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 (!root->fs_info->closing) {
 102                 block_group->inode = igrab(inode);
 103                 block_group->iref = 1;
 104         }
 105         spin_unlock(&block_group->lock);
 106
 107         return inode;
 108 }
 109
 110 int __create_free_space_inode(struct btrfs_root *root,
 111                               struct btrfs_trans_handle *trans,
 112                               struct btrfs_path *path, u64 ino, u64 offset)
 113 {
 114         struct btrfs_key key;
 115         struct btrfs_disk_key disk_key;
 116         struct btrfs_free_space_header *header;
 117         struct btrfs_inode_item *inode_item;
 118         struct extent_buffer *leaf;
 119         int ret;
 120
 121         ret = btrfs_insert_empty_inode(trans, root, path, ino);
 122         if (ret)
 123                 return ret;
 124
 125         leaf = path->nodes[0];
 126         inode_item = btrfs_item_ptr(leaf, path->slots[0],
 127                                     struct btrfs_inode_item);
 128         btrfs_item_key(leaf, &disk_key, path->slots[0]);
 129         memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
 130                              sizeof(*inode_item));
 131         btrfs_set_inode_generation(leaf, inode_item, trans->transid);
 132         btrfs_set_inode_size(leaf, inode_item, 0);
 133         btrfs_set_inode_nbytes(leaf, inode_item, 0);
 134         btrfs_set_inode_uid(leaf, inode_item, 0);
 135         btrfs_set_inode_gid(leaf, inode_item, 0);
 136         btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
 137         btrfs_set_inode_flags(leaf, inode_item, BTRFS_INODE_NOCOMPRESS |
 138                               BTRFS_INODE_PREALLOC | BTRFS_INODE_NODATASUM);
 139         btrfs_set_inode_nlink(leaf, inode_item, 1);
 140         btrfs_set_inode_transid(leaf, inode_item, trans->transid);
 141         btrfs_set_inode_block_group(leaf, inode_item, offset);
 142         btrfs_mark_buffer_dirty(leaf);
 143         btrfs_release_path(path);
 144
 145         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 146         key.offset = offset;
 147         key.type = 0;
 148
 149         ret = btrfs_insert_empty_item(trans, root, path, &key,
 150                                       sizeof(struct btrfs_free_space_header));
 151         if (ret < 0) {
 152                 btrfs_release_path(path);
 153                 return ret;
 154         }
 155         leaf = path->nodes[0];
 156         header = btrfs_item_ptr(leaf, path->slots[0],
 157                                 struct btrfs_free_space_header);
 158         memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
 159         btrfs_set_free_space_key(leaf, header, &disk_key);
 160         btrfs_mark_buffer_dirty(leaf);
 161         btrfs_release_path(path);
 162
 163         return 0;
 164 }
 165
 166 int create_free_space_inode(struct btrfs_root *root,
 167                             struct btrfs_trans_handle *trans,
 168                             struct btrfs_block_group_cache *block_group,
 169                             struct btrfs_path *path)
 170 {
 171         int ret;
 172         u64 ino;
 173
 174         ret = btrfs_find_free_objectid(root, &ino);
 175         if (ret < 0)
 176                 return ret;
 177
 178         return __create_free_space_inode(root, trans, path, ino,
 179                                          block_group->key.objectid);
 180 }
 181
 182 int btrfs_truncate_free_space_cache(struct btrfs_root *root,
 183                                     struct btrfs_trans_handle *trans,
 184                                     struct btrfs_path *path,
 185                                     struct inode *inode)
 186 {
 187         loff_t oldsize;
 188         int ret = 0;
 189
 190         trans->block_rsv = root->orphan_block_rsv;
 191         ret = btrfs_block_rsv_check(trans, root,
 192                                     root->orphan_block_rsv,
 193                                     0, 5);
 194         if (ret)
 195                 return ret;
 196
 197         oldsize = i_size_read(inode);
 198         btrfs_i_size_write(inode, 0);
 199         truncate_pagecache(inode, oldsize, 0);
 200
 201         /*
 202          * We don't need an orphan item because truncating the free space cache
 203          * will never be split across transactions.
 204          */
 205         ret = btrfs_truncate_inode_items(trans, root, inode,
 206                                          0, BTRFS_EXTENT_DATA_KEY);
 207         if (ret) {
 208                 WARN_ON(1);
 209                 return ret;
 210         }
 211
 212         ret = btrfs_update_inode(trans, root, inode);
 213         return ret;
 214 }
 215
 216 static int readahead_cache(struct inode *inode)
 217 {
 218         struct file_ra_state *ra;
 219         unsigned long last_index;
 220
 221         ra = kzalloc(sizeof(*ra), GFP_NOFS);
 222         if (!ra)
 223                 return -ENOMEM;
 224
 225         file_ra_state_init(ra, inode->i_mapping);
 226         last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 227
 228         page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
 229
 230         kfree(ra);
 231
 232         return 0;
 233 }
 234
 235 int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 236                             struct btrfs_free_space_ctl *ctl,
 237                             struct btrfs_path *path, u64 offset)
 238 {
 239         struct btrfs_free_space_header *header;
 240         struct extent_buffer *leaf;
 241         struct page *page;
 242         u32 *checksums = NULL, *crc;
 243         char *disk_crcs = NULL;
 244         struct btrfs_key key;
 245         struct list_head bitmaps;
 246         u64 num_entries;
 247         u64 num_bitmaps;
 248         u64 generation;
 249         u32 cur_crc = ~(u32)0;
 250         pgoff_t index = 0;
 251         unsigned long first_page_offset;
 252         int num_checksums;
 253         int ret = 0, ret2;
 254
 255         INIT_LIST_HEAD(&bitmaps);
 256
 257         /* Nothing in the space cache, goodbye */
 258         if (!i_size_read(inode))
 259                 goto out;
 260
 261         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 262         key.offset = offset;
 263         key.type = 0;
 264
 265         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 266         if (ret < 0)
 267                 goto out;
 268         else if (ret > 0) {
 269                 btrfs_release_path(path);
 270                 ret = 0;
 271                 goto out;
 272         }
 273
 274         ret = -1;
 275
 276         leaf = path->nodes[0];
 277         header = btrfs_item_ptr(leaf, path->slots[0],
 278                                 struct btrfs_free_space_header);
 279         num_entries = btrfs_free_space_entries(leaf, header);
 280         num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
 281         generation = btrfs_free_space_generation(leaf, header);
 282         btrfs_release_path(path);
 283
 284         if (BTRFS_I(inode)->generation != generation) {
 285                 printk(KERN_ERR "btrfs: free space inode generation (%llu) did"
 286                        " not match free space cache generation (%llu)\n",
 287                        (unsigned long long)BTRFS_I(inode)->generation,
 288                        (unsigned long long)generation);
 289                 goto out;
 290         }
 291
 292         if (!num_entries)
 293                 goto out;
 294
 295         /* Setup everything for doing checksumming */
 296         num_checksums = i_size_read(inode) / PAGE_CACHE_SIZE;
 297         checksums = crc = kzalloc(sizeof(u32) * num_checksums, GFP_NOFS);
 298         if (!checksums)
 299                 goto out;
 300         first_page_offset = (sizeof(u32) * num_checksums) + sizeof(u64);
 301         disk_crcs = kzalloc(first_page_offset, GFP_NOFS);
 302         if (!disk_crcs)
 303                 goto out;
 304
 305         ret = readahead_cache(inode);
 306         if (ret)
 307                 goto out;
 308
 309         while (1) {
 310                 struct btrfs_free_space_entry *entry;
 311                 struct btrfs_free_space *e;
 312                 void *addr;
 313                 unsigned long offset = 0;
 314                 unsigned long start_offset = 0;
 315                 int need_loop = 0;
 316
 317                 if (!num_entries && !num_bitmaps)
 318                         break;
 319
 320                 if (index == 0) {
 321                         start_offset = first_page_offset;
 322                         offset = start_offset;
 323                 }
 324
 325                 page = grab_cache_page(inode->i_mapping, index);
 326                 if (!page)
 327                         goto free_cache;
 328
 329                 if (!PageUptodate(page)) {
 330                         btrfs_readpage(NULL, page);
 331                         lock_page(page);
 332                         if (!PageUptodate(page)) {
 333                                 unlock_page(page);
 334                                 page_cache_release(page);
 335                                 printk(KERN_ERR "btrfs: error reading free "
 336                                        "space cache\n");
 337                                 goto free_cache;
 338                         }
 339                 }
 340                 addr = kmap(page);
 341
 342                 if (index == 0) {
 343                         u64 *gen;
 344
 345                         memcpy(disk_crcs, addr, first_page_offset);
 346                         gen = addr + (sizeof(u32) * num_checksums);
 347                         if (*gen != BTRFS_I(inode)->generation) {
 348                                 printk(KERN_ERR "btrfs: space cache generation"
 349                                        " (%llu) does not match inode (%llu)\n",
 350                                        (unsigned long long)*gen,
 351                                        (unsigned long long)
 352                                        BTRFS_I(inode)->generation);
 353                                 kunmap(page);
 354                                 unlock_page(page);
 355                                 page_cache_release(page);
 356                                 goto free_cache;
 357                         }
 358                         crc = (u32 *)disk_crcs;
 359                 }
 360                 entry = addr + start_offset;
 361
 362                 /* First lets check our crc before we do anything fun */
 363                 cur_crc = ~(u32)0;
 364                 cur_crc = btrfs_csum_data(root, addr + start_offset, cur_crc,
 365                                           PAGE_CACHE_SIZE - start_offset);
 366                 btrfs_csum_final(cur_crc, (char *)&cur_crc);
 367                 if (cur_crc != *crc) {
 368                         printk(KERN_ERR "btrfs: crc mismatch for page %lu\n",
 369                                index);
 370                         kunmap(page);
 371                         unlock_page(page);
 372                         page_cache_release(page);
 373                         goto free_cache;
 374                 }
 375                 crc++;
 376
 377                 while (1) {
 378                         if (!num_entries)
 379                                 break;
 380
 381                         need_loop = 1;
 382                         e = kmem_cache_zalloc(btrfs_free_space_cachep,
 383                                               GFP_NOFS);
 384                         if (!e) {
 385                                 kunmap(page);
 386                                 unlock_page(page);
 387                                 page_cache_release(page);
 388                                 goto free_cache;
 389                         }
 390
 391                         e->offset = le64_to_cpu(entry->offset);
 392                         e->bytes = le64_to_cpu(entry->bytes);
 393                         if (!e->bytes) {
 394                                 kunmap(page);
 395                                 kmem_cache_free(btrfs_free_space_cachep, e);
 396                                 unlock_page(page);
 397                                 page_cache_release(page);
 398                                 goto free_cache;
 399                         }
 400
 401                         if (entry->type == BTRFS_FREE_SPACE_EXTENT) {
 402                                 spin_lock(&ctl->tree_lock);
 403                                 ret = link_free_space(ctl, e);
 404                                 spin_unlock(&ctl->tree_lock);
 405                                 BUG_ON(ret);
 406                         } else {
 407                                 e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
 408                                 if (!e->bitmap) {
 409                                         kunmap(page);
 410                                         kmem_cache_free(
 411                                                 btrfs_free_space_cachep, e);
 412                                         unlock_page(page);
 413                                         page_cache_release(page);
 414                                         goto free_cache;
 415                                 }
 416                                 spin_lock(&ctl->tree_lock);
 417                                 ret2 = link_free_space(ctl, e);
 418                                 ctl->total_bitmaps++;
 419                                 ctl->op->recalc_thresholds(ctl);
 420                                 spin_unlock(&ctl->tree_lock);
 421                                 list_add_tail(&e->list, &bitmaps);
 422                         }
 423
 424                         num_entries--;
 425                         offset += sizeof(struct btrfs_free_space_entry);
 426                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 427                             PAGE_CACHE_SIZE)
 428                                 break;
 429                         entry++;
 430                 }
 431
 432                 /*
 433                  * We read an entry out of this page, we need to move on to the
 434                  * next page.
 435                  */
 436                 if (need_loop) {
 437                         kunmap(page);
 438                         goto next;
 439                 }
 440
 441                 /*
 442                  * We add the bitmaps at the end of the entries in order that
 443                  * the bitmap entries are added to the cache.
 444                  */
 445                 e = list_entry(bitmaps.next, struct btrfs_free_space, list);
 446                 list_del_init(&e->list);
 447                 memcpy(e->bitmap, addr, PAGE_CACHE_SIZE);
 448                 kunmap(page);
 449                 num_bitmaps--;
 450 next:
 451                 unlock_page(page);
 452                 page_cache_release(page);
 453                 index++;
 454         }
 455
 456         ret = 1;
 457 out:
 458         kfree(checksums);
 459         kfree(disk_crcs);
 460         return ret;
 461 free_cache:
 462         __btrfs_remove_free_space_cache(ctl);
 463         goto out;
 464 }
 465
 466 int load_free_space_cache(struct btrfs_fs_info *fs_info,
 467                           struct btrfs_block_group_cache *block_group)
 468 {
 469         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 470         struct btrfs_root *root = fs_info->tree_root;
 471         struct inode *inode;
 472         struct btrfs_path *path;
 473         int ret;
 474         bool matched;
 475         u64 used = btrfs_block_group_used(&block_group->item);
 476
 477         /*
 478          * If we're unmounting then just return, since this does a search on the
 479          * normal root and not the commit root and we could deadlock.
 480          */
 481         smp_mb();
 482         if (fs_info->closing)
 483                 return 0;
 484
 485         /*
 486          * If this block group has been marked to be cleared for one reason or
 487          * another then we can't trust the on disk cache, so just return.
 488          */
 489         spin_lock(&block_group->lock);
 490         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 491                 spin_unlock(&block_group->lock);
 492                 return 0;
 493         }
 494         spin_unlock(&block_group->lock);
 495
 496         path = btrfs_alloc_path();
 497         if (!path)
 498                 return 0;
 499
 500         inode = lookup_free_space_inode(root, block_group, path);
 501         if (IS_ERR(inode)) {
 502                 btrfs_free_path(path);
 503                 return 0;
 504         }
 505
 506         ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
 507                                       path, block_group->key.objectid);
 508         btrfs_free_path(path);
 509         if (ret <= 0)
 510                 goto out;
 511
 512         spin_lock(&ctl->tree_lock);
 513         matched = (ctl->free_space == (block_group->key.offset - used -
 514                                        block_group->bytes_super));
 515         spin_unlock(&ctl->tree_lock);
 516
 517         if (!matched) {
 518                 __btrfs_remove_free_space_cache(ctl);
 519                 printk(KERN_ERR "block group %llu has an wrong amount of free "
 520                        "space\n", block_group->key.objectid);
 521                 ret = -1;
 522         }
 523 out:
 524         if (ret < 0) {
 525                 /* This cache is bogus, make sure it gets cleared */
 526                 spin_lock(&block_group->lock);
 527                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 528                 spin_unlock(&block_group->lock);
 529                 ret = 0;
 530
 531                 printk(KERN_ERR "btrfs: failed to load free space cache "
 532                        "for block group %llu\n", block_group->key.objectid);
 533         }
 534
 535         iput(inode);
 536         return ret;
 537 }
 538
 539 int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 540                             struct btrfs_free_space_ctl *ctl,
 541                             struct btrfs_block_group_cache *block_group,
 542                             struct btrfs_trans_handle *trans,
 543                             struct btrfs_path *path, u64 offset)
 544 {
 545         struct btrfs_free_space_header *header;
 546         struct extent_buffer *leaf;
 547         struct rb_node *node;
 548         struct list_head *pos, *n;
 549         struct page **pages;
 550         struct page *page;
 551         struct extent_state *cached_state = NULL;
 552         struct btrfs_free_cluster *cluster = NULL;
 553         struct extent_io_tree *unpin = NULL;
 554         struct list_head bitmap_list;
 555         struct btrfs_key key;
 556         u64 start, end, len;
 557         u64 bytes = 0;
 558         u32 *crc, *checksums;
 559         unsigned long first_page_offset;
 560         int index = 0, num_pages = 0;
 561         int entries = 0;
 562         int bitmaps = 0;
 563         int ret = -1;
 564         bool next_page = false;
 565         bool out_of_space = false;
 566
 567         INIT_LIST_HEAD(&bitmap_list);
 568
 569         node = rb_first(&ctl->free_space_offset);
 570         if (!node)
 571                 return 0;
 572
 573         if (!i_size_read(inode))
 574                 return -1;
 575
 576         num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
 577                 PAGE_CACHE_SHIFT;
 578         filemap_write_and_wait(inode->i_mapping);
 579         btrfs_wait_ordered_range(inode, inode->i_size &
 580                                  ~(root->sectorsize - 1), (u64)-1);
 581
 582         /* We need a checksum per page. */
 583         crc = checksums = kzalloc(sizeof(u32) * num_pages, GFP_NOFS);
 584         if (!crc)
 585                 return -1;
 586
 587         pages = kzalloc(sizeof(struct page *) * num_pages, GFP_NOFS);
 588         if (!pages) {
 589                 kfree(crc);
 590                 return -1;
 591         }
 592
 593         /* Since the first page has all of our checksums and our generation we
 594          * need to calculate the offset into the page that we can start writing
 595          * our entries.
 596          */
 597         first_page_offset = (sizeof(u32) * num_pages) + sizeof(u64);
 598
 599         /* Get the cluster for this block_group if it exists */
 600         if (block_group && !list_empty(&block_group->cluster_list))
 601                 cluster = list_entry(block_group->cluster_list.next,
 602                                      struct btrfs_free_cluster,
 603                                      block_group_list);
 604
 605         /*
 606          * We shouldn't have switched the pinned extents yet so this is the
 607          * right one
 608          */
 609         unpin = root->fs_info->pinned_extents;
 610
 611         /*
 612          * Lock all pages first so we can lock the extent safely.
 613          *
 614          * NOTE: Because we hold the ref the entire time we're going to write to
 615          * the page find_get_page should never fail, so we don't do a check
 616          * after find_get_page at this point.  Just putting this here so people
 617          * know and don't freak out.
 618          */
 619         while (index < num_pages) {
 620                 page = grab_cache_page(inode->i_mapping, index);
 621                 if (!page) {
 622                         int i;
 623
 624                         for (i = 0; i < num_pages; i++) {
 625                                 unlock_page(pages[i]);
 626                                 page_cache_release(pages[i]);
 627                         }
 628                         goto out_free;
 629                 }
 630                 pages[index] = page;
 631                 index++;
 632         }
 633
 634         index = 0;
 635         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
 636                          0, &cached_state, GFP_NOFS);
 637
 638         /*
 639          * When searching for pinned extents, we need to start at our start
 640          * offset.
 641          */
 642         if (block_group)
 643                 start = block_group->key.objectid;
 644
 645         /* Write out the extent entries */
 646         do {
 647                 struct btrfs_free_space_entry *entry;
 648                 void *addr;
 649                 unsigned long offset = 0;
 650                 unsigned long start_offset = 0;
 651
 652                 next_page = false;
 653
 654                 if (index == 0) {
 655                         start_offset = first_page_offset;
 656                         offset = start_offset;
 657                 }
 658
 659                 if (index >= num_pages) {
 660                         out_of_space = true;
 661                         break;
 662                 }
 663
 664                 page = pages[index];
 665
 666                 addr = kmap(page);
 667                 entry = addr + start_offset;
 668
 669                 memset(addr, 0, PAGE_CACHE_SIZE);
 670                 while (node && !next_page) {
 671                         struct btrfs_free_space *e;
 672
 673                         e = rb_entry(node, struct btrfs_free_space, offset_index);
 674                         entries++;
 675
 676                         entry->offset = cpu_to_le64(e->offset);
 677                         entry->bytes = cpu_to_le64(e->bytes);
 678                         if (e->bitmap) {
 679                                 entry->type = BTRFS_FREE_SPACE_BITMAP;
 680                                 list_add_tail(&e->list, &bitmap_list);
 681                                 bitmaps++;
 682                         } else {
 683                                 entry->type = BTRFS_FREE_SPACE_EXTENT;
 684                         }
 685                         node = rb_next(node);
 686                         if (!node && cluster) {
 687                                 node = rb_first(&cluster->root);
 688                                 cluster = NULL;
 689                         }
 690                         offset += sizeof(struct btrfs_free_space_entry);
 691                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 692                             PAGE_CACHE_SIZE)
 693                                 next_page = true;
 694                         entry++;
 695                 }
 696
 697                 /*
 698                  * We want to add any pinned extents to our free space cache
 699                  * so we don't leak the space
 700                  */
 701                 while (block_group && !next_page &&
 702                        (start < block_group->key.objectid +
 703                         block_group->key.offset)) {
 704                         ret = find_first_extent_bit(unpin, start, &start, &end,
 705                                                     EXTENT_DIRTY);
 706                         if (ret) {
 707                                 ret = 0;
 708                                 break;
 709                         }
 710
 711                         /* This pinned extent is out of our range */
 712                         if (start >= block_group->key.objectid +
 713                             block_group->key.offset)
 714                                 break;
 715
 716                         len = block_group->key.objectid +
 717                                 block_group->key.offset - start;
 718                         len = min(len, end + 1 - start);
 719
 720                         entries++;
 721                         entry->offset = cpu_to_le64(start);
 722                         entry->bytes = cpu_to_le64(len);
 723                         entry->type = BTRFS_FREE_SPACE_EXTENT;
 724
 725                         start = end + 1;
 726                         offset += sizeof(struct btrfs_free_space_entry);
 727                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 728                             PAGE_CACHE_SIZE)
 729                                 next_page = true;
 730                         entry++;
 731                 }
 732                 *crc = ~(u32)0;
 733                 *crc = btrfs_csum_data(root, addr + start_offset, *crc,
 734                                        PAGE_CACHE_SIZE - start_offset);
 735                 kunmap(page);
 736
 737                 btrfs_csum_final(*crc, (char *)crc);
 738                 crc++;
 739
 740                 bytes += PAGE_CACHE_SIZE;
 741
 742                 index++;
 743         } while (node || next_page);
 744
 745         /* Write out the bitmaps */
 746         list_for_each_safe(pos, n, &bitmap_list) {
 747                 void *addr;
 748                 struct btrfs_free_space *entry =
 749                         list_entry(pos, struct btrfs_free_space, list);
 750
 751                 if (index >= num_pages) {
 752                         out_of_space = true;
 753                         break;
 754                 }
 755                 page = pages[index];
 756
 757                 addr = kmap(page);
 758                 memcpy(addr, entry->bitmap, PAGE_CACHE_SIZE);
 759                 *crc = ~(u32)0;
 760                 *crc = btrfs_csum_data(root, addr, *crc, PAGE_CACHE_SIZE);
 761                 kunmap(page);
 762                 btrfs_csum_final(*crc, (char *)crc);
 763                 crc++;
 764                 bytes += PAGE_CACHE_SIZE;
 765
 766                 list_del_init(&entry->list);
 767                 index++;
 768         }
 769
 770         if (out_of_space) {
 771                 btrfs_drop_pages(pages, num_pages);
 772                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 773                                      i_size_read(inode) - 1, &cached_state,
 774                                      GFP_NOFS);
 775                 ret = 0;
 776                 goto out_free;
 777         }
 778
 779         /* Zero out the rest of the pages just to make sure */
 780         while (index < num_pages) {
 781                 void *addr;
 782
 783                 page = pages[index];
 784                 addr = kmap(page);
 785                 memset(addr, 0, PAGE_CACHE_SIZE);
 786                 kunmap(page);
 787                 bytes += PAGE_CACHE_SIZE;
 788                 index++;
 789         }
 790
 791         /* Write the checksums and trans id to the first page */
 792         {
 793                 void *addr;
 794                 u64 *gen;
 795
 796                 page = pages[0];
 797
 798                 addr = kmap(page);
 799                 memcpy(addr, checksums, sizeof(u32) * num_pages);
 800                 gen = addr + (sizeof(u32) * num_pages);
 801                 *gen = trans->transid;
 802                 kunmap(page);
 803         }
 804
 805         ret = btrfs_dirty_pages(root, inode, pages, num_pages, 0,
 806                                             bytes, &cached_state);
 807         btrfs_drop_pages(pages, num_pages);
 808         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 809                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
 810
 811         if (ret) {
 812                 ret = 0;
 813                 goto out_free;
 814         }
 815
 816         BTRFS_I(inode)->generation = trans->transid;
 817
 818         filemap_write_and_wait(inode->i_mapping);
 819
 820         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 821         key.offset = offset;
 822         key.type = 0;
 823
 824         ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
 825         if (ret < 0) {
 826                 ret = -1;
 827                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 828                                  EXTENT_DIRTY | EXTENT_DELALLOC |
 829                                  EXTENT_DO_ACCOUNTING, 0, 0, NULL, GFP_NOFS);
 830                 goto out_free;
 831         }
 832         leaf = path->nodes[0];
 833         if (ret > 0) {
 834                 struct btrfs_key found_key;
 835                 BUG_ON(!path->slots[0]);
 836                 path->slots[0]--;
 837                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 838                 if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
 839                     found_key.offset != offset) {
 840                         ret = -1;
 841                         clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 842                                          EXTENT_DIRTY | EXTENT_DELALLOC |
 843                                          EXTENT_DO_ACCOUNTING, 0, 0, NULL,
 844                                          GFP_NOFS);
 845                         btrfs_release_path(path);
 846                         goto out_free;
 847                 }
 848         }
 849         header = btrfs_item_ptr(leaf, path->slots[0],
 850                                 struct btrfs_free_space_header);
 851         btrfs_set_free_space_entries(leaf, header, entries);
 852         btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
 853         btrfs_set_free_space_generation(leaf, header, trans->transid);
 854         btrfs_mark_buffer_dirty(leaf);
 855         btrfs_release_path(path);
 856
 857         ret = 1;
 858
 859 out_free:
 860         if (ret != 1) {
 861                 invalidate_inode_pages2_range(inode->i_mapping, 0, index);
 862                 BTRFS_I(inode)->generation = 0;
 863         }
 864         kfree(checksums);
 865         kfree(pages);
 866         btrfs_update_inode(trans, root, inode);
 867         return ret;
 868 }
 869
 870 int btrfs_write_out_cache(struct btrfs_root *root,
 871                           struct btrfs_trans_handle *trans,
 872                           struct btrfs_block_group_cache *block_group,
 873                           struct btrfs_path *path)
 874 {
 875         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 876         struct inode *inode;
 877         int ret = 0;
 878
 879         root = root->fs_info->tree_root;
 880
 881         spin_lock(&block_group->lock);
 882         if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
 883                 spin_unlock(&block_group->lock);
 884                 return 0;
 885         }
 886         spin_unlock(&block_group->lock);
 887
 888         inode = lookup_free_space_inode(root, block_group, path);
 889         if (IS_ERR(inode))
 890                 return 0;
 891
 892         ret = __btrfs_write_out_cache(root, inode, ctl, block_group, trans,
 893                                       path, block_group->key.objectid);
 894         if (ret < 0) {
 895                 spin_lock(&block_group->lock);
 896                 block_group->disk_cache_state = BTRFS_DC_ERROR;
 897                 spin_unlock(&block_group->lock);
 898                 ret = 0;
 899
 900                 printk(KERN_ERR "btrfs: failed to write free space cace "
 901                        "for block group %llu\n", block_group->key.objectid);
 902         }
 903
 904         iput(inode);
 905         return ret;
 906 }
 907
 908 static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
 909                                           u64 offset)
 910 {
 911         BUG_ON(offset < bitmap_start);
 912         offset -= bitmap_start;
 913         return (unsigned long)(div_u64(offset, unit));
 914 }
 915
 916 static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
 917 {
 918         return (unsigned long)(div_u64(bytes, unit));
 919 }
 920
 921 static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
 922                                    u64 offset)
 923 {
 924         u64 bitmap_start;
 925         u64 bytes_per_bitmap;
 926
 927         bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
 928         bitmap_start = offset - ctl->start;
 929         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
 930         bitmap_start *= bytes_per_bitmap;
 931         bitmap_start += ctl->start;
 932
 933         return bitmap_start;
 934 }
 935
 936 static int tree_insert_offset(struct rb_root *root, u64 offset,
 937                               struct rb_node *node, int bitmap)
 938 {
 939         struct rb_node **p = &root->rb_node;
 940         struct rb_node *parent = NULL;
 941         struct btrfs_free_space *info;
 942
 943         while (*p) {
 944                 parent = *p;
 945                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
 946
 947                 if (offset < info->offset) {
 948                         p = &(*p)->rb_left;
 949                 } else if (offset > info->offset) {
 950                         p = &(*p)->rb_right;
 951                 } else {
 952                         /*
 953                          * we could have a bitmap entry and an extent entry
 954                          * share the same offset.  If this is the case, we want
 955                          * the extent entry to always be found first if we do a
 956                          * linear search through the tree, since we want to have
 957                          * the quickest allocation time, and allocating from an
 958                          * extent is faster than allocating from a bitmap.  So
 959                          * if we're inserting a bitmap and we find an entry at
 960                          * this offset, we want to go right, or after this entry
 961                          * logically.  If we are inserting an extent and we've
 962                          * found a bitmap, we want to go left, or before
 963                          * logically.
 964                          */
 965                         if (bitmap) {
 966                                 WARN_ON(info->bitmap);
 967                                 p = &(*p)->rb_right;
 968                         } else {
 969                                 WARN_ON(!info->bitmap);
 970                                 p = &(*p)->rb_left;
 971                         }
 972                 }
 973         }
 974
 975         rb_link_node(node, parent, p);
 976         rb_insert_color(node, root);
 977
 978         return 0;
 979 }
 980
 981 /*
 982  * searches the tree for the given offset.
 983  *
 984  * fuzzy - If this is set, then we are trying to make an allocation, and we just
 985  * want a section that has at least bytes size and comes at or after the given
 986  * offset.
 987  */
 988 static struct btrfs_free_space *
 989 tree_search_offset(struct btrfs_free_space_ctl *ctl,
 990                    u64 offset, int bitmap_only, int fuzzy)
 991 {
 992         struct rb_node *n = ctl->free_space_offset.rb_node;
 993         struct btrfs_free_space *entry, *prev = NULL;
 994
 995         /* find entry that is closest to the 'offset' */
 996         while (1) {
 997                 if (!n) {
 998                         entry = NULL;
 999                         break;
1000                 }
1001
1002                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1003                 prev = entry;
1004
1005                 if (offset < entry->offset)
1006                         n = n->rb_left;
1007                 else if (offset > entry->offset)
1008                         n = n->rb_right;
1009                 else
1010                         break;
1011         }
1012
1013         if (bitmap_only) {
1014                 if (!entry)
1015                         return NULL;
1016                 if (entry->bitmap)
1017                         return entry;
1018
1019                 /*
1020                  * bitmap entry and extent entry may share same offset,
1021                  * in that case, bitmap entry comes after extent entry.
1022                  */
1023                 n = rb_next(n);
1024                 if (!n)
1025                         return NULL;
1026                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1027                 if (entry->offset != offset)
1028                         return NULL;
1029
1030                 WARN_ON(!entry->bitmap);
1031                 return entry;
1032         } else if (entry) {
1033                 if (entry->bitmap) {
1034                         /*
1035                          * if previous extent entry covers the offset,
1036                          * we should return it instead of the bitmap entry
1037                          */
1038                         n = &entry->offset_index;
1039                         while (1) {
1040                                 n = rb_prev(n);
1041                                 if (!n)
1042                                         break;
1043                                 prev = rb_entry(n, struct btrfs_free_space,
1044                                                 offset_index);
1045                                 if (!prev->bitmap) {
1046                                         if (prev->offset + prev->bytes > offset)
1047                                                 entry = prev;
1048                                         break;
1049                                 }
1050                         }
1051                 }
1052                 return entry;
1053         }
1054
1055         if (!prev)
1056                 return NULL;
1057
1058         /* find last entry before the 'offset' */
1059         entry = prev;
1060         if (entry->offset > offset) {
1061                 n = rb_prev(&entry->offset_index);
1062                 if (n) {
1063                         entry = rb_entry(n, struct btrfs_free_space,
1064                                         offset_index);
1065                         BUG_ON(entry->offset > offset);
1066                 } else {
1067                         if (fuzzy)
1068                                 return entry;
1069                         else
1070                                 return NULL;
1071                 }
1072         }
1073
1074         if (entry->bitmap) {
1075                 n = &entry->offset_index;
1076                 while (1) {
1077                         n = rb_prev(n);
1078                         if (!n)
1079                                 break;
1080                         prev = rb_entry(n, struct btrfs_free_space,
1081                                         offset_index);
1082                         if (!prev->bitmap) {
1083                                 if (prev->offset + prev->bytes > offset)
1084                                         return prev;
1085                                 break;
1086                         }
1087                 }
1088                 if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
1089                         return entry;
1090         } else if (entry->offset + entry->bytes > offset)
1091                 return entry;
1092
1093         if (!fuzzy)
1094                 return NULL;
1095
1096         while (1) {
1097                 if (entry->bitmap) {
1098                         if (entry->offset + BITS_PER_BITMAP *
1099                             ctl->unit > offset)
1100                                 break;
1101                 } else {
1102                         if (entry->offset + entry->bytes > offset)
1103                                 break;
1104                 }
1105
1106                 n = rb_next(&entry->offset_index);
1107                 if (!n)
1108                         return NULL;
1109                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1110         }
1111         return entry;
1112 }
1113
1114 static inline void
1115 __unlink_free_space(struct btrfs_free_space_ctl *ctl,
1116                     struct btrfs_free_space *info)
1117 {
1118         rb_erase(&info->offset_index, &ctl->free_space_offset);
1119         ctl->free_extents--;
1120 }
1121
1122 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
1123                               struct btrfs_free_space *info)
1124 {
1125         __unlink_free_space(ctl, info);
1126         ctl->free_space -= info->bytes;
1127 }
1128
1129 static int link_free_space(struct btrfs_free_space_ctl *ctl,
1130                            struct btrfs_free_space *info)
1131 {
1132         int ret = 0;
1133
1134         BUG_ON(!info->bitmap && !info->bytes);
1135         ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
1136                                  &info->offset_index, (info->bitmap != NULL));
1137         if (ret)
1138                 return ret;
1139
1140         ctl->free_space += info->bytes;
1141         ctl->free_extents++;
1142         return ret;
1143 }
1144
1145 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
1146 {
1147         struct btrfs_block_group_cache *block_group = ctl->private;
1148         u64 max_bytes;
1149         u64 bitmap_bytes;
1150         u64 extent_bytes;
1151         u64 size = block_group->key.offset;
1152         u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
1153         int max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
1154
1155         BUG_ON(ctl->total_bitmaps > max_bitmaps);
1156
1157         /*
1158          * The goal is to keep the total amount of memory used per 1gb of space
1159          * at or below 32k, so we need to adjust how much memory we allow to be
1160          * used by extent based free space tracking
1161          */
1162         if (size < 1024 * 1024 * 1024)
1163                 max_bytes = MAX_CACHE_BYTES_PER_GIG;
1164         else
1165                 max_bytes = MAX_CACHE_BYTES_PER_GIG *
1166                         div64_u64(size, 1024 * 1024 * 1024);
1167
1168         /*
1169          * we want to account for 1 more bitmap than what we have so we can make
1170          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1171          * we add more bitmaps.
1172          */
1173         bitmap_bytes = (ctl->total_bitmaps + 1) * PAGE_CACHE_SIZE;
1174
1175         if (bitmap_bytes >= max_bytes) {
1176                 ctl->extents_thresh = 0;
1177                 return;
1178         }
1179
1180         /*
1181          * we want the extent entry threshold to always be at most 1/2 the maxw
1182          * bytes we can have, or whatever is less than that.
1183          */
1184         extent_bytes = max_bytes - bitmap_bytes;
1185         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
1186
1187         ctl->extents_thresh =
1188                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
1189 }
1190
1191 static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1192                               struct btrfs_free_space *info, u64 offset,
1193                               u64 bytes)
1194 {
1195         unsigned long start, count;
1196
1197         start = offset_to_bit(info->offset, ctl->unit, offset);
1198         count = bytes_to_bits(bytes, ctl->unit);
1199         BUG_ON(start + count > BITS_PER_BITMAP);
1200
1201         bitmap_clear(info->bitmap, start, count);
1202
1203         info->bytes -= bytes;
1204         ctl->free_space -= bytes;
1205 }
1206
1207 static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
1208                             struct btrfs_free_space *info, u64 offset,
1209                             u64 bytes)
1210 {
1211         unsigned long start, count;
1212
1213         start = offset_to_bit(info->offset, ctl->unit, offset);
1214         count = bytes_to_bits(bytes, ctl->unit);
1215         BUG_ON(start + count > BITS_PER_BITMAP);
1216
1217         bitmap_set(info->bitmap, start, count);
1218
1219         info->bytes += bytes;
1220         ctl->free_space += bytes;
1221 }
1222
1223 static int search_bitmap(struct btrfs_free_space_ctl *ctl,
1224                          struct btrfs_free_space *bitmap_info, u64 *offset,
1225                          u64 *bytes)
1226 {
1227         unsigned long found_bits = 0;
1228         unsigned long bits, i;
1229         unsigned long next_zero;
1230
1231         i = offset_to_bit(bitmap_info->offset, ctl->unit,
1232                           max_t(u64, *offset, bitmap_info->offset));
1233         bits = bytes_to_bits(*bytes, ctl->unit);
1234
1235         for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
1236              i < BITS_PER_BITMAP;
1237              i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
1238                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
1239                                                BITS_PER_BITMAP, i);
1240                 if ((next_zero - i) >= bits) {
1241                         found_bits = next_zero - i;
1242                         break;
1243                 }
1244                 i = next_zero;
1245         }
1246
1247         if (found_bits) {
1248                 *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
1249                 *bytes = (u64)(found_bits) * ctl->unit;
1250                 return 0;
1251         }
1252
1253         return -1;
1254 }
1255
1256 static struct btrfs_free_space *
1257 find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes)
1258 {
1259         struct btrfs_free_space *entry;
1260         struct rb_node *node;
1261         int ret;
1262
1263         if (!ctl->free_space_offset.rb_node)
1264                 return NULL;
1265
1266         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
1267         if (!entry)
1268                 return NULL;
1269
1270         for (node = &entry->offset_index; node; node = rb_next(node)) {
1271                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1272                 if (entry->bytes < *bytes)
1273                         continue;
1274
1275                 if (entry->bitmap) {
1276                         ret = search_bitmap(ctl, entry, offset, bytes);
1277                         if (!ret)
1278                                 return entry;
1279                         continue;
1280                 }
1281
1282                 *offset = entry->offset;
1283                 *bytes = entry->bytes;
1284                 return entry;
1285         }
1286
1287         return NULL;
1288 }
1289
1290 static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
1291                            struct btrfs_free_space *info, u64 offset)
1292 {
1293         info->offset = offset_to_bitmap(ctl, offset);
1294         info->bytes = 0;
1295         link_free_space(ctl, info);
1296         ctl->total_bitmaps++;
1297
1298         ctl->op->recalc_thresholds(ctl);
1299 }
1300
1301 static void free_bitmap(struct btrfs_free_space_ctl *ctl,
1302                         struct btrfs_free_space *bitmap_info)
1303 {
1304         unlink_free_space(ctl, bitmap_info);
1305         kfree(bitmap_info->bitmap);
1306         kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1307         ctl->total_bitmaps--;
1308         ctl->op->recalc_thresholds(ctl);
1309 }
1310
1311 static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
1312                               struct btrfs_free_space *bitmap_info,
1313                               u64 *offset, u64 *bytes)
1314 {
1315         u64 end;
1316         u64 search_start, search_bytes;
1317         int ret;
1318
1319 again:
1320         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
1321
1322         /*
1323          * XXX - this can go away after a few releases.
1324          *
1325          * since the only user of btrfs_remove_free_space is the tree logging
1326          * stuff, and the only way to test that is under crash conditions, we
1327          * want to have this debug stuff here just in case somethings not
1328          * working.  Search the bitmap for the space we are trying to use to
1329          * make sure its actually there.  If its not there then we need to stop
1330          * because something has gone wrong.
1331          */
1332         search_start = *offset;
1333         search_bytes = *bytes;
1334         search_bytes = min(search_bytes, end - search_start + 1);
1335         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
1336         BUG_ON(ret < 0 || search_start != *offset);
1337
1338         if (*offset > bitmap_info->offset && *offset + *bytes > end) {
1339                 bitmap_clear_bits(ctl, bitmap_info, *offset, end - *offset + 1);
1340                 *bytes -= end - *offset + 1;
1341                 *offset = end + 1;
1342         } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
1343                 bitmap_clear_bits(ctl, bitmap_info, *offset, *bytes);
1344                 *bytes = 0;
1345         }
1346
1347         if (*bytes) {
1348                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
1349                 if (!bitmap_info->bytes)
1350                         free_bitmap(ctl, bitmap_info);
1351
1352                 /*
1353                  * no entry after this bitmap, but we still have bytes to
1354                  * remove, so something has gone wrong.
1355                  */
1356                 if (!next)
1357                         return -EINVAL;
1358
1359                 bitmap_info = rb_entry(next, struct btrfs_free_space,
1360                                        offset_index);
1361
1362                 /*
1363                  * if the next entry isn't a bitmap we need to return to let the
1364                  * extent stuff do its work.
1365                  */
1366                 if (!bitmap_info->bitmap)
1367                         return -EAGAIN;
1368
1369                 /*
1370                  * Ok the next item is a bitmap, but it may not actually hold
1371                  * the information for the rest of this free space stuff, so
1372                  * look for it, and if we don't find it return so we can try
1373                  * everything over again.
1374                  */
1375                 search_start = *offset;
1376                 search_bytes = *bytes;
1377                 ret = search_bitmap(ctl, bitmap_info, &search_start,
1378                                     &search_bytes);
1379                 if (ret < 0 || search_start != *offset)
1380                         return -EAGAIN;
1381
1382                 goto again;
1383         } else if (!bitmap_info->bytes)
1384                 free_bitmap(ctl, bitmap_info);
1385
1386         return 0;
1387 }
1388
1389 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
1390                       struct btrfs_free_space *info)
1391 {
1392         struct btrfs_block_group_cache *block_group = ctl->private;
1393
1394         /*
1395          * If we are below the extents threshold then we can add this as an
1396          * extent, and don't have to deal with the bitmap
1397          */
1398         if (ctl->free_extents < ctl->extents_thresh) {
1399                 /*
1400                  * If this block group has some small extents we don't want to
1401                  * use up all of our free slots in the cache with them, we want
1402                  * to reserve them to larger extents, however if we have plent
1403                  * of cache left then go ahead an dadd them, no sense in adding
1404                  * the overhead of a bitmap if we don't have to.
1405                  */
1406                 if (info->bytes <= block_group->sectorsize * 4) {
1407                         if (ctl->free_extents * 2 <= ctl->extents_thresh)
1408                                 return false;
1409                 } else {
1410                         return false;
1411                 }
1412         }
1413
1414         /*
1415          * some block groups are so tiny they can't be enveloped by a bitmap, so
1416          * don't even bother to create a bitmap for this
1417          */
1418         if (BITS_PER_BITMAP * block_group->sectorsize >
1419             block_group->key.offset)
1420                 return false;
1421
1422         return true;
1423 }
1424
1425 static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
1426                               struct btrfs_free_space *info)
1427 {
1428         struct btrfs_free_space *bitmap_info;
1429         int added = 0;
1430         u64 bytes, offset, end;
1431         int ret;
1432
1433         bytes = info->bytes;
1434         offset = info->offset;
1435
1436         if (!ctl->op->use_bitmap(ctl, info))
1437                 return 0;
1438
1439 again:
1440         bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1441                                          1, 0);
1442         if (!bitmap_info) {
1443                 BUG_ON(added);
1444                 goto new_bitmap;
1445         }
1446
1447         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
1448
1449         if (offset >= bitmap_info->offset && offset + bytes > end) {
1450                 bitmap_set_bits(ctl, bitmap_info, offset, end - offset);
1451                 bytes -= end - offset;
1452                 offset = end;
1453                 added = 0;
1454         } else if (offset >= bitmap_info->offset && offset + bytes <= end) {
1455                 bitmap_set_bits(ctl, bitmap_info, offset, bytes);
1456                 bytes = 0;
1457         } else {
1458                 BUG();
1459         }
1460
1461         if (!bytes) {
1462                 ret = 1;
1463                 goto out;
1464         } else
1465                 goto again;
1466
1467 new_bitmap:
1468         if (info && info->bitmap) {
1469                 add_new_bitmap(ctl, info, offset);
1470                 added = 1;
1471                 info = NULL;
1472                 goto again;
1473         } else {
1474                 spin_unlock(&ctl->tree_lock);
1475
1476                 /* no pre-allocated info, allocate a new one */
1477                 if (!info) {
1478                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
1479                                                  GFP_NOFS);
1480                         if (!info) {
1481                                 spin_lock(&ctl->tree_lock);
1482                                 ret = -ENOMEM;
1483                                 goto out;
1484                         }
1485                 }
1486
1487                 /* allocate the bitmap */
1488                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
1489                 spin_lock(&ctl->tree_lock);
1490                 if (!info->bitmap) {
1491                         ret = -ENOMEM;
1492                         goto out;
1493                 }
1494                 goto again;
1495         }
1496
1497 out:
1498         if (info) {
1499                 if (info->bitmap)
1500                         kfree(info->bitmap);
1501                 kmem_cache_free(btrfs_free_space_cachep, info);
1502         }
1503
1504         return ret;
1505 }
1506
1507 static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
1508                           struct btrfs_free_space *info, bool update_stat)
1509 {
1510         struct btrfs_free_space *left_info;
1511         struct btrfs_free_space *right_info;
1512         bool merged = false;
1513         u64 offset = info->offset;
1514         u64 bytes = info->bytes;
1515
1516         /*
1517          * first we want to see if there is free space adjacent to the range we
1518          * are adding, if there is remove that struct and add a new one to
1519          * cover the entire range
1520          */
1521         right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
1522         if (right_info && rb_prev(&right_info->offset_index))
1523                 left_info = rb_entry(rb_prev(&right_info->offset_index),
1524                                      struct btrfs_free_space, offset_index);
1525         else
1526                 left_info = tree_search_offset(ctl, offset - 1, 0, 0);
1527
1528         if (right_info && !right_info->bitmap) {
1529                 if (update_stat)
1530                         unlink_free_space(ctl, right_info);
1531                 else
1532                         __unlink_free_space(ctl, right_info);
1533                 info->bytes += right_info->bytes;
1534                 kmem_cache_free(btrfs_free_space_cachep, right_info);
1535                 merged = true;
1536         }
1537
1538         if (left_info && !left_info->bitmap &&
1539             left_info->offset + left_info->bytes == offset) {
1540                 if (update_stat)
1541                         unlink_free_space(ctl, left_info);
1542                 else
1543                         __unlink_free_space(ctl, left_info);
1544                 info->offset = left_info->offset;
1545                 info->bytes += left_info->bytes;
1546                 kmem_cache_free(btrfs_free_space_cachep, left_info);
1547                 merged = true;
1548         }
1549
1550         return merged;
1551 }
1552
1553 int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
1554                            u64 offset, u64 bytes)
1555 {
1556         struct btrfs_free_space *info;
1557         int ret = 0;
1558
1559         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
1560         if (!info)
1561                 return -ENOMEM;
1562
1563         info->offset = offset;
1564         info->bytes = bytes;
1565
1566         spin_lock(&ctl->tree_lock);
1567
1568         if (try_merge_free_space(ctl, info, true))
1569                 goto link;
1570
1571         /*
1572          * There was no extent directly to the left or right of this new
1573          * extent then we know we're going to have to allocate a new extent, so
1574          * before we do that see if we need to drop this into a bitmap
1575          */
1576         ret = insert_into_bitmap(ctl, info);
1577         if (ret < 0) {
1578                 goto out;
1579         } else if (ret) {
1580                 ret = 0;
1581                 goto out;
1582         }
1583 link:
1584         ret = link_free_space(ctl, info);
1585         if (ret)
1586                 kmem_cache_free(btrfs_free_space_cachep, info);
1587 out:
1588         spin_unlock(&ctl->tree_lock);
1589
1590         if (ret) {
1591                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
1592                 BUG_ON(ret == -EEXIST);
1593         }
1594
1595         return ret;
1596 }
1597
1598 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
1599                             u64 offset, u64 bytes)
1600 {
1601         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1602         struct btrfs_free_space *info;
1603         struct btrfs_free_space *next_info = NULL;
1604         int ret = 0;
1605
1606         spin_lock(&ctl->tree_lock);
1607
1608 again:
1609         info = tree_search_offset(ctl, offset, 0, 0);
1610         if (!info) {
1611                 /*
1612                  * oops didn't find an extent that matched the space we wanted
1613                  * to remove, look for a bitmap instead
1614                  */
1615                 info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1616                                           1, 0);
1617                 if (!info) {
1618                         WARN_ON(1);
1619                         goto out_lock;
1620                 }
1621         }
1622
1623         if (info->bytes < bytes && rb_next(&info->offset_index)) {
1624                 u64 end;
1625                 next_info = rb_entry(rb_next(&info->offset_index),
1626                                              struct btrfs_free_space,
1627                                              offset_index);
1628
1629                 if (next_info->bitmap)
1630                         end = next_info->offset +
1631                               BITS_PER_BITMAP * ctl->unit - 1;
1632                 else
1633                         end = next_info->offset + next_info->bytes;
1634
1635                 if (next_info->bytes < bytes ||
1636                     next_info->offset > offset || offset > end) {
1637                         printk(KERN_CRIT "Found free space at %llu, size %llu,"
1638                               " trying to use %llu\n",
1639                               (unsigned long long)info->offset,
1640                               (unsigned long long)info->bytes,
1641                               (unsigned long long)bytes);
1642                         WARN_ON(1);
1643                         ret = -EINVAL;
1644                         goto out_lock;
1645                 }
1646
1647                 info = next_info;
1648         }
1649
1650         if (info->bytes == bytes) {
1651                 unlink_free_space(ctl, info);
1652                 if (info->bitmap) {
1653                         kfree(info->bitmap);
1654                         ctl->total_bitmaps--;
1655                 }
1656                 kmem_cache_free(btrfs_free_space_cachep, info);
1657                 goto out_lock;
1658         }
1659
1660         if (!info->bitmap && info->offset == offset) {
1661                 unlink_free_space(ctl, info);
1662                 info->offset += bytes;
1663                 info->bytes -= bytes;
1664                 link_free_space(ctl, info);
1665                 goto out_lock;
1666         }
1667
1668         if (!info->bitmap && info->offset <= offset &&
1669             info->offset + info->bytes >= offset + bytes) {
1670                 u64 old_start = info->offset;
1671                 /*
1672                  * we're freeing space in the middle of the info,
1673                  * this can happen during tree log replay
1674                  *
1675                  * first unlink the old info and then
1676                  * insert it again after the hole we're creating
1677                  */
1678                 unlink_free_space(ctl, info);
1679                 if (offset + bytes < info->offset + info->bytes) {
1680                         u64 old_end = info->offset + info->bytes;
1681
1682                         info->offset = offset + bytes;
1683                         info->bytes = old_end - info->offset;
1684                         ret = link_free_space(ctl, info);
1685                         WARN_ON(ret);
1686                         if (ret)
1687                                 goto out_lock;
1688                 } else {
1689                         /* the hole we're creating ends at the end
1690                          * of the info struct, just free the info
1691                          */
1692                         kmem_cache_free(btrfs_free_space_cachep, info);
1693                 }
1694                 spin_unlock(&ctl->tree_lock);
1695
1696                 /* step two, insert a new info struct to cover
1697                  * anything before the hole
1698                  */
1699                 ret = btrfs_add_free_space(block_group, old_start,
1700                                            offset - old_start);
1701                 WARN_ON(ret);
1702                 goto out;
1703         }
1704
1705         ret = remove_from_bitmap(ctl, info, &offset, &bytes);
1706         if (ret == -EAGAIN)
1707                 goto again;
1708         BUG_ON(ret);
1709 out_lock:
1710         spin_unlock(&ctl->tree_lock);
1711 out:
1712         return ret;
1713 }
1714
1715 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
1716                            u64 bytes)
1717 {
1718         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1719         struct btrfs_free_space *info;
1720         struct rb_node *n;
1721         int count = 0;
1722
1723         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
1724                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1725                 if (info->bytes >= bytes)
1726                         count++;
1727                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
1728                        (unsigned long long)info->offset,
1729                        (unsigned long long)info->bytes,
1730                        (info->bitmap) ? "yes" : "no");
1731         }
1732         printk(KERN_INFO "block group has cluster?: %s\n",
1733                list_empty(&block_group->cluster_list) ? "no" : "yes");
1734         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
1735                "\n", count);
1736 }
1737
1738 static struct btrfs_free_space_op free_space_op = {
1739         .recalc_thresholds      = recalculate_thresholds,
1740         .use_bitmap             = use_bitmap,
1741 };
1742
1743 void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
1744 {
1745         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1746
1747         spin_lock_init(&ctl->tree_lock);
1748         ctl->unit = block_group->sectorsize;
1749         ctl->start = block_group->key.objectid;
1750         ctl->private = block_group;
1751         ctl->op = &free_space_op;
1752
1753         /*
1754          * we only want to have 32k of ram per block group for keeping
1755          * track of free space, and if we pass 1/2 of that we want to
1756          * start converting things over to using bitmaps
1757          */
1758         ctl->extents_thresh = ((1024 * 32) / 2) /
1759                                 sizeof(struct btrfs_free_space);
1760 }
1761
1762 /*
1763  * for a given cluster, put all of its extents back into the free
1764  * space cache.  If the block group passed doesn't match the block group
1765  * pointed to by the cluster, someone else raced in and freed the
1766  * cluster already.  In that case, we just return without changing anything
1767  */
1768 static int
1769 __btrfs_return_cluster_to_free_space(
1770                              struct btrfs_block_group_cache *block_group,
1771                              struct btrfs_free_cluster *cluster)
1772 {
1773         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1774         struct btrfs_free_space *entry;
1775         struct rb_node *node;
1776
1777         spin_lock(&cluster->lock);
1778         if (cluster->block_group != block_group)
1779                 goto out;
1780
1781         cluster->block_group = NULL;
1782         cluster->window_start = 0;
1783         list_del_init(&cluster->block_group_list);
1784
1785         node = rb_first(&cluster->root);
1786         while (node) {
1787                 bool bitmap;
1788
1789                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1790                 node = rb_next(&entry->offset_index);
1791                 rb_erase(&entry->offset_index, &cluster->root);
1792
1793                 bitmap = (entry->bitmap != NULL);
1794                 if (!bitmap)
1795                         try_merge_free_space(ctl, entry, false);
1796                 tree_insert_offset(&ctl->free_space_offset,
1797                                    entry->offset, &entry->offset_index, bitmap);
1798         }
1799         cluster->root = RB_ROOT;
1800
1801 out:
1802         spin_unlock(&cluster->lock);
1803         btrfs_put_block_group(block_group);
1804         return 0;
1805 }
1806
1807 void __btrfs_remove_free_space_cache_locked(struct btrfs_free_space_ctl *ctl)
1808 {
1809         struct btrfs_free_space *info;
1810         struct rb_node *node;
1811
1812         while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
1813                 info = rb_entry(node, struct btrfs_free_space, offset_index);
1814                 unlink_free_space(ctl, info);
1815                 kfree(info->bitmap);
1816                 kmem_cache_free(btrfs_free_space_cachep, info);
1817                 if (need_resched()) {
1818                         spin_unlock(&ctl->tree_lock);
1819                         cond_resched();
1820                         spin_lock(&ctl->tree_lock);
1821                 }
1822         }
1823 }
1824
1825 void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
1826 {
1827         spin_lock(&ctl->tree_lock);
1828         __btrfs_remove_free_space_cache_locked(ctl);
1829         spin_unlock(&ctl->tree_lock);
1830 }
1831
1832 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
1833 {
1834         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1835         struct btrfs_free_cluster *cluster;
1836         struct list_head *head;
1837
1838         spin_lock(&ctl->tree_lock);
1839         while ((head = block_group->cluster_list.next) !=
1840                &block_group->cluster_list) {
1841                 cluster = list_entry(head, struct btrfs_free_cluster,
1842                                      block_group_list);
1843
1844                 WARN_ON(cluster->block_group != block_group);
1845                 __btrfs_return_cluster_to_free_space(block_group, cluster);
1846                 if (need_resched()) {
1847                         spin_unlock(&ctl->tree_lock);
1848                         cond_resched();
1849                         spin_lock(&ctl->tree_lock);
1850                 }
1851         }
1852         __btrfs_remove_free_space_cache_locked(ctl);
1853         spin_unlock(&ctl->tree_lock);
1854
1855 }
1856
1857 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
1858                                u64 offset, u64 bytes, u64 empty_size)
1859 {
1860         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1861         struct btrfs_free_space *entry = NULL;
1862         u64 bytes_search = bytes + empty_size;
1863         u64 ret = 0;
1864
1865         spin_lock(&ctl->tree_lock);
1866         entry = find_free_space(ctl, &offset, &bytes_search);
1867         if (!entry)
1868                 goto out;
1869
1870         ret = offset;
1871         if (entry->bitmap) {
1872                 bitmap_clear_bits(ctl, entry, offset, bytes);
1873                 if (!entry->bytes)
1874                         free_bitmap(ctl, entry);
1875         } else {
1876                 unlink_free_space(ctl, entry);
1877                 entry->offset += bytes;
1878                 entry->bytes -= bytes;
1879                 if (!entry->bytes)
1880                         kmem_cache_free(btrfs_free_space_cachep, entry);
1881                 else
1882                         link_free_space(ctl, entry);
1883         }
1884
1885 out:
1886         spin_unlock(&ctl->tree_lock);
1887
1888         return ret;
1889 }
1890
1891 /*
1892  * given a cluster, put all of its extents back into the free space
1893  * cache.  If a block group is passed, this function will only free
1894  * a cluster that belongs to the passed block group.
1895  *
1896  * Otherwise, it'll get a reference on the block group pointed to by the
1897  * cluster and remove the cluster from it.
1898  */
1899 int btrfs_return_cluster_to_free_space(
1900                                struct btrfs_block_group_cache *block_group,
1901                                struct btrfs_free_cluster *cluster)
1902 {
1903         struct btrfs_free_space_ctl *ctl;
1904         int ret;
1905
1906         /* first, get a safe pointer to the block group */
1907         spin_lock(&cluster->lock);
1908         if (!block_group) {
1909                 block_group = cluster->block_group;
1910                 if (!block_group) {
1911                         spin_unlock(&cluster->lock);
1912                         return 0;
1913                 }
1914         } else if (cluster->block_group != block_group) {
1915                 /* someone else has already freed it don't redo their work */
1916                 spin_unlock(&cluster->lock);
1917                 return 0;
1918         }
1919         atomic_inc(&block_group->count);
1920         spin_unlock(&cluster->lock);
1921
1922         ctl = block_group->free_space_ctl;
1923
1924         /* now return any extents the cluster had on it */
1925         spin_lock(&ctl->tree_lock);
1926         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
1927         spin_unlock(&ctl->tree_lock);
1928
1929         /* finally drop our ref */
1930         btrfs_put_block_group(block_group);
1931         return ret;
1932 }
1933
1934 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
1935                                    struct btrfs_free_cluster *cluster,
1936                                    struct btrfs_free_space *entry,
1937                                    u64 bytes, u64 min_start)
1938 {
1939         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1940         int err;
1941         u64 search_start = cluster->window_start;
1942         u64 search_bytes = bytes;
1943         u64 ret = 0;
1944
1945         search_start = min_start;
1946         search_bytes = bytes;
1947
1948         err = search_bitmap(ctl, entry, &search_start, &search_bytes);
1949         if (err)
1950                 return 0;
1951
1952         ret = search_start;
1953         bitmap_clear_bits(ctl, entry, ret, bytes);
1954
1955         return ret;
1956 }
1957
1958 /*
1959  * given a cluster, try to allocate 'bytes' from it, returns 0
1960  * if it couldn't find anything suitably large, or a logical disk offset
1961  * if things worked out
1962  */
1963 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
1964                              struct btrfs_free_cluster *cluster, u64 bytes,
1965                              u64 min_start)
1966 {
1967         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1968         struct btrfs_free_space *entry = NULL;
1969         struct rb_node *node;
1970         u64 ret = 0;
1971
1972         spin_lock(&cluster->lock);
1973         if (bytes > cluster->max_size)
1974                 goto out;
1975
1976         if (cluster->block_group != block_group)
1977                 goto out;
1978
1979         node = rb_first(&cluster->root);
1980         if (!node)
1981                 goto out;
1982
1983         entry = rb_entry(node, struct btrfs_free_space, offset_index);
1984         while(1) {
1985                 if (entry->bytes < bytes ||
1986                     (!entry->bitmap && entry->offset < min_start)) {
1987                         node = rb_next(&entry->offset_index);
1988                         if (!node)
1989                                 break;
1990                         entry = rb_entry(node, struct btrfs_free_space,
1991                                          offset_index);
1992                         continue;
1993                 }
1994
1995                 if (entry->bitmap) {
1996                         ret = btrfs_alloc_from_bitmap(block_group,
1997                                                       cluster, entry, bytes,
1998                                                       min_start);
1999                         if (ret == 0) {
2000                                 node = rb_next(&entry->offset_index);
2001                                 if (!node)
2002                                         break;
2003                                 entry = rb_entry(node, struct btrfs_free_space,
2004                                                  offset_index);
2005                                 continue;
2006                         }
2007                 } else {
2008
2009                         ret = entry->offset;
2010
2011                         entry->offset += bytes;
2012                         entry->bytes -= bytes;
2013                 }
2014
2015                 if (entry->bytes == 0)
2016                         rb_erase(&entry->offset_index, &cluster->root);
2017                 break;
2018         }
2019 out:
2020         spin_unlock(&cluster->lock);
2021
2022         if (!ret)
2023                 return 0;
2024
2025         spin_lock(&ctl->tree_lock);
2026
2027         ctl->free_space -= bytes;
2028         if (entry->bytes == 0) {
2029                 ctl->free_extents--;
2030                 if (entry->bitmap) {
2031                         kfree(entry->bitmap);
2032                         ctl->total_bitmaps--;
2033                         ctl->op->recalc_thresholds(ctl);
2034                 }
2035                 kmem_cache_free(btrfs_free_space_cachep, entry);
2036         }
2037
2038         spin_unlock(&ctl->tree_lock);
2039
2040         return ret;
2041 }
2042
2043 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
2044                                 struct btrfs_free_space *entry,
2045                                 struct btrfs_free_cluster *cluster,
2046                                 u64 offset, u64 bytes, u64 min_bytes)
2047 {
2048         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2049         unsigned long next_zero;
2050         unsigned long i;
2051         unsigned long search_bits;
2052         unsigned long total_bits;
2053         unsigned long found_bits;
2054         unsigned long start = 0;
2055         unsigned long total_found = 0;
2056         int ret;
2057         bool found = false;
2058
2059         i = offset_to_bit(entry->offset, block_group->sectorsize,
2060                           max_t(u64, offset, entry->offset));
2061         search_bits = bytes_to_bits(bytes, block_group->sectorsize);
2062         total_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
2063
2064 again:
2065         found_bits = 0;
2066         for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
2067              i < BITS_PER_BITMAP;
2068              i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
2069                 next_zero = find_next_zero_bit(entry->bitmap,
2070                                                BITS_PER_BITMAP, i);
2071                 if (next_zero - i >= search_bits) {
2072                         found_bits = next_zero - i;
2073                         break;
2074                 }
2075                 i = next_zero;
2076         }
2077
2078         if (!found_bits)
2079                 return -ENOSPC;
2080
2081         if (!found) {
2082                 start = i;
2083                 found = true;
2084         }
2085
2086         total_found += found_bits;
2087
2088         if (cluster->max_size < found_bits * block_group->sectorsize)
2089                 cluster->max_size = found_bits * block_group->sectorsize;
2090
2091         if (total_found < total_bits) {
2092                 i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero);
2093                 if (i - start > total_bits * 2) {
2094                         total_found = 0;
2095                         cluster->max_size = 0;
2096                         found = false;
2097                 }
2098                 goto again;
2099         }
2100
2101         cluster->window_start = start * block_group->sectorsize +
2102                 entry->offset;
2103         rb_erase(&entry->offset_index, &ctl->free_space_offset);
2104         ret = tree_insert_offset(&cluster->root, entry->offset,
2105                                  &entry->offset_index, 1);
2106         BUG_ON(ret);
2107
2108         return 0;
2109 }
2110
2111 /*
2112  * This searches the block group for just extents to fill the cluster with.
2113  */
2114 static int setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
2115                                    struct btrfs_free_cluster *cluster,
2116                                    u64 offset, u64 bytes, u64 min_bytes)
2117 {
2118         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2119         struct btrfs_free_space *first = NULL;
2120         struct btrfs_free_space *entry = NULL;
2121         struct btrfs_free_space *prev = NULL;
2122         struct btrfs_free_space *last;
2123         struct rb_node *node;
2124         u64 window_start;
2125         u64 window_free;
2126         u64 max_extent;
2127         u64 max_gap = 128 * 1024;
2128
2129         entry = tree_search_offset(ctl, offset, 0, 1);
2130         if (!entry)
2131                 return -ENOSPC;
2132
2133         /*
2134          * We don't want bitmaps, so just move along until we find a normal
2135          * extent entry.
2136          */
2137         while (entry->bitmap) {
2138                 node = rb_next(&entry->offset_index);
2139                 if (!node)
2140                         return -ENOSPC;
2141                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2142         }
2143
2144         window_start = entry->offset;
2145         window_free = entry->bytes;
2146         max_extent = entry->bytes;
2147         first = entry;
2148         last = entry;
2149         prev = entry;
2150
2151         while (window_free <= min_bytes) {
2152                 node = rb_next(&entry->offset_index);
2153                 if (!node)
2154                         return -ENOSPC;
2155                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2156
2157                 if (entry->bitmap)
2158                         continue;
2159                 /*
2160                  * we haven't filled the empty size and the window is
2161                  * very large.  reset and try again
2162                  */
2163                 if (entry->offset - (prev->offset + prev->bytes) > max_gap ||
2164                     entry->offset - window_start > (min_bytes * 2)) {
2165                         first = entry;
2166                         window_start = entry->offset;
2167                         window_free = entry->bytes;
2168                         last = entry;
2169                         max_extent = entry->bytes;
2170                 } else {
2171                         last = entry;
2172                         window_free += entry->bytes;
2173                         if (entry->bytes > max_extent)
2174                                 max_extent = entry->bytes;
2175                 }
2176                 prev = entry;
2177         }
2178
2179         cluster->window_start = first->offset;
2180
2181         node = &first->offset_index;
2182
2183         /*
2184          * now we've found our entries, pull them out of the free space
2185          * cache and put them into the cluster rbtree
2186          */
2187         do {
2188                 int ret;
2189
2190                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2191                 node = rb_next(&entry->offset_index);
2192                 if (entry->bitmap)
2193                         continue;
2194
2195                 rb_erase(&entry->offset_index, &ctl->free_space_offset);
2196                 ret = tree_insert_offset(&cluster->root, entry->offset,
2197                                          &entry->offset_index, 0);
2198                 BUG_ON(ret);
2199         } while (node && entry != last);
2200
2201         cluster->max_size = max_extent;
2202
2203         return 0;
2204 }
2205
2206 /*
2207  * This specifically looks for bitmaps that may work in the cluster, we assume
2208  * that we have already failed to find extents that will work.
2209  */
2210 static int setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2211                                 struct btrfs_free_cluster *cluster,
2212                                 u64 offset, u64 bytes, u64 min_bytes)
2213 {
2214         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2215         struct btrfs_free_space *entry;
2216         struct rb_node *node;
2217         int ret = -ENOSPC;
2218
2219         if (ctl->total_bitmaps == 0)
2220                 return -ENOSPC;
2221
2222         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, offset), 0, 1);
2223         if (!entry)
2224                 return -ENOSPC;
2225
2226         node = &entry->offset_index;
2227         do {
2228                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2229                 node = rb_next(&entry->offset_index);
2230                 if (!entry->bitmap)
2231                         continue;
2232                 if (entry->bytes < min_bytes)
2233                         continue;
2234                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2235                                            bytes, min_bytes);
2236         } while (ret && node);
2237
2238         return ret;
2239 }
2240
2241 /*
2242  * here we try to find a cluster of blocks in a block group.  The goal
2243  * is to find at least bytes free and up to empty_size + bytes free.
2244  * We might not find them all in one contiguous area.
2245  *
2246  * returns zero and sets up cluster if things worked out, otherwise
2247  * it returns -enospc
2248  */
2249 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
2250                              struct btrfs_root *root,
2251                              struct btrfs_block_group_cache *block_group,
2252                              struct btrfs_free_cluster *cluster,
2253                              u64 offset, u64 bytes, u64 empty_size)
2254 {
2255         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2256         u64 min_bytes;
2257         int ret;
2258
2259         /* for metadata, allow allocates with more holes */
2260         if (btrfs_test_opt(root, SSD_SPREAD)) {
2261                 min_bytes = bytes + empty_size;
2262         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
2263                 /*
2264                  * we want to do larger allocations when we are
2265                  * flushing out the delayed refs, it helps prevent
2266                  * making more work as we go along.
2267                  */
2268                 if (trans->transaction->delayed_refs.flushing)
2269                         min_bytes = max(bytes, (bytes + empty_size) >> 1);
2270                 else
2271                         min_bytes = max(bytes, (bytes + empty_size) >> 4);
2272         } else
2273                 min_bytes = max(bytes, (bytes + empty_size) >> 2);
2274
2275         spin_lock(&ctl->tree_lock);
2276
2277         /*
2278          * If we know we don't have enough space to make a cluster don't even
2279          * bother doing all the work to try and find one.
2280          */
2281         if (ctl->free_space < min_bytes) {
2282                 spin_unlock(&ctl->tree_lock);
2283                 return -ENOSPC;
2284         }
2285
2286         spin_lock(&cluster->lock);
2287
2288         /* someone already found a cluster, hooray */
2289         if (cluster->block_group) {
2290                 ret = 0;
2291                 goto out;
2292         }
2293
2294         ret = setup_cluster_no_bitmap(block_group, cluster, offset, bytes,
2295                                       min_bytes);
2296         if (ret)
2297                 ret = setup_cluster_bitmap(block_group, cluster, offset,
2298                                            bytes, min_bytes);
2299
2300         if (!ret) {
2301                 atomic_inc(&block_group->count);
2302                 list_add_tail(&cluster->block_group_list,
2303                               &block_group->cluster_list);
2304                 cluster->block_group = block_group;
2305         }
2306 out:
2307         spin_unlock(&cluster->lock);
2308         spin_unlock(&ctl->tree_lock);
2309
2310         return ret;
2311 }
2312
2313 /*
2314  * simple code to zero out a cluster
2315  */
2316 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
2317 {
2318         spin_lock_init(&cluster->lock);
2319         spin_lock_init(&cluster->refill_lock);
2320         cluster->root = RB_ROOT;
2321         cluster->max_size = 0;
2322         INIT_LIST_HEAD(&cluster->block_group_list);
2323         cluster->block_group = NULL;
2324 }
2325
2326 int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
2327                            u64 *trimmed, u64 start, u64 end, u64 minlen)
2328 {
2329         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2330         struct btrfs_free_space *entry = NULL;
2331         struct btrfs_fs_info *fs_info = block_group->fs_info;
2332         u64 bytes = 0;
2333         u64 actually_trimmed;
2334         int ret = 0;
2335
2336         *trimmed = 0;
2337
2338         while (start < end) {
2339                 spin_lock(&ctl->tree_lock);
2340
2341                 if (ctl->free_space < minlen) {
2342                         spin_unlock(&ctl->tree_lock);
2343                         break;
2344                 }
2345
2346                 entry = tree_search_offset(ctl, start, 0, 1);
2347                 if (!entry)
2348                         entry = tree_search_offset(ctl,
2349                                                    offset_to_bitmap(ctl, start),
2350                                                    1, 1);
2351
2352                 if (!entry || entry->offset >= end) {
2353                         spin_unlock(&ctl->tree_lock);
2354                         break;
2355                 }
2356
2357                 if (entry->bitmap) {
2358                         ret = search_bitmap(ctl, entry, &start, &bytes);
2359                         if (!ret) {
2360                                 if (start >= end) {
2361                                         spin_unlock(&ctl->tree_lock);
2362                                         break;
2363                                 }
2364                                 bytes = min(bytes, end - start);
2365                                 bitmap_clear_bits(ctl, entry, start, bytes);
2366                                 if (entry->bytes == 0)
2367                                         free_bitmap(ctl, entry);
2368                         } else {
2369                                 start = entry->offset + BITS_PER_BITMAP *
2370                                         block_group->sectorsize;
2371                                 spin_unlock(&ctl->tree_lock);
2372                                 ret = 0;
2373                                 continue;
2374                         }
2375                 } else {
2376                         start = entry->offset;
2377                         bytes = min(entry->bytes, end - start);
2378                         unlink_free_space(ctl, entry);
2379                         kmem_cache_free(btrfs_free_space_cachep, entry);
2380                 }
2381
2382                 spin_unlock(&ctl->tree_lock);
2383
2384                 if (bytes >= minlen) {
2385                         int update_ret;
2386                         update_ret = btrfs_update_reserved_bytes(block_group,
2387                                                                  bytes, 1, 1);
2388
2389                         ret = btrfs_error_discard_extent(fs_info->extent_root,
2390                                                          start,
2391                                                          bytes,
2392                                                          &actually_trimmed);
2393
2394                         btrfs_add_free_space(block_group, start, bytes);
2395                         if (!update_ret)
2396                                 btrfs_update_reserved_bytes(block_group,
2397                                                             bytes, 0, 1);
2398
2399                         if (ret)
2400                                 break;
2401                         *trimmed += actually_trimmed;
2402                 }
2403                 start += bytes;
2404                 bytes = 0;
2405
2406                 if (fatal_signal_pending(current)) {
2407                         ret = -ERESTARTSYS;
2408                         break;
2409                 }
2410
2411                 cond_resched();
2412         }
2413
2414         return ret;
2415 }
2416
2417 /*
2418  * Find the left-most item in the cache tree, and then return the
2419  * smallest inode number in the item.
2420  *
2421  * Note: the returned inode number may not be the smallest one in
2422  * the tree, if the left-most item is a bitmap.
2423  */
2424 u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root)
2425 {
2426         struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl;
2427         struct btrfs_free_space *entry = NULL;
2428         u64 ino = 0;
2429
2430         spin_lock(&ctl->tree_lock);
2431
2432         if (RB_EMPTY_ROOT(&ctl->free_space_offset))
2433                 goto out;
2434
2435         entry = rb_entry(rb_first(&ctl->free_space_offset),
2436                          struct btrfs_free_space, offset_index);
2437
2438         if (!entry->bitmap) {
2439                 ino = entry->offset;
2440
2441                 unlink_free_space(ctl, entry);
2442                 entry->offset++;
2443                 entry->bytes--;
2444                 if (!entry->bytes)
2445                         kmem_cache_free(btrfs_free_space_cachep, entry);
2446                 else
2447                         link_free_space(ctl, entry);
2448         } else {
2449                 u64 offset = 0;
2450                 u64 count = 1;
2451                 int ret;
2452
2453                 ret = search_bitmap(ctl, entry, &offset, &count);
2454                 BUG_ON(ret);
2455
2456                 ino = offset;
2457                 bitmap_clear_bits(ctl, entry, offset, 1);
2458                 if (entry->bytes == 0)
2459                         free_bitmap(ctl, entry);
2460         }
2461 out:
2462         spin_unlock(&ctl->tree_lock);
2463
2464         return ino;
2465 }
2466
2467 struct inode *lookup_free_ino_inode(struct btrfs_root *root,
2468                                     struct btrfs_path *path)
2469 {
2470         struct inode *inode = NULL;
2471
2472         spin_lock(&root->cache_lock);
2473         if (root->cache_inode)
2474                 inode = igrab(root->cache_inode);
2475         spin_unlock(&root->cache_lock);
2476         if (inode)
2477                 return inode;
2478
2479         inode = __lookup_free_space_inode(root, path, 0);
2480         if (IS_ERR(inode))
2481                 return inode;
2482
2483         spin_lock(&root->cache_lock);
2484         if (!root->fs_info->closing)
2485                 root->cache_inode = igrab(inode);
2486         spin_unlock(&root->cache_lock);
2487
2488         return inode;
2489 }
2490
2491 int create_free_ino_inode(struct btrfs_root *root,
2492                           struct btrfs_trans_handle *trans,
2493                           struct btrfs_path *path)
2494 {
2495         return __create_free_space_inode(root, trans, path,
2496                                          BTRFS_FREE_INO_OBJECTID, 0);
2497 }
2498
2499 int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
2500 {
2501         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2502         struct btrfs_path *path;
2503         struct inode *inode;
2504         int ret = 0;
2505         u64 root_gen = btrfs_root_generation(&root->root_item);
2506
2507         /*
2508          * If we're unmounting then just return, since this does a search on the
2509          * normal root and not the commit root and we could deadlock.
2510          */
2511         smp_mb();
2512         if (fs_info->closing)
2513                 return 0;
2514
2515         path = btrfs_alloc_path();
2516         if (!path)
2517                 return 0;
2518
2519         inode = lookup_free_ino_inode(root, path);
2520         if (IS_ERR(inode))
2521                 goto out;
2522
2523         if (root_gen != BTRFS_I(inode)->generation)
2524                 goto out_put;
2525
2526         ret = __load_free_space_cache(root, inode, ctl, path, 0);
2527
2528         if (ret < 0)
2529                 printk(KERN_ERR "btrfs: failed to load free ino cache for "
2530                        "root %llu\n", root->root_key.objectid);
2531 out_put:
2532         iput(inode);
2533 out:
2534         btrfs_free_path(path);
2535         return ret;
2536 }
2537
2538 int btrfs_write_out_ino_cache(struct btrfs_root *root,
2539                               struct btrfs_trans_handle *trans,
2540                               struct btrfs_path *path)
2541 {
2542         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2543         struct inode *inode;
2544         int ret;
2545
2546         inode = lookup_free_ino_inode(root, path);
2547         if (IS_ERR(inode))
2548                 return 0;
2549
2550         ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);
2551         if (ret < 0)
2552                 printk(KERN_ERR "btrfs: failed to write free ino cache "
2553                        "for root %llu\n", root->root_key.objectid);
2554
2555         iput(inode);
2556         return ret;
2557 }