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                 /*
1292                  * If this block group has some small extents we don't want to
1293                  * use up all of our free slots in the cache with them, we want
1294                  * to reserve them to larger extents, however if we have plent
1295                  * of cache left then go ahead an dadd them, no sense in adding
1296                  * the overhead of a bitmap if we don't have to.
1297                  */
1298                 if (info->bytes <= block_group->sectorsize * 4) {
1299                         if (block_group->free_extents * 2 <=
1300                             block_group->extents_thresh)
1301                                 return 0;
1302                 } else {
1303                         return 0;
1304                 }
1305         }
1306
1307         /*
1308          * some block groups are so tiny they can't be enveloped by a bitmap, so
1309          * don't even bother to create a bitmap for this
1310          */
1311         if (BITS_PER_BITMAP * block_group->sectorsize >
1312             block_group->key.offset)
1313                 return 0;
1314
1315         bytes = info->bytes;
1316         offset = info->offset;
1317
1318 again:
1319         bitmap_info = tree_search_offset(block_group,
1320                                          offset_to_bitmap(block_group, offset),
1321                                          1, 0);
1322         if (!bitmap_info) {
1323                 BUG_ON(added);
1324                 goto new_bitmap;
1325         }
1326
1327         end = bitmap_info->offset +
1328                 (u64)(BITS_PER_BITMAP * block_group->sectorsize);
1329
1330         if (offset >= bitmap_info->offset && offset + bytes > end) {
1331                 bitmap_set_bits(block_group, bitmap_info, offset,
1332                                 end - offset);
1333                 bytes -= end - offset;
1334                 offset = end;
1335                 added = 0;
1336         } else if (offset >= bitmap_info->offset && offset + bytes <= end) {
1337                 bitmap_set_bits(block_group, bitmap_info, offset, bytes);
1338                 bytes = 0;
1339         } else {
1340                 BUG();
1341         }
1342
1343         if (!bytes) {
1344                 ret = 1;
1345                 goto out;
1346         } else
1347                 goto again;
1348
1349 new_bitmap:
1350         if (info && info->bitmap) {
1351                 add_new_bitmap(block_group, info, offset);
1352                 added = 1;
1353                 info = NULL;
1354                 goto again;
1355         } else {
1356                 spin_unlock(&block_group->tree_lock);
1357
1358                 /* no pre-allocated info, allocate a new one */
1359                 if (!info) {
1360                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
1361                                                  GFP_NOFS);
1362                         if (!info) {
1363                                 spin_lock(&block_group->tree_lock);
1364                                 ret = -ENOMEM;
1365                                 goto out;
1366                         }
1367                 }
1368
1369                 /* allocate the bitmap */
1370                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
1371                 spin_lock(&block_group->tree_lock);
1372                 if (!info->bitmap) {
1373                         ret = -ENOMEM;
1374                         goto out;
1375                 }
1376                 goto again;
1377         }
1378
1379 out:
1380         if (info) {
1381                 if (info->bitmap)
1382                         kfree(info->bitmap);
1383                 kmem_cache_free(btrfs_free_space_cachep, info);
1384         }
1385
1386         return ret;
1387 }
1388
1389 bool try_merge_free_space(struct btrfs_block_group_cache *block_group,
1390                           struct btrfs_free_space *info, bool update_stat)
1391 {
1392         struct btrfs_free_space *left_info;
1393         struct btrfs_free_space *right_info;
1394         bool merged = false;
1395         u64 offset = info->offset;
1396         u64 bytes = info->bytes;
1397
1398         /*
1399          * first we want to see if there is free space adjacent to the range we
1400          * are adding, if there is remove that struct and add a new one to
1401          * cover the entire range
1402          */
1403         right_info = tree_search_offset(block_group, offset + bytes, 0, 0);
1404         if (right_info && rb_prev(&right_info->offset_index))
1405                 left_info = rb_entry(rb_prev(&right_info->offset_index),
1406                                      struct btrfs_free_space, offset_index);
1407         else
1408                 left_info = tree_search_offset(block_group, offset - 1, 0, 0);
1409
1410         if (right_info && !right_info->bitmap) {
1411                 if (update_stat)
1412                         unlink_free_space(block_group, right_info);
1413                 else
1414                         __unlink_free_space(block_group, right_info);
1415                 info->bytes += right_info->bytes;
1416                 kmem_cache_free(btrfs_free_space_cachep, right_info);
1417                 merged = true;
1418         }
1419
1420         if (left_info && !left_info->bitmap &&
1421             left_info->offset + left_info->bytes == offset) {
1422                 if (update_stat)
1423                         unlink_free_space(block_group, left_info);
1424                 else
1425                         __unlink_free_space(block_group, left_info);
1426                 info->offset = left_info->offset;
1427                 info->bytes += left_info->bytes;
1428                 kmem_cache_free(btrfs_free_space_cachep, left_info);
1429                 merged = true;
1430         }
1431
1432         return merged;
1433 }
1434
1435 int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
1436                          u64 offset, u64 bytes)
1437 {
1438         struct btrfs_free_space *info;
1439         int ret = 0;
1440
1441         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
1442         if (!info)
1443                 return -ENOMEM;
1444
1445         info->offset = offset;
1446         info->bytes = bytes;
1447
1448         spin_lock(&block_group->tree_lock);
1449
1450         if (try_merge_free_space(block_group, info, true))
1451                 goto link;
1452
1453         /*
1454          * There was no extent directly to the left or right of this new
1455          * extent then we know we're going to have to allocate a new extent, so
1456          * before we do that see if we need to drop this into a bitmap
1457          */
1458         ret = insert_into_bitmap(block_group, info);
1459         if (ret < 0) {
1460                 goto out;
1461         } else if (ret) {
1462                 ret = 0;
1463                 goto out;
1464         }
1465 link:
1466         ret = link_free_space(block_group, info);
1467         if (ret)
1468                 kmem_cache_free(btrfs_free_space_cachep, info);
1469 out:
1470         spin_unlock(&block_group->tree_lock);
1471
1472         if (ret) {
1473                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
1474                 BUG_ON(ret == -EEXIST);
1475         }
1476
1477         return ret;
1478 }
1479
1480 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
1481                             u64 offset, u64 bytes)
1482 {
1483         struct btrfs_free_space *info;
1484         struct btrfs_free_space *next_info = NULL;
1485         int ret = 0;
1486
1487         spin_lock(&block_group->tree_lock);
1488
1489 again:
1490         info = tree_search_offset(block_group, offset, 0, 0);
1491         if (!info) {
1492                 /*
1493                  * oops didn't find an extent that matched the space we wanted
1494                  * to remove, look for a bitmap instead
1495                  */
1496                 info = tree_search_offset(block_group,
1497                                           offset_to_bitmap(block_group, offset),
1498                                           1, 0);
1499                 if (!info) {
1500                         WARN_ON(1);
1501                         goto out_lock;
1502                 }
1503         }
1504
1505         if (info->bytes < bytes && rb_next(&info->offset_index)) {
1506                 u64 end;
1507                 next_info = rb_entry(rb_next(&info->offset_index),
1508                                              struct btrfs_free_space,
1509                                              offset_index);
1510
1511                 if (next_info->bitmap)
1512                         end = next_info->offset + BITS_PER_BITMAP *
1513                                 block_group->sectorsize - 1;
1514                 else
1515                         end = next_info->offset + next_info->bytes;
1516
1517                 if (next_info->bytes < bytes ||
1518                     next_info->offset > offset || offset > end) {
1519                         printk(KERN_CRIT "Found free space at %llu, size %llu,"
1520                               " trying to use %llu\n",
1521                               (unsigned long long)info->offset,
1522                               (unsigned long long)info->bytes,
1523                               (unsigned long long)bytes);
1524                         WARN_ON(1);
1525                         ret = -EINVAL;
1526                         goto out_lock;
1527                 }
1528
1529                 info = next_info;
1530         }
1531
1532         if (info->bytes == bytes) {
1533                 unlink_free_space(block_group, info);
1534                 if (info->bitmap) {
1535                         kfree(info->bitmap);
1536                         block_group->total_bitmaps--;
1537                 }
1538                 kmem_cache_free(btrfs_free_space_cachep, info);
1539                 goto out_lock;
1540         }
1541
1542         if (!info->bitmap && info->offset == offset) {
1543                 unlink_free_space(block_group, info);
1544                 info->offset += bytes;
1545                 info->bytes -= bytes;
1546                 link_free_space(block_group, info);
1547                 goto out_lock;
1548         }
1549
1550         if (!info->bitmap && info->offset <= offset &&
1551             info->offset + info->bytes >= offset + bytes) {
1552                 u64 old_start = info->offset;
1553                 /*
1554                  * we're freeing space in the middle of the info,
1555                  * this can happen during tree log replay
1556                  *
1557                  * first unlink the old info and then
1558                  * insert it again after the hole we're creating
1559                  */
1560                 unlink_free_space(block_group, info);
1561                 if (offset + bytes < info->offset + info->bytes) {
1562                         u64 old_end = info->offset + info->bytes;
1563
1564                         info->offset = offset + bytes;
1565                         info->bytes = old_end - info->offset;
1566                         ret = link_free_space(block_group, info);
1567                         WARN_ON(ret);
1568                         if (ret)
1569                                 goto out_lock;
1570                 } else {
1571                         /* the hole we're creating ends at the end
1572                          * of the info struct, just free the info
1573                          */
1574                         kmem_cache_free(btrfs_free_space_cachep, info);
1575                 }
1576                 spin_unlock(&block_group->tree_lock);
1577
1578                 /* step two, insert a new info struct to cover
1579                  * anything before the hole
1580                  */
1581                 ret = btrfs_add_free_space(block_group, old_start,
1582                                            offset - old_start);
1583                 WARN_ON(ret);
1584                 goto out;
1585         }
1586
1587         ret = remove_from_bitmap(block_group, info, &offset, &bytes);
1588         if (ret == -EAGAIN)
1589                 goto again;
1590         BUG_ON(ret);
1591 out_lock:
1592         spin_unlock(&block_group->tree_lock);
1593 out:
1594         return ret;
1595 }
1596
1597 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
1598                            u64 bytes)
1599 {
1600         struct btrfs_free_space *info;
1601         struct rb_node *n;
1602         int count = 0;
1603
1604         for (n = rb_first(&block_group->free_space_offset); n; n = rb_next(n)) {
1605                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1606                 if (info->bytes >= bytes)
1607                         count++;
1608                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
1609                        (unsigned long long)info->offset,
1610                        (unsigned long long)info->bytes,
1611                        (info->bitmap) ? "yes" : "no");
1612         }
1613         printk(KERN_INFO "block group has cluster?: %s\n",
1614                list_empty(&block_group->cluster_list) ? "no" : "yes");
1615         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
1616                "\n", count);
1617 }
1618
1619 u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group)
1620 {
1621         struct btrfs_free_space *info;
1622         struct rb_node *n;
1623         u64 ret = 0;
1624
1625         for (n = rb_first(&block_group->free_space_offset); n;
1626              n = rb_next(n)) {
1627                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1628                 ret += info->bytes;
1629         }
1630
1631         return ret;
1632 }
1633
1634 /*
1635  * for a given cluster, put all of its extents back into the free
1636  * space cache.  If the block group passed doesn't match the block group
1637  * pointed to by the cluster, someone else raced in and freed the
1638  * cluster already.  In that case, we just return without changing anything
1639  */
1640 static int
1641 __btrfs_return_cluster_to_free_space(
1642                              struct btrfs_block_group_cache *block_group,
1643                              struct btrfs_free_cluster *cluster)
1644 {
1645         struct btrfs_free_space *entry;
1646         struct rb_node *node;
1647
1648         spin_lock(&cluster->lock);
1649         if (cluster->block_group != block_group)
1650                 goto out;
1651
1652         cluster->block_group = NULL;
1653         cluster->window_start = 0;
1654         list_del_init(&cluster->block_group_list);
1655
1656         node = rb_first(&cluster->root);
1657         while (node) {
1658                 bool bitmap;
1659
1660                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1661                 node = rb_next(&entry->offset_index);
1662                 rb_erase(&entry->offset_index, &cluster->root);
1663
1664                 bitmap = (entry->bitmap != NULL);
1665                 if (!bitmap)
1666                         try_merge_free_space(block_group, entry, false);
1667                 tree_insert_offset(&block_group->free_space_offset,
1668                                    entry->offset, &entry->offset_index, bitmap);
1669         }
1670         cluster->root = RB_ROOT;
1671
1672 out:
1673         spin_unlock(&cluster->lock);
1674         btrfs_put_block_group(block_group);
1675         return 0;
1676 }
1677
1678 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
1679 {
1680         struct btrfs_free_space *info;
1681         struct rb_node *node;
1682         struct btrfs_free_cluster *cluster;
1683         struct list_head *head;
1684
1685         spin_lock(&block_group->tree_lock);
1686         while ((head = block_group->cluster_list.next) !=
1687                &block_group->cluster_list) {
1688                 cluster = list_entry(head, struct btrfs_free_cluster,
1689                                      block_group_list);
1690
1691                 WARN_ON(cluster->block_group != block_group);
1692                 __btrfs_return_cluster_to_free_space(block_group, cluster);
1693                 if (need_resched()) {
1694                         spin_unlock(&block_group->tree_lock);
1695                         cond_resched();
1696                         spin_lock(&block_group->tree_lock);
1697                 }
1698         }
1699
1700         while ((node = rb_last(&block_group->free_space_offset)) != NULL) {
1701                 info = rb_entry(node, struct btrfs_free_space, offset_index);
1702                 unlink_free_space(block_group, info);
1703                 if (info->bitmap)
1704                         kfree(info->bitmap);
1705                 kmem_cache_free(btrfs_free_space_cachep, info);
1706                 if (need_resched()) {
1707                         spin_unlock(&block_group->tree_lock);
1708                         cond_resched();
1709                         spin_lock(&block_group->tree_lock);
1710                 }
1711         }
1712
1713         spin_unlock(&block_group->tree_lock);
1714 }
1715
1716 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
1717                                u64 offset, u64 bytes, u64 empty_size)
1718 {
1719         struct btrfs_free_space *entry = NULL;
1720         u64 bytes_search = bytes + empty_size;
1721         u64 ret = 0;
1722
1723         spin_lock(&block_group->tree_lock);
1724         entry = find_free_space(block_group, &offset, &bytes_search, 0);
1725         if (!entry)
1726                 goto out;
1727
1728         ret = offset;
1729         if (entry->bitmap) {
1730                 bitmap_clear_bits(block_group, entry, offset, bytes);
1731                 if (!entry->bytes)
1732                         free_bitmap(block_group, entry);
1733         } else {
1734                 unlink_free_space(block_group, entry);
1735                 entry->offset += bytes;
1736                 entry->bytes -= bytes;
1737                 if (!entry->bytes)
1738                         kmem_cache_free(btrfs_free_space_cachep, entry);
1739                 else
1740                         link_free_space(block_group, entry);
1741         }
1742
1743 out:
1744         spin_unlock(&block_group->tree_lock);
1745
1746         return ret;
1747 }
1748
1749 /*
1750  * given a cluster, put all of its extents back into the free space
1751  * cache.  If a block group is passed, this function will only free
1752  * a cluster that belongs to the passed block group.
1753  *
1754  * Otherwise, it'll get a reference on the block group pointed to by the
1755  * cluster and remove the cluster from it.
1756  */
1757 int btrfs_return_cluster_to_free_space(
1758                                struct btrfs_block_group_cache *block_group,
1759                                struct btrfs_free_cluster *cluster)
1760 {
1761         int ret;
1762
1763         /* first, get a safe pointer to the block group */
1764         spin_lock(&cluster->lock);
1765         if (!block_group) {
1766                 block_group = cluster->block_group;
1767                 if (!block_group) {
1768                         spin_unlock(&cluster->lock);
1769                         return 0;
1770                 }
1771         } else if (cluster->block_group != block_group) {
1772                 /* someone else has already freed it don't redo their work */
1773                 spin_unlock(&cluster->lock);
1774                 return 0;
1775         }
1776         atomic_inc(&block_group->count);
1777         spin_unlock(&cluster->lock);
1778
1779         /* now return any extents the cluster had on it */
1780         spin_lock(&block_group->tree_lock);
1781         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
1782         spin_unlock(&block_group->tree_lock);
1783
1784         /* finally drop our ref */
1785         btrfs_put_block_group(block_group);
1786         return ret;
1787 }
1788
1789 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
1790                                    struct btrfs_free_cluster *cluster,
1791                                    struct btrfs_free_space *entry,
1792                                    u64 bytes, u64 min_start)
1793 {
1794         int err;
1795         u64 search_start = cluster->window_start;
1796         u64 search_bytes = bytes;
1797         u64 ret = 0;
1798
1799         search_start = min_start;
1800         search_bytes = bytes;
1801
1802         err = search_bitmap(block_group, entry, &search_start,
1803                             &search_bytes);
1804         if (err)
1805                 return 0;
1806
1807         ret = search_start;
1808         bitmap_clear_bits(block_group, entry, ret, bytes);
1809
1810         return ret;
1811 }
1812
1813 /*
1814  * given a cluster, try to allocate 'bytes' from it, returns 0
1815  * if it couldn't find anything suitably large, or a logical disk offset
1816  * if things worked out
1817  */
1818 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
1819                              struct btrfs_free_cluster *cluster, u64 bytes,
1820                              u64 min_start)
1821 {
1822         struct btrfs_free_space *entry = NULL;
1823         struct rb_node *node;
1824         u64 ret = 0;
1825
1826         spin_lock(&cluster->lock);
1827         if (bytes > cluster->max_size)
1828                 goto out;
1829
1830         if (cluster->block_group != block_group)
1831                 goto out;
1832
1833         node = rb_first(&cluster->root);
1834         if (!node)
1835                 goto out;
1836
1837         entry = rb_entry(node, struct btrfs_free_space, offset_index);
1838         while(1) {
1839                 if (entry->bytes < bytes ||
1840                     (!entry->bitmap && entry->offset < min_start)) {
1841                         struct rb_node *node;
1842
1843                         node = rb_next(&entry->offset_index);
1844                         if (!node)
1845                                 break;
1846                         entry = rb_entry(node, struct btrfs_free_space,
1847                                          offset_index);
1848                         continue;
1849                 }
1850
1851                 if (entry->bitmap) {
1852                         ret = btrfs_alloc_from_bitmap(block_group,
1853                                                       cluster, entry, bytes,
1854                                                       min_start);
1855                         if (ret == 0) {
1856                                 struct rb_node *node;
1857                                 node = rb_next(&entry->offset_index);
1858                                 if (!node)
1859                                         break;
1860                                 entry = rb_entry(node, struct btrfs_free_space,
1861                                                  offset_index);
1862                                 continue;
1863                         }
1864                 } else {
1865
1866                         ret = entry->offset;
1867
1868                         entry->offset += bytes;
1869                         entry->bytes -= bytes;
1870                 }
1871
1872                 if (entry->bytes == 0)
1873                         rb_erase(&entry->offset_index, &cluster->root);
1874                 break;
1875         }
1876 out:
1877         spin_unlock(&cluster->lock);
1878
1879         if (!ret)
1880                 return 0;
1881
1882         spin_lock(&block_group->tree_lock);
1883
1884         block_group->free_space -= bytes;
1885         if (entry->bytes == 0) {
1886                 block_group->free_extents--;
1887                 if (entry->bitmap) {
1888                         kfree(entry->bitmap);
1889                         block_group->total_bitmaps--;
1890                         recalculate_thresholds(block_group);
1891                 }
1892                 kmem_cache_free(btrfs_free_space_cachep, entry);
1893         }
1894
1895         spin_unlock(&block_group->tree_lock);
1896
1897         return ret;
1898 }
1899
1900 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
1901                                 struct btrfs_free_space *entry,
1902                                 struct btrfs_free_cluster *cluster,
1903                                 u64 offset, u64 bytes, u64 min_bytes)
1904 {
1905         unsigned long next_zero;
1906         unsigned long i;
1907         unsigned long search_bits;
1908         unsigned long total_bits;
1909         unsigned long found_bits;
1910         unsigned long start = 0;
1911         unsigned long total_found = 0;
1912         int ret;
1913         bool found = false;
1914
1915         i = offset_to_bit(entry->offset, block_group->sectorsize,
1916                           max_t(u64, offset, entry->offset));
1917         search_bits = bytes_to_bits(bytes, block_group->sectorsize);
1918         total_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
1919
1920 again:
1921         found_bits = 0;
1922         for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
1923              i < BITS_PER_BITMAP;
1924              i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
1925                 next_zero = find_next_zero_bit(entry->bitmap,
1926                                                BITS_PER_BITMAP, i);
1927                 if (next_zero - i >= search_bits) {
1928                         found_bits = next_zero - i;
1929                         break;
1930                 }
1931                 i = next_zero;
1932         }
1933
1934         if (!found_bits)
1935                 return -ENOSPC;
1936
1937         if (!found) {
1938                 start = i;
1939                 found = true;
1940         }
1941
1942         total_found += found_bits;
1943
1944         if (cluster->max_size < found_bits * block_group->sectorsize)
1945                 cluster->max_size = found_bits * block_group->sectorsize;
1946
1947         if (total_found < total_bits) {
1948                 i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero);
1949                 if (i - start > total_bits * 2) {
1950                         total_found = 0;
1951                         cluster->max_size = 0;
1952                         found = false;
1953                 }
1954                 goto again;
1955         }
1956
1957         cluster->window_start = start * block_group->sectorsize +
1958                 entry->offset;
1959         rb_erase(&entry->offset_index, &block_group->free_space_offset);
1960         ret = tree_insert_offset(&cluster->root, entry->offset,
1961                                  &entry->offset_index, 1);
1962         BUG_ON(ret);
1963
1964         return 0;
1965 }
1966
1967 /*
1968  * This searches the block group for just extents to fill the cluster with.
1969  */
1970 static int setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
1971                                    struct btrfs_free_cluster *cluster,
1972                                    u64 offset, u64 bytes, u64 min_bytes)
1973 {
1974         struct btrfs_free_space *first = NULL;
1975         struct btrfs_free_space *entry = NULL;
1976         struct btrfs_free_space *prev = NULL;
1977         struct btrfs_free_space *last;
1978         struct rb_node *node;
1979         u64 window_start;
1980         u64 window_free;
1981         u64 max_extent;
1982         u64 max_gap = 128 * 1024;
1983
1984         entry = tree_search_offset(block_group, offset, 0, 1);
1985         if (!entry)
1986                 return -ENOSPC;
1987
1988         /*
1989          * We don't want bitmaps, so just move along until we find a normal
1990          * extent entry.
1991          */
1992         while (entry->bitmap) {
1993                 node = rb_next(&entry->offset_index);
1994                 if (!node)
1995                         return -ENOSPC;
1996                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1997         }
1998
1999         window_start = entry->offset;
2000         window_free = entry->bytes;
2001         max_extent = entry->bytes;
2002         first = entry;
2003         last = entry;
2004         prev = entry;
2005
2006         while (window_free <= min_bytes) {
2007                 node = rb_next(&entry->offset_index);
2008                 if (!node)
2009                         return -ENOSPC;
2010                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2011
2012                 if (entry->bitmap)
2013                         continue;
2014                 /*
2015                  * we haven't filled the empty size and the window is
2016                  * very large.  reset and try again
2017                  */
2018                 if (entry->offset - (prev->offset + prev->bytes) > max_gap ||
2019                     entry->offset - window_start > (min_bytes * 2)) {
2020                         first = entry;
2021                         window_start = entry->offset;
2022                         window_free = entry->bytes;
2023                         last = entry;
2024                         max_extent = entry->bytes;
2025                 } else {
2026                         last = entry;
2027                         window_free += entry->bytes;
2028                         if (entry->bytes > max_extent)
2029                                 max_extent = entry->bytes;
2030                 }
2031                 prev = entry;
2032         }
2033
2034         cluster->window_start = first->offset;
2035
2036         node = &first->offset_index;
2037
2038         /*
2039          * now we've found our entries, pull them out of the free space
2040          * cache and put them into the cluster rbtree
2041          */
2042         do {
2043                 int ret;
2044
2045                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2046                 node = rb_next(&entry->offset_index);
2047                 if (entry->bitmap)
2048                         continue;
2049
2050                 rb_erase(&entry->offset_index, &block_group->free_space_offset);
2051                 ret = tree_insert_offset(&cluster->root, entry->offset,
2052                                          &entry->offset_index, 0);
2053                 BUG_ON(ret);
2054         } while (node && entry != last);
2055
2056         cluster->max_size = max_extent;
2057
2058         return 0;
2059 }
2060
2061 /*
2062  * This specifically looks for bitmaps that may work in the cluster, we assume
2063  * that we have already failed to find extents that will work.
2064  */
2065 static int setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2066                                 struct btrfs_free_cluster *cluster,
2067                                 u64 offset, u64 bytes, u64 min_bytes)
2068 {
2069         struct btrfs_free_space *entry;
2070         struct rb_node *node;
2071         int ret = -ENOSPC;
2072
2073         if (block_group->total_bitmaps == 0)
2074                 return -ENOSPC;
2075
2076         entry = tree_search_offset(block_group,
2077                                    offset_to_bitmap(block_group, offset),
2078                                    0, 1);
2079         if (!entry)
2080                 return -ENOSPC;
2081
2082         node = &entry->offset_index;
2083         do {
2084                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2085                 node = rb_next(&entry->offset_index);
2086                 if (!entry->bitmap)
2087                         continue;
2088                 if (entry->bytes < min_bytes)
2089                         continue;
2090                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2091                                            bytes, min_bytes);
2092         } while (ret && node);
2093
2094         return ret;
2095 }
2096
2097 /*
2098  * here we try to find a cluster of blocks in a block group.  The goal
2099  * is to find at least bytes free and up to empty_size + bytes free.
2100  * We might not find them all in one contiguous area.
2101  *
2102  * returns zero and sets up cluster if things worked out, otherwise
2103  * it returns -enospc
2104  */
2105 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
2106                              struct btrfs_root *root,
2107                              struct btrfs_block_group_cache *block_group,
2108                              struct btrfs_free_cluster *cluster,
2109                              u64 offset, u64 bytes, u64 empty_size)
2110 {
2111         u64 min_bytes;
2112         int ret;
2113
2114         /* for metadata, allow allocates with more holes */
2115         if (btrfs_test_opt(root, SSD_SPREAD)) {
2116                 min_bytes = bytes + empty_size;
2117         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
2118                 /*
2119                  * we want to do larger allocations when we are
2120                  * flushing out the delayed refs, it helps prevent
2121                  * making more work as we go along.
2122                  */
2123                 if (trans->transaction->delayed_refs.flushing)
2124                         min_bytes = max(bytes, (bytes + empty_size) >> 1);
2125                 else
2126                         min_bytes = max(bytes, (bytes + empty_size) >> 4);
2127         } else
2128                 min_bytes = max(bytes, (bytes + empty_size) >> 2);
2129
2130         spin_lock(&block_group->tree_lock);
2131
2132         /*
2133          * If we know we don't have enough space to make a cluster don't even
2134          * bother doing all the work to try and find one.
2135          */
2136         if (block_group->free_space < min_bytes) {
2137                 spin_unlock(&block_group->tree_lock);
2138                 return -ENOSPC;
2139         }
2140
2141         spin_lock(&cluster->lock);
2142
2143         /* someone already found a cluster, hooray */
2144         if (cluster->block_group) {
2145                 ret = 0;
2146                 goto out;
2147         }
2148
2149         ret = setup_cluster_no_bitmap(block_group, cluster, offset, bytes,
2150                                       min_bytes);
2151         if (ret)
2152                 ret = setup_cluster_bitmap(block_group, cluster, offset,
2153                                            bytes, min_bytes);
2154
2155         if (!ret) {
2156                 atomic_inc(&block_group->count);
2157                 list_add_tail(&cluster->block_group_list,
2158                               &block_group->cluster_list);
2159                 cluster->block_group = block_group;
2160         }
2161 out:
2162         spin_unlock(&cluster->lock);
2163         spin_unlock(&block_group->tree_lock);
2164
2165         return ret;
2166 }
2167
2168 /*
2169  * simple code to zero out a cluster
2170  */
2171 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
2172 {
2173         spin_lock_init(&cluster->lock);
2174         spin_lock_init(&cluster->refill_lock);
2175         cluster->root = RB_ROOT;
2176         cluster->max_size = 0;
2177         INIT_LIST_HEAD(&cluster->block_group_list);
2178         cluster->block_group = NULL;
2179 }
2180
2181 int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
2182                            u64 *trimmed, u64 start, u64 end, u64 minlen)
2183 {
2184         struct btrfs_free_space *entry = NULL;
2185         struct btrfs_fs_info *fs_info = block_group->fs_info;
2186         u64 bytes = 0;
2187         u64 actually_trimmed;
2188         int ret = 0;
2189
2190         *trimmed = 0;
2191
2192         while (start < end) {
2193                 spin_lock(&block_group->tree_lock);
2194
2195                 if (block_group->free_space < minlen) {
2196                         spin_unlock(&block_group->tree_lock);
2197                         break;
2198                 }
2199
2200                 entry = tree_search_offset(block_group, start, 0, 1);
2201                 if (!entry)
2202                         entry = tree_search_offset(block_group,
2203                                                    offset_to_bitmap(block_group,
2204                                                                     start),
2205                                                    1, 1);
2206
2207                 if (!entry || entry->offset >= end) {
2208                         spin_unlock(&block_group->tree_lock);
2209                         break;
2210                 }
2211
2212                 if (entry->bitmap) {
2213                         ret = search_bitmap(block_group, entry, &start, &bytes);
2214                         if (!ret) {
2215                                 if (start >= end) {
2216                                         spin_unlock(&block_group->tree_lock);
2217                                         break;
2218                                 }
2219                                 bytes = min(bytes, end - start);
2220                                 bitmap_clear_bits(block_group, entry,
2221                                                   start, bytes);
2222                                 if (entry->bytes == 0)
2223                                         free_bitmap(block_group, entry);
2224                         } else {
2225                                 start = entry->offset + BITS_PER_BITMAP *
2226                                         block_group->sectorsize;
2227                                 spin_unlock(&block_group->tree_lock);
2228                                 ret = 0;
2229                                 continue;
2230                         }
2231                 } else {
2232                         start = entry->offset;
2233                         bytes = min(entry->bytes, end - start);
2234                         unlink_free_space(block_group, entry);
2235                         kfree(entry);
2236                 }
2237
2238                 spin_unlock(&block_group->tree_lock);
2239
2240                 if (bytes >= minlen) {
2241                         int update_ret;
2242                         update_ret = btrfs_update_reserved_bytes(block_group,
2243                                                                  bytes, 1, 1);
2244
2245                         ret = btrfs_error_discard_extent(fs_info->extent_root,
2246                                                          start,
2247                                                          bytes,
2248                                                          &actually_trimmed);
2249
2250                         btrfs_add_free_space(block_group,
2251                                              start, bytes);
2252                         if (!update_ret)
2253                                 btrfs_update_reserved_bytes(block_group,
2254                                                             bytes, 0, 1);
2255
2256                         if (ret)
2257                                 break;
2258                         *trimmed += actually_trimmed;
2259                 }
2260                 start += bytes;
2261                 bytes = 0;
2262
2263                 if (fatal_signal_pending(current)) {
2264                         ret = -ERESTARTSYS;
2265                         break;
2266                 }
2267
2268                 cond_resched();
2269         }
2270
2271         return ret;
2272 }