fs/btrfs/free-space-cache.c

   1 /*
   2  * Copyright (C) 2008 Red Hat.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/pagemap.h>
  20 #include <linux/sched.h>
  21 #include <linux/slab.h>
  22 #include <linux/math64.h>
  23 #include "ctree.h"
  24 #include "free-space-cache.h"
  25 #include "transaction.h"
  26 #include "disk-io.h"
  27 #include "extent_io.h"
  28 #include "inode-map.h"
  29
  30 #define BITS_PER_BITMAP         (PAGE_CACHE_SIZE * 8)
  31 #define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
  32
  33 static int link_free_space(struct btrfs_free_space_ctl *ctl,
  34                            struct btrfs_free_space *info);
  35
  36 static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
  37                                                struct btrfs_path *path,
  38                                                u64 offset)
  39 {
  40         struct btrfs_key key;
  41         struct btrfs_key location;
  42         struct btrfs_disk_key disk_key;
  43         struct btrfs_free_space_header *header;
  44         struct extent_buffer *leaf;
  45         struct inode *inode = NULL;
  46         int ret;
  47
  48         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
  49         key.offset = offset;
  50         key.type = 0;
  51
  52         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  53         if (ret < 0)
  54                 return ERR_PTR(ret);
  55         if (ret > 0) {
  56                 btrfs_release_path(path);
  57                 return ERR_PTR(-ENOENT);
  58         }
  59
  60         leaf = path->nodes[0];
  61         header = btrfs_item_ptr(leaf, path->slots[0],
  62                                 struct btrfs_free_space_header);
  63         btrfs_free_space_key(leaf, header, &disk_key);
  64         btrfs_disk_key_to_cpu(&location, &disk_key);
  65         btrfs_release_path(path);
  66
  67         inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
  68         if (!inode)
  69                 return ERR_PTR(-ENOENT);
  70         if (IS_ERR(inode))
  71                 return inode;
  72         if (is_bad_inode(inode)) {
  73                 iput(inode);
  74                 return ERR_PTR(-ENOENT);
  75         }
  76
  77         inode->i_mapping->flags &= ~__GFP_FS;
  78
  79         return inode;
  80 }
  81
  82 struct inode *lookup_free_space_inode(struct btrfs_root *root,
  83                                       struct btrfs_block_group_cache
  84                                       *block_group, struct btrfs_path *path)
  85 {
  86         struct inode *inode = NULL;
  87
  88         spin_lock(&block_group->lock);
  89         if (block_group->inode)
  90                 inode = igrab(block_group->inode);
  91         spin_unlock(&block_group->lock);
  92         if (inode)
  93                 return inode;
  94
  95         inode = __lookup_free_space_inode(root, path,
  96                                           block_group->key.objectid);
  97         if (IS_ERR(inode))
  98                 return inode;
  99
 100         spin_lock(&block_group->lock);
 101         if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) {
 102                 printk(KERN_INFO "Old style space inode found, converting.\n");
 103                 BTRFS_I(inode)->flags &= ~BTRFS_INODE_NODATASUM;
 104                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 105         }
 106
 107         if (!btrfs_fs_closing(root->fs_info)) {
 108                 block_group->inode = igrab(inode);
 109                 block_group->iref = 1;
 110         }
 111         spin_unlock(&block_group->lock);
 112
 113         return inode;
 114 }
 115
 116 int __create_free_space_inode(struct btrfs_root *root,
 117                               struct btrfs_trans_handle *trans,
 118                               struct btrfs_path *path, u64 ino, u64 offset)
 119 {
 120         struct btrfs_key key;
 121         struct btrfs_disk_key disk_key;
 122         struct btrfs_free_space_header *header;
 123         struct btrfs_inode_item *inode_item;
 124         struct extent_buffer *leaf;
 125         int ret;
 126
 127         ret = btrfs_insert_empty_inode(trans, root, path, ino);
 128         if (ret)
 129                 return ret;
 130
 131         leaf = path->nodes[0];
 132         inode_item = btrfs_item_ptr(leaf, path->slots[0],
 133                                     struct btrfs_inode_item);
 134         btrfs_item_key(leaf, &disk_key, path->slots[0]);
 135         memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
 136                              sizeof(*inode_item));
 137         btrfs_set_inode_generation(leaf, inode_item, trans->transid);
 138         btrfs_set_inode_size(leaf, inode_item, 0);
 139         btrfs_set_inode_nbytes(leaf, inode_item, 0);
 140         btrfs_set_inode_uid(leaf, inode_item, 0);
 141         btrfs_set_inode_gid(leaf, inode_item, 0);
 142         btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
 143         btrfs_set_inode_flags(leaf, inode_item, BTRFS_INODE_NOCOMPRESS |
 144                               BTRFS_INODE_PREALLOC);
 145         btrfs_set_inode_nlink(leaf, inode_item, 1);
 146         btrfs_set_inode_transid(leaf, inode_item, trans->transid);
 147         btrfs_set_inode_block_group(leaf, inode_item, offset);
 148         btrfs_mark_buffer_dirty(leaf);
 149         btrfs_release_path(path);
 150
 151         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 152         key.offset = offset;
 153         key.type = 0;
 154
 155         ret = btrfs_insert_empty_item(trans, root, path, &key,
 156                                       sizeof(struct btrfs_free_space_header));
 157         if (ret < 0) {
 158                 btrfs_release_path(path);
 159                 return ret;
 160         }
 161         leaf = path->nodes[0];
 162         header = btrfs_item_ptr(leaf, path->slots[0],
 163                                 struct btrfs_free_space_header);
 164         memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
 165         btrfs_set_free_space_key(leaf, header, &disk_key);
 166         btrfs_mark_buffer_dirty(leaf);
 167         btrfs_release_path(path);
 168
 169         return 0;
 170 }
 171
 172 int create_free_space_inode(struct btrfs_root *root,
 173                             struct btrfs_trans_handle *trans,
 174                             struct btrfs_block_group_cache *block_group,
 175                             struct btrfs_path *path)
 176 {
 177         int ret;
 178         u64 ino;
 179
 180         ret = btrfs_find_free_objectid(root, &ino);
 181         if (ret < 0)
 182                 return ret;
 183
 184         return __create_free_space_inode(root, trans, path, ino,
 185                                          block_group->key.objectid);
 186 }
 187
 188 int btrfs_truncate_free_space_cache(struct btrfs_root *root,
 189                                     struct btrfs_trans_handle *trans,
 190                                     struct btrfs_path *path,
 191                                     struct inode *inode)
 192 {
 193         loff_t oldsize;
 194         int ret = 0;
 195
 196         trans->block_rsv = root->orphan_block_rsv;
 197         ret = btrfs_block_rsv_check(trans, root,
 198                                     root->orphan_block_rsv,
 199                                     0, 5);
 200         if (ret)
 201                 return ret;
 202
 203         oldsize = i_size_read(inode);
 204         btrfs_i_size_write(inode, 0);
 205         truncate_pagecache(inode, oldsize, 0);
 206
 207         /*
 208          * We don't need an orphan item because truncating the free space cache
 209          * will never be split across transactions.
 210          */
 211         ret = btrfs_truncate_inode_items(trans, root, inode,
 212                                          0, BTRFS_EXTENT_DATA_KEY);
 213         if (ret) {
 214                 WARN_ON(1);
 215                 return ret;
 216         }
 217
 218         ret = btrfs_update_inode(trans, root, inode);
 219         return ret;
 220 }
 221
 222 static int readahead_cache(struct inode *inode)
 223 {
 224         struct file_ra_state *ra;
 225         unsigned long last_index;
 226
 227         ra = kzalloc(sizeof(*ra), GFP_NOFS);
 228         if (!ra)
 229                 return -ENOMEM;
 230
 231         file_ra_state_init(ra, inode->i_mapping);
 232         last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 233
 234         page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
 235
 236         kfree(ra);
 237
 238         return 0;
 239 }
 240
 241 int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 242                             struct btrfs_free_space_ctl *ctl,
 243                             struct btrfs_path *path, u64 offset)
 244 {
 245         struct btrfs_free_space_header *header;
 246         struct extent_buffer *leaf;
 247         struct page *page;
 248         struct btrfs_key key;
 249         struct list_head bitmaps;
 250         u64 num_entries;
 251         u64 num_bitmaps;
 252         u64 generation;
 253         pgoff_t index = 0;
 254         int ret = 0;
 255
 256         INIT_LIST_HEAD(&bitmaps);
 257
 258         /* Nothing in the space cache, goodbye */
 259         if (!i_size_read(inode))
 260                 goto out;
 261
 262         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 263         key.offset = offset;
 264         key.type = 0;
 265
 266         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 267         if (ret < 0)
 268                 goto out;
 269         else if (ret > 0) {
 270                 btrfs_release_path(path);
 271                 ret = 0;
 272                 goto out;
 273         }
 274
 275         ret = -1;
 276
 277         leaf = path->nodes[0];
 278         header = btrfs_item_ptr(leaf, path->slots[0],
 279                                 struct btrfs_free_space_header);
 280         num_entries = btrfs_free_space_entries(leaf, header);
 281         num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
 282         generation = btrfs_free_space_generation(leaf, header);
 283         btrfs_release_path(path);
 284
 285         if (BTRFS_I(inode)->generation != generation) {
 286                 printk(KERN_ERR "btrfs: free space inode generation (%llu) did"
 287                        " not match free space cache generation (%llu)\n",
 288                        (unsigned long long)BTRFS_I(inode)->generation,
 289                        (unsigned long long)generation);
 290                 goto out;
 291         }
 292
 293         if (!num_entries)
 294                 goto out;
 295
 296         ret = readahead_cache(inode);
 297         if (ret)
 298                 goto out;
 299
 300         while (1) {
 301                 struct btrfs_free_space_entry *entry;
 302                 struct btrfs_free_space *e;
 303                 void *addr;
 304                 unsigned long offset = 0;
 305                 int need_loop = 0;
 306
 307                 if (!num_entries && !num_bitmaps)
 308                         break;
 309
 310                 page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
 311                 if (!page)
 312                         goto free_cache;
 313
 314                 if (!PageUptodate(page)) {
 315                         btrfs_readpage(NULL, page);
 316                         lock_page(page);
 317                         if (!PageUptodate(page)) {
 318                                 unlock_page(page);
 319                                 page_cache_release(page);
 320                                 printk(KERN_ERR "btrfs: error reading free "
 321                                        "space cache\n");
 322                                 goto free_cache;
 323                         }
 324                 }
 325                 addr = kmap(page);
 326
 327                 if (index == 0) {
 328                         u64 *gen;
 329
 330                         /*
 331                          * We put a bogus crc in the front of the first page in
 332                          * case old kernels try to mount a fs with the new
 333                          * format to make sure they discard the cache.
 334                          */
 335                         addr += sizeof(u64);
 336                         offset += sizeof(u64);
 337
 338                         gen = addr;
 339                         if (*gen != BTRFS_I(inode)->generation) {
 340                                 printk(KERN_ERR "btrfs: space cache generation"
 341                                        " (%llu) does not match inode (%llu)\n",
 342                                        (unsigned long long)*gen,
 343                                        (unsigned long long)
 344                                        BTRFS_I(inode)->generation);
 345                                 kunmap(page);
 346                                 unlock_page(page);
 347                                 page_cache_release(page);
 348                                 goto free_cache;
 349                         }
 350                         addr += sizeof(u64);
 351                         offset += sizeof(u64);
 352                 }
 353                 entry = addr;
 354
 355                 while (1) {
 356                         if (!num_entries)
 357                                 break;
 358
 359                         need_loop = 1;
 360                         e = kmem_cache_zalloc(btrfs_free_space_cachep,
 361                                               GFP_NOFS);
 362                         if (!e) {
 363                                 kunmap(page);
 364                                 unlock_page(page);
 365                                 page_cache_release(page);
 366                                 goto free_cache;
 367                         }
 368
 369                         e->offset = le64_to_cpu(entry->offset);
 370                         e->bytes = le64_to_cpu(entry->bytes);
 371                         if (!e->bytes) {
 372                                 kunmap(page);
 373                                 kmem_cache_free(btrfs_free_space_cachep, e);
 374                                 unlock_page(page);
 375                                 page_cache_release(page);
 376                                 goto free_cache;
 377                         }
 378
 379                         if (entry->type == BTRFS_FREE_SPACE_EXTENT) {
 380                                 spin_lock(&ctl->tree_lock);
 381                                 ret = link_free_space(ctl, e);
 382                                 spin_unlock(&ctl->tree_lock);
 383                                 if (ret) {
 384                                         printk(KERN_ERR "Duplicate entries in "
 385                                                "free space cache, dumping\n");
 386                                         kunmap(page);
 387                                         unlock_page(page);
 388                                         page_cache_release(page);
 389                                         goto free_cache;
 390                                 }
 391                         } else {
 392                                 e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
 393                                 if (!e->bitmap) {
 394                                         kunmap(page);
 395                                         kmem_cache_free(
 396                                                 btrfs_free_space_cachep, e);
 397                                         unlock_page(page);
 398                                         page_cache_release(page);
 399                                         goto free_cache;
 400                                 }
 401                                 spin_lock(&ctl->tree_lock);
 402                                 ret = link_free_space(ctl, e);
 403                                 ctl->total_bitmaps++;
 404                                 ctl->op->recalc_thresholds(ctl);
 405                                 spin_unlock(&ctl->tree_lock);
 406                                 if (ret) {
 407                                         printk(KERN_ERR "Duplicate entries in "
 408                                                "free space cache, dumping\n");
 409                                         kunmap(page);
 410                                         unlock_page(page);
 411                                         page_cache_release(page);
 412                                         goto free_cache;
 413                                 }
 414                                 list_add_tail(&e->list, &bitmaps);
 415                         }
 416
 417                         num_entries--;
 418                         offset += sizeof(struct btrfs_free_space_entry);
 419                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 420                             PAGE_CACHE_SIZE)
 421                                 break;
 422                         entry++;
 423                 }
 424
 425                 /*
 426                  * We read an entry out of this page, we need to move on to the
 427                  * next page.
 428                  */
 429                 if (need_loop) {
 430                         kunmap(page);
 431                         goto next;
 432                 }
 433
 434                 /*
 435                  * We add the bitmaps at the end of the entries in order that
 436                  * the bitmap entries are added to the cache.
 437                  */
 438                 e = list_entry(bitmaps.next, struct btrfs_free_space, list);
 439                 list_del_init(&e->list);
 440                 memcpy(e->bitmap, addr, PAGE_CACHE_SIZE);
 441                 kunmap(page);
 442                 num_bitmaps--;
 443 next:
 444                 unlock_page(page);
 445                 page_cache_release(page);
 446                 index++;
 447         }
 448
 449         ret = 1;
 450 out:
 451         return ret;
 452 free_cache:
 453         __btrfs_remove_free_space_cache(ctl);
 454         goto out;
 455 }
 456
 457 int load_free_space_cache(struct btrfs_fs_info *fs_info,
 458                           struct btrfs_block_group_cache *block_group)
 459 {
 460         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 461         struct btrfs_root *root = fs_info->tree_root;
 462         struct inode *inode;
 463         struct btrfs_path *path;
 464         int ret;
 465         bool matched;
 466         u64 used = btrfs_block_group_used(&block_group->item);
 467
 468         /*
 469          * If we're unmounting then just return, since this does a search on the
 470          * normal root and not the commit root and we could deadlock.
 471          */
 472         if (btrfs_fs_closing(fs_info))
 473                 return 0;
 474
 475         /*
 476          * If this block group has been marked to be cleared for one reason or
 477          * another then we can't trust the on disk cache, so just return.
 478          */
 479         spin_lock(&block_group->lock);
 480         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 481                 spin_unlock(&block_group->lock);
 482                 return 0;
 483         }
 484         spin_unlock(&block_group->lock);
 485
 486         path = btrfs_alloc_path();
 487         if (!path)
 488                 return 0;
 489
 490         inode = lookup_free_space_inode(root, block_group, path);
 491         if (IS_ERR(inode)) {
 492                 btrfs_free_path(path);
 493                 return 0;
 494         }
 495
 496         ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
 497                                       path, block_group->key.objectid);
 498         btrfs_free_path(path);
 499         if (ret <= 0)
 500                 goto out;
 501
 502         spin_lock(&ctl->tree_lock);
 503         matched = (ctl->free_space == (block_group->key.offset - used -
 504                                        block_group->bytes_super));
 505         spin_unlock(&ctl->tree_lock);
 506
 507         if (!matched) {
 508                 __btrfs_remove_free_space_cache(ctl);
 509                 printk(KERN_ERR "block group %llu has an wrong amount of free "
 510                        "space\n", block_group->key.objectid);
 511                 ret = -1;
 512         }
 513 out:
 514         if (ret < 0) {
 515                 /* This cache is bogus, make sure it gets cleared */
 516                 spin_lock(&block_group->lock);
 517                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 518                 spin_unlock(&block_group->lock);
 519                 ret = 0;
 520
 521                 printk(KERN_ERR "btrfs: failed to load free space cache "
 522                        "for block group %llu\n", block_group->key.objectid);
 523         }
 524
 525         iput(inode);
 526         return ret;
 527 }
 528
 529 int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 530                             struct btrfs_free_space_ctl *ctl,
 531                             struct btrfs_block_group_cache *block_group,
 532                             struct btrfs_trans_handle *trans,
 533                             struct btrfs_path *path, u64 offset)
 534 {
 535         struct btrfs_free_space_header *header;
 536         struct extent_buffer *leaf;
 537         struct rb_node *node;
 538         struct list_head *pos, *n;
 539         struct page **pages;
 540         struct page *page;
 541         struct extent_state *cached_state = NULL;
 542         struct btrfs_free_cluster *cluster = NULL;
 543         struct extent_io_tree *unpin = NULL;
 544         struct list_head bitmap_list;
 545         struct btrfs_key key;
 546         u64 start, end, len;
 547         u64 bytes = 0;
 548         u32 crc = ~(u32)0;
 549         int index = 0, num_pages = 0;
 550         int entries = 0;
 551         int bitmaps = 0;
 552         int ret = -1;
 553         bool next_page = false;
 554         bool out_of_space = false;
 555
 556         INIT_LIST_HEAD(&bitmap_list);
 557
 558         node = rb_first(&ctl->free_space_offset);
 559         if (!node)
 560                 return 0;
 561
 562         if (!i_size_read(inode))
 563                 return -1;
 564
 565         num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
 566                 PAGE_CACHE_SHIFT;
 567
 568         filemap_write_and_wait(inode->i_mapping);
 569         btrfs_wait_ordered_range(inode, inode->i_size &
 570                                  ~(root->sectorsize - 1), (u64)-1);
 571
 572         pages = kzalloc(sizeof(struct page *) * num_pages, GFP_NOFS);
 573         if (!pages)
 574                 return -1;
 575
 576         /* Get the cluster for this block_group if it exists */
 577         if (block_group && !list_empty(&block_group->cluster_list))
 578                 cluster = list_entry(block_group->cluster_list.next,
 579                                      struct btrfs_free_cluster,
 580                                      block_group_list);
 581
 582         /*
 583          * We shouldn't have switched the pinned extents yet so this is the
 584          * right one
 585          */
 586         unpin = root->fs_info->pinned_extents;
 587
 588         /*
 589          * Lock all pages first so we can lock the extent safely.
 590          *
 591          * NOTE: Because we hold the ref the entire time we're going to write to
 592          * the page find_get_page should never fail, so we don't do a check
 593          * after find_get_page at this point.  Just putting this here so people
 594          * know and don't freak out.
 595          */
 596         while (index < num_pages) {
 597                 page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
 598                 if (!page) {
 599                         int i;
 600
 601                         for (i = 0; i < num_pages; i++) {
 602                                 unlock_page(pages[i]);
 603                                 page_cache_release(pages[i]);
 604                         }
 605                         goto out;
 606                 }
 607                 pages[index] = page;
 608                 index++;
 609         }
 610
 611         index = 0;
 612         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
 613                          0, &cached_state, GFP_NOFS);
 614
 615         /*
 616          * When searching for pinned extents, we need to start at our start
 617          * offset.
 618          */
 619         if (block_group)
 620                 start = block_group->key.objectid;
 621
 622         /* Write out the extent entries */
 623         do {
 624                 struct btrfs_free_space_entry *entry;
 625                 void *addr, *orig;
 626                 unsigned long offset = 0;
 627
 628                 next_page = false;
 629
 630                 if (index >= num_pages) {
 631                         out_of_space = true;
 632                         break;
 633                 }
 634
 635                 page = pages[index];
 636
 637                 orig = addr = kmap(page);
 638                 if (index == 0) {
 639                         u64 *gen;
 640
 641                         /*
 642                          * We're going to put in a bogus crc for this page to
 643                          * make sure that old kernels who aren't aware of this
 644                          * format will be sure to discard the cache.
 645                          */
 646                         addr += sizeof(u64);
 647                         offset += sizeof(u64);
 648
 649                         gen = addr;
 650                         *gen = trans->transid;
 651                         addr += sizeof(u64);
 652                         offset += sizeof(u64);
 653                 }
 654                 entry = addr;
 655
 656                 memset(addr, 0, PAGE_CACHE_SIZE - offset);
 657                 while (node && !next_page) {
 658                         struct btrfs_free_space *e;
 659
 660                         e = rb_entry(node, struct btrfs_free_space, offset_index);
 661                         entries++;
 662
 663                         entry->offset = cpu_to_le64(e->offset);
 664                         entry->bytes = cpu_to_le64(e->bytes);
 665                         if (e->bitmap) {
 666                                 entry->type = BTRFS_FREE_SPACE_BITMAP;
 667                                 list_add_tail(&e->list, &bitmap_list);
 668                                 bitmaps++;
 669                         } else {
 670                                 entry->type = BTRFS_FREE_SPACE_EXTENT;
 671                         }
 672                         node = rb_next(node);
 673                         if (!node && cluster) {
 674                                 node = rb_first(&cluster->root);
 675                                 cluster = NULL;
 676                         }
 677                         offset += sizeof(struct btrfs_free_space_entry);
 678                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 679                             PAGE_CACHE_SIZE)
 680                                 next_page = true;
 681                         entry++;
 682                 }
 683
 684                 /*
 685                  * We want to add any pinned extents to our free space cache
 686                  * so we don't leak the space
 687                  */
 688                 while (block_group && !next_page &&
 689                        (start < block_group->key.objectid +
 690                         block_group->key.offset)) {
 691                         ret = find_first_extent_bit(unpin, start, &start, &end,
 692                                                     EXTENT_DIRTY);
 693                         if (ret) {
 694                                 ret = 0;
 695                                 break;
 696                         }
 697
 698                         /* This pinned extent is out of our range */
 699                         if (start >= block_group->key.objectid +
 700                             block_group->key.offset)
 701                                 break;
 702
 703                         len = block_group->key.objectid +
 704                                 block_group->key.offset - start;
 705                         len = min(len, end + 1 - start);
 706
 707                         entries++;
 708                         entry->offset = cpu_to_le64(start);
 709                         entry->bytes = cpu_to_le64(len);
 710                         entry->type = BTRFS_FREE_SPACE_EXTENT;
 711
 712                         start = end + 1;
 713                         offset += sizeof(struct btrfs_free_space_entry);
 714                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 715                             PAGE_CACHE_SIZE)
 716                                 next_page = true;
 717                         entry++;
 718                 }
 719
 720                 /* Generate bogus crc value */
 721                 if (index == 0) {
 722                         u32 *tmp;
 723                         crc = btrfs_csum_data(root, orig + sizeof(u64), crc,
 724                                               PAGE_CACHE_SIZE - sizeof(u64));
 725                         btrfs_csum_final(crc, (char *)&crc);
 726                         crc++;
 727                         tmp = orig;
 728                         *tmp = crc;
 729                 }
 730
 731                 kunmap(page);
 732
 733                 bytes += PAGE_CACHE_SIZE;
 734
 735                 index++;
 736         } while (node || next_page);
 737
 738         /* Write out the bitmaps */
 739         list_for_each_safe(pos, n, &bitmap_list) {
 740                 void *addr;
 741                 struct btrfs_free_space *entry =
 742                         list_entry(pos, struct btrfs_free_space, list);
 743
 744                 if (index >= num_pages) {
 745                         out_of_space = true;
 746                         break;
 747                 }
 748                 page = pages[index];
 749
 750                 addr = kmap(page);
 751                 memcpy(addr, entry->bitmap, PAGE_CACHE_SIZE);
 752                 kunmap(page);
 753                 bytes += PAGE_CACHE_SIZE;
 754
 755                 list_del_init(&entry->list);
 756                 index++;
 757         }
 758
 759         if (out_of_space) {
 760                 btrfs_drop_pages(pages, num_pages);
 761                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 762                                      i_size_read(inode) - 1, &cached_state,
 763                                      GFP_NOFS);
 764                 ret = 0;
 765                 goto out;
 766         }
 767
 768         /* Zero out the rest of the pages just to make sure */
 769         while (index < num_pages) {
 770                 void *addr;
 771
 772                 page = pages[index];
 773                 addr = kmap(page);
 774                 memset(addr, 0, PAGE_CACHE_SIZE);
 775                 kunmap(page);
 776                 bytes += PAGE_CACHE_SIZE;
 777                 index++;
 778         }
 779
 780         ret = btrfs_dirty_pages(root, inode, pages, num_pages, 0,
 781                                             bytes, &cached_state);
 782         btrfs_drop_pages(pages, num_pages);
 783         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 784                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
 785
 786         if (ret) {
 787                 ret = 0;
 788                 goto out;
 789         }
 790
 791         BTRFS_I(inode)->generation = trans->transid;
 792
 793         filemap_write_and_wait(inode->i_mapping);
 794
 795         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 796         key.offset = offset;
 797         key.type = 0;
 798
 799         ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
 800         if (ret < 0) {
 801                 ret = -1;
 802                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 803                                  EXTENT_DIRTY | EXTENT_DELALLOC |
 804                                  EXTENT_DO_ACCOUNTING, 0, 0, NULL, GFP_NOFS);
 805                 goto out;
 806         }
 807         leaf = path->nodes[0];
 808         if (ret > 0) {
 809                 struct btrfs_key found_key;
 810                 BUG_ON(!path->slots[0]);
 811                 path->slots[0]--;
 812                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 813                 if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
 814                     found_key.offset != offset) {
 815                         ret = -1;
 816                         clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 817                                          EXTENT_DIRTY | EXTENT_DELALLOC |
 818                                          EXTENT_DO_ACCOUNTING, 0, 0, NULL,
 819                                          GFP_NOFS);
 820                         btrfs_release_path(path);
 821                         goto out;
 822                 }
 823         }
 824         header = btrfs_item_ptr(leaf, path->slots[0],
 825                                 struct btrfs_free_space_header);
 826         btrfs_set_free_space_entries(leaf, header, entries);
 827         btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
 828         btrfs_set_free_space_generation(leaf, header, trans->transid);
 829         btrfs_mark_buffer_dirty(leaf);
 830         btrfs_release_path(path);
 831
 832         ret = 1;
 833
 834 out:
 835         kfree(pages);
 836         if (ret != 1) {
 837                 invalidate_inode_pages2_range(inode->i_mapping, 0, index);
 838                 BTRFS_I(inode)->generation = 0;
 839         }
 840         btrfs_update_inode(trans, root, inode);
 841         return ret;
 842 }
 843
 844 int btrfs_write_out_cache(struct btrfs_root *root,
 845                           struct btrfs_trans_handle *trans,
 846                           struct btrfs_block_group_cache *block_group,
 847                           struct btrfs_path *path)
 848 {
 849         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 850         struct inode *inode;
 851         int ret = 0;
 852
 853         root = root->fs_info->tree_root;
 854
 855         spin_lock(&block_group->lock);
 856         if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
 857                 spin_unlock(&block_group->lock);
 858                 return 0;
 859         }
 860         spin_unlock(&block_group->lock);
 861
 862         inode = lookup_free_space_inode(root, block_group, path);
 863         if (IS_ERR(inode))
 864                 return 0;
 865
 866         ret = __btrfs_write_out_cache(root, inode, ctl, block_group, trans,
 867                                       path, block_group->key.objectid);
 868         if (ret < 0) {
 869                 spin_lock(&block_group->lock);
 870                 block_group->disk_cache_state = BTRFS_DC_ERROR;
 871                 spin_unlock(&block_group->lock);
 872                 ret = 0;
 873
 874                 printk(KERN_ERR "btrfs: failed to write free space cace "
 875                        "for block group %llu\n", block_group->key.objectid);
 876         }
 877
 878         iput(inode);
 879         return ret;
 880 }
 881
 882 static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
 883                                           u64 offset)
 884 {
 885         BUG_ON(offset < bitmap_start);
 886         offset -= bitmap_start;
 887         return (unsigned long)(div_u64(offset, unit));
 888 }
 889
 890 static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
 891 {
 892         return (unsigned long)(div_u64(bytes, unit));
 893 }
 894
 895 static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
 896                                    u64 offset)
 897 {
 898         u64 bitmap_start;
 899         u64 bytes_per_bitmap;
 900
 901         bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
 902         bitmap_start = offset - ctl->start;
 903         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
 904         bitmap_start *= bytes_per_bitmap;
 905         bitmap_start += ctl->start;
 906
 907         return bitmap_start;
 908 }
 909
 910 static int tree_insert_offset(struct rb_root *root, u64 offset,
 911                               struct rb_node *node, int bitmap)
 912 {
 913         struct rb_node **p = &root->rb_node;
 914         struct rb_node *parent = NULL;
 915         struct btrfs_free_space *info;
 916
 917         while (*p) {
 918                 parent = *p;
 919                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
 920
 921                 if (offset < info->offset) {
 922                         p = &(*p)->rb_left;
 923                 } else if (offset > info->offset) {
 924                         p = &(*p)->rb_right;
 925                 } else {
 926                         /*
 927                          * we could have a bitmap entry and an extent entry
 928                          * share the same offset.  If this is the case, we want
 929                          * the extent entry to always be found first if we do a
 930                          * linear search through the tree, since we want to have
 931                          * the quickest allocation time, and allocating from an
 932                          * extent is faster than allocating from a bitmap.  So
 933                          * if we're inserting a bitmap and we find an entry at
 934                          * this offset, we want to go right, or after this entry
 935                          * logically.  If we are inserting an extent and we've
 936                          * found a bitmap, we want to go left, or before
 937                          * logically.
 938                          */
 939                         if (bitmap) {
 940                                 if (info->bitmap) {
 941                                         WARN_ON_ONCE(1);
 942                                         return -EEXIST;
 943                                 }
 944                                 p = &(*p)->rb_right;
 945                         } else {
 946                                 if (!info->bitmap) {
 947                                         WARN_ON_ONCE(1);
 948                                         return -EEXIST;
 949                                 }
 950                                 p = &(*p)->rb_left;
 951                         }
 952                 }
 953         }
 954
 955         rb_link_node(node, parent, p);
 956         rb_insert_color(node, root);
 957
 958         return 0;
 959 }
 960
 961 /*
 962  * searches the tree for the given offset.
 963  *
 964  * fuzzy - If this is set, then we are trying to make an allocation, and we just
 965  * want a section that has at least bytes size and comes at or after the given
 966  * offset.
 967  */
 968 static struct btrfs_free_space *
 969 tree_search_offset(struct btrfs_free_space_ctl *ctl,
 970                    u64 offset, int bitmap_only, int fuzzy)
 971 {
 972         struct rb_node *n = ctl->free_space_offset.rb_node;
 973         struct btrfs_free_space *entry, *prev = NULL;
 974
 975         /* find entry that is closest to the 'offset' */
 976         while (1) {
 977                 if (!n) {
 978                         entry = NULL;
 979                         break;
 980                 }
 981
 982                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
 983                 prev = entry;
 984
 985                 if (offset < entry->offset)
 986                         n = n->rb_left;
 987                 else if (offset > entry->offset)
 988                         n = n->rb_right;
 989                 else
 990                         break;
 991         }
 992
 993         if (bitmap_only) {
 994                 if (!entry)
 995                         return NULL;
 996                 if (entry->bitmap)
 997                         return entry;
 998
 999                 /*
1000                  * bitmap entry and extent entry may share same offset,
1001                  * in that case, bitmap entry comes after extent entry.
1002                  */
1003                 n = rb_next(n);
1004                 if (!n)
1005                         return NULL;
1006                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1007                 if (entry->offset != offset)
1008                         return NULL;
1009
1010                 WARN_ON(!entry->bitmap);
1011                 return entry;
1012         } else if (entry) {
1013                 if (entry->bitmap) {
1014                         /*
1015                          * if previous extent entry covers the offset,
1016                          * we should return it instead of the bitmap entry
1017                          */
1018                         n = &entry->offset_index;
1019                         while (1) {
1020                                 n = rb_prev(n);
1021                                 if (!n)
1022                                         break;
1023                                 prev = rb_entry(n, struct btrfs_free_space,
1024                                                 offset_index);
1025                                 if (!prev->bitmap) {
1026                                         if (prev->offset + prev->bytes > offset)
1027                                                 entry = prev;
1028                                         break;
1029                                 }
1030                         }
1031                 }
1032                 return entry;
1033         }
1034
1035         if (!prev)
1036                 return NULL;
1037
1038         /* find last entry before the 'offset' */
1039         entry = prev;
1040         if (entry->offset > offset) {
1041                 n = rb_prev(&entry->offset_index);
1042                 if (n) {
1043                         entry = rb_entry(n, struct btrfs_free_space,
1044                                         offset_index);
1045                         BUG_ON(entry->offset > offset);
1046                 } else {
1047                         if (fuzzy)
1048                                 return entry;
1049                         else
1050                                 return NULL;
1051                 }
1052         }
1053
1054         if (entry->bitmap) {
1055                 n = &entry->offset_index;
1056                 while (1) {
1057                         n = rb_prev(n);
1058                         if (!n)
1059                                 break;
1060                         prev = rb_entry(n, struct btrfs_free_space,
1061                                         offset_index);
1062                         if (!prev->bitmap) {
1063                                 if (prev->offset + prev->bytes > offset)
1064                                         return prev;
1065                                 break;
1066                         }
1067                 }
1068                 if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
1069                         return entry;
1070         } else if (entry->offset + entry->bytes > offset)
1071                 return entry;
1072
1073         if (!fuzzy)
1074                 return NULL;
1075
1076         while (1) {
1077                 if (entry->bitmap) {
1078                         if (entry->offset + BITS_PER_BITMAP *
1079                             ctl->unit > offset)
1080                                 break;
1081                 } else {
1082                         if (entry->offset + entry->bytes > offset)
1083                                 break;
1084                 }
1085
1086                 n = rb_next(&entry->offset_index);
1087                 if (!n)
1088                         return NULL;
1089                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1090         }
1091         return entry;
1092 }
1093
1094 static inline void
1095 __unlink_free_space(struct btrfs_free_space_ctl *ctl,
1096                     struct btrfs_free_space *info)
1097 {
1098         rb_erase(&info->offset_index, &ctl->free_space_offset);
1099         ctl->free_extents--;
1100 }
1101
1102 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
1103                               struct btrfs_free_space *info)
1104 {
1105         __unlink_free_space(ctl, info);
1106         ctl->free_space -= info->bytes;
1107 }
1108
1109 static int link_free_space(struct btrfs_free_space_ctl *ctl,
1110                            struct btrfs_free_space *info)
1111 {
1112         int ret = 0;
1113
1114         BUG_ON(!info->bitmap && !info->bytes);
1115         ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
1116                                  &info->offset_index, (info->bitmap != NULL));
1117         if (ret)
1118                 return ret;
1119
1120         ctl->free_space += info->bytes;
1121         ctl->free_extents++;
1122         return ret;
1123 }
1124
1125 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
1126 {
1127         struct btrfs_block_group_cache *block_group = ctl->private;
1128         u64 max_bytes;
1129         u64 bitmap_bytes;
1130         u64 extent_bytes;
1131         u64 size = block_group->key.offset;
1132         u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
1133         int max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
1134
1135         BUG_ON(ctl->total_bitmaps > max_bitmaps);
1136
1137         /*
1138          * The goal is to keep the total amount of memory used per 1gb of space
1139          * at or below 32k, so we need to adjust how much memory we allow to be
1140          * used by extent based free space tracking
1141          */
1142         if (size < 1024 * 1024 * 1024)
1143                 max_bytes = MAX_CACHE_BYTES_PER_GIG;
1144         else
1145                 max_bytes = MAX_CACHE_BYTES_PER_GIG *
1146                         div64_u64(size, 1024 * 1024 * 1024);
1147
1148         /*
1149          * we want to account for 1 more bitmap than what we have so we can make
1150          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1151          * we add more bitmaps.
1152          */
1153         bitmap_bytes = (ctl->total_bitmaps + 1) * PAGE_CACHE_SIZE;
1154
1155         if (bitmap_bytes >= max_bytes) {
1156                 ctl->extents_thresh = 0;
1157                 return;
1158         }
1159
1160         /*
1161          * we want the extent entry threshold to always be at most 1/2 the maxw
1162          * bytes we can have, or whatever is less than that.
1163          */
1164         extent_bytes = max_bytes - bitmap_bytes;
1165         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
1166
1167         ctl->extents_thresh =
1168                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
1169 }
1170
1171 static inline void __bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1172                                        struct btrfs_free_space *info,
1173                                        u64 offset, u64 bytes)
1174 {
1175         unsigned long start, count;
1176
1177         start = offset_to_bit(info->offset, ctl->unit, offset);
1178         count = bytes_to_bits(bytes, ctl->unit);
1179         BUG_ON(start + count > BITS_PER_BITMAP);
1180
1181         bitmap_clear(info->bitmap, start, count);
1182
1183         info->bytes -= bytes;
1184 }
1185
1186 static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1187                               struct btrfs_free_space *info, u64 offset,
1188                               u64 bytes)
1189 {
1190         __bitmap_clear_bits(ctl, info, offset, bytes);
1191         ctl->free_space -= bytes;
1192 }
1193
1194 static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
1195                             struct btrfs_free_space *info, u64 offset,
1196                             u64 bytes)
1197 {
1198         unsigned long start, count;
1199
1200         start = offset_to_bit(info->offset, ctl->unit, offset);
1201         count = bytes_to_bits(bytes, ctl->unit);
1202         BUG_ON(start + count > BITS_PER_BITMAP);
1203
1204         bitmap_set(info->bitmap, start, count);
1205
1206         info->bytes += bytes;
1207         ctl->free_space += bytes;
1208 }
1209
1210 static int search_bitmap(struct btrfs_free_space_ctl *ctl,
1211                          struct btrfs_free_space *bitmap_info, u64 *offset,
1212                          u64 *bytes)
1213 {
1214         unsigned long found_bits = 0;
1215         unsigned long bits, i;
1216         unsigned long next_zero;
1217
1218         i = offset_to_bit(bitmap_info->offset, ctl->unit,
1219                           max_t(u64, *offset, bitmap_info->offset));
1220         bits = bytes_to_bits(*bytes, ctl->unit);
1221
1222         for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
1223              i < BITS_PER_BITMAP;
1224              i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
1225                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
1226                                                BITS_PER_BITMAP, i);
1227                 if ((next_zero - i) >= bits) {
1228                         found_bits = next_zero - i;
1229                         break;
1230                 }
1231                 i = next_zero;
1232         }
1233
1234         if (found_bits) {
1235                 *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
1236                 *bytes = (u64)(found_bits) * ctl->unit;
1237                 return 0;
1238         }
1239
1240         return -1;
1241 }
1242
1243 static struct btrfs_free_space *
1244 find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes)
1245 {
1246         struct btrfs_free_space *entry;
1247         struct rb_node *node;
1248         int ret;
1249
1250         if (!ctl->free_space_offset.rb_node)
1251                 return NULL;
1252
1253         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
1254         if (!entry)
1255                 return NULL;
1256
1257         for (node = &entry->offset_index; node; node = rb_next(node)) {
1258                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1259                 if (entry->bytes < *bytes)
1260                         continue;
1261
1262                 if (entry->bitmap) {
1263                         ret = search_bitmap(ctl, entry, offset, bytes);
1264                         if (!ret)
1265                                 return entry;
1266                         continue;
1267                 }
1268
1269                 *offset = entry->offset;
1270                 *bytes = entry->bytes;
1271                 return entry;
1272         }
1273
1274         return NULL;
1275 }
1276
1277 static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
1278                            struct btrfs_free_space *info, u64 offset)
1279 {
1280         info->offset = offset_to_bitmap(ctl, offset);
1281         info->bytes = 0;
1282         link_free_space(ctl, info);
1283         ctl->total_bitmaps++;
1284
1285         ctl->op->recalc_thresholds(ctl);
1286 }
1287
1288 static void free_bitmap(struct btrfs_free_space_ctl *ctl,
1289                         struct btrfs_free_space *bitmap_info)
1290 {
1291         unlink_free_space(ctl, bitmap_info);
1292         kfree(bitmap_info->bitmap);
1293         kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1294         ctl->total_bitmaps--;
1295         ctl->op->recalc_thresholds(ctl);
1296 }
1297
1298 static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
1299                               struct btrfs_free_space *bitmap_info,
1300                               u64 *offset, u64 *bytes)
1301 {
1302         u64 end;
1303         u64 search_start, search_bytes;
1304         int ret;
1305
1306 again:
1307         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
1308
1309         /*
1310          * XXX - this can go away after a few releases.
1311          *
1312          * since the only user of btrfs_remove_free_space is the tree logging
1313          * stuff, and the only way to test that is under crash conditions, we
1314          * want to have this debug stuff here just in case somethings not
1315          * working.  Search the bitmap for the space we are trying to use to
1316          * make sure its actually there.  If its not there then we need to stop
1317          * because something has gone wrong.
1318          */
1319         search_start = *offset;
1320         search_bytes = *bytes;
1321         search_bytes = min(search_bytes, end - search_start + 1);
1322         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
1323         BUG_ON(ret < 0 || search_start != *offset);
1324
1325         if (*offset > bitmap_info->offset && *offset + *bytes > end) {
1326                 bitmap_clear_bits(ctl, bitmap_info, *offset, end - *offset + 1);
1327                 *bytes -= end - *offset + 1;
1328                 *offset = end + 1;
1329         } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
1330                 bitmap_clear_bits(ctl, bitmap_info, *offset, *bytes);
1331                 *bytes = 0;
1332         }
1333
1334         if (*bytes) {
1335                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
1336                 if (!bitmap_info->bytes)
1337                         free_bitmap(ctl, bitmap_info);
1338
1339                 /*
1340                  * no entry after this bitmap, but we still have bytes to
1341                  * remove, so something has gone wrong.
1342                  */
1343                 if (!next)
1344                         return -EINVAL;
1345
1346                 bitmap_info = rb_entry(next, struct btrfs_free_space,
1347                                        offset_index);
1348
1349                 /*
1350                  * if the next entry isn't a bitmap we need to return to let the
1351                  * extent stuff do its work.
1352                  */
1353                 if (!bitmap_info->bitmap)
1354                         return -EAGAIN;
1355
1356                 /*
1357                  * Ok the next item is a bitmap, but it may not actually hold
1358                  * the information for the rest of this free space stuff, so
1359                  * look for it, and if we don't find it return so we can try
1360                  * everything over again.
1361                  */
1362                 search_start = *offset;
1363                 search_bytes = *bytes;
1364                 ret = search_bitmap(ctl, bitmap_info, &search_start,
1365                                     &search_bytes);
1366                 if (ret < 0 || search_start != *offset)
1367                         return -EAGAIN;
1368
1369                 goto again;
1370         } else if (!bitmap_info->bytes)
1371                 free_bitmap(ctl, bitmap_info);
1372
1373         return 0;
1374 }
1375
1376 static u64 add_bytes_to_bitmap(struct btrfs_free_space_ctl *ctl,
1377                                struct btrfs_free_space *info, u64 offset,
1378                                u64 bytes)
1379 {
1380         u64 bytes_to_set = 0;
1381         u64 end;
1382
1383         end = info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
1384
1385         bytes_to_set = min(end - offset, bytes);
1386
1387         bitmap_set_bits(ctl, info, offset, bytes_to_set);
1388
1389         return bytes_to_set;
1390
1391 }
1392
1393 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
1394                       struct btrfs_free_space *info)
1395 {
1396         struct btrfs_block_group_cache *block_group = ctl->private;
1397
1398         /*
1399          * If we are below the extents threshold then we can add this as an
1400          * extent, and don't have to deal with the bitmap
1401          */
1402         if (ctl->free_extents < ctl->extents_thresh) {
1403                 /*
1404                  * If this block group has some small extents we don't want to
1405                  * use up all of our free slots in the cache with them, we want
1406                  * to reserve them to larger extents, however if we have plent
1407                  * of cache left then go ahead an dadd them, no sense in adding
1408                  * the overhead of a bitmap if we don't have to.
1409                  */
1410                 if (info->bytes <= block_group->sectorsize * 4) {
1411                         if (ctl->free_extents * 2 <= ctl->extents_thresh)
1412                                 return false;
1413                 } else {
1414                         return false;
1415                 }
1416         }
1417
1418         /*
1419          * some block groups are so tiny they can't be enveloped by a bitmap, so
1420          * don't even bother to create a bitmap for this
1421          */
1422         if (BITS_PER_BITMAP * block_group->sectorsize >
1423             block_group->key.offset)
1424                 return false;
1425
1426         return true;
1427 }
1428
1429 static struct btrfs_free_space_op free_space_op = {
1430         .recalc_thresholds      = recalculate_thresholds,
1431         .use_bitmap             = use_bitmap,
1432 };
1433
1434 static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
1435                               struct btrfs_free_space *info)
1436 {
1437         struct btrfs_free_space *bitmap_info;
1438         struct btrfs_block_group_cache *block_group = NULL;
1439         int added = 0;
1440         u64 bytes, offset, bytes_added;
1441         int ret;
1442
1443         bytes = info->bytes;
1444         offset = info->offset;
1445
1446         if (!ctl->op->use_bitmap(ctl, info))
1447                 return 0;
1448
1449         if (ctl->op == &free_space_op)
1450                 block_group = ctl->private;
1451 again:
1452         /*
1453          * Since we link bitmaps right into the cluster we need to see if we
1454          * have a cluster here, and if so and it has our bitmap we need to add
1455          * the free space to that bitmap.
1456          */
1457         if (block_group && !list_empty(&block_group->cluster_list)) {
1458                 struct btrfs_free_cluster *cluster;
1459                 struct rb_node *node;
1460                 struct btrfs_free_space *entry;
1461
1462                 cluster = list_entry(block_group->cluster_list.next,
1463                                      struct btrfs_free_cluster,
1464                                      block_group_list);
1465                 spin_lock(&cluster->lock);
1466                 node = rb_first(&cluster->root);
1467                 if (!node) {
1468                         spin_unlock(&cluster->lock);
1469                         goto no_cluster_bitmap;
1470                 }
1471
1472                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1473                 if (!entry->bitmap) {
1474                         spin_unlock(&cluster->lock);
1475                         goto no_cluster_bitmap;
1476                 }
1477
1478                 if (entry->offset == offset_to_bitmap(ctl, offset)) {
1479                         bytes_added = add_bytes_to_bitmap(ctl, entry,
1480                                                           offset, bytes);
1481                         bytes -= bytes_added;
1482                         offset += bytes_added;
1483                 }
1484                 spin_unlock(&cluster->lock);
1485                 if (!bytes) {
1486                         ret = 1;
1487                         goto out;
1488                 }
1489         }
1490
1491 no_cluster_bitmap:
1492         bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1493                                          1, 0);
1494         if (!bitmap_info) {
1495                 BUG_ON(added);
1496                 goto new_bitmap;
1497         }
1498
1499         bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
1500         bytes -= bytes_added;
1501         offset += bytes_added;
1502         added = 0;
1503
1504         if (!bytes) {
1505                 ret = 1;
1506                 goto out;
1507         } else
1508                 goto again;
1509
1510 new_bitmap:
1511         if (info && info->bitmap) {
1512                 add_new_bitmap(ctl, info, offset);
1513                 added = 1;
1514                 info = NULL;
1515                 goto again;
1516         } else {
1517                 spin_unlock(&ctl->tree_lock);
1518
1519                 /* no pre-allocated info, allocate a new one */
1520                 if (!info) {
1521                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
1522                                                  GFP_NOFS);
1523                         if (!info) {
1524                                 spin_lock(&ctl->tree_lock);
1525                                 ret = -ENOMEM;
1526                                 goto out;
1527                         }
1528                 }
1529
1530                 /* allocate the bitmap */
1531                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
1532                 spin_lock(&ctl->tree_lock);
1533                 if (!info->bitmap) {
1534                         ret = -ENOMEM;
1535                         goto out;
1536                 }
1537                 goto again;
1538         }
1539
1540 out:
1541         if (info) {
1542                 if (info->bitmap)
1543                         kfree(info->bitmap);
1544                 kmem_cache_free(btrfs_free_space_cachep, info);
1545         }
1546
1547         return ret;
1548 }
1549
1550 static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
1551                           struct btrfs_free_space *info, bool update_stat)
1552 {
1553         struct btrfs_free_space *left_info;
1554         struct btrfs_free_space *right_info;
1555         bool merged = false;
1556         u64 offset = info->offset;
1557         u64 bytes = info->bytes;
1558
1559         /*
1560          * first we want to see if there is free space adjacent to the range we
1561          * are adding, if there is remove that struct and add a new one to
1562          * cover the entire range
1563          */
1564         right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
1565         if (right_info && rb_prev(&right_info->offset_index))
1566                 left_info = rb_entry(rb_prev(&right_info->offset_index),
1567                                      struct btrfs_free_space, offset_index);
1568         else
1569                 left_info = tree_search_offset(ctl, offset - 1, 0, 0);
1570
1571         if (right_info && !right_info->bitmap) {
1572                 if (update_stat)
1573                         unlink_free_space(ctl, right_info);
1574                 else
1575                         __unlink_free_space(ctl, right_info);
1576                 info->bytes += right_info->bytes;
1577                 kmem_cache_free(btrfs_free_space_cachep, right_info);
1578                 merged = true;
1579         }
1580
1581         if (left_info && !left_info->bitmap &&
1582             left_info->offset + left_info->bytes == offset) {
1583                 if (update_stat)
1584                         unlink_free_space(ctl, left_info);
1585                 else
1586                         __unlink_free_space(ctl, left_info);
1587                 info->offset = left_info->offset;
1588                 info->bytes += left_info->bytes;
1589                 kmem_cache_free(btrfs_free_space_cachep, left_info);
1590                 merged = true;
1591         }
1592
1593         return merged;
1594 }
1595
1596 int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
1597                            u64 offset, u64 bytes)
1598 {
1599         struct btrfs_free_space *info;
1600         int ret = 0;
1601
1602         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
1603         if (!info)
1604                 return -ENOMEM;
1605
1606         info->offset = offset;
1607         info->bytes = bytes;
1608
1609         spin_lock(&ctl->tree_lock);
1610
1611         if (try_merge_free_space(ctl, info, true))
1612                 goto link;
1613
1614         /*
1615          * There was no extent directly to the left or right of this new
1616          * extent then we know we're going to have to allocate a new extent, so
1617          * before we do that see if we need to drop this into a bitmap
1618          */
1619         ret = insert_into_bitmap(ctl, info);
1620         if (ret < 0) {
1621                 goto out;
1622         } else if (ret) {
1623                 ret = 0;
1624                 goto out;
1625         }
1626 link:
1627         ret = link_free_space(ctl, info);
1628         if (ret)
1629                 kmem_cache_free(btrfs_free_space_cachep, info);
1630 out:
1631         spin_unlock(&ctl->tree_lock);
1632
1633         if (ret) {
1634                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
1635                 BUG_ON(ret == -EEXIST);
1636         }
1637
1638         return ret;
1639 }
1640
1641 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
1642                             u64 offset, u64 bytes)
1643 {
1644         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1645         struct btrfs_free_space *info;
1646         struct btrfs_free_space *next_info = NULL;
1647         int ret = 0;
1648
1649         spin_lock(&ctl->tree_lock);
1650
1651 again:
1652         info = tree_search_offset(ctl, offset, 0, 0);
1653         if (!info) {
1654                 /*
1655                  * oops didn't find an extent that matched the space we wanted
1656                  * to remove, look for a bitmap instead
1657                  */
1658                 info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1659                                           1, 0);
1660                 if (!info) {
1661                         WARN_ON(1);
1662                         goto out_lock;
1663                 }
1664         }
1665
1666         if (info->bytes < bytes && rb_next(&info->offset_index)) {
1667                 u64 end;
1668                 next_info = rb_entry(rb_next(&info->offset_index),
1669                                              struct btrfs_free_space,
1670                                              offset_index);
1671
1672                 if (next_info->bitmap)
1673                         end = next_info->offset +
1674                               BITS_PER_BITMAP * ctl->unit - 1;
1675                 else
1676                         end = next_info->offset + next_info->bytes;
1677
1678                 if (next_info->bytes < bytes ||
1679                     next_info->offset > offset || offset > end) {
1680                         printk(KERN_CRIT "Found free space at %llu, size %llu,"
1681                               " trying to use %llu\n",
1682                               (unsigned long long)info->offset,
1683                               (unsigned long long)info->bytes,
1684                               (unsigned long long)bytes);
1685                         WARN_ON(1);
1686                         ret = -EINVAL;
1687                         goto out_lock;
1688                 }
1689
1690                 info = next_info;
1691         }
1692
1693         if (info->bytes == bytes) {
1694                 unlink_free_space(ctl, info);
1695                 if (info->bitmap) {
1696                         kfree(info->bitmap);
1697                         ctl->total_bitmaps--;
1698                 }
1699                 kmem_cache_free(btrfs_free_space_cachep, info);
1700                 goto out_lock;
1701         }
1702
1703         if (!info->bitmap && info->offset == offset) {
1704                 unlink_free_space(ctl, info);
1705                 info->offset += bytes;
1706                 info->bytes -= bytes;
1707                 link_free_space(ctl, info);
1708                 goto out_lock;
1709         }
1710
1711         if (!info->bitmap && info->offset <= offset &&
1712             info->offset + info->bytes >= offset + bytes) {
1713                 u64 old_start = info->offset;
1714                 /*
1715                  * we're freeing space in the middle of the info,
1716                  * this can happen during tree log replay
1717                  *
1718                  * first unlink the old info and then
1719                  * insert it again after the hole we're creating
1720                  */
1721                 unlink_free_space(ctl, info);
1722                 if (offset + bytes < info->offset + info->bytes) {
1723                         u64 old_end = info->offset + info->bytes;
1724
1725                         info->offset = offset + bytes;
1726                         info->bytes = old_end - info->offset;
1727                         ret = link_free_space(ctl, info);
1728                         WARN_ON(ret);
1729                         if (ret)
1730                                 goto out_lock;
1731                 } else {
1732                         /* the hole we're creating ends at the end
1733                          * of the info struct, just free the info
1734                          */
1735                         kmem_cache_free(btrfs_free_space_cachep, info);
1736                 }
1737                 spin_unlock(&ctl->tree_lock);
1738
1739                 /* step two, insert a new info struct to cover
1740                  * anything before the hole
1741                  */
1742                 ret = btrfs_add_free_space(block_group, old_start,
1743                                            offset - old_start);
1744                 WARN_ON(ret);
1745                 goto out;
1746         }
1747
1748         ret = remove_from_bitmap(ctl, info, &offset, &bytes);
1749         if (ret == -EAGAIN)
1750                 goto again;
1751         BUG_ON(ret);
1752 out_lock:
1753         spin_unlock(&ctl->tree_lock);
1754 out:
1755         return ret;
1756 }
1757
1758 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
1759                            u64 bytes)
1760 {
1761         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1762         struct btrfs_free_space *info;
1763         struct rb_node *n;
1764         int count = 0;
1765
1766         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
1767                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1768                 if (info->bytes >= bytes)
1769                         count++;
1770                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
1771                        (unsigned long long)info->offset,
1772                        (unsigned long long)info->bytes,
1773                        (info->bitmap) ? "yes" : "no");
1774         }
1775         printk(KERN_INFO "block group has cluster?: %s\n",
1776                list_empty(&block_group->cluster_list) ? "no" : "yes");
1777         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
1778                "\n", count);
1779 }
1780
1781 void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
1782 {
1783         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1784
1785         spin_lock_init(&ctl->tree_lock);
1786         ctl->unit = block_group->sectorsize;
1787         ctl->start = block_group->key.objectid;
1788         ctl->private = block_group;
1789         ctl->op = &free_space_op;
1790
1791         /*
1792          * we only want to have 32k of ram per block group for keeping
1793          * track of free space, and if we pass 1/2 of that we want to
1794          * start converting things over to using bitmaps
1795          */
1796         ctl->extents_thresh = ((1024 * 32) / 2) /
1797                                 sizeof(struct btrfs_free_space);
1798 }
1799
1800 /*
1801  * for a given cluster, put all of its extents back into the free
1802  * space cache.  If the block group passed doesn't match the block group
1803  * pointed to by the cluster, someone else raced in and freed the
1804  * cluster already.  In that case, we just return without changing anything
1805  */
1806 static int
1807 __btrfs_return_cluster_to_free_space(
1808                              struct btrfs_block_group_cache *block_group,
1809                              struct btrfs_free_cluster *cluster)
1810 {
1811         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1812         struct btrfs_free_space *entry;
1813         struct rb_node *node;
1814
1815         spin_lock(&cluster->lock);
1816         if (cluster->block_group != block_group)
1817                 goto out;
1818
1819         cluster->block_group = NULL;
1820         cluster->window_start = 0;
1821         list_del_init(&cluster->block_group_list);
1822
1823         node = rb_first(&cluster->root);
1824         while (node) {
1825                 bool bitmap;
1826
1827                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1828                 node = rb_next(&entry->offset_index);
1829                 rb_erase(&entry->offset_index, &cluster->root);
1830
1831                 bitmap = (entry->bitmap != NULL);
1832                 if (!bitmap)
1833                         try_merge_free_space(ctl, entry, false);
1834                 tree_insert_offset(&ctl->free_space_offset,
1835                                    entry->offset, &entry->offset_index, bitmap);
1836         }
1837         cluster->root = RB_ROOT;
1838
1839 out:
1840         spin_unlock(&cluster->lock);
1841         btrfs_put_block_group(block_group);
1842         return 0;
1843 }
1844
1845 void __btrfs_remove_free_space_cache_locked(struct btrfs_free_space_ctl *ctl)
1846 {
1847         struct btrfs_free_space *info;
1848         struct rb_node *node;
1849
1850         while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
1851                 info = rb_entry(node, struct btrfs_free_space, offset_index);
1852                 if (!info->bitmap) {
1853                         unlink_free_space(ctl, info);
1854                         kmem_cache_free(btrfs_free_space_cachep, info);
1855                 } else {
1856                         free_bitmap(ctl, info);
1857                 }
1858                 if (need_resched()) {
1859                         spin_unlock(&ctl->tree_lock);
1860                         cond_resched();
1861                         spin_lock(&ctl->tree_lock);
1862                 }
1863         }
1864 }
1865
1866 void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
1867 {
1868         spin_lock(&ctl->tree_lock);
1869         __btrfs_remove_free_space_cache_locked(ctl);
1870         spin_unlock(&ctl->tree_lock);
1871 }
1872
1873 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
1874 {
1875         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1876         struct btrfs_free_cluster *cluster;
1877         struct list_head *head;
1878
1879         spin_lock(&ctl->tree_lock);
1880         while ((head = block_group->cluster_list.next) !=
1881                &block_group->cluster_list) {
1882                 cluster = list_entry(head, struct btrfs_free_cluster,
1883                                      block_group_list);
1884
1885                 WARN_ON(cluster->block_group != block_group);
1886                 __btrfs_return_cluster_to_free_space(block_group, cluster);
1887                 if (need_resched()) {
1888                         spin_unlock(&ctl->tree_lock);
1889                         cond_resched();
1890                         spin_lock(&ctl->tree_lock);
1891                 }
1892         }
1893         __btrfs_remove_free_space_cache_locked(ctl);
1894         spin_unlock(&ctl->tree_lock);
1895
1896 }
1897
1898 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
1899                                u64 offset, u64 bytes, u64 empty_size)
1900 {
1901         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1902         struct btrfs_free_space *entry = NULL;
1903         u64 bytes_search = bytes + empty_size;
1904         u64 ret = 0;
1905
1906         spin_lock(&ctl->tree_lock);
1907         entry = find_free_space(ctl, &offset, &bytes_search);
1908         if (!entry)
1909                 goto out;
1910
1911         ret = offset;
1912         if (entry->bitmap) {
1913                 bitmap_clear_bits(ctl, entry, offset, bytes);
1914                 if (!entry->bytes)
1915                         free_bitmap(ctl, entry);
1916         } else {
1917                 unlink_free_space(ctl, entry);
1918                 entry->offset += bytes;
1919                 entry->bytes -= bytes;
1920                 if (!entry->bytes)
1921                         kmem_cache_free(btrfs_free_space_cachep, entry);
1922                 else
1923                         link_free_space(ctl, entry);
1924         }
1925
1926 out:
1927         spin_unlock(&ctl->tree_lock);
1928
1929         return ret;
1930 }
1931
1932 /*
1933  * given a cluster, put all of its extents back into the free space
1934  * cache.  If a block group is passed, this function will only free
1935  * a cluster that belongs to the passed block group.
1936  *
1937  * Otherwise, it'll get a reference on the block group pointed to by the
1938  * cluster and remove the cluster from it.
1939  */
1940 int btrfs_return_cluster_to_free_space(
1941                                struct btrfs_block_group_cache *block_group,
1942                                struct btrfs_free_cluster *cluster)
1943 {
1944         struct btrfs_free_space_ctl *ctl;
1945         int ret;
1946
1947         /* first, get a safe pointer to the block group */
1948         spin_lock(&cluster->lock);
1949         if (!block_group) {
1950                 block_group = cluster->block_group;
1951                 if (!block_group) {
1952                         spin_unlock(&cluster->lock);
1953                         return 0;
1954                 }
1955         } else if (cluster->block_group != block_group) {
1956                 /* someone else has already freed it don't redo their work */
1957                 spin_unlock(&cluster->lock);
1958                 return 0;
1959         }
1960         atomic_inc(&block_group->count);
1961         spin_unlock(&cluster->lock);
1962
1963         ctl = block_group->free_space_ctl;
1964
1965         /* now return any extents the cluster had on it */
1966         spin_lock(&ctl->tree_lock);
1967         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
1968         spin_unlock(&ctl->tree_lock);
1969
1970         /* finally drop our ref */
1971         btrfs_put_block_group(block_group);
1972         return ret;
1973 }
1974
1975 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
1976                                    struct btrfs_free_cluster *cluster,
1977                                    struct btrfs_free_space *entry,
1978                                    u64 bytes, u64 min_start)
1979 {
1980         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1981         int err;
1982         u64 search_start = cluster->window_start;
1983         u64 search_bytes = bytes;
1984         u64 ret = 0;
1985
1986         search_start = min_start;
1987         search_bytes = bytes;
1988
1989         err = search_bitmap(ctl, entry, &search_start, &search_bytes);
1990         if (err)
1991                 return 0;
1992
1993         ret = search_start;
1994         __bitmap_clear_bits(ctl, entry, ret, bytes);
1995
1996         return ret;
1997 }
1998
1999 /*
2000  * given a cluster, try to allocate 'bytes' from it, returns 0
2001  * if it couldn't find anything suitably large, or a logical disk offset
2002  * if things worked out
2003  */
2004 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
2005                              struct btrfs_free_cluster *cluster, u64 bytes,
2006                              u64 min_start)
2007 {
2008         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2009         struct btrfs_free_space *entry = NULL;
2010         struct rb_node *node;
2011         u64 ret = 0;
2012
2013         spin_lock(&cluster->lock);
2014         if (bytes > cluster->max_size)
2015                 goto out;
2016
2017         if (cluster->block_group != block_group)
2018                 goto out;
2019
2020         node = rb_first(&cluster->root);
2021         if (!node)
2022                 goto out;
2023
2024         entry = rb_entry(node, struct btrfs_free_space, offset_index);
2025         while(1) {
2026                 if (entry->bytes < bytes ||
2027                     (!entry->bitmap && entry->offset < min_start)) {
2028                         node = rb_next(&entry->offset_index);
2029                         if (!node)
2030                                 break;
2031                         entry = rb_entry(node, struct btrfs_free_space,
2032                                          offset_index);
2033                         continue;
2034                 }
2035
2036                 if (entry->bitmap) {
2037                         ret = btrfs_alloc_from_bitmap(block_group,
2038                                                       cluster, entry, bytes,
2039                                                       min_start);
2040                         if (ret == 0) {
2041                                 node = rb_next(&entry->offset_index);
2042                                 if (!node)
2043                                         break;
2044                                 entry = rb_entry(node, struct btrfs_free_space,
2045                                                  offset_index);
2046                                 continue;
2047                         }
2048                 } else {
2049                         ret = entry->offset;
2050
2051                         entry->offset += bytes;
2052                         entry->bytes -= bytes;
2053                 }
2054
2055                 if (entry->bytes == 0)
2056                         rb_erase(&entry->offset_index, &cluster->root);
2057                 break;
2058         }
2059 out:
2060         spin_unlock(&cluster->lock);
2061
2062         if (!ret)
2063                 return 0;
2064
2065         spin_lock(&ctl->tree_lock);
2066
2067         ctl->free_space -= bytes;
2068         if (entry->bytes == 0) {
2069                 ctl->free_extents--;
2070                 if (entry->bitmap) {
2071                         kfree(entry->bitmap);
2072                         ctl->total_bitmaps--;
2073                         ctl->op->recalc_thresholds(ctl);
2074                 }
2075                 kmem_cache_free(btrfs_free_space_cachep, entry);
2076         }
2077
2078         spin_unlock(&ctl->tree_lock);
2079
2080         return ret;
2081 }
2082
2083 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
2084                                 struct btrfs_free_space *entry,
2085                                 struct btrfs_free_cluster *cluster,
2086                                 u64 offset, u64 bytes, u64 min_bytes)
2087 {
2088         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2089         unsigned long next_zero;
2090         unsigned long i;
2091         unsigned long search_bits;
2092         unsigned long total_bits;
2093         unsigned long found_bits;
2094         unsigned long start = 0;
2095         unsigned long total_found = 0;
2096         int ret;
2097         bool found = false;
2098
2099         i = offset_to_bit(entry->offset, block_group->sectorsize,
2100                           max_t(u64, offset, entry->offset));
2101         search_bits = bytes_to_bits(bytes, block_group->sectorsize);
2102         total_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
2103
2104 again:
2105         found_bits = 0;
2106         for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
2107              i < BITS_PER_BITMAP;
2108              i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
2109                 next_zero = find_next_zero_bit(entry->bitmap,
2110                                                BITS_PER_BITMAP, i);
2111                 if (next_zero - i >= search_bits) {
2112                         found_bits = next_zero - i;
2113                         break;
2114                 }
2115                 i = next_zero;
2116         }
2117
2118         if (!found_bits)
2119                 return -ENOSPC;
2120
2121         if (!found) {
2122                 start = i;
2123                 found = true;
2124         }
2125
2126         total_found += found_bits;
2127
2128         if (cluster->max_size < found_bits * block_group->sectorsize)
2129                 cluster->max_size = found_bits * block_group->sectorsize;
2130
2131         if (total_found < total_bits) {
2132                 i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero);
2133                 if (i - start > total_bits * 2) {
2134                         total_found = 0;
2135                         cluster->max_size = 0;
2136                         found = false;
2137                 }
2138                 goto again;
2139         }
2140
2141         cluster->window_start = start * block_group->sectorsize +
2142                 entry->offset;
2143         rb_erase(&entry->offset_index, &ctl->free_space_offset);
2144         ret = tree_insert_offset(&cluster->root, entry->offset,
2145                                  &entry->offset_index, 1);
2146         BUG_ON(ret);
2147
2148         return 0;
2149 }
2150
2151 /*
2152  * This searches the block group for just extents to fill the cluster with.
2153  */
2154 static noinline int
2155 setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
2156                         struct btrfs_free_cluster *cluster,
2157                         struct list_head *bitmaps, u64 offset, u64 bytes,
2158                         u64 min_bytes)
2159 {
2160         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2161         struct btrfs_free_space *first = NULL;
2162         struct btrfs_free_space *entry = NULL;
2163         struct btrfs_free_space *prev = NULL;
2164         struct btrfs_free_space *last;
2165         struct rb_node *node;
2166         u64 window_start;
2167         u64 window_free;
2168         u64 max_extent;
2169         u64 max_gap = 128 * 1024;
2170
2171         entry = tree_search_offset(ctl, offset, 0, 1);
2172         if (!entry)
2173                 return -ENOSPC;
2174
2175         /*
2176          * We don't want bitmaps, so just move along until we find a normal
2177          * extent entry.
2178          */
2179         while (entry->bitmap) {
2180                 if (list_empty(&entry->list))
2181                         list_add_tail(&entry->list, bitmaps);
2182                 node = rb_next(&entry->offset_index);
2183                 if (!node)
2184                         return -ENOSPC;
2185                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2186         }
2187
2188         window_start = entry->offset;
2189         window_free = entry->bytes;
2190         max_extent = entry->bytes;
2191         first = entry;
2192         last = entry;
2193         prev = entry;
2194
2195         while (window_free <= min_bytes) {
2196                 node = rb_next(&entry->offset_index);
2197                 if (!node)
2198                         return -ENOSPC;
2199                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2200
2201                 if (entry->bitmap) {
2202                         if (list_empty(&entry->list))
2203                                 list_add_tail(&entry->list, bitmaps);
2204                         continue;
2205                 }
2206
2207                 /*
2208                  * we haven't filled the empty size and the window is
2209                  * very large.  reset and try again
2210                  */
2211                 if (entry->offset - (prev->offset + prev->bytes) > max_gap ||
2212                     entry->offset - window_start > (min_bytes * 2)) {
2213                         first = entry;
2214                         window_start = entry->offset;
2215                         window_free = entry->bytes;
2216                         last = entry;
2217                         max_extent = entry->bytes;
2218                 } else {
2219                         last = entry;
2220                         window_free += entry->bytes;
2221                         if (entry->bytes > max_extent)
2222                                 max_extent = entry->bytes;
2223                 }
2224                 prev = entry;
2225         }
2226
2227         cluster->window_start = first->offset;
2228
2229         node = &first->offset_index;
2230
2231         /*
2232          * now we've found our entries, pull them out of the free space
2233          * cache and put them into the cluster rbtree
2234          */
2235         do {
2236                 int ret;
2237
2238                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2239                 node = rb_next(&entry->offset_index);
2240                 if (entry->bitmap)
2241                         continue;
2242
2243                 rb_erase(&entry->offset_index, &ctl->free_space_offset);
2244                 ret = tree_insert_offset(&cluster->root, entry->offset,
2245                                          &entry->offset_index, 0);
2246                 BUG_ON(ret);
2247         } while (node && entry != last);
2248
2249         cluster->max_size = max_extent;
2250
2251         return 0;
2252 }
2253
2254 /*
2255  * This specifically looks for bitmaps that may work in the cluster, we assume
2256  * that we have already failed to find extents that will work.
2257  */
2258 static noinline int
2259 setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2260                      struct btrfs_free_cluster *cluster,
2261                      struct list_head *bitmaps, u64 offset, u64 bytes,
2262                      u64 min_bytes)
2263 {
2264         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2265         struct btrfs_free_space *entry;
2266         struct rb_node *node;
2267         int ret = -ENOSPC;
2268
2269         if (ctl->total_bitmaps == 0)
2270                 return -ENOSPC;
2271
2272         /*
2273          * First check our cached list of bitmaps and see if there is an entry
2274          * here that will work.
2275          */
2276         list_for_each_entry(entry, bitmaps, list) {
2277                 if (entry->bytes < min_bytes)
2278                         continue;
2279                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2280                                            bytes, min_bytes);
2281                 if (!ret)
2282                         return 0;
2283         }
2284
2285         /*
2286          * If we do have entries on our list and we are here then we didn't find
2287          * anything, so go ahead and get the next entry after the last entry in
2288          * this list and start the search from there.
2289          */
2290         if (!list_empty(bitmaps)) {
2291                 entry = list_entry(bitmaps->prev, struct btrfs_free_space,
2292                                    list);
2293                 node = rb_next(&entry->offset_index);
2294                 if (!node)
2295                         return -ENOSPC;
2296                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2297                 goto search;
2298         }
2299
2300         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, offset), 0, 1);
2301         if (!entry)
2302                 return -ENOSPC;
2303
2304 search:
2305         node = &entry->offset_index;
2306         do {
2307                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2308                 node = rb_next(&entry->offset_index);
2309                 if (!entry->bitmap)
2310                         continue;
2311                 if (entry->bytes < min_bytes)
2312                         continue;
2313                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2314                                            bytes, min_bytes);
2315         } while (ret && node);
2316
2317         return ret;
2318 }
2319
2320 /*
2321  * here we try to find a cluster of blocks in a block group.  The goal
2322  * is to find at least bytes free and up to empty_size + bytes free.
2323  * We might not find them all in one contiguous area.
2324  *
2325  * returns zero and sets up cluster if things worked out, otherwise
2326  * it returns -enospc
2327  */
2328 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
2329                              struct btrfs_root *root,
2330                              struct btrfs_block_group_cache *block_group,
2331                              struct btrfs_free_cluster *cluster,
2332                              u64 offset, u64 bytes, u64 empty_size)
2333 {
2334         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2335         struct list_head bitmaps;
2336         struct btrfs_free_space *entry, *tmp;
2337         u64 min_bytes;
2338         int ret;
2339
2340         /* for metadata, allow allocates with more holes */
2341         if (btrfs_test_opt(root, SSD_SPREAD)) {
2342                 min_bytes = bytes + empty_size;
2343         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
2344                 /*
2345                  * we want to do larger allocations when we are
2346                  * flushing out the delayed refs, it helps prevent
2347                  * making more work as we go along.
2348                  */
2349                 if (trans->transaction->delayed_refs.flushing)
2350                         min_bytes = max(bytes, (bytes + empty_size) >> 1);
2351                 else
2352                         min_bytes = max(bytes, (bytes + empty_size) >> 4);
2353         } else
2354                 min_bytes = max(bytes, (bytes + empty_size) >> 2);
2355
2356         spin_lock(&ctl->tree_lock);
2357
2358         /*
2359          * If we know we don't have enough space to make a cluster don't even
2360          * bother doing all the work to try and find one.
2361          */
2362         if (ctl->free_space < min_bytes) {
2363                 spin_unlock(&ctl->tree_lock);
2364                 return -ENOSPC;
2365         }
2366
2367         spin_lock(&cluster->lock);
2368
2369         /* someone already found a cluster, hooray */
2370         if (cluster->block_group) {
2371                 ret = 0;
2372                 goto out;
2373         }
2374
2375         INIT_LIST_HEAD(&bitmaps);
2376         ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
2377                                       bytes, min_bytes);
2378         if (ret)
2379                 ret = setup_cluster_bitmap(block_group, cluster, &bitmaps,
2380                                            offset, bytes, min_bytes);
2381
2382         /* Clear our temporary list */
2383         list_for_each_entry_safe(entry, tmp, &bitmaps, list)
2384                 list_del_init(&entry->list);
2385
2386         if (!ret) {
2387                 atomic_inc(&block_group->count);
2388                 list_add_tail(&cluster->block_group_list,
2389                               &block_group->cluster_list);
2390                 cluster->block_group = block_group;
2391         }
2392 out:
2393         spin_unlock(&cluster->lock);
2394         spin_unlock(&ctl->tree_lock);
2395
2396         return ret;
2397 }
2398
2399 /*
2400  * simple code to zero out a cluster
2401  */
2402 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
2403 {
2404         spin_lock_init(&cluster->lock);
2405         spin_lock_init(&cluster->refill_lock);
2406         cluster->root = RB_ROOT;
2407         cluster->max_size = 0;
2408         INIT_LIST_HEAD(&cluster->block_group_list);
2409         cluster->block_group = NULL;
2410 }
2411
2412 int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
2413                            u64 *trimmed, u64 start, u64 end, u64 minlen)
2414 {
2415         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2416         struct btrfs_free_space *entry = NULL;
2417         struct btrfs_fs_info *fs_info = block_group->fs_info;
2418         u64 bytes = 0;
2419         u64 actually_trimmed;
2420         int ret = 0;
2421
2422         *trimmed = 0;
2423
2424         while (start < end) {
2425                 spin_lock(&ctl->tree_lock);
2426
2427                 if (ctl->free_space < minlen) {
2428                         spin_unlock(&ctl->tree_lock);
2429                         break;
2430                 }
2431
2432                 entry = tree_search_offset(ctl, start, 0, 1);
2433                 if (!entry)
2434                         entry = tree_search_offset(ctl,
2435                                                    offset_to_bitmap(ctl, start),
2436                                                    1, 1);
2437
2438                 if (!entry || entry->offset >= end) {
2439                         spin_unlock(&ctl->tree_lock);
2440                         break;
2441                 }
2442
2443                 if (entry->bitmap) {
2444                         ret = search_bitmap(ctl, entry, &start, &bytes);
2445                         if (!ret) {
2446                                 if (start >= end) {
2447                                         spin_unlock(&ctl->tree_lock);
2448                                         break;
2449                                 }
2450                                 bytes = min(bytes, end - start);
2451                                 bitmap_clear_bits(ctl, entry, start, bytes);
2452                                 if (entry->bytes == 0)
2453                                         free_bitmap(ctl, entry);
2454                         } else {
2455                                 start = entry->offset + BITS_PER_BITMAP *
2456                                         block_group->sectorsize;
2457                                 spin_unlock(&ctl->tree_lock);
2458                                 ret = 0;
2459                                 continue;
2460                         }
2461                 } else {
2462                         start = entry->offset;
2463                         bytes = min(entry->bytes, end - start);
2464                         unlink_free_space(ctl, entry);
2465                         kmem_cache_free(btrfs_free_space_cachep, entry);
2466                 }
2467
2468                 spin_unlock(&ctl->tree_lock);
2469
2470                 if (bytes >= minlen) {
2471                         int update_ret;
2472                         update_ret = btrfs_update_reserved_bytes(block_group,
2473                                                                  bytes, 1, 1);
2474
2475                         ret = btrfs_error_discard_extent(fs_info->extent_root,
2476                                                          start,
2477                                                          bytes,
2478                                                          &actually_trimmed);
2479
2480                         btrfs_add_free_space(block_group, start, bytes);
2481                         if (!update_ret)
2482                                 btrfs_update_reserved_bytes(block_group,
2483                                                             bytes, 0, 1);
2484
2485                         if (ret)
2486                                 break;
2487                         *trimmed += actually_trimmed;
2488                 }
2489                 start += bytes;
2490                 bytes = 0;
2491
2492                 if (fatal_signal_pending(current)) {
2493                         ret = -ERESTARTSYS;
2494                         break;
2495                 }
2496
2497                 cond_resched();
2498         }
2499
2500         return ret;
2501 }
2502
2503 /*
2504  * Find the left-most item in the cache tree, and then return the
2505  * smallest inode number in the item.
2506  *
2507  * Note: the returned inode number may not be the smallest one in
2508  * the tree, if the left-most item is a bitmap.
2509  */
2510 u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root)
2511 {
2512         struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl;
2513         struct btrfs_free_space *entry = NULL;
2514         u64 ino = 0;
2515
2516         spin_lock(&ctl->tree_lock);
2517
2518         if (RB_EMPTY_ROOT(&ctl->free_space_offset))
2519                 goto out;
2520
2521         entry = rb_entry(rb_first(&ctl->free_space_offset),
2522                          struct btrfs_free_space, offset_index);
2523
2524         if (!entry->bitmap) {
2525                 ino = entry->offset;
2526
2527                 unlink_free_space(ctl, entry);
2528                 entry->offset++;
2529                 entry->bytes--;
2530                 if (!entry->bytes)
2531                         kmem_cache_free(btrfs_free_space_cachep, entry);
2532                 else
2533                         link_free_space(ctl, entry);
2534         } else {
2535                 u64 offset = 0;
2536                 u64 count = 1;
2537                 int ret;
2538
2539                 ret = search_bitmap(ctl, entry, &offset, &count);
2540                 BUG_ON(ret);
2541
2542                 ino = offset;
2543                 bitmap_clear_bits(ctl, entry, offset, 1);
2544                 if (entry->bytes == 0)
2545                         free_bitmap(ctl, entry);
2546         }
2547 out:
2548         spin_unlock(&ctl->tree_lock);
2549
2550         return ino;
2551 }
2552
2553 struct inode *lookup_free_ino_inode(struct btrfs_root *root,
2554                                     struct btrfs_path *path)
2555 {
2556         struct inode *inode = NULL;
2557
2558         spin_lock(&root->cache_lock);
2559         if (root->cache_inode)
2560                 inode = igrab(root->cache_inode);
2561         spin_unlock(&root->cache_lock);
2562         if (inode)
2563                 return inode;
2564
2565         inode = __lookup_free_space_inode(root, path, 0);
2566         if (IS_ERR(inode))
2567                 return inode;
2568
2569         spin_lock(&root->cache_lock);
2570         if (!btrfs_fs_closing(root->fs_info))
2571                 root->cache_inode = igrab(inode);
2572         spin_unlock(&root->cache_lock);
2573
2574         return inode;
2575 }
2576
2577 int create_free_ino_inode(struct btrfs_root *root,
2578                           struct btrfs_trans_handle *trans,
2579                           struct btrfs_path *path)
2580 {
2581         return __create_free_space_inode(root, trans, path,
2582                                          BTRFS_FREE_INO_OBJECTID, 0);
2583 }
2584
2585 int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
2586 {
2587         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2588         struct btrfs_path *path;
2589         struct inode *inode;
2590         int ret = 0;
2591         u64 root_gen = btrfs_root_generation(&root->root_item);
2592
2593         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
2594                 return 0;
2595
2596         /*
2597          * If we're unmounting then just return, since this does a search on the
2598          * normal root and not the commit root and we could deadlock.
2599          */
2600         if (btrfs_fs_closing(fs_info))
2601                 return 0;
2602
2603         path = btrfs_alloc_path();
2604         if (!path)
2605                 return 0;
2606
2607         inode = lookup_free_ino_inode(root, path);
2608         if (IS_ERR(inode))
2609                 goto out;
2610
2611         if (root_gen != BTRFS_I(inode)->generation)
2612                 goto out_put;
2613
2614         ret = __load_free_space_cache(root, inode, ctl, path, 0);
2615
2616         if (ret < 0)
2617                 printk(KERN_ERR "btrfs: failed to load free ino cache for "
2618                        "root %llu\n", root->root_key.objectid);
2619 out_put:
2620         iput(inode);
2621 out:
2622         btrfs_free_path(path);
2623         return ret;
2624 }
2625
2626 int btrfs_write_out_ino_cache(struct btrfs_root *root,
2627                               struct btrfs_trans_handle *trans,
2628                               struct btrfs_path *path)
2629 {
2630         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2631         struct inode *inode;
2632         int ret;
2633
2634         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
2635                 return 0;
2636
2637         inode = lookup_free_ino_inode(root, path);
2638         if (IS_ERR(inode))
2639                 return 0;
2640
2641         ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);
2642         if (ret < 0)
2643                 printk(KERN_ERR "btrfs: failed to write free ino cache "
2644                        "for root %llu\n", root->root_key.objectid);
2645
2646         iput(inode);
2647         return ret;
2648 }