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                                 if (ret) {
 406                                         printk(KERN_ERR "Duplicate entries in "
 407                                                "free space cache, dumping\n");
 408                                         kunmap(page);
 409                                         unlock_page(page);
 410                                         page_cache_release(page);
 411                                         goto free_cache;
 412                                 }
 413                         } else {
 414                                 e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
 415                                 if (!e->bitmap) {
 416                                         kunmap(page);
 417                                         kmem_cache_free(
 418                                                 btrfs_free_space_cachep, e);
 419                                         unlock_page(page);
 420                                         page_cache_release(page);
 421                                         goto free_cache;
 422                                 }
 423                                 spin_lock(&ctl->tree_lock);
 424                                 ret2 = link_free_space(ctl, e);
 425                                 ctl->total_bitmaps++;
 426                                 ctl->op->recalc_thresholds(ctl);
 427                                 spin_unlock(&ctl->tree_lock);
 428                                 list_add_tail(&e->list, &bitmaps);
 429                                 if (ret) {
 430                                         printk(KERN_ERR "Duplicate entries in "
 431                                                "free space cache, dumping\n");
 432                                         kunmap(page);
 433                                         unlock_page(page);
 434                                         page_cache_release(page);
 435                                         goto free_cache;
 436                                 }
 437                         }
 438
 439                         num_entries--;
 440                         offset += sizeof(struct btrfs_free_space_entry);
 441                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 442                             PAGE_CACHE_SIZE)
 443                                 break;
 444                         entry++;
 445                 }
 446
 447                 /*
 448                  * We read an entry out of this page, we need to move on to the
 449                  * next page.
 450                  */
 451                 if (need_loop) {
 452                         kunmap(page);
 453                         goto next;
 454                 }
 455
 456                 /*
 457                  * We add the bitmaps at the end of the entries in order that
 458                  * the bitmap entries are added to the cache.
 459                  */
 460                 e = list_entry(bitmaps.next, struct btrfs_free_space, list);
 461                 list_del_init(&e->list);
 462                 memcpy(e->bitmap, addr, PAGE_CACHE_SIZE);
 463                 kunmap(page);
 464                 num_bitmaps--;
 465 next:
 466                 unlock_page(page);
 467                 page_cache_release(page);
 468                 index++;
 469         }
 470
 471         ret = 1;
 472 out:
 473         kfree(checksums);
 474         kfree(disk_crcs);
 475         return ret;
 476 free_cache:
 477         __btrfs_remove_free_space_cache(ctl);
 478         goto out;
 479 }
 480
 481 int load_free_space_cache(struct btrfs_fs_info *fs_info,
 482                           struct btrfs_block_group_cache *block_group)
 483 {
 484         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 485         struct btrfs_root *root = fs_info->tree_root;
 486         struct inode *inode;
 487         struct btrfs_path *path;
 488         int ret;
 489         bool matched;
 490         u64 used = btrfs_block_group_used(&block_group->item);
 491
 492         /*
 493          * If we're unmounting then just return, since this does a search on the
 494          * normal root and not the commit root and we could deadlock.
 495          */
 496         smp_mb();
 497         if (fs_info->closing)
 498                 return 0;
 499
 500         /*
 501          * If this block group has been marked to be cleared for one reason or
 502          * another then we can't trust the on disk cache, so just return.
 503          */
 504         spin_lock(&block_group->lock);
 505         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 506                 spin_unlock(&block_group->lock);
 507                 return 0;
 508         }
 509         spin_unlock(&block_group->lock);
 510
 511         path = btrfs_alloc_path();
 512         if (!path)
 513                 return 0;
 514
 515         inode = lookup_free_space_inode(root, block_group, path);
 516         if (IS_ERR(inode)) {
 517                 btrfs_free_path(path);
 518                 return 0;
 519         }
 520
 521         ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
 522                                       path, block_group->key.objectid);
 523         btrfs_free_path(path);
 524         if (ret <= 0)
 525                 goto out;
 526
 527         spin_lock(&ctl->tree_lock);
 528         matched = (ctl->free_space == (block_group->key.offset - used -
 529                                        block_group->bytes_super));
 530         spin_unlock(&ctl->tree_lock);
 531
 532         if (!matched) {
 533                 __btrfs_remove_free_space_cache(ctl);
 534                 printk(KERN_ERR "block group %llu has an wrong amount of free "
 535                        "space\n", block_group->key.objectid);
 536                 ret = -1;
 537         }
 538 out:
 539         if (ret < 0) {
 540                 /* This cache is bogus, make sure it gets cleared */
 541                 spin_lock(&block_group->lock);
 542                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 543                 spin_unlock(&block_group->lock);
 544                 ret = 0;
 545
 546                 printk(KERN_ERR "btrfs: failed to load free space cache "
 547                        "for block group %llu\n", block_group->key.objectid);
 548         }
 549
 550         iput(inode);
 551         return ret;
 552 }
 553
 554 int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 555                             struct btrfs_free_space_ctl *ctl,
 556                             struct btrfs_block_group_cache *block_group,
 557                             struct btrfs_trans_handle *trans,
 558                             struct btrfs_path *path, u64 offset)
 559 {
 560         struct btrfs_free_space_header *header;
 561         struct extent_buffer *leaf;
 562         struct rb_node *node;
 563         struct list_head *pos, *n;
 564         struct page **pages;
 565         struct page *page;
 566         struct extent_state *cached_state = NULL;
 567         struct btrfs_free_cluster *cluster = NULL;
 568         struct extent_io_tree *unpin = NULL;
 569         struct list_head bitmap_list;
 570         struct btrfs_key key;
 571         u64 start, end, len;
 572         u64 bytes = 0;
 573         u32 *crc, *checksums;
 574         unsigned long first_page_offset;
 575         int index = 0, num_pages = 0;
 576         int entries = 0;
 577         int bitmaps = 0;
 578         int ret = -1;
 579         bool next_page = false;
 580         bool out_of_space = false;
 581
 582         INIT_LIST_HEAD(&bitmap_list);
 583
 584         node = rb_first(&ctl->free_space_offset);
 585         if (!node)
 586                 return 0;
 587
 588         if (!i_size_read(inode))
 589                 return -1;
 590
 591         num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
 592                 PAGE_CACHE_SHIFT;
 593         filemap_write_and_wait(inode->i_mapping);
 594         btrfs_wait_ordered_range(inode, inode->i_size &
 595                                  ~(root->sectorsize - 1), (u64)-1);
 596
 597         /* We need a checksum per page. */
 598         crc = checksums = kzalloc(sizeof(u32) * num_pages, GFP_NOFS);
 599         if (!crc)
 600                 return -1;
 601
 602         pages = kzalloc(sizeof(struct page *) * num_pages, GFP_NOFS);
 603         if (!pages) {
 604                 kfree(crc);
 605                 return -1;
 606         }
 607
 608         /* Since the first page has all of our checksums and our generation we
 609          * need to calculate the offset into the page that we can start writing
 610          * our entries.
 611          */
 612         first_page_offset = (sizeof(u32) * num_pages) + sizeof(u64);
 613
 614         /* Get the cluster for this block_group if it exists */
 615         if (block_group && !list_empty(&block_group->cluster_list))
 616                 cluster = list_entry(block_group->cluster_list.next,
 617                                      struct btrfs_free_cluster,
 618                                      block_group_list);
 619
 620         /*
 621          * We shouldn't have switched the pinned extents yet so this is the
 622          * right one
 623          */
 624         unpin = root->fs_info->pinned_extents;
 625
 626         /*
 627          * Lock all pages first so we can lock the extent safely.
 628          *
 629          * NOTE: Because we hold the ref the entire time we're going to write to
 630          * the page find_get_page should never fail, so we don't do a check
 631          * after find_get_page at this point.  Just putting this here so people
 632          * know and don't freak out.
 633          */
 634         while (index < num_pages) {
 635                 page = grab_cache_page(inode->i_mapping, index);
 636                 if (!page) {
 637                         int i;
 638
 639                         for (i = 0; i < num_pages; i++) {
 640                                 unlock_page(pages[i]);
 641                                 page_cache_release(pages[i]);
 642                         }
 643                         goto out_free;
 644                 }
 645                 pages[index] = page;
 646                 index++;
 647         }
 648
 649         index = 0;
 650         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
 651                          0, &cached_state, GFP_NOFS);
 652
 653         /*
 654          * When searching for pinned extents, we need to start at our start
 655          * offset.
 656          */
 657         if (block_group)
 658                 start = block_group->key.objectid;
 659
 660         /* Write out the extent entries */
 661         do {
 662                 struct btrfs_free_space_entry *entry;
 663                 void *addr;
 664                 unsigned long offset = 0;
 665                 unsigned long start_offset = 0;
 666
 667                 next_page = false;
 668
 669                 if (index == 0) {
 670                         start_offset = first_page_offset;
 671                         offset = start_offset;
 672                 }
 673
 674                 if (index >= num_pages) {
 675                         out_of_space = true;
 676                         break;
 677                 }
 678
 679                 page = pages[index];
 680
 681                 addr = kmap(page);
 682                 entry = addr + start_offset;
 683
 684                 memset(addr, 0, PAGE_CACHE_SIZE);
 685                 while (node && !next_page) {
 686                         struct btrfs_free_space *e;
 687
 688                         e = rb_entry(node, struct btrfs_free_space, offset_index);
 689                         entries++;
 690
 691                         entry->offset = cpu_to_le64(e->offset);
 692                         entry->bytes = cpu_to_le64(e->bytes);
 693                         if (e->bitmap) {
 694                                 entry->type = BTRFS_FREE_SPACE_BITMAP;
 695                                 list_add_tail(&e->list, &bitmap_list);
 696                                 bitmaps++;
 697                         } else {
 698                                 entry->type = BTRFS_FREE_SPACE_EXTENT;
 699                         }
 700                         node = rb_next(node);
 701                         if (!node && cluster) {
 702                                 node = rb_first(&cluster->root);
 703                                 cluster = NULL;
 704                         }
 705                         offset += sizeof(struct btrfs_free_space_entry);
 706                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 707                             PAGE_CACHE_SIZE)
 708                                 next_page = true;
 709                         entry++;
 710                 }
 711
 712                 /*
 713                  * We want to add any pinned extents to our free space cache
 714                  * so we don't leak the space
 715                  */
 716                 while (block_group && !next_page &&
 717                        (start < block_group->key.objectid +
 718                         block_group->key.offset)) {
 719                         ret = find_first_extent_bit(unpin, start, &start, &end,
 720                                                     EXTENT_DIRTY);
 721                         if (ret) {
 722                                 ret = 0;
 723                                 break;
 724                         }
 725
 726                         /* This pinned extent is out of our range */
 727                         if (start >= block_group->key.objectid +
 728                             block_group->key.offset)
 729                                 break;
 730
 731                         len = block_group->key.objectid +
 732                                 block_group->key.offset - start;
 733                         len = min(len, end + 1 - start);
 734
 735                         entries++;
 736                         entry->offset = cpu_to_le64(start);
 737                         entry->bytes = cpu_to_le64(len);
 738                         entry->type = BTRFS_FREE_SPACE_EXTENT;
 739
 740                         start = end + 1;
 741                         offset += sizeof(struct btrfs_free_space_entry);
 742                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 743                             PAGE_CACHE_SIZE)
 744                                 next_page = true;
 745                         entry++;
 746                 }
 747                 *crc = ~(u32)0;
 748                 *crc = btrfs_csum_data(root, addr + start_offset, *crc,
 749                                        PAGE_CACHE_SIZE - start_offset);
 750                 kunmap(page);
 751
 752                 btrfs_csum_final(*crc, (char *)crc);
 753                 crc++;
 754
 755                 bytes += PAGE_CACHE_SIZE;
 756
 757                 index++;
 758         } while (node || next_page);
 759
 760         /* Write out the bitmaps */
 761         list_for_each_safe(pos, n, &bitmap_list) {
 762                 void *addr;
 763                 struct btrfs_free_space *entry =
 764                         list_entry(pos, struct btrfs_free_space, list);
 765
 766                 if (index >= num_pages) {
 767                         out_of_space = true;
 768                         break;
 769                 }
 770                 page = pages[index];
 771
 772                 addr = kmap(page);
 773                 memcpy(addr, entry->bitmap, PAGE_CACHE_SIZE);
 774                 *crc = ~(u32)0;
 775                 *crc = btrfs_csum_data(root, addr, *crc, PAGE_CACHE_SIZE);
 776                 kunmap(page);
 777                 btrfs_csum_final(*crc, (char *)crc);
 778                 crc++;
 779                 bytes += PAGE_CACHE_SIZE;
 780
 781                 list_del_init(&entry->list);
 782                 index++;
 783         }
 784
 785         if (out_of_space) {
 786                 btrfs_drop_pages(pages, num_pages);
 787                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 788                                      i_size_read(inode) - 1, &cached_state,
 789                                      GFP_NOFS);
 790                 ret = 0;
 791                 goto out_free;
 792         }
 793
 794         /* Zero out the rest of the pages just to make sure */
 795         while (index < num_pages) {
 796                 void *addr;
 797
 798                 page = pages[index];
 799                 addr = kmap(page);
 800                 memset(addr, 0, PAGE_CACHE_SIZE);
 801                 kunmap(page);
 802                 bytes += PAGE_CACHE_SIZE;
 803                 index++;
 804         }
 805
 806         /* Write the checksums and trans id to the first page */
 807         {
 808                 void *addr;
 809                 u64 *gen;
 810
 811                 page = pages[0];
 812
 813                 addr = kmap(page);
 814                 memcpy(addr, checksums, sizeof(u32) * num_pages);
 815                 gen = addr + (sizeof(u32) * num_pages);
 816                 *gen = trans->transid;
 817                 kunmap(page);
 818         }
 819
 820         ret = btrfs_dirty_pages(root, inode, pages, num_pages, 0,
 821                                             bytes, &cached_state);
 822         btrfs_drop_pages(pages, num_pages);
 823         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 824                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
 825
 826         if (ret) {
 827                 ret = 0;
 828                 goto out_free;
 829         }
 830
 831         BTRFS_I(inode)->generation = trans->transid;
 832
 833         filemap_write_and_wait(inode->i_mapping);
 834
 835         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 836         key.offset = offset;
 837         key.type = 0;
 838
 839         ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
 840         if (ret < 0) {
 841                 ret = -1;
 842                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 843                                  EXTENT_DIRTY | EXTENT_DELALLOC |
 844                                  EXTENT_DO_ACCOUNTING, 0, 0, NULL, GFP_NOFS);
 845                 goto out_free;
 846         }
 847         leaf = path->nodes[0];
 848         if (ret > 0) {
 849                 struct btrfs_key found_key;
 850                 BUG_ON(!path->slots[0]);
 851                 path->slots[0]--;
 852                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 853                 if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
 854                     found_key.offset != offset) {
 855                         ret = -1;
 856                         clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 857                                          EXTENT_DIRTY | EXTENT_DELALLOC |
 858                                          EXTENT_DO_ACCOUNTING, 0, 0, NULL,
 859                                          GFP_NOFS);
 860                         btrfs_release_path(path);
 861                         goto out_free;
 862                 }
 863         }
 864         header = btrfs_item_ptr(leaf, path->slots[0],
 865                                 struct btrfs_free_space_header);
 866         btrfs_set_free_space_entries(leaf, header, entries);
 867         btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
 868         btrfs_set_free_space_generation(leaf, header, trans->transid);
 869         btrfs_mark_buffer_dirty(leaf);
 870         btrfs_release_path(path);
 871
 872         ret = 1;
 873
 874 out_free:
 875         if (ret != 1) {
 876                 invalidate_inode_pages2_range(inode->i_mapping, 0, index);
 877                 BTRFS_I(inode)->generation = 0;
 878         }
 879         kfree(checksums);
 880         kfree(pages);
 881         btrfs_update_inode(trans, root, inode);
 882         return ret;
 883 }
 884
 885 int btrfs_write_out_cache(struct btrfs_root *root,
 886                           struct btrfs_trans_handle *trans,
 887                           struct btrfs_block_group_cache *block_group,
 888                           struct btrfs_path *path)
 889 {
 890         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 891         struct inode *inode;
 892         int ret = 0;
 893
 894         root = root->fs_info->tree_root;
 895
 896         spin_lock(&block_group->lock);
 897         if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
 898                 spin_unlock(&block_group->lock);
 899                 return 0;
 900         }
 901         spin_unlock(&block_group->lock);
 902
 903         inode = lookup_free_space_inode(root, block_group, path);
 904         if (IS_ERR(inode))
 905                 return 0;
 906
 907         ret = __btrfs_write_out_cache(root, inode, ctl, block_group, trans,
 908                                       path, block_group->key.objectid);
 909         if (ret < 0) {
 910                 spin_lock(&block_group->lock);
 911                 block_group->disk_cache_state = BTRFS_DC_ERROR;
 912                 spin_unlock(&block_group->lock);
 913                 ret = 0;
 914
 915                 printk(KERN_ERR "btrfs: failed to write free space cace "
 916                        "for block group %llu\n", block_group->key.objectid);
 917         }
 918
 919         iput(inode);
 920         return ret;
 921 }
 922
 923 static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
 924                                           u64 offset)
 925 {
 926         BUG_ON(offset < bitmap_start);
 927         offset -= bitmap_start;
 928         return (unsigned long)(div_u64(offset, unit));
 929 }
 930
 931 static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
 932 {
 933         return (unsigned long)(div_u64(bytes, unit));
 934 }
 935
 936 static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
 937                                    u64 offset)
 938 {
 939         u64 bitmap_start;
 940         u64 bytes_per_bitmap;
 941
 942         bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
 943         bitmap_start = offset - ctl->start;
 944         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
 945         bitmap_start *= bytes_per_bitmap;
 946         bitmap_start += ctl->start;
 947
 948         return bitmap_start;
 949 }
 950
 951 static int tree_insert_offset(struct rb_root *root, u64 offset,
 952                               struct rb_node *node, int bitmap)
 953 {
 954         struct rb_node **p = &root->rb_node;
 955         struct rb_node *parent = NULL;
 956         struct btrfs_free_space *info;
 957
 958         while (*p) {
 959                 parent = *p;
 960                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
 961
 962                 if (offset < info->offset) {
 963                         p = &(*p)->rb_left;
 964                 } else if (offset > info->offset) {
 965                         p = &(*p)->rb_right;
 966                 } else {
 967                         /*
 968                          * we could have a bitmap entry and an extent entry
 969                          * share the same offset.  If this is the case, we want
 970                          * the extent entry to always be found first if we do a
 971                          * linear search through the tree, since we want to have
 972                          * the quickest allocation time, and allocating from an
 973                          * extent is faster than allocating from a bitmap.  So
 974                          * if we're inserting a bitmap and we find an entry at
 975                          * this offset, we want to go right, or after this entry
 976                          * logically.  If we are inserting an extent and we've
 977                          * found a bitmap, we want to go left, or before
 978                          * logically.
 979                          */
 980                         if (bitmap) {
 981                                 if (info->bitmap) {
 982                                         WARN_ON_ONCE(1);
 983                                         return -EEXIST;
 984                                 }
 985                                 p = &(*p)->rb_right;
 986                         } else {
 987                                 if (!info->bitmap) {
 988                                         WARN_ON_ONCE(1);
 989                                         return -EEXIST;
 990                                 }
 991                                 p = &(*p)->rb_left;
 992                         }
 993                 }
 994         }
 995
 996         rb_link_node(node, parent, p);
 997         rb_insert_color(node, root);
 998
 999         return 0;
1000 }
1001
1002 /*
1003  * searches the tree for the given offset.
1004  *
1005  * fuzzy - If this is set, then we are trying to make an allocation, and we just
1006  * want a section that has at least bytes size and comes at or after the given
1007  * offset.
1008  */
1009 static struct btrfs_free_space *
1010 tree_search_offset(struct btrfs_free_space_ctl *ctl,
1011                    u64 offset, int bitmap_only, int fuzzy)
1012 {
1013         struct rb_node *n = ctl->free_space_offset.rb_node;
1014         struct btrfs_free_space *entry, *prev = NULL;
1015
1016         /* find entry that is closest to the 'offset' */
1017         while (1) {
1018                 if (!n) {
1019                         entry = NULL;
1020                         break;
1021                 }
1022
1023                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1024                 prev = entry;
1025
1026                 if (offset < entry->offset)
1027                         n = n->rb_left;
1028                 else if (offset > entry->offset)
1029                         n = n->rb_right;
1030                 else
1031                         break;
1032         }
1033
1034         if (bitmap_only) {
1035                 if (!entry)
1036                         return NULL;
1037                 if (entry->bitmap)
1038                         return entry;
1039
1040                 /*
1041                  * bitmap entry and extent entry may share same offset,
1042                  * in that case, bitmap entry comes after extent entry.
1043                  */
1044                 n = rb_next(n);
1045                 if (!n)
1046                         return NULL;
1047                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1048                 if (entry->offset != offset)
1049                         return NULL;
1050
1051                 WARN_ON(!entry->bitmap);
1052                 return entry;
1053         } else if (entry) {
1054                 if (entry->bitmap) {
1055                         /*
1056                          * if previous extent entry covers the offset,
1057                          * we should return it instead of the bitmap entry
1058                          */
1059                         n = &entry->offset_index;
1060                         while (1) {
1061                                 n = rb_prev(n);
1062                                 if (!n)
1063                                         break;
1064                                 prev = rb_entry(n, struct btrfs_free_space,
1065                                                 offset_index);
1066                                 if (!prev->bitmap) {
1067                                         if (prev->offset + prev->bytes > offset)
1068                                                 entry = prev;
1069                                         break;
1070                                 }
1071                         }
1072                 }
1073                 return entry;
1074         }
1075
1076         if (!prev)
1077                 return NULL;
1078
1079         /* find last entry before the 'offset' */
1080         entry = prev;
1081         if (entry->offset > offset) {
1082                 n = rb_prev(&entry->offset_index);
1083                 if (n) {
1084                         entry = rb_entry(n, struct btrfs_free_space,
1085                                         offset_index);
1086                         BUG_ON(entry->offset > offset);
1087                 } else {
1088                         if (fuzzy)
1089                                 return entry;
1090                         else
1091                                 return NULL;
1092                 }
1093         }
1094
1095         if (entry->bitmap) {
1096                 n = &entry->offset_index;
1097                 while (1) {
1098                         n = rb_prev(n);
1099                         if (!n)
1100                                 break;
1101                         prev = rb_entry(n, struct btrfs_free_space,
1102                                         offset_index);
1103                         if (!prev->bitmap) {
1104                                 if (prev->offset + prev->bytes > offset)
1105                                         return prev;
1106                                 break;
1107                         }
1108                 }
1109                 if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
1110                         return entry;
1111         } else if (entry->offset + entry->bytes > offset)
1112                 return entry;
1113
1114         if (!fuzzy)
1115                 return NULL;
1116
1117         while (1) {
1118                 if (entry->bitmap) {
1119                         if (entry->offset + BITS_PER_BITMAP *
1120                             ctl->unit > offset)
1121                                 break;
1122                 } else {
1123                         if (entry->offset + entry->bytes > offset)
1124                                 break;
1125                 }
1126
1127                 n = rb_next(&entry->offset_index);
1128                 if (!n)
1129                         return NULL;
1130                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1131         }
1132         return entry;
1133 }
1134
1135 static inline void
1136 __unlink_free_space(struct btrfs_free_space_ctl *ctl,
1137                     struct btrfs_free_space *info)
1138 {
1139         rb_erase(&info->offset_index, &ctl->free_space_offset);
1140         ctl->free_extents--;
1141 }
1142
1143 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
1144                               struct btrfs_free_space *info)
1145 {
1146         __unlink_free_space(ctl, info);
1147         ctl->free_space -= info->bytes;
1148 }
1149
1150 static int link_free_space(struct btrfs_free_space_ctl *ctl,
1151                            struct btrfs_free_space *info)
1152 {
1153         int ret = 0;
1154
1155         BUG_ON(!info->bitmap && !info->bytes);
1156         ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
1157                                  &info->offset_index, (info->bitmap != NULL));
1158         if (ret)
1159                 return ret;
1160
1161         ctl->free_space += info->bytes;
1162         ctl->free_extents++;
1163         return ret;
1164 }
1165
1166 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
1167 {
1168         struct btrfs_block_group_cache *block_group = ctl->private;
1169         u64 max_bytes;
1170         u64 bitmap_bytes;
1171         u64 extent_bytes;
1172         u64 size = block_group->key.offset;
1173         u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
1174         int max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
1175
1176         BUG_ON(ctl->total_bitmaps > max_bitmaps);
1177
1178         /*
1179          * The goal is to keep the total amount of memory used per 1gb of space
1180          * at or below 32k, so we need to adjust how much memory we allow to be
1181          * used by extent based free space tracking
1182          */
1183         if (size < 1024 * 1024 * 1024)
1184                 max_bytes = MAX_CACHE_BYTES_PER_GIG;
1185         else
1186                 max_bytes = MAX_CACHE_BYTES_PER_GIG *
1187                         div64_u64(size, 1024 * 1024 * 1024);
1188
1189         /*
1190          * we want to account for 1 more bitmap than what we have so we can make
1191          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1192          * we add more bitmaps.
1193          */
1194         bitmap_bytes = (ctl->total_bitmaps + 1) * PAGE_CACHE_SIZE;
1195
1196         if (bitmap_bytes >= max_bytes) {
1197                 ctl->extents_thresh = 0;
1198                 return;
1199         }
1200
1201         /*
1202          * we want the extent entry threshold to always be at most 1/2 the maxw
1203          * bytes we can have, or whatever is less than that.
1204          */
1205         extent_bytes = max_bytes - bitmap_bytes;
1206         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
1207
1208         ctl->extents_thresh =
1209                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
1210 }
1211
1212 static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1213                               struct btrfs_free_space *info, u64 offset,
1214                               u64 bytes)
1215 {
1216         unsigned long start, count;
1217
1218         start = offset_to_bit(info->offset, ctl->unit, offset);
1219         count = bytes_to_bits(bytes, ctl->unit);
1220         BUG_ON(start + count > BITS_PER_BITMAP);
1221
1222         bitmap_clear(info->bitmap, start, count);
1223
1224         info->bytes -= bytes;
1225         ctl->free_space -= bytes;
1226 }
1227
1228 static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
1229                             struct btrfs_free_space *info, u64 offset,
1230                             u64 bytes)
1231 {
1232         unsigned long start, count;
1233
1234         start = offset_to_bit(info->offset, ctl->unit, offset);
1235         count = bytes_to_bits(bytes, ctl->unit);
1236         BUG_ON(start + count > BITS_PER_BITMAP);
1237
1238         bitmap_set(info->bitmap, start, count);
1239
1240         info->bytes += bytes;
1241         ctl->free_space += bytes;
1242 }
1243
1244 static int search_bitmap(struct btrfs_free_space_ctl *ctl,
1245                          struct btrfs_free_space *bitmap_info, u64 *offset,
1246                          u64 *bytes)
1247 {
1248         unsigned long found_bits = 0;
1249         unsigned long bits, i;
1250         unsigned long next_zero;
1251
1252         i = offset_to_bit(bitmap_info->offset, ctl->unit,
1253                           max_t(u64, *offset, bitmap_info->offset));
1254         bits = bytes_to_bits(*bytes, ctl->unit);
1255
1256         for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
1257              i < BITS_PER_BITMAP;
1258              i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
1259                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
1260                                                BITS_PER_BITMAP, i);
1261                 if ((next_zero - i) >= bits) {
1262                         found_bits = next_zero - i;
1263                         break;
1264                 }
1265                 i = next_zero;
1266         }
1267
1268         if (found_bits) {
1269                 *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
1270                 *bytes = (u64)(found_bits) * ctl->unit;
1271                 return 0;
1272         }
1273
1274         return -1;
1275 }
1276
1277 static struct btrfs_free_space *
1278 find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes)
1279 {
1280         struct btrfs_free_space *entry;
1281         struct rb_node *node;
1282         int ret;
1283
1284         if (!ctl->free_space_offset.rb_node)
1285                 return NULL;
1286
1287         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
1288         if (!entry)
1289                 return NULL;
1290
1291         for (node = &entry->offset_index; node; node = rb_next(node)) {
1292                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1293                 if (entry->bytes < *bytes)
1294                         continue;
1295
1296                 if (entry->bitmap) {
1297                         ret = search_bitmap(ctl, entry, offset, bytes);
1298                         if (!ret)
1299                                 return entry;
1300                         continue;
1301                 }
1302
1303                 *offset = entry->offset;
1304                 *bytes = entry->bytes;
1305                 return entry;
1306         }
1307
1308         return NULL;
1309 }
1310
1311 static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
1312                            struct btrfs_free_space *info, u64 offset)
1313 {
1314         info->offset = offset_to_bitmap(ctl, offset);
1315         info->bytes = 0;
1316         link_free_space(ctl, info);
1317         ctl->total_bitmaps++;
1318
1319         ctl->op->recalc_thresholds(ctl);
1320 }
1321
1322 static void free_bitmap(struct btrfs_free_space_ctl *ctl,
1323                         struct btrfs_free_space *bitmap_info)
1324 {
1325         unlink_free_space(ctl, bitmap_info);
1326         kfree(bitmap_info->bitmap);
1327         kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1328         ctl->total_bitmaps--;
1329         ctl->op->recalc_thresholds(ctl);
1330 }
1331
1332 static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
1333                               struct btrfs_free_space *bitmap_info,
1334                               u64 *offset, u64 *bytes)
1335 {
1336         u64 end;
1337         u64 search_start, search_bytes;
1338         int ret;
1339
1340 again:
1341         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
1342
1343         /*
1344          * XXX - this can go away after a few releases.
1345          *
1346          * since the only user of btrfs_remove_free_space is the tree logging
1347          * stuff, and the only way to test that is under crash conditions, we
1348          * want to have this debug stuff here just in case somethings not
1349          * working.  Search the bitmap for the space we are trying to use to
1350          * make sure its actually there.  If its not there then we need to stop
1351          * because something has gone wrong.
1352          */
1353         search_start = *offset;
1354         search_bytes = *bytes;
1355         search_bytes = min(search_bytes, end - search_start + 1);
1356         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
1357         BUG_ON(ret < 0 || search_start != *offset);
1358
1359         if (*offset > bitmap_info->offset && *offset + *bytes > end) {
1360                 bitmap_clear_bits(ctl, bitmap_info, *offset, end - *offset + 1);
1361                 *bytes -= end - *offset + 1;
1362                 *offset = end + 1;
1363         } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
1364                 bitmap_clear_bits(ctl, bitmap_info, *offset, *bytes);
1365                 *bytes = 0;
1366         }
1367
1368         if (*bytes) {
1369                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
1370                 if (!bitmap_info->bytes)
1371                         free_bitmap(ctl, bitmap_info);
1372
1373                 /*
1374                  * no entry after this bitmap, but we still have bytes to
1375                  * remove, so something has gone wrong.
1376                  */
1377                 if (!next)
1378                         return -EINVAL;
1379
1380                 bitmap_info = rb_entry(next, struct btrfs_free_space,
1381                                        offset_index);
1382
1383                 /*
1384                  * if the next entry isn't a bitmap we need to return to let the
1385                  * extent stuff do its work.
1386                  */
1387                 if (!bitmap_info->bitmap)
1388                         return -EAGAIN;
1389
1390                 /*
1391                  * Ok the next item is a bitmap, but it may not actually hold
1392                  * the information for the rest of this free space stuff, so
1393                  * look for it, and if we don't find it return so we can try
1394                  * everything over again.
1395                  */
1396                 search_start = *offset;
1397                 search_bytes = *bytes;
1398                 ret = search_bitmap(ctl, bitmap_info, &search_start,
1399                                     &search_bytes);
1400                 if (ret < 0 || search_start != *offset)
1401                         return -EAGAIN;
1402
1403                 goto again;
1404         } else if (!bitmap_info->bytes)
1405                 free_bitmap(ctl, bitmap_info);
1406
1407         return 0;
1408 }
1409
1410 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
1411                       struct btrfs_free_space *info)
1412 {
1413         struct btrfs_block_group_cache *block_group = ctl->private;
1414
1415         /*
1416          * If we are below the extents threshold then we can add this as an
1417          * extent, and don't have to deal with the bitmap
1418          */
1419         if (ctl->free_extents < ctl->extents_thresh) {
1420                 /*
1421                  * If this block group has some small extents we don't want to
1422                  * use up all of our free slots in the cache with them, we want
1423                  * to reserve them to larger extents, however if we have plent
1424                  * of cache left then go ahead an dadd them, no sense in adding
1425                  * the overhead of a bitmap if we don't have to.
1426                  */
1427                 if (info->bytes <= block_group->sectorsize * 4) {
1428                         if (ctl->free_extents * 2 <= ctl->extents_thresh)
1429                                 return false;
1430                 } else {
1431                         return false;
1432                 }
1433         }
1434
1435         /*
1436          * some block groups are so tiny they can't be enveloped by a bitmap, so
1437          * don't even bother to create a bitmap for this
1438          */
1439         if (BITS_PER_BITMAP * block_group->sectorsize >
1440             block_group->key.offset)
1441                 return false;
1442
1443         return true;
1444 }
1445
1446 static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
1447                               struct btrfs_free_space *info)
1448 {
1449         struct btrfs_free_space *bitmap_info;
1450         int added = 0;
1451         u64 bytes, offset, end;
1452         int ret;
1453
1454         bytes = info->bytes;
1455         offset = info->offset;
1456
1457         if (!ctl->op->use_bitmap(ctl, info))
1458                 return 0;
1459
1460 again:
1461         bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1462                                          1, 0);
1463         if (!bitmap_info) {
1464                 BUG_ON(added);
1465                 goto new_bitmap;
1466         }
1467
1468         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
1469
1470         if (offset >= bitmap_info->offset && offset + bytes > end) {
1471                 bitmap_set_bits(ctl, bitmap_info, offset, end - offset);
1472                 bytes -= end - offset;
1473                 offset = end;
1474                 added = 0;
1475         } else if (offset >= bitmap_info->offset && offset + bytes <= end) {
1476                 bitmap_set_bits(ctl, bitmap_info, offset, bytes);
1477                 bytes = 0;
1478         } else {
1479                 BUG();
1480         }
1481
1482         if (!bytes) {
1483                 ret = 1;
1484                 goto out;
1485         } else
1486                 goto again;
1487
1488 new_bitmap:
1489         if (info && info->bitmap) {
1490                 add_new_bitmap(ctl, info, offset);
1491                 added = 1;
1492                 info = NULL;
1493                 goto again;
1494         } else {
1495                 spin_unlock(&ctl->tree_lock);
1496
1497                 /* no pre-allocated info, allocate a new one */
1498                 if (!info) {
1499                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
1500                                                  GFP_NOFS);
1501                         if (!info) {
1502                                 spin_lock(&ctl->tree_lock);
1503                                 ret = -ENOMEM;
1504                                 goto out;
1505                         }
1506                 }
1507
1508                 /* allocate the bitmap */
1509                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
1510                 spin_lock(&ctl->tree_lock);
1511                 if (!info->bitmap) {
1512                         ret = -ENOMEM;
1513                         goto out;
1514                 }
1515                 goto again;
1516         }
1517
1518 out:
1519         if (info) {
1520                 if (info->bitmap)
1521                         kfree(info->bitmap);
1522                 kmem_cache_free(btrfs_free_space_cachep, info);
1523         }
1524
1525         return ret;
1526 }
1527
1528 static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
1529                           struct btrfs_free_space *info, bool update_stat)
1530 {
1531         struct btrfs_free_space *left_info;
1532         struct btrfs_free_space *right_info;
1533         bool merged = false;
1534         u64 offset = info->offset;
1535         u64 bytes = info->bytes;
1536
1537         /*
1538          * first we want to see if there is free space adjacent to the range we
1539          * are adding, if there is remove that struct and add a new one to
1540          * cover the entire range
1541          */
1542         right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
1543         if (right_info && rb_prev(&right_info->offset_index))
1544                 left_info = rb_entry(rb_prev(&right_info->offset_index),
1545                                      struct btrfs_free_space, offset_index);
1546         else
1547                 left_info = tree_search_offset(ctl, offset - 1, 0, 0);
1548
1549         if (right_info && !right_info->bitmap) {
1550                 if (update_stat)
1551                         unlink_free_space(ctl, right_info);
1552                 else
1553                         __unlink_free_space(ctl, right_info);
1554                 info->bytes += right_info->bytes;
1555                 kmem_cache_free(btrfs_free_space_cachep, right_info);
1556                 merged = true;
1557         }
1558
1559         if (left_info && !left_info->bitmap &&
1560             left_info->offset + left_info->bytes == offset) {
1561                 if (update_stat)
1562                         unlink_free_space(ctl, left_info);
1563                 else
1564                         __unlink_free_space(ctl, left_info);
1565                 info->offset = left_info->offset;
1566                 info->bytes += left_info->bytes;
1567                 kmem_cache_free(btrfs_free_space_cachep, left_info);
1568                 merged = true;
1569         }
1570
1571         return merged;
1572 }
1573
1574 int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
1575                            u64 offset, u64 bytes)
1576 {
1577         struct btrfs_free_space *info;
1578         int ret = 0;
1579
1580         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
1581         if (!info)
1582                 return -ENOMEM;
1583
1584         info->offset = offset;
1585         info->bytes = bytes;
1586
1587         spin_lock(&ctl->tree_lock);
1588
1589         if (try_merge_free_space(ctl, info, true))
1590                 goto link;
1591
1592         /*
1593          * There was no extent directly to the left or right of this new
1594          * extent then we know we're going to have to allocate a new extent, so
1595          * before we do that see if we need to drop this into a bitmap
1596          */
1597         ret = insert_into_bitmap(ctl, info);
1598         if (ret < 0) {
1599                 goto out;
1600         } else if (ret) {
1601                 ret = 0;
1602                 goto out;
1603         }
1604 link:
1605         ret = link_free_space(ctl, info);
1606         if (ret)
1607                 kmem_cache_free(btrfs_free_space_cachep, info);
1608 out:
1609         spin_unlock(&ctl->tree_lock);
1610
1611         if (ret) {
1612                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
1613                 BUG_ON(ret == -EEXIST);
1614         }
1615
1616         return ret;
1617 }
1618
1619 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
1620                             u64 offset, u64 bytes)
1621 {
1622         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1623         struct btrfs_free_space *info;
1624         struct btrfs_free_space *next_info = NULL;
1625         int ret = 0;
1626
1627         spin_lock(&ctl->tree_lock);
1628
1629 again:
1630         info = tree_search_offset(ctl, offset, 0, 0);
1631         if (!info) {
1632                 /*
1633                  * oops didn't find an extent that matched the space we wanted
1634                  * to remove, look for a bitmap instead
1635                  */
1636                 info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1637                                           1, 0);
1638                 if (!info) {
1639                         WARN_ON(1);
1640                         goto out_lock;
1641                 }
1642         }
1643
1644         if (info->bytes < bytes && rb_next(&info->offset_index)) {
1645                 u64 end;
1646                 next_info = rb_entry(rb_next(&info->offset_index),
1647                                              struct btrfs_free_space,
1648                                              offset_index);
1649
1650                 if (next_info->bitmap)
1651                         end = next_info->offset +
1652                               BITS_PER_BITMAP * ctl->unit - 1;
1653                 else
1654                         end = next_info->offset + next_info->bytes;
1655
1656                 if (next_info->bytes < bytes ||
1657                     next_info->offset > offset || offset > end) {
1658                         printk(KERN_CRIT "Found free space at %llu, size %llu,"
1659                               " trying to use %llu\n",
1660                               (unsigned long long)info->offset,
1661                               (unsigned long long)info->bytes,
1662                               (unsigned long long)bytes);
1663                         WARN_ON(1);
1664                         ret = -EINVAL;
1665                         goto out_lock;
1666                 }
1667
1668                 info = next_info;
1669         }
1670
1671         if (info->bytes == bytes) {
1672                 unlink_free_space(ctl, info);
1673                 if (info->bitmap) {
1674                         kfree(info->bitmap);
1675                         ctl->total_bitmaps--;
1676                 }
1677                 kmem_cache_free(btrfs_free_space_cachep, info);
1678                 goto out_lock;
1679         }
1680
1681         if (!info->bitmap && info->offset == offset) {
1682                 unlink_free_space(ctl, info);
1683                 info->offset += bytes;
1684                 info->bytes -= bytes;
1685                 link_free_space(ctl, info);
1686                 goto out_lock;
1687         }
1688
1689         if (!info->bitmap && info->offset <= offset &&
1690             info->offset + info->bytes >= offset + bytes) {
1691                 u64 old_start = info->offset;
1692                 /*
1693                  * we're freeing space in the middle of the info,
1694                  * this can happen during tree log replay
1695                  *
1696                  * first unlink the old info and then
1697                  * insert it again after the hole we're creating
1698                  */
1699                 unlink_free_space(ctl, info);
1700                 if (offset + bytes < info->offset + info->bytes) {
1701                         u64 old_end = info->offset + info->bytes;
1702
1703                         info->offset = offset + bytes;
1704                         info->bytes = old_end - info->offset;
1705                         ret = link_free_space(ctl, info);
1706                         WARN_ON(ret);
1707                         if (ret)
1708                                 goto out_lock;
1709                 } else {
1710                         /* the hole we're creating ends at the end
1711                          * of the info struct, just free the info
1712                          */
1713                         kmem_cache_free(btrfs_free_space_cachep, info);
1714                 }
1715                 spin_unlock(&ctl->tree_lock);
1716
1717                 /* step two, insert a new info struct to cover
1718                  * anything before the hole
1719                  */
1720                 ret = btrfs_add_free_space(block_group, old_start,
1721                                            offset - old_start);
1722                 WARN_ON(ret);
1723                 goto out;
1724         }
1725
1726         ret = remove_from_bitmap(ctl, info, &offset, &bytes);
1727         if (ret == -EAGAIN)
1728                 goto again;
1729         BUG_ON(ret);
1730 out_lock:
1731         spin_unlock(&ctl->tree_lock);
1732 out:
1733         return ret;
1734 }
1735
1736 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
1737                            u64 bytes)
1738 {
1739         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1740         struct btrfs_free_space *info;
1741         struct rb_node *n;
1742         int count = 0;
1743
1744         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
1745                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1746                 if (info->bytes >= bytes)
1747                         count++;
1748                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
1749                        (unsigned long long)info->offset,
1750                        (unsigned long long)info->bytes,
1751                        (info->bitmap) ? "yes" : "no");
1752         }
1753         printk(KERN_INFO "block group has cluster?: %s\n",
1754                list_empty(&block_group->cluster_list) ? "no" : "yes");
1755         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
1756                "\n", count);
1757 }
1758
1759 static struct btrfs_free_space_op free_space_op = {
1760         .recalc_thresholds      = recalculate_thresholds,
1761         .use_bitmap             = use_bitmap,
1762 };
1763
1764 void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
1765 {
1766         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1767
1768         spin_lock_init(&ctl->tree_lock);
1769         ctl->unit = block_group->sectorsize;
1770         ctl->start = block_group->key.objectid;
1771         ctl->private = block_group;
1772         ctl->op = &free_space_op;
1773
1774         /*
1775          * we only want to have 32k of ram per block group for keeping
1776          * track of free space, and if we pass 1/2 of that we want to
1777          * start converting things over to using bitmaps
1778          */
1779         ctl->extents_thresh = ((1024 * 32) / 2) /
1780                                 sizeof(struct btrfs_free_space);
1781 }
1782
1783 /*
1784  * for a given cluster, put all of its extents back into the free
1785  * space cache.  If the block group passed doesn't match the block group
1786  * pointed to by the cluster, someone else raced in and freed the
1787  * cluster already.  In that case, we just return without changing anything
1788  */
1789 static int
1790 __btrfs_return_cluster_to_free_space(
1791                              struct btrfs_block_group_cache *block_group,
1792                              struct btrfs_free_cluster *cluster)
1793 {
1794         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1795         struct btrfs_free_space *entry;
1796         struct rb_node *node;
1797
1798         spin_lock(&cluster->lock);
1799         if (cluster->block_group != block_group)
1800                 goto out;
1801
1802         cluster->block_group = NULL;
1803         cluster->window_start = 0;
1804         list_del_init(&cluster->block_group_list);
1805
1806         node = rb_first(&cluster->root);
1807         while (node) {
1808                 bool bitmap;
1809
1810                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1811                 node = rb_next(&entry->offset_index);
1812                 rb_erase(&entry->offset_index, &cluster->root);
1813
1814                 bitmap = (entry->bitmap != NULL);
1815                 if (!bitmap)
1816                         try_merge_free_space(ctl, entry, false);
1817                 tree_insert_offset(&ctl->free_space_offset,
1818                                    entry->offset, &entry->offset_index, bitmap);
1819         }
1820         cluster->root = RB_ROOT;
1821
1822 out:
1823         spin_unlock(&cluster->lock);
1824         btrfs_put_block_group(block_group);
1825         return 0;
1826 }
1827
1828 void __btrfs_remove_free_space_cache_locked(struct btrfs_free_space_ctl *ctl)
1829 {
1830         struct btrfs_free_space *info;
1831         struct rb_node *node;
1832
1833         while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
1834                 info = rb_entry(node, struct btrfs_free_space, offset_index);
1835                 unlink_free_space(ctl, info);
1836                 kfree(info->bitmap);
1837                 kmem_cache_free(btrfs_free_space_cachep, info);
1838                 if (need_resched()) {
1839                         spin_unlock(&ctl->tree_lock);
1840                         cond_resched();
1841                         spin_lock(&ctl->tree_lock);
1842                 }
1843         }
1844 }
1845
1846 void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
1847 {
1848         spin_lock(&ctl->tree_lock);
1849         __btrfs_remove_free_space_cache_locked(ctl);
1850         spin_unlock(&ctl->tree_lock);
1851 }
1852
1853 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
1854 {
1855         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1856         struct btrfs_free_cluster *cluster;
1857         struct list_head *head;
1858
1859         spin_lock(&ctl->tree_lock);
1860         while ((head = block_group->cluster_list.next) !=
1861                &block_group->cluster_list) {
1862                 cluster = list_entry(head, struct btrfs_free_cluster,
1863                                      block_group_list);
1864
1865                 WARN_ON(cluster->block_group != block_group);
1866                 __btrfs_return_cluster_to_free_space(block_group, cluster);
1867                 if (need_resched()) {
1868                         spin_unlock(&ctl->tree_lock);
1869                         cond_resched();
1870                         spin_lock(&ctl->tree_lock);
1871                 }
1872         }
1873         __btrfs_remove_free_space_cache_locked(ctl);
1874         spin_unlock(&ctl->tree_lock);
1875
1876 }
1877
1878 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
1879                                u64 offset, u64 bytes, u64 empty_size)
1880 {
1881         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1882         struct btrfs_free_space *entry = NULL;
1883         u64 bytes_search = bytes + empty_size;
1884         u64 ret = 0;
1885
1886         spin_lock(&ctl->tree_lock);
1887         entry = find_free_space(ctl, &offset, &bytes_search);
1888         if (!entry)
1889                 goto out;
1890
1891         ret = offset;
1892         if (entry->bitmap) {
1893                 bitmap_clear_bits(ctl, entry, offset, bytes);
1894                 if (!entry->bytes)
1895                         free_bitmap(ctl, entry);
1896         } else {
1897                 unlink_free_space(ctl, entry);
1898                 entry->offset += bytes;
1899                 entry->bytes -= bytes;
1900                 if (!entry->bytes)
1901                         kmem_cache_free(btrfs_free_space_cachep, entry);
1902                 else
1903                         link_free_space(ctl, entry);
1904         }
1905
1906 out:
1907         spin_unlock(&ctl->tree_lock);
1908
1909         return ret;
1910 }
1911
1912 /*
1913  * given a cluster, put all of its extents back into the free space
1914  * cache.  If a block group is passed, this function will only free
1915  * a cluster that belongs to the passed block group.
1916  *
1917  * Otherwise, it'll get a reference on the block group pointed to by the
1918  * cluster and remove the cluster from it.
1919  */
1920 int btrfs_return_cluster_to_free_space(
1921                                struct btrfs_block_group_cache *block_group,
1922                                struct btrfs_free_cluster *cluster)
1923 {
1924         struct btrfs_free_space_ctl *ctl;
1925         int ret;
1926
1927         /* first, get a safe pointer to the block group */
1928         spin_lock(&cluster->lock);
1929         if (!block_group) {
1930                 block_group = cluster->block_group;
1931                 if (!block_group) {
1932                         spin_unlock(&cluster->lock);
1933                         return 0;
1934                 }
1935         } else if (cluster->block_group != block_group) {
1936                 /* someone else has already freed it don't redo their work */
1937                 spin_unlock(&cluster->lock);
1938                 return 0;
1939         }
1940         atomic_inc(&block_group->count);
1941         spin_unlock(&cluster->lock);
1942
1943         ctl = block_group->free_space_ctl;
1944
1945         /* now return any extents the cluster had on it */
1946         spin_lock(&ctl->tree_lock);
1947         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
1948         spin_unlock(&ctl->tree_lock);
1949
1950         /* finally drop our ref */
1951         btrfs_put_block_group(block_group);
1952         return ret;
1953 }
1954
1955 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
1956                                    struct btrfs_free_cluster *cluster,
1957                                    struct btrfs_free_space *entry,
1958                                    u64 bytes, u64 min_start)
1959 {
1960         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1961         int err;
1962         u64 search_start = cluster->window_start;
1963         u64 search_bytes = bytes;
1964         u64 ret = 0;
1965
1966         search_start = min_start;
1967         search_bytes = bytes;
1968
1969         err = search_bitmap(ctl, entry, &search_start, &search_bytes);
1970         if (err)
1971                 return 0;
1972
1973         ret = search_start;
1974         bitmap_clear_bits(ctl, entry, ret, bytes);
1975
1976         return ret;
1977 }
1978
1979 /*
1980  * given a cluster, try to allocate 'bytes' from it, returns 0
1981  * if it couldn't find anything suitably large, or a logical disk offset
1982  * if things worked out
1983  */
1984 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
1985                              struct btrfs_free_cluster *cluster, u64 bytes,
1986                              u64 min_start)
1987 {
1988         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1989         struct btrfs_free_space *entry = NULL;
1990         struct rb_node *node;
1991         u64 ret = 0;
1992
1993         spin_lock(&cluster->lock);
1994         if (bytes > cluster->max_size)
1995                 goto out;
1996
1997         if (cluster->block_group != block_group)
1998                 goto out;
1999
2000         node = rb_first(&cluster->root);
2001         if (!node)
2002                 goto out;
2003
2004         entry = rb_entry(node, struct btrfs_free_space, offset_index);
2005         while(1) {
2006                 if (entry->bytes < bytes ||
2007                     (!entry->bitmap && entry->offset < min_start)) {
2008                         node = rb_next(&entry->offset_index);
2009                         if (!node)
2010                                 break;
2011                         entry = rb_entry(node, struct btrfs_free_space,
2012                                          offset_index);
2013                         continue;
2014                 }
2015
2016                 if (entry->bitmap) {
2017                         ret = btrfs_alloc_from_bitmap(block_group,
2018                                                       cluster, entry, bytes,
2019                                                       min_start);
2020                         if (ret == 0) {
2021                                 node = rb_next(&entry->offset_index);
2022                                 if (!node)
2023                                         break;
2024                                 entry = rb_entry(node, struct btrfs_free_space,
2025                                                  offset_index);
2026                                 continue;
2027                         }
2028                 } else {
2029
2030                         ret = entry->offset;
2031
2032                         entry->offset += bytes;
2033                         entry->bytes -= bytes;
2034                 }
2035
2036                 if (entry->bytes == 0)
2037                         rb_erase(&entry->offset_index, &cluster->root);
2038                 break;
2039         }
2040 out:
2041         spin_unlock(&cluster->lock);
2042
2043         if (!ret)
2044                 return 0;
2045
2046         spin_lock(&ctl->tree_lock);
2047
2048         ctl->free_space -= bytes;
2049         if (entry->bytes == 0) {
2050                 ctl->free_extents--;
2051                 if (entry->bitmap) {
2052                         kfree(entry->bitmap);
2053                         ctl->total_bitmaps--;
2054                         ctl->op->recalc_thresholds(ctl);
2055                 }
2056                 kmem_cache_free(btrfs_free_space_cachep, entry);
2057         }
2058
2059         spin_unlock(&ctl->tree_lock);
2060
2061         return ret;
2062 }
2063
2064 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
2065                                 struct btrfs_free_space *entry,
2066                                 struct btrfs_free_cluster *cluster,
2067                                 u64 offset, u64 bytes, u64 min_bytes)
2068 {
2069         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2070         unsigned long next_zero;
2071         unsigned long i;
2072         unsigned long search_bits;
2073         unsigned long total_bits;
2074         unsigned long found_bits;
2075         unsigned long start = 0;
2076         unsigned long total_found = 0;
2077         int ret;
2078         bool found = false;
2079
2080         i = offset_to_bit(entry->offset, block_group->sectorsize,
2081                           max_t(u64, offset, entry->offset));
2082         search_bits = bytes_to_bits(bytes, block_group->sectorsize);
2083         total_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
2084
2085 again:
2086         found_bits = 0;
2087         for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
2088              i < BITS_PER_BITMAP;
2089              i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
2090                 next_zero = find_next_zero_bit(entry->bitmap,
2091                                                BITS_PER_BITMAP, i);
2092                 if (next_zero - i >= search_bits) {
2093                         found_bits = next_zero - i;
2094                         break;
2095                 }
2096                 i = next_zero;
2097         }
2098
2099         if (!found_bits)
2100                 return -ENOSPC;
2101
2102         if (!found) {
2103                 start = i;
2104                 found = true;
2105         }
2106
2107         total_found += found_bits;
2108
2109         if (cluster->max_size < found_bits * block_group->sectorsize)
2110                 cluster->max_size = found_bits * block_group->sectorsize;
2111
2112         if (total_found < total_bits) {
2113                 i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero);
2114                 if (i - start > total_bits * 2) {
2115                         total_found = 0;
2116                         cluster->max_size = 0;
2117                         found = false;
2118                 }
2119                 goto again;
2120         }
2121
2122         cluster->window_start = start * block_group->sectorsize +
2123                 entry->offset;
2124         rb_erase(&entry->offset_index, &ctl->free_space_offset);
2125         ret = tree_insert_offset(&cluster->root, entry->offset,
2126                                  &entry->offset_index, 1);
2127         BUG_ON(ret);
2128
2129         return 0;
2130 }
2131
2132 /*
2133  * This searches the block group for just extents to fill the cluster with.
2134  */
2135 static int setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
2136                                    struct btrfs_free_cluster *cluster,
2137                                    u64 offset, u64 bytes, u64 min_bytes)
2138 {
2139         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2140         struct btrfs_free_space *first = NULL;
2141         struct btrfs_free_space *entry = NULL;
2142         struct btrfs_free_space *prev = NULL;
2143         struct btrfs_free_space *last;
2144         struct rb_node *node;
2145         u64 window_start;
2146         u64 window_free;
2147         u64 max_extent;
2148         u64 max_gap = 128 * 1024;
2149
2150         entry = tree_search_offset(ctl, offset, 0, 1);
2151         if (!entry)
2152                 return -ENOSPC;
2153
2154         /*
2155          * We don't want bitmaps, so just move along until we find a normal
2156          * extent entry.
2157          */
2158         while (entry->bitmap) {
2159                 node = rb_next(&entry->offset_index);
2160                 if (!node)
2161                         return -ENOSPC;
2162                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2163         }
2164
2165         window_start = entry->offset;
2166         window_free = entry->bytes;
2167         max_extent = entry->bytes;
2168         first = entry;
2169         last = entry;
2170         prev = entry;
2171
2172         while (window_free <= min_bytes) {
2173                 node = rb_next(&entry->offset_index);
2174                 if (!node)
2175                         return -ENOSPC;
2176                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2177
2178                 if (entry->bitmap)
2179                         continue;
2180                 /*
2181                  * we haven't filled the empty size and the window is
2182                  * very large.  reset and try again
2183                  */
2184                 if (entry->offset - (prev->offset + prev->bytes) > max_gap ||
2185                     entry->offset - window_start > (min_bytes * 2)) {
2186                         first = entry;
2187                         window_start = entry->offset;
2188                         window_free = entry->bytes;
2189                         last = entry;
2190                         max_extent = entry->bytes;
2191                 } else {
2192                         last = entry;
2193                         window_free += entry->bytes;
2194                         if (entry->bytes > max_extent)
2195                                 max_extent = entry->bytes;
2196                 }
2197                 prev = entry;
2198         }
2199
2200         cluster->window_start = first->offset;
2201
2202         node = &first->offset_index;
2203
2204         /*
2205          * now we've found our entries, pull them out of the free space
2206          * cache and put them into the cluster rbtree
2207          */
2208         do {
2209                 int ret;
2210
2211                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2212                 node = rb_next(&entry->offset_index);
2213                 if (entry->bitmap)
2214                         continue;
2215
2216                 rb_erase(&entry->offset_index, &ctl->free_space_offset);
2217                 ret = tree_insert_offset(&cluster->root, entry->offset,
2218                                          &entry->offset_index, 0);
2219                 BUG_ON(ret);
2220         } while (node && entry != last);
2221
2222         cluster->max_size = max_extent;
2223
2224         return 0;
2225 }
2226
2227 /*
2228  * This specifically looks for bitmaps that may work in the cluster, we assume
2229  * that we have already failed to find extents that will work.
2230  */
2231 static int setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2232                                 struct btrfs_free_cluster *cluster,
2233                                 u64 offset, u64 bytes, u64 min_bytes)
2234 {
2235         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2236         struct btrfs_free_space *entry;
2237         struct rb_node *node;
2238         int ret = -ENOSPC;
2239
2240         if (ctl->total_bitmaps == 0)
2241                 return -ENOSPC;
2242
2243         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, offset), 0, 1);
2244         if (!entry)
2245                 return -ENOSPC;
2246
2247         node = &entry->offset_index;
2248         do {
2249                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2250                 node = rb_next(&entry->offset_index);
2251                 if (!entry->bitmap)
2252                         continue;
2253                 if (entry->bytes < min_bytes)
2254                         continue;
2255                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2256                                            bytes, min_bytes);
2257         } while (ret && node);
2258
2259         return ret;
2260 }
2261
2262 /*
2263  * here we try to find a cluster of blocks in a block group.  The goal
2264  * is to find at least bytes free and up to empty_size + bytes free.
2265  * We might not find them all in one contiguous area.
2266  *
2267  * returns zero and sets up cluster if things worked out, otherwise
2268  * it returns -enospc
2269  */
2270 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
2271                              struct btrfs_root *root,
2272                              struct btrfs_block_group_cache *block_group,
2273                              struct btrfs_free_cluster *cluster,
2274                              u64 offset, u64 bytes, u64 empty_size)
2275 {
2276         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2277         u64 min_bytes;
2278         int ret;
2279
2280         /* for metadata, allow allocates with more holes */
2281         if (btrfs_test_opt(root, SSD_SPREAD)) {
2282                 min_bytes = bytes + empty_size;
2283         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
2284                 /*
2285                  * we want to do larger allocations when we are
2286                  * flushing out the delayed refs, it helps prevent
2287                  * making more work as we go along.
2288                  */
2289                 if (trans->transaction->delayed_refs.flushing)
2290                         min_bytes = max(bytes, (bytes + empty_size) >> 1);
2291                 else
2292                         min_bytes = max(bytes, (bytes + empty_size) >> 4);
2293         } else
2294                 min_bytes = max(bytes, (bytes + empty_size) >> 2);
2295
2296         spin_lock(&ctl->tree_lock);
2297
2298         /*
2299          * If we know we don't have enough space to make a cluster don't even
2300          * bother doing all the work to try and find one.
2301          */
2302         if (ctl->free_space < min_bytes) {
2303                 spin_unlock(&ctl->tree_lock);
2304                 return -ENOSPC;
2305         }
2306
2307         spin_lock(&cluster->lock);
2308
2309         /* someone already found a cluster, hooray */
2310         if (cluster->block_group) {
2311                 ret = 0;
2312                 goto out;
2313         }
2314
2315         ret = setup_cluster_no_bitmap(block_group, cluster, offset, bytes,
2316                                       min_bytes);
2317         if (ret)
2318                 ret = setup_cluster_bitmap(block_group, cluster, offset,
2319                                            bytes, min_bytes);
2320
2321         if (!ret) {
2322                 atomic_inc(&block_group->count);
2323                 list_add_tail(&cluster->block_group_list,
2324                               &block_group->cluster_list);
2325                 cluster->block_group = block_group;
2326         }
2327 out:
2328         spin_unlock(&cluster->lock);
2329         spin_unlock(&ctl->tree_lock);
2330
2331         return ret;
2332 }
2333
2334 /*
2335  * simple code to zero out a cluster
2336  */
2337 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
2338 {
2339         spin_lock_init(&cluster->lock);
2340         spin_lock_init(&cluster->refill_lock);
2341         cluster->root = RB_ROOT;
2342         cluster->max_size = 0;
2343         INIT_LIST_HEAD(&cluster->block_group_list);
2344         cluster->block_group = NULL;
2345 }
2346
2347 int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
2348                            u64 *trimmed, u64 start, u64 end, u64 minlen)
2349 {
2350         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2351         struct btrfs_free_space *entry = NULL;
2352         struct btrfs_fs_info *fs_info = block_group->fs_info;
2353         u64 bytes = 0;
2354         u64 actually_trimmed;
2355         int ret = 0;
2356
2357         *trimmed = 0;
2358
2359         while (start < end) {
2360                 spin_lock(&ctl->tree_lock);
2361
2362                 if (ctl->free_space < minlen) {
2363                         spin_unlock(&ctl->tree_lock);
2364                         break;
2365                 }
2366
2367                 entry = tree_search_offset(ctl, start, 0, 1);
2368                 if (!entry)
2369                         entry = tree_search_offset(ctl,
2370                                                    offset_to_bitmap(ctl, start),
2371                                                    1, 1);
2372
2373                 if (!entry || entry->offset >= end) {
2374                         spin_unlock(&ctl->tree_lock);
2375                         break;
2376                 }
2377
2378                 if (entry->bitmap) {
2379                         ret = search_bitmap(ctl, entry, &start, &bytes);
2380                         if (!ret) {
2381                                 if (start >= end) {
2382                                         spin_unlock(&ctl->tree_lock);
2383                                         break;
2384                                 }
2385                                 bytes = min(bytes, end - start);
2386                                 bitmap_clear_bits(ctl, entry, start, bytes);
2387                                 if (entry->bytes == 0)
2388                                         free_bitmap(ctl, entry);
2389                         } else {
2390                                 start = entry->offset + BITS_PER_BITMAP *
2391                                         block_group->sectorsize;
2392                                 spin_unlock(&ctl->tree_lock);
2393                                 ret = 0;
2394                                 continue;
2395                         }
2396                 } else {
2397                         start = entry->offset;
2398                         bytes = min(entry->bytes, end - start);
2399                         unlink_free_space(ctl, entry);
2400                         kmem_cache_free(btrfs_free_space_cachep, entry);
2401                 }
2402
2403                 spin_unlock(&ctl->tree_lock);
2404
2405                 if (bytes >= minlen) {
2406                         int update_ret;
2407                         update_ret = btrfs_update_reserved_bytes(block_group,
2408                                                                  bytes, 1, 1);
2409
2410                         ret = btrfs_error_discard_extent(fs_info->extent_root,
2411                                                          start,
2412                                                          bytes,
2413                                                          &actually_trimmed);
2414
2415                         btrfs_add_free_space(block_group, start, bytes);
2416                         if (!update_ret)
2417                                 btrfs_update_reserved_bytes(block_group,
2418                                                             bytes, 0, 1);
2419
2420                         if (ret)
2421                                 break;
2422                         *trimmed += actually_trimmed;
2423                 }
2424                 start += bytes;
2425                 bytes = 0;
2426
2427                 if (fatal_signal_pending(current)) {
2428                         ret = -ERESTARTSYS;
2429                         break;
2430                 }
2431
2432                 cond_resched();
2433         }
2434
2435         return ret;
2436 }
2437
2438 /*
2439  * Find the left-most item in the cache tree, and then return the
2440  * smallest inode number in the item.
2441  *
2442  * Note: the returned inode number may not be the smallest one in
2443  * the tree, if the left-most item is a bitmap.
2444  */
2445 u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root)
2446 {
2447         struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl;
2448         struct btrfs_free_space *entry = NULL;
2449         u64 ino = 0;
2450
2451         spin_lock(&ctl->tree_lock);
2452
2453         if (RB_EMPTY_ROOT(&ctl->free_space_offset))
2454                 goto out;
2455
2456         entry = rb_entry(rb_first(&ctl->free_space_offset),
2457                          struct btrfs_free_space, offset_index);
2458
2459         if (!entry->bitmap) {
2460                 ino = entry->offset;
2461
2462                 unlink_free_space(ctl, entry);
2463                 entry->offset++;
2464                 entry->bytes--;
2465                 if (!entry->bytes)
2466                         kmem_cache_free(btrfs_free_space_cachep, entry);
2467                 else
2468                         link_free_space(ctl, entry);
2469         } else {
2470                 u64 offset = 0;
2471                 u64 count = 1;
2472                 int ret;
2473
2474                 ret = search_bitmap(ctl, entry, &offset, &count);
2475                 BUG_ON(ret);
2476
2477                 ino = offset;
2478                 bitmap_clear_bits(ctl, entry, offset, 1);
2479                 if (entry->bytes == 0)
2480                         free_bitmap(ctl, entry);
2481         }
2482 out:
2483         spin_unlock(&ctl->tree_lock);
2484
2485         return ino;
2486 }
2487
2488 struct inode *lookup_free_ino_inode(struct btrfs_root *root,
2489                                     struct btrfs_path *path)
2490 {
2491         struct inode *inode = NULL;
2492
2493         spin_lock(&root->cache_lock);
2494         if (root->cache_inode)
2495                 inode = igrab(root->cache_inode);
2496         spin_unlock(&root->cache_lock);
2497         if (inode)
2498                 return inode;
2499
2500         inode = __lookup_free_space_inode(root, path, 0);
2501         if (IS_ERR(inode))
2502                 return inode;
2503
2504         spin_lock(&root->cache_lock);
2505         if (!root->fs_info->closing)
2506                 root->cache_inode = igrab(inode);
2507         spin_unlock(&root->cache_lock);
2508
2509         return inode;
2510 }
2511
2512 int create_free_ino_inode(struct btrfs_root *root,
2513                           struct btrfs_trans_handle *trans,
2514                           struct btrfs_path *path)
2515 {
2516         return __create_free_space_inode(root, trans, path,
2517                                          BTRFS_FREE_INO_OBJECTID, 0);
2518 }
2519
2520 int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
2521 {
2522         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2523         struct btrfs_path *path;
2524         struct inode *inode;
2525         int ret = 0;
2526         u64 root_gen = btrfs_root_generation(&root->root_item);
2527
2528         /*
2529          * If we're unmounting then just return, since this does a search on the
2530          * normal root and not the commit root and we could deadlock.
2531          */
2532         smp_mb();
2533         if (fs_info->closing)
2534                 return 0;
2535
2536         path = btrfs_alloc_path();
2537         if (!path)
2538                 return 0;
2539
2540         inode = lookup_free_ino_inode(root, path);
2541         if (IS_ERR(inode))
2542                 goto out;
2543
2544         if (root_gen != BTRFS_I(inode)->generation)
2545                 goto out_put;
2546
2547         ret = __load_free_space_cache(root, inode, ctl, path, 0);
2548
2549         if (ret < 0)
2550                 printk(KERN_ERR "btrfs: failed to load free ino cache for "
2551                        "root %llu\n", root->root_key.objectid);
2552 out_put:
2553         iput(inode);
2554 out:
2555         btrfs_free_path(path);
2556         return ret;
2557 }
2558
2559 int btrfs_write_out_ino_cache(struct btrfs_root *root,
2560                               struct btrfs_trans_handle *trans,
2561                               struct btrfs_path *path)
2562 {
2563         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2564         struct inode *inode;
2565         int ret;
2566
2567         inode = lookup_free_ino_inode(root, path);
2568         if (IS_ERR(inode))
2569                 return 0;
2570
2571         ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);
2572         if (ret < 0)
2573                 printk(KERN_ERR "btrfs: failed to write free ino cache "
2574                        "for root %llu\n", root->root_key.objectid);
2575
2576         iput(inode);
2577         return ret;
2578 }