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 #include "extent_io.h"
  28 #include "inode-map.h"
  29
  30 #define BITS_PER_BITMAP         (PAGE_CACHE_SIZE * 8)
  31 #define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
  32
  33 static int link_free_space(struct btrfs_free_space_ctl *ctl,
  34                            struct btrfs_free_space *info);
  35
  36 static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
  37                                                struct btrfs_path *path,
  38                                                u64 offset)
  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         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
  49         key.offset = offset;
  50         key.type = 0;
  51
  52         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  53         if (ret < 0)
  54                 return ERR_PTR(ret);
  55         if (ret > 0) {
  56                 btrfs_release_path(path);
  57                 return ERR_PTR(-ENOENT);
  58         }
  59
  60         leaf = path->nodes[0];
  61         header = btrfs_item_ptr(leaf, path->slots[0],
  62                                 struct btrfs_free_space_header);
  63         btrfs_free_space_key(leaf, header, &disk_key);
  64         btrfs_disk_key_to_cpu(&location, &disk_key);
  65         btrfs_release_path(path);
  66
  67         inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
  68         if (!inode)
  69                 return ERR_PTR(-ENOENT);
  70         if (IS_ERR(inode))
  71                 return inode;
  72         if (is_bad_inode(inode)) {
  73                 iput(inode);
  74                 return ERR_PTR(-ENOENT);
  75         }
  76
  77         inode->i_mapping->flags &= ~__GFP_FS;
  78
  79         return inode;
  80 }
  81
  82 struct inode *lookup_free_space_inode(struct btrfs_root *root,
  83                                       struct btrfs_block_group_cache
  84                                       *block_group, struct btrfs_path *path)
  85 {
  86         struct inode *inode = NULL;
  87
  88         spin_lock(&block_group->lock);
  89         if (block_group->inode)
  90                 inode = igrab(block_group->inode);
  91         spin_unlock(&block_group->lock);
  92         if (inode)
  93                 return inode;
  94
  95         inode = __lookup_free_space_inode(root, path,
  96                                           block_group->key.objectid);
  97         if (IS_ERR(inode))
  98                 return inode;
  99
 100         spin_lock(&block_group->lock);
 101         if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) {
 102                 printk(KERN_INFO "Old style space inode found, converting.\n");
 103                 BTRFS_I(inode)->flags &= ~BTRFS_INODE_NODATASUM;
 104                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 105         }
 106
 107         if (!btrfs_fs_closing(root->fs_info)) {
 108                 block_group->inode = igrab(inode);
 109                 block_group->iref = 1;
 110         }
 111         spin_unlock(&block_group->lock);
 112
 113         return inode;
 114 }
 115
 116 int __create_free_space_inode(struct btrfs_root *root,
 117                               struct btrfs_trans_handle *trans,
 118                               struct btrfs_path *path, u64 ino, u64 offset)
 119 {
 120         struct btrfs_key key;
 121         struct btrfs_disk_key disk_key;
 122         struct btrfs_free_space_header *header;
 123         struct btrfs_inode_item *inode_item;
 124         struct extent_buffer *leaf;
 125         int ret;
 126
 127         ret = btrfs_insert_empty_inode(trans, root, path, ino);
 128         if (ret)
 129                 return ret;
 130
 131         leaf = path->nodes[0];
 132         inode_item = btrfs_item_ptr(leaf, path->slots[0],
 133                                     struct btrfs_inode_item);
 134         btrfs_item_key(leaf, &disk_key, path->slots[0]);
 135         memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
 136                              sizeof(*inode_item));
 137         btrfs_set_inode_generation(leaf, inode_item, trans->transid);
 138         btrfs_set_inode_size(leaf, inode_item, 0);
 139         btrfs_set_inode_nbytes(leaf, inode_item, 0);
 140         btrfs_set_inode_uid(leaf, inode_item, 0);
 141         btrfs_set_inode_gid(leaf, inode_item, 0);
 142         btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
 143         btrfs_set_inode_flags(leaf, inode_item, BTRFS_INODE_NOCOMPRESS |
 144                               BTRFS_INODE_PREALLOC);
 145         btrfs_set_inode_nlink(leaf, inode_item, 1);
 146         btrfs_set_inode_transid(leaf, inode_item, trans->transid);
 147         btrfs_set_inode_block_group(leaf, inode_item, offset);
 148         btrfs_mark_buffer_dirty(leaf);
 149         btrfs_release_path(path);
 150
 151         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 152         key.offset = offset;
 153         key.type = 0;
 154
 155         ret = btrfs_insert_empty_item(trans, root, path, &key,
 156                                       sizeof(struct btrfs_free_space_header));
 157         if (ret < 0) {
 158                 btrfs_release_path(path);
 159                 return ret;
 160         }
 161         leaf = path->nodes[0];
 162         header = btrfs_item_ptr(leaf, path->slots[0],
 163                                 struct btrfs_free_space_header);
 164         memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
 165         btrfs_set_free_space_key(leaf, header, &disk_key);
 166         btrfs_mark_buffer_dirty(leaf);
 167         btrfs_release_path(path);
 168
 169         return 0;
 170 }
 171
 172 int create_free_space_inode(struct btrfs_root *root,
 173                             struct btrfs_trans_handle *trans,
 174                             struct btrfs_block_group_cache *block_group,
 175                             struct btrfs_path *path)
 176 {
 177         int ret;
 178         u64 ino;
 179
 180         ret = btrfs_find_free_objectid(root, &ino);
 181         if (ret < 0)
 182                 return ret;
 183
 184         return __create_free_space_inode(root, trans, path, ino,
 185                                          block_group->key.objectid);
 186 }
 187
 188 int btrfs_truncate_free_space_cache(struct btrfs_root *root,
 189                                     struct btrfs_trans_handle *trans,
 190                                     struct btrfs_path *path,
 191                                     struct inode *inode)
 192 {
 193         struct btrfs_block_rsv *rsv;
 194         loff_t oldsize;
 195         int ret = 0;
 196
 197         rsv = trans->block_rsv;
 198         trans->block_rsv = root->orphan_block_rsv;
 199         ret = btrfs_block_rsv_check(trans, root,
 200                                     root->orphan_block_rsv,
 201                                     0, 5);
 202         if (ret)
 203                 return ret;
 204
 205         oldsize = i_size_read(inode);
 206         btrfs_i_size_write(inode, 0);
 207         truncate_pagecache(inode, oldsize, 0);
 208
 209         /*
 210          * We don't need an orphan item because truncating the free space cache
 211          * will never be split across transactions.
 212          */
 213         ret = btrfs_truncate_inode_items(trans, root, inode,
 214                                          0, BTRFS_EXTENT_DATA_KEY);
 215
 216         trans->block_rsv = rsv;
 217         if (ret) {
 218                 WARN_ON(1);
 219                 return ret;
 220         }
 221
 222         ret = btrfs_update_inode(trans, root, inode);
 223         return ret;
 224 }
 225
 226 static int readahead_cache(struct inode *inode)
 227 {
 228         struct file_ra_state *ra;
 229         unsigned long last_index;
 230
 231         ra = kzalloc(sizeof(*ra), GFP_NOFS);
 232         if (!ra)
 233                 return -ENOMEM;
 234
 235         file_ra_state_init(ra, inode->i_mapping);
 236         last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 237
 238         page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
 239
 240         kfree(ra);
 241
 242         return 0;
 243 }
 244
 245 int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 246                             struct btrfs_free_space_ctl *ctl,
 247                             struct btrfs_path *path, u64 offset)
 248 {
 249         struct btrfs_free_space_header *header;
 250         struct extent_buffer *leaf;
 251         struct page *page;
 252         struct btrfs_key key;
 253         struct list_head bitmaps;
 254         u64 num_entries;
 255         u64 num_bitmaps;
 256         u64 generation;
 257         pgoff_t index = 0;
 258         int ret = 0;
 259
 260         INIT_LIST_HEAD(&bitmaps);
 261
 262         /* Nothing in the space cache, goodbye */
 263         if (!i_size_read(inode))
 264                 goto out;
 265
 266         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 267         key.offset = offset;
 268         key.type = 0;
 269
 270         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 271         if (ret < 0)
 272                 goto out;
 273         else if (ret > 0) {
 274                 btrfs_release_path(path);
 275                 ret = 0;
 276                 goto out;
 277         }
 278
 279         ret = -1;
 280
 281         leaf = path->nodes[0];
 282         header = btrfs_item_ptr(leaf, path->slots[0],
 283                                 struct btrfs_free_space_header);
 284         num_entries = btrfs_free_space_entries(leaf, header);
 285         num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
 286         generation = btrfs_free_space_generation(leaf, header);
 287         btrfs_release_path(path);
 288
 289         if (BTRFS_I(inode)->generation != generation) {
 290                 printk(KERN_ERR "btrfs: free space inode generation (%llu) did"
 291                        " not match free space cache generation (%llu)\n",
 292                        (unsigned long long)BTRFS_I(inode)->generation,
 293                        (unsigned long long)generation);
 294                 goto out;
 295         }
 296
 297         if (!num_entries)
 298                 goto out;
 299
 300         ret = readahead_cache(inode);
 301         if (ret)
 302                 goto out;
 303
 304         while (1) {
 305                 struct btrfs_free_space_entry *entry;
 306                 struct btrfs_free_space *e;
 307                 void *addr;
 308                 unsigned long offset = 0;
 309                 int need_loop = 0;
 310
 311                 if (!num_entries && !num_bitmaps)
 312                         break;
 313
 314                 page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
 315                 if (!page)
 316                         goto free_cache;
 317
 318                 if (!PageUptodate(page)) {
 319                         btrfs_readpage(NULL, page);
 320                         lock_page(page);
 321                         if (!PageUptodate(page)) {
 322                                 unlock_page(page);
 323                                 page_cache_release(page);
 324                                 printk(KERN_ERR "btrfs: error reading free "
 325                                        "space cache\n");
 326                                 goto free_cache;
 327                         }
 328                 }
 329                 addr = kmap(page);
 330
 331                 if (index == 0) {
 332                         u64 *gen;
 333
 334                         /*
 335                          * We put a bogus crc in the front of the first page in
 336                          * case old kernels try to mount a fs with the new
 337                          * format to make sure they discard the cache.
 338                          */
 339                         addr += sizeof(u64);
 340                         offset += sizeof(u64);
 341
 342                         gen = addr;
 343                         if (*gen != BTRFS_I(inode)->generation) {
 344                                 printk(KERN_ERR "btrfs: space cache generation"
 345                                        " (%llu) does not match inode (%llu)\n",
 346                                        (unsigned long long)*gen,
 347                                        (unsigned long long)
 348                                        BTRFS_I(inode)->generation);
 349                                 kunmap(page);
 350                                 unlock_page(page);
 351                                 page_cache_release(page);
 352                                 goto free_cache;
 353                         }
 354                         addr += sizeof(u64);
 355                         offset += sizeof(u64);
 356                 }
 357                 entry = addr;
 358
 359                 while (1) {
 360                         if (!num_entries)
 361                                 break;
 362
 363                         need_loop = 1;
 364                         e = kmem_cache_zalloc(btrfs_free_space_cachep,
 365                                               GFP_NOFS);
 366                         if (!e) {
 367                                 kunmap(page);
 368                                 unlock_page(page);
 369                                 page_cache_release(page);
 370                                 goto free_cache;
 371                         }
 372
 373                         e->offset = le64_to_cpu(entry->offset);
 374                         e->bytes = le64_to_cpu(entry->bytes);
 375                         if (!e->bytes) {
 376                                 kunmap(page);
 377                                 kmem_cache_free(btrfs_free_space_cachep, e);
 378                                 unlock_page(page);
 379                                 page_cache_release(page);
 380                                 goto free_cache;
 381                         }
 382
 383                         if (entry->type == BTRFS_FREE_SPACE_EXTENT) {
 384                                 spin_lock(&ctl->tree_lock);
 385                                 ret = link_free_space(ctl, e);
 386                                 spin_unlock(&ctl->tree_lock);
 387                                 if (ret) {
 388                                         printk(KERN_ERR "Duplicate entries in "
 389                                                "free space cache, dumping\n");
 390                                         kunmap(page);
 391                                         unlock_page(page);
 392                                         page_cache_release(page);
 393                                         goto free_cache;
 394                                 }
 395                         } else {
 396                                 e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
 397                                 if (!e->bitmap) {
 398                                         kunmap(page);
 399                                         kmem_cache_free(
 400                                                 btrfs_free_space_cachep, e);
 401                                         unlock_page(page);
 402                                         page_cache_release(page);
 403                                         goto free_cache;
 404                                 }
 405                                 spin_lock(&ctl->tree_lock);
 406                                 ret = link_free_space(ctl, e);
 407                                 ctl->total_bitmaps++;
 408                                 ctl->op->recalc_thresholds(ctl);
 409                                 spin_unlock(&ctl->tree_lock);
 410                                 if (ret) {
 411                                         printk(KERN_ERR "Duplicate entries in "
 412                                                "free space cache, dumping\n");
 413                                         kunmap(page);
 414                                         unlock_page(page);
 415                                         page_cache_release(page);
 416                                         goto free_cache;
 417                                 }
 418                                 list_add_tail(&e->list, &bitmaps);
 419                         }
 420
 421                         num_entries--;
 422                         offset += sizeof(struct btrfs_free_space_entry);
 423                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 424                             PAGE_CACHE_SIZE)
 425                                 break;
 426                         entry++;
 427                 }
 428
 429                 /*
 430                  * We read an entry out of this page, we need to move on to the
 431                  * next page.
 432                  */
 433                 if (need_loop) {
 434                         kunmap(page);
 435                         goto next;
 436                 }
 437
 438                 /*
 439                  * We add the bitmaps at the end of the entries in order that
 440                  * the bitmap entries are added to the cache.
 441                  */
 442                 e = list_entry(bitmaps.next, struct btrfs_free_space, list);
 443                 list_del_init(&e->list);
 444                 memcpy(e->bitmap, addr, PAGE_CACHE_SIZE);
 445                 kunmap(page);
 446                 num_bitmaps--;
 447 next:
 448                 unlock_page(page);
 449                 page_cache_release(page);
 450                 index++;
 451         }
 452
 453         ret = 1;
 454 out:
 455         return ret;
 456 free_cache:
 457         __btrfs_remove_free_space_cache(ctl);
 458         goto out;
 459 }
 460
 461 int load_free_space_cache(struct btrfs_fs_info *fs_info,
 462                           struct btrfs_block_group_cache *block_group)
 463 {
 464         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 465         struct btrfs_root *root = fs_info->tree_root;
 466         struct inode *inode;
 467         struct btrfs_path *path;
 468         int ret;
 469         bool matched;
 470         u64 used = btrfs_block_group_used(&block_group->item);
 471
 472         /*
 473          * If we're unmounting then just return, since this does a search on the
 474          * normal root and not the commit root and we could deadlock.
 475          */
 476         if (btrfs_fs_closing(fs_info))
 477                 return 0;
 478
 479         /*
 480          * If this block group has been marked to be cleared for one reason or
 481          * another then we can't trust the on disk cache, so just return.
 482          */
 483         spin_lock(&block_group->lock);
 484         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 485                 spin_unlock(&block_group->lock);
 486                 return 0;
 487         }
 488         spin_unlock(&block_group->lock);
 489
 490         path = btrfs_alloc_path();
 491         if (!path)
 492                 return 0;
 493
 494         inode = lookup_free_space_inode(root, block_group, path);
 495         if (IS_ERR(inode)) {
 496                 btrfs_free_path(path);
 497                 return 0;
 498         }
 499
 500         ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
 501                                       path, block_group->key.objectid);
 502         btrfs_free_path(path);
 503         if (ret <= 0)
 504                 goto out;
 505
 506         spin_lock(&ctl->tree_lock);
 507         matched = (ctl->free_space == (block_group->key.offset - used -
 508                                        block_group->bytes_super));
 509         spin_unlock(&ctl->tree_lock);
 510
 511         if (!matched) {
 512                 __btrfs_remove_free_space_cache(ctl);
 513                 printk(KERN_ERR "block group %llu has an wrong amount of free "
 514                        "space\n", block_group->key.objectid);
 515                 ret = -1;
 516         }
 517 out:
 518         if (ret < 0) {
 519                 /* This cache is bogus, make sure it gets cleared */
 520                 spin_lock(&block_group->lock);
 521                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 522                 spin_unlock(&block_group->lock);
 523                 ret = 0;
 524
 525                 printk(KERN_ERR "btrfs: failed to load free space cache "
 526                        "for block group %llu\n", block_group->key.objectid);
 527         }
 528
 529         iput(inode);
 530         return ret;
 531 }
 532
 533 int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 534                             struct btrfs_free_space_ctl *ctl,
 535                             struct btrfs_block_group_cache *block_group,
 536                             struct btrfs_trans_handle *trans,
 537                             struct btrfs_path *path, u64 offset)
 538 {
 539         struct btrfs_free_space_header *header;
 540         struct extent_buffer *leaf;
 541         struct rb_node *node;
 542         struct list_head *pos, *n;
 543         struct page **pages;
 544         struct page *page;
 545         struct extent_state *cached_state = NULL;
 546         struct btrfs_free_cluster *cluster = NULL;
 547         struct extent_io_tree *unpin = NULL;
 548         struct list_head bitmap_list;
 549         struct btrfs_key key;
 550         u64 start, end, len;
 551         u64 bytes = 0;
 552         u32 crc = ~(u32)0;
 553         int index = 0, num_pages = 0;
 554         int entries = 0;
 555         int bitmaps = 0;
 556         int ret = -1;
 557         bool next_page = false;
 558         bool out_of_space = false;
 559
 560         INIT_LIST_HEAD(&bitmap_list);
 561
 562         node = rb_first(&ctl->free_space_offset);
 563         if (!node)
 564                 return 0;
 565
 566         if (!i_size_read(inode))
 567                 return -1;
 568
 569         num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
 570                 PAGE_CACHE_SHIFT;
 571
 572         filemap_write_and_wait(inode->i_mapping);
 573         btrfs_wait_ordered_range(inode, inode->i_size &
 574                                  ~(root->sectorsize - 1), (u64)-1);
 575
 576         pages = kzalloc(sizeof(struct page *) * num_pages, GFP_NOFS);
 577         if (!pages)
 578                 return -1;
 579
 580         /* Get the cluster for this block_group if it exists */
 581         if (block_group && !list_empty(&block_group->cluster_list))
 582                 cluster = list_entry(block_group->cluster_list.next,
 583                                      struct btrfs_free_cluster,
 584                                      block_group_list);
 585
 586         /*
 587          * We shouldn't have switched the pinned extents yet so this is the
 588          * right one
 589          */
 590         unpin = root->fs_info->pinned_extents;
 591
 592         /*
 593          * Lock all pages first so we can lock the extent safely.
 594          *
 595          * NOTE: Because we hold the ref the entire time we're going to write to
 596          * the page find_get_page should never fail, so we don't do a check
 597          * after find_get_page at this point.  Just putting this here so people
 598          * know and don't freak out.
 599          */
 600         while (index < num_pages) {
 601                 page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
 602                 if (!page) {
 603                         int i;
 604
 605                         for (i = 0; i < num_pages; i++) {
 606                                 unlock_page(pages[i]);
 607                                 page_cache_release(pages[i]);
 608                         }
 609                         goto out;
 610                 }
 611                 pages[index] = page;
 612                 index++;
 613         }
 614
 615         index = 0;
 616         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
 617                          0, &cached_state, GFP_NOFS);
 618
 619         /*
 620          * When searching for pinned extents, we need to start at our start
 621          * offset.
 622          */
 623         if (block_group)
 624                 start = block_group->key.objectid;
 625
 626         /* Write out the extent entries */
 627         do {
 628                 struct btrfs_free_space_entry *entry;
 629                 void *addr, *orig;
 630                 unsigned long offset = 0;
 631
 632                 next_page = false;
 633
 634                 if (index >= num_pages) {
 635                         out_of_space = true;
 636                         break;
 637                 }
 638
 639                 page = pages[index];
 640
 641                 orig = addr = kmap(page);
 642                 if (index == 0) {
 643                         u64 *gen;
 644
 645                         /*
 646                          * We're going to put in a bogus crc for this page to
 647                          * make sure that old kernels who aren't aware of this
 648                          * format will be sure to discard the cache.
 649                          */
 650                         addr += sizeof(u64);
 651                         offset += sizeof(u64);
 652
 653                         gen = addr;
 654                         *gen = trans->transid;
 655                         addr += sizeof(u64);
 656                         offset += sizeof(u64);
 657                 }
 658                 entry = addr;
 659
 660                 memset(addr, 0, PAGE_CACHE_SIZE - offset);
 661                 while (node && !next_page) {
 662                         struct btrfs_free_space *e;
 663
 664                         e = rb_entry(node, struct btrfs_free_space, offset_index);
 665                         entries++;
 666
 667                         entry->offset = cpu_to_le64(e->offset);
 668                         entry->bytes = cpu_to_le64(e->bytes);
 669                         if (e->bitmap) {
 670                                 entry->type = BTRFS_FREE_SPACE_BITMAP;
 671                                 list_add_tail(&e->list, &bitmap_list);
 672                                 bitmaps++;
 673                         } else {
 674                                 entry->type = BTRFS_FREE_SPACE_EXTENT;
 675                         }
 676                         node = rb_next(node);
 677                         if (!node && cluster) {
 678                                 node = rb_first(&cluster->root);
 679                                 cluster = NULL;
 680                         }
 681                         offset += sizeof(struct btrfs_free_space_entry);
 682                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 683                             PAGE_CACHE_SIZE)
 684                                 next_page = true;
 685                         entry++;
 686                 }
 687
 688                 /*
 689                  * We want to add any pinned extents to our free space cache
 690                  * so we don't leak the space
 691                  */
 692                 while (block_group && !next_page &&
 693                        (start < block_group->key.objectid +
 694                         block_group->key.offset)) {
 695                         ret = find_first_extent_bit(unpin, start, &start, &end,
 696                                                     EXTENT_DIRTY);
 697                         if (ret) {
 698                                 ret = 0;
 699                                 break;
 700                         }
 701
 702                         /* This pinned extent is out of our range */
 703                         if (start >= block_group->key.objectid +
 704                             block_group->key.offset)
 705                                 break;
 706
 707                         len = block_group->key.objectid +
 708                                 block_group->key.offset - start;
 709                         len = min(len, end + 1 - start);
 710
 711                         entries++;
 712                         entry->offset = cpu_to_le64(start);
 713                         entry->bytes = cpu_to_le64(len);
 714                         entry->type = BTRFS_FREE_SPACE_EXTENT;
 715
 716                         start = end + 1;
 717                         offset += sizeof(struct btrfs_free_space_entry);
 718                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 719                             PAGE_CACHE_SIZE)
 720                                 next_page = true;
 721                         entry++;
 722                 }
 723
 724                 /* Generate bogus crc value */
 725                 if (index == 0) {
 726                         u32 *tmp;
 727                         crc = btrfs_csum_data(root, orig + sizeof(u64), crc,
 728                                               PAGE_CACHE_SIZE - sizeof(u64));
 729                         btrfs_csum_final(crc, (char *)&crc);
 730                         crc++;
 731                         tmp = orig;
 732                         *tmp = crc;
 733                 }
 734
 735                 kunmap(page);
 736
 737                 bytes += PAGE_CACHE_SIZE;
 738
 739                 index++;
 740         } while (node || next_page);
 741
 742         /* Write out the bitmaps */
 743         list_for_each_safe(pos, n, &bitmap_list) {
 744                 void *addr;
 745                 struct btrfs_free_space *entry =
 746                         list_entry(pos, struct btrfs_free_space, list);
 747
 748                 if (index >= num_pages) {
 749                         out_of_space = true;
 750                         break;
 751                 }
 752                 page = pages[index];
 753
 754                 addr = kmap(page);
 755                 memcpy(addr, entry->bitmap, PAGE_CACHE_SIZE);
 756                 kunmap(page);
 757                 bytes += PAGE_CACHE_SIZE;
 758
 759                 list_del_init(&entry->list);
 760                 index++;
 761         }
 762
 763         if (out_of_space) {
 764                 btrfs_drop_pages(pages, num_pages);
 765                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 766                                      i_size_read(inode) - 1, &cached_state,
 767                                      GFP_NOFS);
 768                 ret = 0;
 769                 goto out;
 770         }
 771
 772         /* Zero out the rest of the pages just to make sure */
 773         while (index < num_pages) {
 774                 void *addr;
 775
 776                 page = pages[index];
 777                 addr = kmap(page);
 778                 memset(addr, 0, PAGE_CACHE_SIZE);
 779                 kunmap(page);
 780                 bytes += PAGE_CACHE_SIZE;
 781                 index++;
 782         }
 783
 784         ret = btrfs_dirty_pages(root, inode, pages, num_pages, 0,
 785                                             bytes, &cached_state);
 786         btrfs_drop_pages(pages, num_pages);
 787         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 788                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
 789
 790         if (ret) {
 791                 ret = 0;
 792                 goto out;
 793         }
 794
 795         BTRFS_I(inode)->generation = trans->transid;
 796
 797         filemap_write_and_wait(inode->i_mapping);
 798
 799         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 800         key.offset = offset;
 801         key.type = 0;
 802
 803         ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
 804         if (ret < 0) {
 805                 ret = -1;
 806                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 807                                  EXTENT_DIRTY | EXTENT_DELALLOC |
 808                                  EXTENT_DO_ACCOUNTING, 0, 0, NULL, GFP_NOFS);
 809                 goto out;
 810         }
 811         leaf = path->nodes[0];
 812         if (ret > 0) {
 813                 struct btrfs_key found_key;
 814                 BUG_ON(!path->slots[0]);
 815                 path->slots[0]--;
 816                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 817                 if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
 818                     found_key.offset != offset) {
 819                         ret = -1;
 820                         clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 821                                          EXTENT_DIRTY | EXTENT_DELALLOC |
 822                                          EXTENT_DO_ACCOUNTING, 0, 0, NULL,
 823                                          GFP_NOFS);
 824                         btrfs_release_path(path);
 825                         goto out;
 826                 }
 827         }
 828         header = btrfs_item_ptr(leaf, path->slots[0],
 829                                 struct btrfs_free_space_header);
 830         btrfs_set_free_space_entries(leaf, header, entries);
 831         btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
 832         btrfs_set_free_space_generation(leaf, header, trans->transid);
 833         btrfs_mark_buffer_dirty(leaf);
 834         btrfs_release_path(path);
 835
 836         ret = 1;
 837
 838 out:
 839         kfree(pages);
 840         if (ret != 1) {
 841                 invalidate_inode_pages2_range(inode->i_mapping, 0, index);
 842                 BTRFS_I(inode)->generation = 0;
 843         }
 844         btrfs_update_inode(trans, root, inode);
 845         return ret;
 846 }
 847
 848 int btrfs_write_out_cache(struct btrfs_root *root,
 849                           struct btrfs_trans_handle *trans,
 850                           struct btrfs_block_group_cache *block_group,
 851                           struct btrfs_path *path)
 852 {
 853         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 854         struct inode *inode;
 855         int ret = 0;
 856
 857         root = root->fs_info->tree_root;
 858
 859         spin_lock(&block_group->lock);
 860         if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
 861                 spin_unlock(&block_group->lock);
 862                 return 0;
 863         }
 864         spin_unlock(&block_group->lock);
 865
 866         inode = lookup_free_space_inode(root, block_group, path);
 867         if (IS_ERR(inode))
 868                 return 0;
 869
 870         ret = __btrfs_write_out_cache(root, inode, ctl, block_group, trans,
 871                                       path, block_group->key.objectid);
 872         if (ret < 0) {
 873                 spin_lock(&block_group->lock);
 874                 block_group->disk_cache_state = BTRFS_DC_ERROR;
 875                 spin_unlock(&block_group->lock);
 876                 ret = 0;
 877
 878                 printk(KERN_ERR "btrfs: failed to write free space cace "
 879                        "for block group %llu\n", block_group->key.objectid);
 880         }
 881
 882         iput(inode);
 883         return ret;
 884 }
 885
 886 static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
 887                                           u64 offset)
 888 {
 889         BUG_ON(offset < bitmap_start);
 890         offset -= bitmap_start;
 891         return (unsigned long)(div_u64(offset, unit));
 892 }
 893
 894 static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
 895 {
 896         return (unsigned long)(div_u64(bytes, unit));
 897 }
 898
 899 static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
 900                                    u64 offset)
 901 {
 902         u64 bitmap_start;
 903         u64 bytes_per_bitmap;
 904
 905         bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
 906         bitmap_start = offset - ctl->start;
 907         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
 908         bitmap_start *= bytes_per_bitmap;
 909         bitmap_start += ctl->start;
 910
 911         return bitmap_start;
 912 }
 913
 914 static int tree_insert_offset(struct rb_root *root, u64 offset,
 915                               struct rb_node *node, int bitmap)
 916 {
 917         struct rb_node **p = &root->rb_node;
 918         struct rb_node *parent = NULL;
 919         struct btrfs_free_space *info;
 920
 921         while (*p) {
 922                 parent = *p;
 923                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
 924
 925                 if (offset < info->offset) {
 926                         p = &(*p)->rb_left;
 927                 } else if (offset > info->offset) {
 928                         p = &(*p)->rb_right;
 929                 } else {
 930                         /*
 931                          * we could have a bitmap entry and an extent entry
 932                          * share the same offset.  If this is the case, we want
 933                          * the extent entry to always be found first if we do a
 934                          * linear search through the tree, since we want to have
 935                          * the quickest allocation time, and allocating from an
 936                          * extent is faster than allocating from a bitmap.  So
 937                          * if we're inserting a bitmap and we find an entry at
 938                          * this offset, we want to go right, or after this entry
 939                          * logically.  If we are inserting an extent and we've
 940                          * found a bitmap, we want to go left, or before
 941                          * logically.
 942                          */
 943                         if (bitmap) {
 944                                 if (info->bitmap) {
 945                                         WARN_ON_ONCE(1);
 946                                         return -EEXIST;
 947                                 }
 948                                 p = &(*p)->rb_right;
 949                         } else {
 950                                 if (!info->bitmap) {
 951                                         WARN_ON_ONCE(1);
 952                                         return -EEXIST;
 953                                 }
 954                                 p = &(*p)->rb_left;
 955                         }
 956                 }
 957         }
 958
 959         rb_link_node(node, parent, p);
 960         rb_insert_color(node, root);
 961
 962         return 0;
 963 }
 964
 965 /*
 966  * searches the tree for the given offset.
 967  *
 968  * fuzzy - If this is set, then we are trying to make an allocation, and we just
 969  * want a section that has at least bytes size and comes at or after the given
 970  * offset.
 971  */
 972 static struct btrfs_free_space *
 973 tree_search_offset(struct btrfs_free_space_ctl *ctl,
 974                    u64 offset, int bitmap_only, int fuzzy)
 975 {
 976         struct rb_node *n = ctl->free_space_offset.rb_node;
 977         struct btrfs_free_space *entry, *prev = NULL;
 978
 979         /* find entry that is closest to the 'offset' */
 980         while (1) {
 981                 if (!n) {
 982                         entry = NULL;
 983                         break;
 984                 }
 985
 986                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
 987                 prev = entry;
 988
 989                 if (offset < entry->offset)
 990                         n = n->rb_left;
 991                 else if (offset > entry->offset)
 992                         n = n->rb_right;
 993                 else
 994                         break;
 995         }
 996
 997         if (bitmap_only) {
 998                 if (!entry)
 999                         return NULL;
1000                 if (entry->bitmap)
1001                         return entry;
1002
1003                 /*
1004                  * bitmap entry and extent entry may share same offset,
1005                  * in that case, bitmap entry comes after extent entry.
1006                  */
1007                 n = rb_next(n);
1008                 if (!n)
1009                         return NULL;
1010                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1011                 if (entry->offset != offset)
1012                         return NULL;
1013
1014                 WARN_ON(!entry->bitmap);
1015                 return entry;
1016         } else if (entry) {
1017                 if (entry->bitmap) {
1018                         /*
1019                          * if previous extent entry covers the offset,
1020                          * we should return it instead of the bitmap entry
1021                          */
1022                         n = &entry->offset_index;
1023                         while (1) {
1024                                 n = rb_prev(n);
1025                                 if (!n)
1026                                         break;
1027                                 prev = rb_entry(n, struct btrfs_free_space,
1028                                                 offset_index);
1029                                 if (!prev->bitmap) {
1030                                         if (prev->offset + prev->bytes > offset)
1031                                                 entry = prev;
1032                                         break;
1033                                 }
1034                         }
1035                 }
1036                 return entry;
1037         }
1038
1039         if (!prev)
1040                 return NULL;
1041
1042         /* find last entry before the 'offset' */
1043         entry = prev;
1044         if (entry->offset > offset) {
1045                 n = rb_prev(&entry->offset_index);
1046                 if (n) {
1047                         entry = rb_entry(n, struct btrfs_free_space,
1048                                         offset_index);
1049                         BUG_ON(entry->offset > offset);
1050                 } else {
1051                         if (fuzzy)
1052                                 return entry;
1053                         else
1054                                 return NULL;
1055                 }
1056         }
1057
1058         if (entry->bitmap) {
1059                 n = &entry->offset_index;
1060                 while (1) {
1061                         n = rb_prev(n);
1062                         if (!n)
1063                                 break;
1064                         prev = rb_entry(n, struct btrfs_free_space,
1065                                         offset_index);
1066                         if (!prev->bitmap) {
1067                                 if (prev->offset + prev->bytes > offset)
1068                                         return prev;
1069                                 break;
1070                         }
1071                 }
1072                 if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
1073                         return entry;
1074         } else if (entry->offset + entry->bytes > offset)
1075                 return entry;
1076
1077         if (!fuzzy)
1078                 return NULL;
1079
1080         while (1) {
1081                 if (entry->bitmap) {
1082                         if (entry->offset + BITS_PER_BITMAP *
1083                             ctl->unit > offset)
1084                                 break;
1085                 } else {
1086                         if (entry->offset + entry->bytes > offset)
1087                                 break;
1088                 }
1089
1090                 n = rb_next(&entry->offset_index);
1091                 if (!n)
1092                         return NULL;
1093                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1094         }
1095         return entry;
1096 }
1097
1098 static inline void
1099 __unlink_free_space(struct btrfs_free_space_ctl *ctl,
1100                     struct btrfs_free_space *info)
1101 {
1102         rb_erase(&info->offset_index, &ctl->free_space_offset);
1103         ctl->free_extents--;
1104 }
1105
1106 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
1107                               struct btrfs_free_space *info)
1108 {
1109         __unlink_free_space(ctl, info);
1110         ctl->free_space -= info->bytes;
1111 }
1112
1113 static int link_free_space(struct btrfs_free_space_ctl *ctl,
1114                            struct btrfs_free_space *info)
1115 {
1116         int ret = 0;
1117
1118         BUG_ON(!info->bitmap && !info->bytes);
1119         ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
1120                                  &info->offset_index, (info->bitmap != NULL));
1121         if (ret)
1122                 return ret;
1123
1124         ctl->free_space += info->bytes;
1125         ctl->free_extents++;
1126         return ret;
1127 }
1128
1129 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
1130 {
1131         struct btrfs_block_group_cache *block_group = ctl->private;
1132         u64 max_bytes;
1133         u64 bitmap_bytes;
1134         u64 extent_bytes;
1135         u64 size = block_group->key.offset;
1136         u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
1137         int max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
1138
1139         BUG_ON(ctl->total_bitmaps > max_bitmaps);
1140
1141         /*
1142          * The goal is to keep the total amount of memory used per 1gb of space
1143          * at or below 32k, so we need to adjust how much memory we allow to be
1144          * used by extent based free space tracking
1145          */
1146         if (size < 1024 * 1024 * 1024)
1147                 max_bytes = MAX_CACHE_BYTES_PER_GIG;
1148         else
1149                 max_bytes = MAX_CACHE_BYTES_PER_GIG *
1150                         div64_u64(size, 1024 * 1024 * 1024);
1151
1152         /*
1153          * we want to account for 1 more bitmap than what we have so we can make
1154          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1155          * we add more bitmaps.
1156          */
1157         bitmap_bytes = (ctl->total_bitmaps + 1) * PAGE_CACHE_SIZE;
1158
1159         if (bitmap_bytes >= max_bytes) {
1160                 ctl->extents_thresh = 0;
1161                 return;
1162         }
1163
1164         /*
1165          * we want the extent entry threshold to always be at most 1/2 the maxw
1166          * bytes we can have, or whatever is less than that.
1167          */
1168         extent_bytes = max_bytes - bitmap_bytes;
1169         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
1170
1171         ctl->extents_thresh =
1172                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
1173 }
1174
1175 static inline void __bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1176                                        struct btrfs_free_space *info,
1177                                        u64 offset, u64 bytes)
1178 {
1179         unsigned long start, count;
1180
1181         start = offset_to_bit(info->offset, ctl->unit, offset);
1182         count = bytes_to_bits(bytes, ctl->unit);
1183         BUG_ON(start + count > BITS_PER_BITMAP);
1184
1185         bitmap_clear(info->bitmap, start, count);
1186
1187         info->bytes -= bytes;
1188 }
1189
1190 static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1191                               struct btrfs_free_space *info, u64 offset,
1192                               u64 bytes)
1193 {
1194         __bitmap_clear_bits(ctl, info, offset, bytes);
1195         ctl->free_space -= bytes;
1196 }
1197
1198 static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
1199                             struct btrfs_free_space *info, u64 offset,
1200                             u64 bytes)
1201 {
1202         unsigned long start, count;
1203
1204         start = offset_to_bit(info->offset, ctl->unit, offset);
1205         count = bytes_to_bits(bytes, ctl->unit);
1206         BUG_ON(start + count > BITS_PER_BITMAP);
1207
1208         bitmap_set(info->bitmap, start, count);
1209
1210         info->bytes += bytes;
1211         ctl->free_space += bytes;
1212 }
1213
1214 static int search_bitmap(struct btrfs_free_space_ctl *ctl,
1215                          struct btrfs_free_space *bitmap_info, u64 *offset,
1216                          u64 *bytes)
1217 {
1218         unsigned long found_bits = 0;
1219         unsigned long bits, i;
1220         unsigned long next_zero;
1221
1222         i = offset_to_bit(bitmap_info->offset, ctl->unit,
1223                           max_t(u64, *offset, bitmap_info->offset));
1224         bits = bytes_to_bits(*bytes, ctl->unit);
1225
1226         for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
1227              i < BITS_PER_BITMAP;
1228              i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
1229                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
1230                                                BITS_PER_BITMAP, i);
1231                 if ((next_zero - i) >= bits) {
1232                         found_bits = next_zero - i;
1233                         break;
1234                 }
1235                 i = next_zero;
1236         }
1237
1238         if (found_bits) {
1239                 *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
1240                 *bytes = (u64)(found_bits) * ctl->unit;
1241                 return 0;
1242         }
1243
1244         return -1;
1245 }
1246
1247 static struct btrfs_free_space *
1248 find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes)
1249 {
1250         struct btrfs_free_space *entry;
1251         struct rb_node *node;
1252         int ret;
1253
1254         if (!ctl->free_space_offset.rb_node)
1255                 return NULL;
1256
1257         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
1258         if (!entry)
1259                 return NULL;
1260
1261         for (node = &entry->offset_index; node; node = rb_next(node)) {
1262                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1263                 if (entry->bytes < *bytes)
1264                         continue;
1265
1266                 if (entry->bitmap) {
1267                         ret = search_bitmap(ctl, entry, offset, bytes);
1268                         if (!ret)
1269                                 return entry;
1270                         continue;
1271                 }
1272
1273                 *offset = entry->offset;
1274                 *bytes = entry->bytes;
1275                 return entry;
1276         }
1277
1278         return NULL;
1279 }
1280
1281 static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
1282                            struct btrfs_free_space *info, u64 offset)
1283 {
1284         info->offset = offset_to_bitmap(ctl, offset);
1285         info->bytes = 0;
1286         link_free_space(ctl, info);
1287         ctl->total_bitmaps++;
1288
1289         ctl->op->recalc_thresholds(ctl);
1290 }
1291
1292 static void free_bitmap(struct btrfs_free_space_ctl *ctl,
1293                         struct btrfs_free_space *bitmap_info)
1294 {
1295         unlink_free_space(ctl, bitmap_info);
1296         kfree(bitmap_info->bitmap);
1297         kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1298         ctl->total_bitmaps--;
1299         ctl->op->recalc_thresholds(ctl);
1300 }
1301
1302 static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
1303                               struct btrfs_free_space *bitmap_info,
1304                               u64 *offset, u64 *bytes)
1305 {
1306         u64 end;
1307         u64 search_start, search_bytes;
1308         int ret;
1309
1310 again:
1311         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
1312
1313         /*
1314          * XXX - this can go away after a few releases.
1315          *
1316          * since the only user of btrfs_remove_free_space is the tree logging
1317          * stuff, and the only way to test that is under crash conditions, we
1318          * want to have this debug stuff here just in case somethings not
1319          * working.  Search the bitmap for the space we are trying to use to
1320          * make sure its actually there.  If its not there then we need to stop
1321          * because something has gone wrong.
1322          */
1323         search_start = *offset;
1324         search_bytes = *bytes;
1325         search_bytes = min(search_bytes, end - search_start + 1);
1326         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
1327         BUG_ON(ret < 0 || search_start != *offset);
1328
1329         if (*offset > bitmap_info->offset && *offset + *bytes > end) {
1330                 bitmap_clear_bits(ctl, bitmap_info, *offset, end - *offset + 1);
1331                 *bytes -= end - *offset + 1;
1332                 *offset = end + 1;
1333         } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
1334                 bitmap_clear_bits(ctl, bitmap_info, *offset, *bytes);
1335                 *bytes = 0;
1336         }
1337
1338         if (*bytes) {
1339                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
1340                 if (!bitmap_info->bytes)
1341                         free_bitmap(ctl, bitmap_info);
1342
1343                 /*
1344                  * no entry after this bitmap, but we still have bytes to
1345                  * remove, so something has gone wrong.
1346                  */
1347                 if (!next)
1348                         return -EINVAL;
1349
1350                 bitmap_info = rb_entry(next, struct btrfs_free_space,
1351                                        offset_index);
1352
1353                 /*
1354                  * if the next entry isn't a bitmap we need to return to let the
1355                  * extent stuff do its work.
1356                  */
1357                 if (!bitmap_info->bitmap)
1358                         return -EAGAIN;
1359
1360                 /*
1361                  * Ok the next item is a bitmap, but it may not actually hold
1362                  * the information for the rest of this free space stuff, so
1363                  * look for it, and if we don't find it return so we can try
1364                  * everything over again.
1365                  */
1366                 search_start = *offset;
1367                 search_bytes = *bytes;
1368                 ret = search_bitmap(ctl, bitmap_info, &search_start,
1369                                     &search_bytes);
1370                 if (ret < 0 || search_start != *offset)
1371                         return -EAGAIN;
1372
1373                 goto again;
1374         } else if (!bitmap_info->bytes)
1375                 free_bitmap(ctl, bitmap_info);
1376
1377         return 0;
1378 }
1379
1380 static u64 add_bytes_to_bitmap(struct btrfs_free_space_ctl *ctl,
1381                                struct btrfs_free_space *info, u64 offset,
1382                                u64 bytes)
1383 {
1384         u64 bytes_to_set = 0;
1385         u64 end;
1386
1387         end = info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
1388
1389         bytes_to_set = min(end - offset, bytes);
1390
1391         bitmap_set_bits(ctl, info, offset, bytes_to_set);
1392
1393         return bytes_to_set;
1394
1395 }
1396
1397 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
1398                       struct btrfs_free_space *info)
1399 {
1400         struct btrfs_block_group_cache *block_group = ctl->private;
1401
1402         /*
1403          * If we are below the extents threshold then we can add this as an
1404          * extent, and don't have to deal with the bitmap
1405          */
1406         if (ctl->free_extents < ctl->extents_thresh) {
1407                 /*
1408                  * If this block group has some small extents we don't want to
1409                  * use up all of our free slots in the cache with them, we want
1410                  * to reserve them to larger extents, however if we have plent
1411                  * of cache left then go ahead an dadd them, no sense in adding
1412                  * the overhead of a bitmap if we don't have to.
1413                  */
1414                 if (info->bytes <= block_group->sectorsize * 4) {
1415                         if (ctl->free_extents * 2 <= ctl->extents_thresh)
1416                                 return false;
1417                 } else {
1418                         return false;
1419                 }
1420         }
1421
1422         /*
1423          * some block groups are so tiny they can't be enveloped by a bitmap, so
1424          * don't even bother to create a bitmap for this
1425          */
1426         if (BITS_PER_BITMAP * block_group->sectorsize >
1427             block_group->key.offset)
1428                 return false;
1429
1430         return true;
1431 }
1432
1433 static struct btrfs_free_space_op free_space_op = {
1434         .recalc_thresholds      = recalculate_thresholds,
1435         .use_bitmap             = use_bitmap,
1436 };
1437
1438 static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
1439                               struct btrfs_free_space *info)
1440 {
1441         struct btrfs_free_space *bitmap_info;
1442         struct btrfs_block_group_cache *block_group = NULL;
1443         int added = 0;
1444         u64 bytes, offset, bytes_added;
1445         int ret;
1446
1447         bytes = info->bytes;
1448         offset = info->offset;
1449
1450         if (!ctl->op->use_bitmap(ctl, info))
1451                 return 0;
1452
1453         if (ctl->op == &free_space_op)
1454                 block_group = ctl->private;
1455 again:
1456         /*
1457          * Since we link bitmaps right into the cluster we need to see if we
1458          * have a cluster here, and if so and it has our bitmap we need to add
1459          * the free space to that bitmap.
1460          */
1461         if (block_group && !list_empty(&block_group->cluster_list)) {
1462                 struct btrfs_free_cluster *cluster;
1463                 struct rb_node *node;
1464                 struct btrfs_free_space *entry;
1465
1466                 cluster = list_entry(block_group->cluster_list.next,
1467                                      struct btrfs_free_cluster,
1468                                      block_group_list);
1469                 spin_lock(&cluster->lock);
1470                 node = rb_first(&cluster->root);
1471                 if (!node) {
1472                         spin_unlock(&cluster->lock);
1473                         goto no_cluster_bitmap;
1474                 }
1475
1476                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1477                 if (!entry->bitmap) {
1478                         spin_unlock(&cluster->lock);
1479                         goto no_cluster_bitmap;
1480                 }
1481
1482                 if (entry->offset == offset_to_bitmap(ctl, offset)) {
1483                         bytes_added = add_bytes_to_bitmap(ctl, entry,
1484                                                           offset, bytes);
1485                         bytes -= bytes_added;
1486                         offset += bytes_added;
1487                 }
1488                 spin_unlock(&cluster->lock);
1489                 if (!bytes) {
1490                         ret = 1;
1491                         goto out;
1492                 }
1493         }
1494
1495 no_cluster_bitmap:
1496         bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1497                                          1, 0);
1498         if (!bitmap_info) {
1499                 BUG_ON(added);
1500                 goto new_bitmap;
1501         }
1502
1503         bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
1504         bytes -= bytes_added;
1505         offset += bytes_added;
1506         added = 0;
1507
1508         if (!bytes) {
1509                 ret = 1;
1510                 goto out;
1511         } else
1512                 goto again;
1513
1514 new_bitmap:
1515         if (info && info->bitmap) {
1516                 add_new_bitmap(ctl, info, offset);
1517                 added = 1;
1518                 info = NULL;
1519                 goto again;
1520         } else {
1521                 spin_unlock(&ctl->tree_lock);
1522
1523                 /* no pre-allocated info, allocate a new one */
1524                 if (!info) {
1525                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
1526                                                  GFP_NOFS);
1527                         if (!info) {
1528                                 spin_lock(&ctl->tree_lock);
1529                                 ret = -ENOMEM;
1530                                 goto out;
1531                         }
1532                 }
1533
1534                 /* allocate the bitmap */
1535                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
1536                 spin_lock(&ctl->tree_lock);
1537                 if (!info->bitmap) {
1538                         ret = -ENOMEM;
1539                         goto out;
1540                 }
1541                 goto again;
1542         }
1543
1544 out:
1545         if (info) {
1546                 if (info->bitmap)
1547                         kfree(info->bitmap);
1548                 kmem_cache_free(btrfs_free_space_cachep, info);
1549         }
1550
1551         return ret;
1552 }
1553
1554 static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
1555                           struct btrfs_free_space *info, bool update_stat)
1556 {
1557         struct btrfs_free_space *left_info;
1558         struct btrfs_free_space *right_info;
1559         bool merged = false;
1560         u64 offset = info->offset;
1561         u64 bytes = info->bytes;
1562
1563         /*
1564          * first we want to see if there is free space adjacent to the range we
1565          * are adding, if there is remove that struct and add a new one to
1566          * cover the entire range
1567          */
1568         right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
1569         if (right_info && rb_prev(&right_info->offset_index))
1570                 left_info = rb_entry(rb_prev(&right_info->offset_index),
1571                                      struct btrfs_free_space, offset_index);
1572         else
1573                 left_info = tree_search_offset(ctl, offset - 1, 0, 0);
1574
1575         if (right_info && !right_info->bitmap) {
1576                 if (update_stat)
1577                         unlink_free_space(ctl, right_info);
1578                 else
1579                         __unlink_free_space(ctl, right_info);
1580                 info->bytes += right_info->bytes;
1581                 kmem_cache_free(btrfs_free_space_cachep, right_info);
1582                 merged = true;
1583         }
1584
1585         if (left_info && !left_info->bitmap &&
1586             left_info->offset + left_info->bytes == offset) {
1587                 if (update_stat)
1588                         unlink_free_space(ctl, left_info);
1589                 else
1590                         __unlink_free_space(ctl, left_info);
1591                 info->offset = left_info->offset;
1592                 info->bytes += left_info->bytes;
1593                 kmem_cache_free(btrfs_free_space_cachep, left_info);
1594                 merged = true;
1595         }
1596
1597         return merged;
1598 }
1599
1600 int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
1601                            u64 offset, u64 bytes)
1602 {
1603         struct btrfs_free_space *info;
1604         int ret = 0;
1605
1606         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
1607         if (!info)
1608                 return -ENOMEM;
1609
1610         info->offset = offset;
1611         info->bytes = bytes;
1612
1613         spin_lock(&ctl->tree_lock);
1614
1615         if (try_merge_free_space(ctl, info, true))
1616                 goto link;
1617
1618         /*
1619          * There was no extent directly to the left or right of this new
1620          * extent then we know we're going to have to allocate a new extent, so
1621          * before we do that see if we need to drop this into a bitmap
1622          */
1623         ret = insert_into_bitmap(ctl, info);
1624         if (ret < 0) {
1625                 goto out;
1626         } else if (ret) {
1627                 ret = 0;
1628                 goto out;
1629         }
1630 link:
1631         ret = link_free_space(ctl, info);
1632         if (ret)
1633                 kmem_cache_free(btrfs_free_space_cachep, info);
1634 out:
1635         spin_unlock(&ctl->tree_lock);
1636
1637         if (ret) {
1638                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
1639                 BUG_ON(ret == -EEXIST);
1640         }
1641
1642         return ret;
1643 }
1644
1645 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
1646                             u64 offset, u64 bytes)
1647 {
1648         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1649         struct btrfs_free_space *info;
1650         struct btrfs_free_space *next_info = NULL;
1651         int ret = 0;
1652
1653         spin_lock(&ctl->tree_lock);
1654
1655 again:
1656         info = tree_search_offset(ctl, offset, 0, 0);
1657         if (!info) {
1658                 /*
1659                  * oops didn't find an extent that matched the space we wanted
1660                  * to remove, look for a bitmap instead
1661                  */
1662                 info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1663                                           1, 0);
1664                 if (!info) {
1665                         WARN_ON(1);
1666                         goto out_lock;
1667                 }
1668         }
1669
1670         if (info->bytes < bytes && rb_next(&info->offset_index)) {
1671                 u64 end;
1672                 next_info = rb_entry(rb_next(&info->offset_index),
1673                                              struct btrfs_free_space,
1674                                              offset_index);
1675
1676                 if (next_info->bitmap)
1677                         end = next_info->offset +
1678                               BITS_PER_BITMAP * ctl->unit - 1;
1679                 else
1680                         end = next_info->offset + next_info->bytes;
1681
1682                 if (next_info->bytes < bytes ||
1683                     next_info->offset > offset || offset > end) {
1684                         printk(KERN_CRIT "Found free space at %llu, size %llu,"
1685                               " trying to use %llu\n",
1686                               (unsigned long long)info->offset,
1687                               (unsigned long long)info->bytes,
1688                               (unsigned long long)bytes);
1689                         WARN_ON(1);
1690                         ret = -EINVAL;
1691                         goto out_lock;
1692                 }
1693
1694                 info = next_info;
1695         }
1696
1697         if (info->bytes == bytes) {
1698                 unlink_free_space(ctl, info);
1699                 if (info->bitmap) {
1700                         kfree(info->bitmap);
1701                         ctl->total_bitmaps--;
1702                 }
1703                 kmem_cache_free(btrfs_free_space_cachep, info);
1704                 goto out_lock;
1705         }
1706
1707         if (!info->bitmap && info->offset == offset) {
1708                 unlink_free_space(ctl, info);
1709                 info->offset += bytes;
1710                 info->bytes -= bytes;
1711                 link_free_space(ctl, info);
1712                 goto out_lock;
1713         }
1714
1715         if (!info->bitmap && info->offset <= offset &&
1716             info->offset + info->bytes >= offset + bytes) {
1717                 u64 old_start = info->offset;
1718                 /*
1719                  * we're freeing space in the middle of the info,
1720                  * this can happen during tree log replay
1721                  *
1722                  * first unlink the old info and then
1723                  * insert it again after the hole we're creating
1724                  */
1725                 unlink_free_space(ctl, info);
1726                 if (offset + bytes < info->offset + info->bytes) {
1727                         u64 old_end = info->offset + info->bytes;
1728
1729                         info->offset = offset + bytes;
1730                         info->bytes = old_end - info->offset;
1731                         ret = link_free_space(ctl, info);
1732                         WARN_ON(ret);
1733                         if (ret)
1734                                 goto out_lock;
1735                 } else {
1736                         /* the hole we're creating ends at the end
1737                          * of the info struct, just free the info
1738                          */
1739                         kmem_cache_free(btrfs_free_space_cachep, info);
1740                 }
1741                 spin_unlock(&ctl->tree_lock);
1742
1743                 /* step two, insert a new info struct to cover
1744                  * anything before the hole
1745                  */
1746                 ret = btrfs_add_free_space(block_group, old_start,
1747                                            offset - old_start);
1748                 WARN_ON(ret);
1749                 goto out;
1750         }
1751
1752         ret = remove_from_bitmap(ctl, info, &offset, &bytes);
1753         if (ret == -EAGAIN)
1754                 goto again;
1755         BUG_ON(ret);
1756 out_lock:
1757         spin_unlock(&ctl->tree_lock);
1758 out:
1759         return ret;
1760 }
1761
1762 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
1763                            u64 bytes)
1764 {
1765         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1766         struct btrfs_free_space *info;
1767         struct rb_node *n;
1768         int count = 0;
1769
1770         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
1771                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1772                 if (info->bytes >= bytes)
1773                         count++;
1774                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
1775                        (unsigned long long)info->offset,
1776                        (unsigned long long)info->bytes,
1777                        (info->bitmap) ? "yes" : "no");
1778         }
1779         printk(KERN_INFO "block group has cluster?: %s\n",
1780                list_empty(&block_group->cluster_list) ? "no" : "yes");
1781         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
1782                "\n", count);
1783 }
1784
1785 void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
1786 {
1787         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1788
1789         spin_lock_init(&ctl->tree_lock);
1790         ctl->unit = block_group->sectorsize;
1791         ctl->start = block_group->key.objectid;
1792         ctl->private = block_group;
1793         ctl->op = &free_space_op;
1794
1795         /*
1796          * we only want to have 32k of ram per block group for keeping
1797          * track of free space, and if we pass 1/2 of that we want to
1798          * start converting things over to using bitmaps
1799          */
1800         ctl->extents_thresh = ((1024 * 32) / 2) /
1801                                 sizeof(struct btrfs_free_space);
1802 }
1803
1804 /*
1805  * for a given cluster, put all of its extents back into the free
1806  * space cache.  If the block group passed doesn't match the block group
1807  * pointed to by the cluster, someone else raced in and freed the
1808  * cluster already.  In that case, we just return without changing anything
1809  */
1810 static int
1811 __btrfs_return_cluster_to_free_space(
1812                              struct btrfs_block_group_cache *block_group,
1813                              struct btrfs_free_cluster *cluster)
1814 {
1815         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1816         struct btrfs_free_space *entry;
1817         struct rb_node *node;
1818
1819         spin_lock(&cluster->lock);
1820         if (cluster->block_group != block_group)
1821                 goto out;
1822
1823         cluster->block_group = NULL;
1824         cluster->window_start = 0;
1825         list_del_init(&cluster->block_group_list);
1826
1827         node = rb_first(&cluster->root);
1828         while (node) {
1829                 bool bitmap;
1830
1831                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1832                 node = rb_next(&entry->offset_index);
1833                 rb_erase(&entry->offset_index, &cluster->root);
1834
1835                 bitmap = (entry->bitmap != NULL);
1836                 if (!bitmap)
1837                         try_merge_free_space(ctl, entry, false);
1838                 tree_insert_offset(&ctl->free_space_offset,
1839                                    entry->offset, &entry->offset_index, bitmap);
1840         }
1841         cluster->root = RB_ROOT;
1842
1843 out:
1844         spin_unlock(&cluster->lock);
1845         btrfs_put_block_group(block_group);
1846         return 0;
1847 }
1848
1849 void __btrfs_remove_free_space_cache_locked(struct btrfs_free_space_ctl *ctl)
1850 {
1851         struct btrfs_free_space *info;
1852         struct rb_node *node;
1853
1854         while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
1855                 info = rb_entry(node, struct btrfs_free_space, offset_index);
1856                 if (!info->bitmap) {
1857                         unlink_free_space(ctl, info);
1858                         kmem_cache_free(btrfs_free_space_cachep, info);
1859                 } else {
1860                         free_bitmap(ctl, info);
1861                 }
1862                 if (need_resched()) {
1863                         spin_unlock(&ctl->tree_lock);
1864                         cond_resched();
1865                         spin_lock(&ctl->tree_lock);
1866                 }
1867         }
1868 }
1869
1870 void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
1871 {
1872         spin_lock(&ctl->tree_lock);
1873         __btrfs_remove_free_space_cache_locked(ctl);
1874         spin_unlock(&ctl->tree_lock);
1875 }
1876
1877 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
1878 {
1879         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1880         struct btrfs_free_cluster *cluster;
1881         struct list_head *head;
1882
1883         spin_lock(&ctl->tree_lock);
1884         while ((head = block_group->cluster_list.next) !=
1885                &block_group->cluster_list) {
1886                 cluster = list_entry(head, struct btrfs_free_cluster,
1887                                      block_group_list);
1888
1889                 WARN_ON(cluster->block_group != block_group);
1890                 __btrfs_return_cluster_to_free_space(block_group, cluster);
1891                 if (need_resched()) {
1892                         spin_unlock(&ctl->tree_lock);
1893                         cond_resched();
1894                         spin_lock(&ctl->tree_lock);
1895                 }
1896         }
1897         __btrfs_remove_free_space_cache_locked(ctl);
1898         spin_unlock(&ctl->tree_lock);
1899
1900 }
1901
1902 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
1903                                u64 offset, u64 bytes, u64 empty_size)
1904 {
1905         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1906         struct btrfs_free_space *entry = NULL;
1907         u64 bytes_search = bytes + empty_size;
1908         u64 ret = 0;
1909
1910         spin_lock(&ctl->tree_lock);
1911         entry = find_free_space(ctl, &offset, &bytes_search);
1912         if (!entry)
1913                 goto out;
1914
1915         ret = offset;
1916         if (entry->bitmap) {
1917                 bitmap_clear_bits(ctl, entry, offset, bytes);
1918                 if (!entry->bytes)
1919                         free_bitmap(ctl, entry);
1920         } else {
1921                 unlink_free_space(ctl, entry);
1922                 entry->offset += bytes;
1923                 entry->bytes -= bytes;
1924                 if (!entry->bytes)
1925                         kmem_cache_free(btrfs_free_space_cachep, entry);
1926                 else
1927                         link_free_space(ctl, entry);
1928         }
1929
1930 out:
1931         spin_unlock(&ctl->tree_lock);
1932
1933         return ret;
1934 }
1935
1936 /*
1937  * given a cluster, put all of its extents back into the free space
1938  * cache.  If a block group is passed, this function will only free
1939  * a cluster that belongs to the passed block group.
1940  *
1941  * Otherwise, it'll get a reference on the block group pointed to by the
1942  * cluster and remove the cluster from it.
1943  */
1944 int btrfs_return_cluster_to_free_space(
1945                                struct btrfs_block_group_cache *block_group,
1946                                struct btrfs_free_cluster *cluster)
1947 {
1948         struct btrfs_free_space_ctl *ctl;
1949         int ret;
1950
1951         /* first, get a safe pointer to the block group */
1952         spin_lock(&cluster->lock);
1953         if (!block_group) {
1954                 block_group = cluster->block_group;
1955                 if (!block_group) {
1956                         spin_unlock(&cluster->lock);
1957                         return 0;
1958                 }
1959         } else if (cluster->block_group != block_group) {
1960                 /* someone else has already freed it don't redo their work */
1961                 spin_unlock(&cluster->lock);
1962                 return 0;
1963         }
1964         atomic_inc(&block_group->count);
1965         spin_unlock(&cluster->lock);
1966
1967         ctl = block_group->free_space_ctl;
1968
1969         /* now return any extents the cluster had on it */
1970         spin_lock(&ctl->tree_lock);
1971         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
1972         spin_unlock(&ctl->tree_lock);
1973
1974         /* finally drop our ref */
1975         btrfs_put_block_group(block_group);
1976         return ret;
1977 }
1978
1979 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
1980                                    struct btrfs_free_cluster *cluster,
1981                                    struct btrfs_free_space *entry,
1982                                    u64 bytes, u64 min_start)
1983 {
1984         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1985         int err;
1986         u64 search_start = cluster->window_start;
1987         u64 search_bytes = bytes;
1988         u64 ret = 0;
1989
1990         search_start = min_start;
1991         search_bytes = bytes;
1992
1993         err = search_bitmap(ctl, entry, &search_start, &search_bytes);
1994         if (err)
1995                 return 0;
1996
1997         ret = search_start;
1998         __bitmap_clear_bits(ctl, entry, ret, bytes);
1999
2000         return ret;
2001 }
2002
2003 /*
2004  * given a cluster, try to allocate 'bytes' from it, returns 0
2005  * if it couldn't find anything suitably large, or a logical disk offset
2006  * if things worked out
2007  */
2008 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
2009                              struct btrfs_free_cluster *cluster, u64 bytes,
2010                              u64 min_start)
2011 {
2012         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2013         struct btrfs_free_space *entry = NULL;
2014         struct rb_node *node;
2015         u64 ret = 0;
2016
2017         spin_lock(&cluster->lock);
2018         if (bytes > cluster->max_size)
2019                 goto out;
2020
2021         if (cluster->block_group != block_group)
2022                 goto out;
2023
2024         node = rb_first(&cluster->root);
2025         if (!node)
2026                 goto out;
2027
2028         entry = rb_entry(node, struct btrfs_free_space, offset_index);
2029         while(1) {
2030                 if (entry->bytes < bytes ||
2031                     (!entry->bitmap && entry->offset < min_start)) {
2032                         node = rb_next(&entry->offset_index);
2033                         if (!node)
2034                                 break;
2035                         entry = rb_entry(node, struct btrfs_free_space,
2036                                          offset_index);
2037                         continue;
2038                 }
2039
2040                 if (entry->bitmap) {
2041                         ret = btrfs_alloc_from_bitmap(block_group,
2042                                                       cluster, entry, bytes,
2043                                                       min_start);
2044                         if (ret == 0) {
2045                                 node = rb_next(&entry->offset_index);
2046                                 if (!node)
2047                                         break;
2048                                 entry = rb_entry(node, struct btrfs_free_space,
2049                                                  offset_index);
2050                                 continue;
2051                         }
2052                 } else {
2053                         ret = entry->offset;
2054
2055                         entry->offset += bytes;
2056                         entry->bytes -= bytes;
2057                 }
2058
2059                 if (entry->bytes == 0)
2060                         rb_erase(&entry->offset_index, &cluster->root);
2061                 break;
2062         }
2063 out:
2064         spin_unlock(&cluster->lock);
2065
2066         if (!ret)
2067                 return 0;
2068
2069         spin_lock(&ctl->tree_lock);
2070
2071         ctl->free_space -= bytes;
2072         if (entry->bytes == 0) {
2073                 ctl->free_extents--;
2074                 if (entry->bitmap) {
2075                         kfree(entry->bitmap);
2076                         ctl->total_bitmaps--;
2077                         ctl->op->recalc_thresholds(ctl);
2078                 }
2079                 kmem_cache_free(btrfs_free_space_cachep, entry);
2080         }
2081
2082         spin_unlock(&ctl->tree_lock);
2083
2084         return ret;
2085 }
2086
2087 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
2088                                 struct btrfs_free_space *entry,
2089                                 struct btrfs_free_cluster *cluster,
2090                                 u64 offset, u64 bytes, u64 min_bytes)
2091 {
2092         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2093         unsigned long next_zero;
2094         unsigned long i;
2095         unsigned long search_bits;
2096         unsigned long total_bits;
2097         unsigned long found_bits;
2098         unsigned long start = 0;
2099         unsigned long total_found = 0;
2100         int ret;
2101         bool found = false;
2102
2103         i = offset_to_bit(entry->offset, block_group->sectorsize,
2104                           max_t(u64, offset, entry->offset));
2105         search_bits = bytes_to_bits(bytes, block_group->sectorsize);
2106         total_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
2107
2108 again:
2109         found_bits = 0;
2110         for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
2111              i < BITS_PER_BITMAP;
2112              i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
2113                 next_zero = find_next_zero_bit(entry->bitmap,
2114                                                BITS_PER_BITMAP, i);
2115                 if (next_zero - i >= search_bits) {
2116                         found_bits = next_zero - i;
2117                         break;
2118                 }
2119                 i = next_zero;
2120         }
2121
2122         if (!found_bits)
2123                 return -ENOSPC;
2124
2125         if (!found) {
2126                 start = i;
2127                 found = true;
2128         }
2129
2130         total_found += found_bits;
2131
2132         if (cluster->max_size < found_bits * block_group->sectorsize)
2133                 cluster->max_size = found_bits * block_group->sectorsize;
2134
2135         if (total_found < total_bits) {
2136                 i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero);
2137                 if (i - start > total_bits * 2) {
2138                         total_found = 0;
2139                         cluster->max_size = 0;
2140                         found = false;
2141                 }
2142                 goto again;
2143         }
2144
2145         cluster->window_start = start * block_group->sectorsize +
2146                 entry->offset;
2147         rb_erase(&entry->offset_index, &ctl->free_space_offset);
2148         ret = tree_insert_offset(&cluster->root, entry->offset,
2149                                  &entry->offset_index, 1);
2150         BUG_ON(ret);
2151
2152         return 0;
2153 }
2154
2155 /*
2156  * This searches the block group for just extents to fill the cluster with.
2157  */
2158 static noinline int
2159 setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
2160                         struct btrfs_free_cluster *cluster,
2161                         struct list_head *bitmaps, u64 offset, u64 bytes,
2162                         u64 min_bytes)
2163 {
2164         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2165         struct btrfs_free_space *first = NULL;
2166         struct btrfs_free_space *entry = NULL;
2167         struct btrfs_free_space *prev = NULL;
2168         struct btrfs_free_space *last;
2169         struct rb_node *node;
2170         u64 window_start;
2171         u64 window_free;
2172         u64 max_extent;
2173         u64 max_gap = 128 * 1024;
2174
2175         entry = tree_search_offset(ctl, offset, 0, 1);
2176         if (!entry)
2177                 return -ENOSPC;
2178
2179         /*
2180          * We don't want bitmaps, so just move along until we find a normal
2181          * extent entry.
2182          */
2183         while (entry->bitmap) {
2184                 if (list_empty(&entry->list))
2185                         list_add_tail(&entry->list, bitmaps);
2186                 node = rb_next(&entry->offset_index);
2187                 if (!node)
2188                         return -ENOSPC;
2189                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2190         }
2191
2192         window_start = entry->offset;
2193         window_free = entry->bytes;
2194         max_extent = entry->bytes;
2195         first = entry;
2196         last = entry;
2197         prev = entry;
2198
2199         while (window_free <= min_bytes) {
2200                 node = rb_next(&entry->offset_index);
2201                 if (!node)
2202                         return -ENOSPC;
2203                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2204
2205                 if (entry->bitmap) {
2206                         if (list_empty(&entry->list))
2207                                 list_add_tail(&entry->list, bitmaps);
2208                         continue;
2209                 }
2210
2211                 /*
2212                  * we haven't filled the empty size and the window is
2213                  * very large.  reset and try again
2214                  */
2215                 if (entry->offset - (prev->offset + prev->bytes) > max_gap ||
2216                     entry->offset - window_start > (min_bytes * 2)) {
2217                         first = entry;
2218                         window_start = entry->offset;
2219                         window_free = entry->bytes;
2220                         last = entry;
2221                         max_extent = entry->bytes;
2222                 } else {
2223                         last = entry;
2224                         window_free += entry->bytes;
2225                         if (entry->bytes > max_extent)
2226                                 max_extent = entry->bytes;
2227                 }
2228                 prev = entry;
2229         }
2230
2231         cluster->window_start = first->offset;
2232
2233         node = &first->offset_index;
2234
2235         /*
2236          * now we've found our entries, pull them out of the free space
2237          * cache and put them into the cluster rbtree
2238          */
2239         do {
2240                 int ret;
2241
2242                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2243                 node = rb_next(&entry->offset_index);
2244                 if (entry->bitmap)
2245                         continue;
2246
2247                 rb_erase(&entry->offset_index, &ctl->free_space_offset);
2248                 ret = tree_insert_offset(&cluster->root, entry->offset,
2249                                          &entry->offset_index, 0);
2250                 BUG_ON(ret);
2251         } while (node && entry != last);
2252
2253         cluster->max_size = max_extent;
2254
2255         return 0;
2256 }
2257
2258 /*
2259  * This specifically looks for bitmaps that may work in the cluster, we assume
2260  * that we have already failed to find extents that will work.
2261  */
2262 static noinline int
2263 setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2264                      struct btrfs_free_cluster *cluster,
2265                      struct list_head *bitmaps, u64 offset, u64 bytes,
2266                      u64 min_bytes)
2267 {
2268         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2269         struct btrfs_free_space *entry;
2270         struct rb_node *node;
2271         int ret = -ENOSPC;
2272
2273         if (ctl->total_bitmaps == 0)
2274                 return -ENOSPC;
2275
2276         /*
2277          * First check our cached list of bitmaps and see if there is an entry
2278          * here that will work.
2279          */
2280         list_for_each_entry(entry, bitmaps, list) {
2281                 if (entry->bytes < min_bytes)
2282                         continue;
2283                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2284                                            bytes, min_bytes);
2285                 if (!ret)
2286                         return 0;
2287         }
2288
2289         /*
2290          * If we do have entries on our list and we are here then we didn't find
2291          * anything, so go ahead and get the next entry after the last entry in
2292          * this list and start the search from there.
2293          */
2294         if (!list_empty(bitmaps)) {
2295                 entry = list_entry(bitmaps->prev, struct btrfs_free_space,
2296                                    list);
2297                 node = rb_next(&entry->offset_index);
2298                 if (!node)
2299                         return -ENOSPC;
2300                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2301                 goto search;
2302         }
2303
2304         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, offset), 0, 1);
2305         if (!entry)
2306                 return -ENOSPC;
2307
2308 search:
2309         node = &entry->offset_index;
2310         do {
2311                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2312                 node = rb_next(&entry->offset_index);
2313                 if (!entry->bitmap)
2314                         continue;
2315                 if (entry->bytes < min_bytes)
2316                         continue;
2317                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2318                                            bytes, min_bytes);
2319         } while (ret && node);
2320
2321         return ret;
2322 }
2323
2324 /*
2325  * here we try to find a cluster of blocks in a block group.  The goal
2326  * is to find at least bytes free and up to empty_size + bytes free.
2327  * We might not find them all in one contiguous area.
2328  *
2329  * returns zero and sets up cluster if things worked out, otherwise
2330  * it returns -enospc
2331  */
2332 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
2333                              struct btrfs_root *root,
2334                              struct btrfs_block_group_cache *block_group,
2335                              struct btrfs_free_cluster *cluster,
2336                              u64 offset, u64 bytes, u64 empty_size)
2337 {
2338         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2339         struct list_head bitmaps;
2340         struct btrfs_free_space *entry, *tmp;
2341         u64 min_bytes;
2342         int ret;
2343
2344         /* for metadata, allow allocates with more holes */
2345         if (btrfs_test_opt(root, SSD_SPREAD)) {
2346                 min_bytes = bytes + empty_size;
2347         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
2348                 /*
2349                  * we want to do larger allocations when we are
2350                  * flushing out the delayed refs, it helps prevent
2351                  * making more work as we go along.
2352                  */
2353                 if (trans->transaction->delayed_refs.flushing)
2354                         min_bytes = max(bytes, (bytes + empty_size) >> 1);
2355                 else
2356                         min_bytes = max(bytes, (bytes + empty_size) >> 4);
2357         } else
2358                 min_bytes = max(bytes, (bytes + empty_size) >> 2);
2359
2360         spin_lock(&ctl->tree_lock);
2361
2362         /*
2363          * If we know we don't have enough space to make a cluster don't even
2364          * bother doing all the work to try and find one.
2365          */
2366         if (ctl->free_space < min_bytes) {
2367                 spin_unlock(&ctl->tree_lock);
2368                 return -ENOSPC;
2369         }
2370
2371         spin_lock(&cluster->lock);
2372
2373         /* someone already found a cluster, hooray */
2374         if (cluster->block_group) {
2375                 ret = 0;
2376                 goto out;
2377         }
2378
2379         INIT_LIST_HEAD(&bitmaps);
2380         ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
2381                                       bytes, min_bytes);
2382         if (ret)
2383                 ret = setup_cluster_bitmap(block_group, cluster, &bitmaps,
2384                                            offset, bytes, min_bytes);
2385
2386         /* Clear our temporary list */
2387         list_for_each_entry_safe(entry, tmp, &bitmaps, list)
2388                 list_del_init(&entry->list);
2389
2390         if (!ret) {
2391                 atomic_inc(&block_group->count);
2392                 list_add_tail(&cluster->block_group_list,
2393                               &block_group->cluster_list);
2394                 cluster->block_group = block_group;
2395         }
2396 out:
2397         spin_unlock(&cluster->lock);
2398         spin_unlock(&ctl->tree_lock);
2399
2400         return ret;
2401 }
2402
2403 /*
2404  * simple code to zero out a cluster
2405  */
2406 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
2407 {
2408         spin_lock_init(&cluster->lock);
2409         spin_lock_init(&cluster->refill_lock);
2410         cluster->root = RB_ROOT;
2411         cluster->max_size = 0;
2412         INIT_LIST_HEAD(&cluster->block_group_list);
2413         cluster->block_group = NULL;
2414 }
2415
2416 int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
2417                            u64 *trimmed, u64 start, u64 end, u64 minlen)
2418 {
2419         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2420         struct btrfs_free_space *entry = NULL;
2421         struct btrfs_fs_info *fs_info = block_group->fs_info;
2422         u64 bytes = 0;
2423         u64 actually_trimmed;
2424         int ret = 0;
2425
2426         *trimmed = 0;
2427
2428         while (start < end) {
2429                 spin_lock(&ctl->tree_lock);
2430
2431                 if (ctl->free_space < minlen) {
2432                         spin_unlock(&ctl->tree_lock);
2433                         break;
2434                 }
2435
2436                 entry = tree_search_offset(ctl, start, 0, 1);
2437                 if (!entry)
2438                         entry = tree_search_offset(ctl,
2439                                                    offset_to_bitmap(ctl, start),
2440                                                    1, 1);
2441
2442                 if (!entry || entry->offset >= end) {
2443                         spin_unlock(&ctl->tree_lock);
2444                         break;
2445                 }
2446
2447                 if (entry->bitmap) {
2448                         ret = search_bitmap(ctl, entry, &start, &bytes);
2449                         if (!ret) {
2450                                 if (start >= end) {
2451                                         spin_unlock(&ctl->tree_lock);
2452                                         break;
2453                                 }
2454                                 bytes = min(bytes, end - start);
2455                                 bitmap_clear_bits(ctl, entry, start, bytes);
2456                                 if (entry->bytes == 0)
2457                                         free_bitmap(ctl, entry);
2458                         } else {
2459                                 start = entry->offset + BITS_PER_BITMAP *
2460                                         block_group->sectorsize;
2461                                 spin_unlock(&ctl->tree_lock);
2462                                 ret = 0;
2463                                 continue;
2464                         }
2465                 } else {
2466                         start = entry->offset;
2467                         bytes = min(entry->bytes, end - start);
2468                         unlink_free_space(ctl, entry);
2469                         kmem_cache_free(btrfs_free_space_cachep, entry);
2470                 }
2471
2472                 spin_unlock(&ctl->tree_lock);
2473
2474                 if (bytes >= minlen) {
2475                         int update_ret;
2476                         update_ret = btrfs_update_reserved_bytes(block_group,
2477                                                                  bytes, 1, 1);
2478
2479                         ret = btrfs_error_discard_extent(fs_info->extent_root,
2480                                                          start,
2481                                                          bytes,
2482                                                          &actually_trimmed);
2483
2484                         btrfs_add_free_space(block_group, start, bytes);
2485                         if (!update_ret)
2486                                 btrfs_update_reserved_bytes(block_group,
2487                                                             bytes, 0, 1);
2488
2489                         if (ret)
2490                                 break;
2491                         *trimmed += actually_trimmed;
2492                 }
2493                 start += bytes;
2494                 bytes = 0;
2495
2496                 if (fatal_signal_pending(current)) {
2497                         ret = -ERESTARTSYS;
2498                         break;
2499                 }
2500
2501                 cond_resched();
2502         }
2503
2504         return ret;
2505 }
2506
2507 /*
2508  * Find the left-most item in the cache tree, and then return the
2509  * smallest inode number in the item.
2510  *
2511  * Note: the returned inode number may not be the smallest one in
2512  * the tree, if the left-most item is a bitmap.
2513  */
2514 u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root)
2515 {
2516         struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl;
2517         struct btrfs_free_space *entry = NULL;
2518         u64 ino = 0;
2519
2520         spin_lock(&ctl->tree_lock);
2521
2522         if (RB_EMPTY_ROOT(&ctl->free_space_offset))
2523                 goto out;
2524
2525         entry = rb_entry(rb_first(&ctl->free_space_offset),
2526                          struct btrfs_free_space, offset_index);
2527
2528         if (!entry->bitmap) {
2529                 ino = entry->offset;
2530
2531                 unlink_free_space(ctl, entry);
2532                 entry->offset++;
2533                 entry->bytes--;
2534                 if (!entry->bytes)
2535                         kmem_cache_free(btrfs_free_space_cachep, entry);
2536                 else
2537                         link_free_space(ctl, entry);
2538         } else {
2539                 u64 offset = 0;
2540                 u64 count = 1;
2541                 int ret;
2542
2543                 ret = search_bitmap(ctl, entry, &offset, &count);
2544                 BUG_ON(ret);
2545
2546                 ino = offset;
2547                 bitmap_clear_bits(ctl, entry, offset, 1);
2548                 if (entry->bytes == 0)
2549                         free_bitmap(ctl, entry);
2550         }
2551 out:
2552         spin_unlock(&ctl->tree_lock);
2553
2554         return ino;
2555 }
2556
2557 struct inode *lookup_free_ino_inode(struct btrfs_root *root,
2558                                     struct btrfs_path *path)
2559 {
2560         struct inode *inode = NULL;
2561
2562         spin_lock(&root->cache_lock);
2563         if (root->cache_inode)
2564                 inode = igrab(root->cache_inode);
2565         spin_unlock(&root->cache_lock);
2566         if (inode)
2567                 return inode;
2568
2569         inode = __lookup_free_space_inode(root, path, 0);
2570         if (IS_ERR(inode))
2571                 return inode;
2572
2573         spin_lock(&root->cache_lock);
2574         if (!btrfs_fs_closing(root->fs_info))
2575                 root->cache_inode = igrab(inode);
2576         spin_unlock(&root->cache_lock);
2577
2578         return inode;
2579 }
2580
2581 int create_free_ino_inode(struct btrfs_root *root,
2582                           struct btrfs_trans_handle *trans,
2583                           struct btrfs_path *path)
2584 {
2585         return __create_free_space_inode(root, trans, path,
2586                                          BTRFS_FREE_INO_OBJECTID, 0);
2587 }
2588
2589 int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
2590 {
2591         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2592         struct btrfs_path *path;
2593         struct inode *inode;
2594         int ret = 0;
2595         u64 root_gen = btrfs_root_generation(&root->root_item);
2596
2597         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
2598                 return 0;
2599
2600         /*
2601          * If we're unmounting then just return, since this does a search on the
2602          * normal root and not the commit root and we could deadlock.
2603          */
2604         if (btrfs_fs_closing(fs_info))
2605                 return 0;
2606
2607         path = btrfs_alloc_path();
2608         if (!path)
2609                 return 0;
2610
2611         inode = lookup_free_ino_inode(root, path);
2612         if (IS_ERR(inode))
2613                 goto out;
2614
2615         if (root_gen != BTRFS_I(inode)->generation)
2616                 goto out_put;
2617
2618         ret = __load_free_space_cache(root, inode, ctl, path, 0);
2619
2620         if (ret < 0)
2621                 printk(KERN_ERR "btrfs: failed to load free ino cache for "
2622                        "root %llu\n", root->root_key.objectid);
2623 out_put:
2624         iput(inode);
2625 out:
2626         btrfs_free_path(path);
2627         return ret;
2628 }
2629
2630 int btrfs_write_out_ino_cache(struct btrfs_root *root,
2631                               struct btrfs_trans_handle *trans,
2632                               struct btrfs_path *path)
2633 {
2634         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2635         struct inode *inode;
2636         int ret;
2637
2638         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
2639                 return 0;
2640
2641         inode = lookup_free_ino_inode(root, path);
2642         if (IS_ERR(inode))
2643                 return 0;
2644
2645         ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);
2646         if (ret < 0)
2647                 printk(KERN_ERR "btrfs: failed to write free ino cache "
2648                        "for root %llu\n", root->root_key.objectid);
2649
2650         iput(inode);
2651         return ret;
2652 }