1320                 bytes -= end - offset;
1321                 offset = end;
1322                 added = 0;
1323         } else if (offset >= bitmap_info->offset && offset + bytes <= end) {
1324                 bitmap_set_bits(block_group, bitmap_info, offset, bytes);
1325                 bytes = 0;
1326         } else {
1327                 BUG();
1328         }
1329
1330         if (!bytes) {
1331                 ret = 1;
1332                 goto out;
1333         } else
1334                 goto again;
1335
1336 new_bitmap:
1337         if (info && info->bitmap) {
1338                 add_new_bitmap(block_group, info, offset);
1339                 added = 1;
1340                 info = NULL;
1341                 goto again;
1342         } else {
1343                 spin_unlock(&block_group->tree_lock);
1344
1345                 /* no pre-allocated info, allocate a new one */
1346                 if (!info) {
1347                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
1348                                                  GFP_NOFS);
1349                         if (!info) {
1350                                 spin_lock(&block_group->tree_lock);
1351                                 ret = -ENOMEM;
1352                                 goto out;
1353                         }
1354                 }
1355
1356                 /* allocate the bitmap */
1357                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
1358                 spin_lock(&block_group->tree_lock);
1359                 if (!info->bitmap) {
1360                         ret = -ENOMEM;
1361                         goto out;
1362                 }
1363                 goto again;
1364         }
1365
1366 out:
1367         if (info) {
1368                 if (info->bitmap)
1369                         kfree(info->bitmap);
1370                 kmem_cache_free(btrfs_free_space_cachep, info);
1371         }
1372
1373         return ret;
1374 }
1375
1376 bool try_merge_free_space(struct btrfs_block_group_cache *block_group,
1377                           struct btrfs_free_space *info, bool update_stat)
1378 {
1379         struct btrfs_free_space *left_info;
1380         struct btrfs_free_space *right_info;
1381         bool merged = false;
1382         u64 offset = info->offset;
1383         u64 bytes = info->bytes;
1384
1385         /*
1386          * first we want to see if there is free space adjacent to the range we
1387          * are adding, if there is remove that struct and add a new one to
1388          * cover the entire range
1389          */
1390         right_info = tree_search_offset(block_group, offset + bytes, 0, 0);
1391         if (right_info && rb_prev(&right_info->offset_index))
1392                 left_info = rb_entry(rb_prev(&right_info->offset_index),
1393                                      struct btrfs_free_space, offset_index);
1394         else
1395                 left_info = tree_search_offset(block_group, offset - 1, 0, 0);
1396
1397         if (right_info && !right_info->bitmap) {
1398                 if (update_stat)
1399                         unlink_free_space(block_group, right_info);
1400                 else
1401                         __unlink_free_space(block_group, right_info);
1402                 info->bytes += right_info->bytes;
1403                 kmem_cache_free(btrfs_free_space_cachep, right_info);
1404                 merged = true;
1405         }
1406
1407         if (left_info && !left_info->bitmap &&
1408             left_info->offset + left_info->bytes == offset) {
1409                 if (update_stat)
1410                         unlink_free_space(block_group, left_info);
1411                 else
1412                         __unlink_free_space(block_group, left_info);
1413                 info->offset = left_info->offset;
1414                 info->bytes += left_info->bytes;
1415                 kmem_cache_free(btrfs_free_space_cachep, left_info);
1416                 merged = true;
1417         }
1418
1419         return merged;
1420 }
1421
1422 int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
1423                          u64 offset, u64 bytes)
1424 {
1425         struct btrfs_free_space *info;
1426         int ret = 0;
1427
1428         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
1429         if (!info)
1430                 return -ENOMEM;
1431
1432         info->offset = offset;
1433         info->bytes = bytes;
1434
1435         spin_lock(&block_group->tree_lock);
1436
1437         if (try_merge_free_space(block_group, info, true))
1438                 goto link;
1439
1440         /*
1441          * There was no extent directly to the left or right of this new
1442          * extent then we know we're going to have to allocate a new extent, so
1443          * before we do that see if we need to drop this into a bitmap
1444          */
1445         ret = insert_into_bitmap(block_group, info);
1446         if (ret < 0) {
1447                 goto out;
1448         } else if (ret) {
1449                 ret = 0;
1450                 goto out;
1451         }
1452 link:
1453         ret = link_free_space(block_group, info);
1454         if (ret)
1455                 kmem_cache_free(btrfs_free_space_cachep, info);
1456 out:
1457         spin_unlock(&block_group->tree_lock);
1458
1459         if (ret) {
1460                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
1461                 BUG_ON(ret == -EEXIST);
1462         }
1463
1464         return ret;
1465 }
1466
1467 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
1468                             u64 offset, u64 bytes)
1469 {
1470         struct btrfs_free_space *info;
1471         struct btrfs_free_space *next_info = NULL;
1472         int ret = 0;
1473
1474         spin_lock(&block_group->tree_lock);
1475
1476 again:
1477         info = tree_search_offset(block_group, offset, 0, 0);
1478         if (!info) {
1479                 /*
1480                  * oops didn't find an extent that matched the space we wanted
1481                  * to remove, look for a bitmap instead
1482                  */
1483                 info = tree_search_offset(block_group,
1484                                           offset_to_bitmap(block_group, offset),
1485                                           1, 0);
1486                 if (!info) {
1487                         WARN_ON(1);
1488                         goto out_lock;
1489                 }
1490         }
1491
1492         if (info->bytes < bytes && rb_next(&info->offset_index)) {
1493                 u64 end;
1494                 next_info = rb_entry(rb_next(&info->offset_index),
1495                                              struct btrfs_free_space,
1496                                              offset_index);
1497
1498                 if (next_info->bitmap)
1499                         end = next_info->offset + BITS_PER_BITMAP *
1500                                 block_group->sectorsize - 1;
1501                 else
1502                         end = next_info->offset + next_info->bytes;
1503
1504                 if (next_info->bytes < bytes ||
1505                     next_info->offset > offset || offset > end) {
1506                         printk(KERN_CRIT "Found free space at %llu, size %llu,"
1507                               " trying to use %llu\n",
1508                               (unsigned long long)info->offset,
1509                               (unsigned long long)info->bytes,
1510                               (unsigned long long)bytes);
1511                         WARN_ON(1);
1512                         ret = -EINVAL;
1513                         goto out_lock;
1514                 }
1515
1516                 info = next_info;
1517         }
1518
1519         if (info->bytes == bytes) {
1520                 unlink_free_space(block_group, info);
1521                 if (info->bitmap) {
1522                         kfree(info->bitmap);
1523                         block_group->total_bitmaps--;
1524                 }
1525                 kmem_cache_free(btrfs_free_space_cachep, info);
1526                 goto out_lock;
1527         }
1528
1529         if (!info->bitmap && info->offset == offset) {
1530                 unlink_free_space(block_group, info);
1531                 info->offset += bytes;
1532                 info->bytes -= bytes;
1533                 link_free_space(block_group, info);
1534                 goto out_lock;
1535         }
1536
1537         if (!info->bitmap && info->offset <= offset &&
1538             info->offset + info->bytes >= offset + bytes) {
1539                 u64 old_start = info->offset;
1540                 /*
1541                  * we're freeing space in the middle of the info,
1542                  * this can happen during tree log replay
1543                  *
1544                  * first unlink the old info and then
1545                  * insert it again after the hole we're creating
1546                  */
1547                 unlink_free_space(block_group, info);
1548                 if (offset + bytes < info->offset + info->bytes) {
1549                         u64 old_end = info->offset + info->bytes;
1550
1551                         info->offset = offset + bytes;
1552                         info->bytes = old_end - info->offset;
1553                         ret = link_free_space(block_group, info);
1554                         WARN_ON(ret);
1555                         if (ret)
1556                                 goto out_lock;
1557                 } else {
1558                         /* the hole we're creating ends at the end
1559                          * of the info struct, just free the info
1560                          */
1561                         kmem_cache_free(btrfs_free_space_cachep, info);
1562                 }
1563                 spin_unlock(&block_group->tree_lock);
1564
1565                 /* step two, insert a new info struct to cover
1566                  * anything before the hole
1567                  */
1568                 ret = btrfs_add_free_space(block_group, old_start,
1569                                            offset - old_start);
1570                 WARN_ON(ret);
1571                 goto out;
1572         }
1573
1574         ret = remove_from_bitmap(block_group, info, &offset, &bytes);
1575         if (ret == -EAGAIN)
1576                 goto again;
1577         BUG_ON(ret);
1578 out_lock:
1579         spin_unlock(&block_group->tree_lock);
1580 out:
1581         return ret;
1582 }
1583
1584 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
1585                            u64 bytes)
1586 {
1587         struct btrfs_free_space *info;
1588         struct rb_node *n;
1589         int count = 0;
1590
1591         for (n = rb_first(&block_group->free_space_offset); n; n = rb_next(n)) {
1592                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1593                 if (info->bytes >= bytes)
1594                         count++;
1595                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
1596                        (unsigned long long)info->offset,
1597                        (unsigned long long)info->bytes,
1598                        (info->bitmap) ? "yes" : "no");
1599         }
1600         printk(KERN_INFO "block group has cluster?: %s\n",
1601                list_empty(&block_group->cluster_list) ? "no" : "yes");
1602         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
1603                "\n", count);
1604 }
1605
1606 u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group)
1607 {
1608         struct btrfs_free_space *info;
1609         struct rb_node *n;
1610         u64 ret = 0;
1611
1612         for (n = rb_first(&block_group->free_space_offset); n;
1613              n = rb_next(n)) {
1614                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1615                 ret += info->bytes;
1616         }
1617
1618         return ret;
1619 }
1620
1621 /*
1622  * for a given cluster, put all of its extents back into the free
1623  * space cache.  If the block group passed doesn't match the block group
1624  * pointed to by the cluster, someone else raced in and freed the
1625  * cluster already.  In that case, we just return without changing anything
1626  */
1627 static int
1628 __btrfs_return_cluster_to_free_space(
1629                              struct btrfs_block_group_cache *block_group,
1630                              struct btrfs_free_cluster *cluster)
1631 {
1632         struct btrfs_free_space *entry;
1633         struct rb_node *node;
1634         bool bitmap;
1635
1636         spin_lock(&cluster->lock);
1637         if (cluster->block_group != block_group)
1638                 goto out;
1639
1640         bitmap = cluster->points_to_bitmap;
1641         cluster->block_group = NULL;
1642         cluster->window_start = 0;
1643         list_del_init(&cluster->block_group_list);
1644         cluster->points_to_bitmap = false;
1645
1646         if (bitmap)
1647                 goto out;
1648
1649         node = rb_first(&cluster->root);
1650         while (node) {
1651                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1652                 node = rb_next(&entry->offset_index);
1653                 rb_erase(&entry->offset_index, &cluster->root);
1654                 BUG_ON(entry->bitmap);
1655                 try_merge_free_space(block_group, entry, false);
1656                 tree_insert_offset(&block_group->free_space_offset,
1657                                    entry->offset, &entry->offset_index, 0);
1658         }
1659         cluster->root = RB_ROOT;
1660
1661 out:
1662         spin_unlock(&cluster->lock);
1663         btrfs_put_block_group(block_group);
1664         return 0;
1665 }
1666
1667 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
1668 {
1669         struct btrfs_free_space *info;
1670         struct rb_node *node;
1671         struct btrfs_free_cluster *cluster;
1672         struct list_head *head;
1673
1674         spin_lock(&block_group->tree_lock);
1675         while ((head = block_group->cluster_list.next) !=
1676                &block_group->cluster_list) {
1677                 cluster = list_entry(head, struct btrfs_free_cluster,
1678                                      block_group_list);
1679
1680                 WARN_ON(cluster->block_group != block_group);
1681                 __btrfs_return_cluster_to_free_space(block_group, cluster);
1682                 if (need_resched()) {
1683                         spin_unlock(&block_group->tree_lock);
1684                         cond_resched();
1685                         spin_lock(&block_group->tree_lock);
1686                 }
1687         }
1688
1689         while ((node = rb_last(&block_group->free_space_offset)) != NULL) {
1690                 info = rb_entry(node, struct btrfs_free_space, offset_index);
1691                 unlink_free_space(block_group, info);
1692                 if (info->bitmap)
1693                         kfree(info->bitmap);
1694                 kmem_cache_free(btrfs_free_space_cachep, info);
1695                 if (need_resched()) {
1696                         spin_unlock(&block_group->tree_lock);
1697                         cond_resched();
1698                         spin_lock(&block_group->tree_lock);
1699                 }
1700         }
1701
1702         spin_unlock(&block_group->tree_lock);
1703 }
1704
1705 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
1706                                u64 offset, u64 bytes, u64 empty_size)
1707 {
1708         struct btrfs_free_space *entry = NULL;
1709         u64 bytes_search = bytes + empty_size;
1710         u64 ret = 0;
1711
1712         spin_lock(&block_group->tree_lock);
1713         entry = find_free_space(block_group, &offset, &bytes_search, 0);
1714         if (!entry)
1715                 goto out;
1716
1717         ret = offset;
1718         if (entry->bitmap) {
1719                 bitmap_clear_bits(block_group, entry, offset, bytes);
1720                 if (!entry->bytes)
1721                         free_bitmap(block_group, entry);
1722         } else {
1723                 unlink_free_space(block_group, entry);
1724                 entry->offset += bytes;
1725                 entry->bytes -= bytes;
1726                 if (!entry->bytes)
1727                         kmem_cache_free(btrfs_free_space_cachep, entry);
1728                 else
1729                         link_free_space(block_group, entry);
1730         }
1731
1732 out:
1733         spin_unlock(&block_group->tree_lock);
1734
1735         return ret;
1736 }
1737
1738 /*
1739  * given a cluster, put all of its extents back into the free space
1740  * cache.  If a block group is passed, this function will only free
1741  * a cluster that belongs to the passed block group.
1742  *
1743  * Otherwise, it'll get a reference on the block group pointed to by the
1744  * cluster and remove the cluster from it.
1745  */
1746 int btrfs_return_cluster_to_free_space(
1747                                struct btrfs_block_group_cache *block_group,
1748                                struct btrfs_free_cluster *cluster)
1749 {
1750         int ret;
1751
1752         /* first, get a safe pointer to the block group */
1753         spin_lock(&cluster->lock);
1754         if (!block_group) {
1755                 block_group = cluster->block_group;
1756                 if (!block_group) {
1757                         spin_unlock(&cluster->lock);
1758                         return 0;
1759                 }
1760         } else if (cluster->block_group != block_group) {
1761                 /* someone else has already freed it don't redo their work */
1762                 spin_unlock(&cluster->lock);
1763                 return 0;
1764         }
1765         atomic_inc(&block_group->count);
1766         spin_unlock(&cluster->lock);
1767
1768         /* now return any extents the cluster had on it */
1769         spin_lock(&block_group->tree_lock);
1770         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
1771         spin_unlock(&block_group->tree_lock);
1772
1773         /* finally drop our ref */
1774         btrfs_put_block_group(block_group);
1775         return ret;
1776 }
1777
1778 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
1779                                    struct btrfs_free_cluster *cluster,
1780                                    u64 bytes, u64 min_start)
1781 {
1782         struct btrfs_free_space *entry;
1783         int err;
1784         u64 search_start = cluster->window_start;
1785         u64 search_bytes = bytes;
1786         u64 ret = 0;
1787
1788         spin_lock(&block_group->tree_lock);
1789         spin_lock(&cluster->lock);
1790
1791         if (!cluster->points_to_bitmap)
1792                 goto out;
1793
1794         if (cluster->block_group != block_group)
1795                 goto out;
1796
1797         /*
1798          * search_start is the beginning of the bitmap, but at some point it may
1799          * be a good idea to point to the actual start of the free area in the
1800          * bitmap, so do the offset_to_bitmap trick anyway, and set bitmap_only
1801          * to 1 to make sure we get the bitmap entry
1802          */
1803         entry = tree_search_offset(block_group,
1804                                    offset_to_bitmap(block_group, search_start),
1805                                    1, 0);
1806         if (!entry || !entry->bitmap)
1807                 goto out;
1808
1809         search_start = min_start;
1810         search_bytes = bytes;
1811
1812         err = search_bitmap(block_group, entry, &search_start,
1813                             &search_bytes);
1814         if (err)
1815                 goto out;
1816
1817         ret = search_start;
1818         bitmap_clear_bits(block_group, entry, ret, bytes);
1819         if (entry->bytes == 0)
1820                 free_bitmap(block_group, entry);
1821 out:
1822         spin_unlock(&cluster->lock);
1823         spin_unlock(&block_group->tree_lock);
1824
1825         return ret;
1826 }
1827
1828 /*
1829  * given a cluster, try to allocate 'bytes' from it, returns 0
1830  * if it couldn't find anything suitably large, or a logical disk offset
1831  * if things worked out
1832  */
1833 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
1834                              struct btrfs_free_cluster *cluster, u64 bytes,
1835                              u64 min_start)
1836 {
1837         struct btrfs_free_space *entry = NULL;
1838         struct rb_node *node;
1839         u64 ret = 0;
1840
1841         if (cluster->points_to_bitmap)
1842                 return btrfs_alloc_from_bitmap(block_group, cluster, bytes,
1843                                                min_start);
1844
1845         spin_lock(&cluster->lock);
1846         if (bytes > cluster->max_size)
1847                 goto out;
1848
1849         if (cluster->block_group != block_group)
1850                 goto out;
1851
1852         node = rb_first(&cluster->root);
1853         if (!node)
1854                 goto out;
1855
1856         entry = rb_entry(node, struct btrfs_free_space, offset_index);
1857
1858         while(1) {
1859                 if (entry->bytes < bytes || entry->offset < min_start) {
1860                         struct rb_node *node;
1861
1862                         node = rb_next(&entry->offset_index);
1863                         if (!node)
1864                                 break;
1865                         entry = rb_entry(node, struct btrfs_free_space,
1866                                          offset_index);
1867                         continue;
1868                 }
1869                 ret = entry->offset;
1870
1871                 entry->offset += bytes;
1872                 entry->bytes -= bytes;
1873
1874                 if (entry->bytes == 0)
1875                         rb_erase(&entry->offset_index, &cluster->root);
1876                 break;
1877         }
1878 out:
1879         spin_unlock(&cluster->lock);
1880
1881         if (!ret)
1882                 return 0;
1883
1884         spin_lock(&block_group->tree_lock);
1885
1886         block_group->free_space -= bytes;
1887         if (entry->bytes == 0) {
1888                 block_group->free_extents--;
1889                 kmem_cache_free(btrfs_free_space_cachep, entry);
1890         }
1891
1892         spin_unlock(&block_group->tree_lock);
1893
1894         return ret;
1895 }
1896
1897 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
1898                                 struct btrfs_free_space *entry,
1899                                 struct btrfs_free_cluster *cluster,
1900                                 u64 offset, u64 bytes, u64 min_bytes)
1901 {
1902         unsigned long next_zero;
1903         unsigned long i;
1904         unsigned long search_bits;
1905         unsigned long total_bits;
1906         unsigned long found_bits;
1907         unsigned long start = 0;
1908         unsigned long total_found = 0;
1909         bool found = false;
1910
1911         i = offset_to_bit(entry->offset, block_group->sectorsize,
1912                           max_t(u64, offset, entry->offset));
1913         search_bits = bytes_to_bits(bytes, block_group->sectorsize);
1914         total_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
1915
1916 again:
1917         found_bits = 0;
1918         for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
1919              i < BITS_PER_BITMAP;
1920              i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
1921                 next_zero = find_next_zero_bit(entry->bitmap,
1922                                                BITS_PER_BITMAP, i);
1923                 if (next_zero - i >= search_bits) {
1924                         found_bits = next_zero - i;
1925                         break;
1926                 }
1927                 i = next_zero;
1928         }
1929
1930         if (!found_bits)
1931                 return -1;
1932
1933         if (!found) {
1934                 start = i;
1935                 found = true;
1936         }
1937
1938         total_found += found_bits;
1939
1940         if (cluster->max_size < found_bits * block_group->sectorsize)
1941                 cluster->max_size = found_bits * block_group->sectorsize;
1942
1943         if (total_found < total_bits) {
1944                 i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero);
1945                 if (i - start > total_bits * 2) {
1946                         total_found = 0;
1947                         cluster->max_size = 0;
1948                         found = false;
1949                 }
1950                 goto again;
1951         }
1952
1953         cluster->window_start = start * block_group->sectorsize +
1954                 entry->offset;
1955         cluster->points_to_bitmap = true;
1956
1957         return 0;
1958 }
1959
1960 /*
1961  * here we try to find a cluster of blocks in a block group.  The goal
1962  * is to find at least bytes free and up to empty_size + bytes free.
1963  * We might not find them all in one contiguous area.
1964  *
1965  * returns zero and sets up cluster if things worked out, otherwise
1966  * it returns -enospc
1967  */
1968 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
1969                              struct btrfs_root *root,
1970                              struct btrfs_block_group_cache *block_group,
1971                              struct btrfs_free_cluster *cluster,
1972                              u64 offset, u64 bytes, u64 empty_size)
1973 {
1974         struct btrfs_free_space *entry = NULL;
1975         struct rb_node *node;
1976         struct btrfs_free_space *next;
1977         struct btrfs_free_space *last = NULL;
1978         u64 min_bytes;
1979         u64 window_start;
1980         u64 window_free;
1981         u64 max_extent = 0;
1982         bool found_bitmap = false;
1983         int ret;
1984
1985         /* for metadata, allow allocates with more holes */
1986         if (btrfs_test_opt(root, SSD_SPREAD)) {
1987                 min_bytes = bytes + empty_size;
1988         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
1989                 /*
1990                  * we want to do larger allocations when we are
1991                  * flushing out the delayed refs, it helps prevent
1992                  * making more work as we go along.
1993                  */
1994                 if (trans->transaction->delayed_refs.flushing)
1995                         min_bytes = max(bytes, (bytes + empty_size) >> 1);
1996                 else
1997                         min_bytes = max(bytes, (bytes + empty_size) >> 4);
1998         } else
1999                 min_bytes = max(bytes, (bytes + empty_size) >> 2);
2000
2001         spin_lock(&block_group->tree_lock);
2002
2003         /*
2004          * If we know we don't have enough space to make a cluster don't even
2005          * bother doing all the work to try and find one.
2006          */
2007         if (block_group->free_space < min_bytes) {
2008                 spin_unlock(&block_group->tree_lock);
2009                 return -ENOSPC;
2010         }
2011
2012         spin_lock(&cluster->lock);
2013
2014         /* someone already found a cluster, hooray */
2015         if (cluster->block_group) {
2016                 ret = 0;
2017                 goto out;
2018         }
2019 again:
2020         entry = tree_search_offset(block_group, offset, found_bitmap, 1);
2021         if (!entry) {
2022                 ret = -ENOSPC;
2023                 goto out;
2024         }
2025
2026         /*
2027          * If found_bitmap is true, we exhausted our search for extent entries,
2028          * and we just want to search all of the bitmaps that we can find, and
2029          * ignore any extent entries we find.
2030          */
2031         while (entry->bitmap || found_bitmap ||
2032                (!entry->bitmap && entry->bytes < min_bytes)) {
2033                 struct rb_node *node = rb_next(&entry->offset_index);
2034
2035                 if (entry->bitmap && entry->bytes > bytes + empty_size) {
2036                         ret = btrfs_bitmap_cluster(block_group, entry, cluster,
2037                                                    offset, bytes, min_bytes);
2038                         if (!ret)
2039                                 goto got_it;
2040                 }
2041
2042                 if (!node) {
2043                         ret = -ENOSPC;
2044                         goto out;
2045                 }
2046                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2047         }
2048
2049         /*
2050          * We already searched all the extent entries from the passed in offset
2051          * to the end and didn't find enough space for the cluster, and we also
2052          * didn't find any bitmaps that met our criteria, just go ahead and exit
2053          */
2054         if (found_bitmap) {
2055                 ret = -ENOSPC;
2056                 goto out;
2057         }
2058
2059         cluster->points_to_bitmap = false;
2060         window_start = entry->offset;
2061         window_free = entry->bytes;
2062         last = entry;
2063         max_extent = entry->bytes;
2064
2065         while (1) {
2066                 /* out window is just right, lets fill it */
2067                 if (window_free >= min_bytes)
2068                         break;
2069
2070                 node = rb_next(&last->offset_index);
2071                 if (!node) {
2072                         if (found_bitmap)
2073                                 goto again;
2074                         ret = -ENOSPC;
2075                         goto out;
2076                 }
2077                 next = rb_entry(node, struct btrfs_free_space, offset_index);
2078
2079                 /*
2080                  * we found a bitmap, so if this search doesn't result in a
2081                  * cluster, we know to go and search again for the bitmaps and
2082                  * start looking for space there
2083                  */
2084                 if (next->bitmap) {
2085                         if (!found_bitmap)
2086                                 offset = next->offset;
2087                         found_bitmap = true;
2088                         last = next;
2089                         continue;
2090                 }
2091
2092                 /*
2093                  * we haven't filled the empty size and the window is
2094                  * very large.  reset and try again
2095                  */
2096                 if (next->offset - (last->offset + last->bytes) > 128 * 1024 ||
2097                     next->offset - window_start > (bytes + empty_size) * 2) {
2098                         entry = next;
2099                         window_start = entry->offset;
2100                         window_free = entry->bytes;
2101                         last = entry;
2102                         max_extent = entry->bytes;
2103                 } else {
2104                         last = next;
2105                         window_free += next->bytes;
2106                         if (entry->bytes > max_extent)
2107                                 max_extent = entry->bytes;
2108                 }
2109         }
2110
2111         cluster->window_start = entry->offset;
2112
2113         /*
2114          * now we've found our entries, pull them out of the free space
2115          * cache and put them into the cluster rbtree
2116          *
2117          * The cluster includes an rbtree, but only uses the offset index
2118          * of each free space cache entry.
2119          */
2120         while (1) {
2121                 node = rb_next(&entry->offset_index);
2122                 if (entry->bitmap && node) {
2123                         entry = rb_entry(node, struct btrfs_free_space,
2124                                          offset_index);
2125                         continue;
2126                 } else if (entry->bitmap && !node) {
2127                         break;
2128                 }
2129
2130                 rb_erase(&entry->offset_index, &block_group->free_space_offset);
2131                 ret = tree_insert_offset(&cluster->root, entry->offset,
2132                                          &entry->offset_index, 0);
2133                 BUG_ON(ret);
2134
2135                 if (!node || entry == last)
2136                         break;
2137
2138                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2139         }
2140
2141         cluster->max_size = max_extent;
2142 got_it:
2143         ret = 0;
2144         atomic_inc(&block_group->count);
2145         list_add_tail(&cluster->block_group_list, &block_group->cluster_list);
2146         cluster->block_group = block_group;
2147 out:
2148         spin_unlock(&cluster->lock);
2149         spin_unlock(&block_group->tree_lock);
2150
2151         return ret;
2152 }
2153
2154 /*
2155  * simple code to zero out a cluster
2156  */
2157 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
2158 {
2159         spin_lock_init(&cluster->lock);
2160         spin_lock_init(&cluster->refill_lock);
2161         cluster->root = RB_ROOT;
2162         cluster->max_size = 0;
2163         cluster->points_to_bitmap = false;
2164         INIT_LIST_HEAD(&cluster->block_group_list);
2165         cluster->block_group = NULL;
2166 }
2167