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 <linux/ratelimit.h>
  24 #include "ctree.h"
  25 #include "free-space-cache.h"
  26 #include "transaction.h"
  27 #include "disk-io.h"
  28 #include "extent_io.h"
  29 #include "inode-map.h"
  30
  31 #define BITS_PER_BITMAP         (PAGE_CACHE_SIZE * 8)
  32 #define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
  33
  34 static int link_free_space(struct btrfs_free_space_ctl *ctl,
  35                            struct btrfs_free_space *info);
  36 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
  37                               struct btrfs_free_space *info);
  38
  39 static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
  40                                                struct btrfs_path *path,
  41                                                u64 offset)
  42 {
  43         struct btrfs_key key;
  44         struct btrfs_key location;
  45         struct btrfs_disk_key disk_key;
  46         struct btrfs_free_space_header *header;
  47         struct extent_buffer *leaf;
  48         struct inode *inode = NULL;
  49         int ret;
  50
  51         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
  52         key.offset = offset;
  53         key.type = 0;
  54
  55         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  56         if (ret < 0)
  57                 return ERR_PTR(ret);
  58         if (ret > 0) {
  59                 btrfs_release_path(path);
  60                 return ERR_PTR(-ENOENT);
  61         }
  62
  63         leaf = path->nodes[0];
  64         header = btrfs_item_ptr(leaf, path->slots[0],
  65                                 struct btrfs_free_space_header);
  66         btrfs_free_space_key(leaf, header, &disk_key);
  67         btrfs_disk_key_to_cpu(&location, &disk_key);
  68         btrfs_release_path(path);
  69
  70         inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
  71         if (!inode)
  72                 return ERR_PTR(-ENOENT);
  73         if (IS_ERR(inode))
  74                 return inode;
  75         if (is_bad_inode(inode)) {
  76                 iput(inode);
  77                 return ERR_PTR(-ENOENT);
  78         }
  79
  80         mapping_set_gfp_mask(inode->i_mapping,
  81                         mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS);
  82
  83         return inode;
  84 }
  85
  86 struct inode *lookup_free_space_inode(struct btrfs_root *root,
  87                                       struct btrfs_block_group_cache
  88                                       *block_group, struct btrfs_path *path)
  89 {
  90         struct inode *inode = NULL;
  91         u32 flags = BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
  92
  93         spin_lock(&block_group->lock);
  94         if (block_group->inode)
  95                 inode = igrab(block_group->inode);
  96         spin_unlock(&block_group->lock);
  97         if (inode)
  98                 return inode;
  99
 100         inode = __lookup_free_space_inode(root, path,
 101                                           block_group->key.objectid);
 102         if (IS_ERR(inode))
 103                 return inode;
 104
 105         spin_lock(&block_group->lock);
 106         if (!((BTRFS_I(inode)->flags & flags) == flags)) {
 107                 printk(KERN_INFO "Old style space inode found, converting.\n");
 108                 BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM |
 109                         BTRFS_INODE_NODATACOW;
 110                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 111         }
 112
 113         if (!block_group->iref) {
 114                 block_group->inode = igrab(inode);
 115                 block_group->iref = 1;
 116         }
 117         spin_unlock(&block_group->lock);
 118
 119         return inode;
 120 }
 121
 122 int __create_free_space_inode(struct btrfs_root *root,
 123                               struct btrfs_trans_handle *trans,
 124                               struct btrfs_path *path, u64 ino, u64 offset)
 125 {
 126         struct btrfs_key key;
 127         struct btrfs_disk_key disk_key;
 128         struct btrfs_free_space_header *header;
 129         struct btrfs_inode_item *inode_item;
 130         struct extent_buffer *leaf;
 131         u64 flags = BTRFS_INODE_NOCOMPRESS | BTRFS_INODE_PREALLOC;
 132         int ret;
 133
 134         ret = btrfs_insert_empty_inode(trans, root, path, ino);
 135         if (ret)
 136                 return ret;
 137
 138         /* We inline crc's for the free disk space cache */
 139         if (ino != BTRFS_FREE_INO_OBJECTID)
 140                 flags |= BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
 141
 142         leaf = path->nodes[0];
 143         inode_item = btrfs_item_ptr(leaf, path->slots[0],
 144                                     struct btrfs_inode_item);
 145         btrfs_item_key(leaf, &disk_key, path->slots[0]);
 146         memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
 147                              sizeof(*inode_item));
 148         btrfs_set_inode_generation(leaf, inode_item, trans->transid);
 149         btrfs_set_inode_size(leaf, inode_item, 0);
 150         btrfs_set_inode_nbytes(leaf, inode_item, 0);
 151         btrfs_set_inode_uid(leaf, inode_item, 0);
 152         btrfs_set_inode_gid(leaf, inode_item, 0);
 153         btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
 154         btrfs_set_inode_flags(leaf, inode_item, flags);
 155         btrfs_set_inode_nlink(leaf, inode_item, 1);
 156         btrfs_set_inode_transid(leaf, inode_item, trans->transid);
 157         btrfs_set_inode_block_group(leaf, inode_item, offset);
 158         btrfs_mark_buffer_dirty(leaf);
 159         btrfs_release_path(path);
 160
 161         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 162         key.offset = offset;
 163         key.type = 0;
 164
 165         ret = btrfs_insert_empty_item(trans, root, path, &key,
 166                                       sizeof(struct btrfs_free_space_header));
 167         if (ret < 0) {
 168                 btrfs_release_path(path);
 169                 return ret;
 170         }
 171         leaf = path->nodes[0];
 172         header = btrfs_item_ptr(leaf, path->slots[0],
 173                                 struct btrfs_free_space_header);
 174         memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
 175         btrfs_set_free_space_key(leaf, header, &disk_key);
 176         btrfs_mark_buffer_dirty(leaf);
 177         btrfs_release_path(path);
 178
 179         return 0;
 180 }
 181
 182 int create_free_space_inode(struct btrfs_root *root,
 183                             struct btrfs_trans_handle *trans,
 184                             struct btrfs_block_group_cache *block_group,
 185                             struct btrfs_path *path)
 186 {
 187         int ret;
 188         u64 ino;
 189
 190         ret = btrfs_find_free_objectid(root, &ino);
 191         if (ret < 0)
 192                 return ret;
 193
 194         return __create_free_space_inode(root, trans, path, ino,
 195                                          block_group->key.objectid);
 196 }
 197
 198 int btrfs_truncate_free_space_cache(struct btrfs_root *root,
 199                                     struct btrfs_trans_handle *trans,
 200                                     struct btrfs_path *path,
 201                                     struct inode *inode)
 202 {
 203         struct btrfs_block_rsv *rsv;
 204         u64 needed_bytes;
 205         loff_t oldsize;
 206         int ret = 0;
 207
 208         rsv = trans->block_rsv;
 209         trans->block_rsv = &root->fs_info->global_block_rsv;
 210
 211         /* 1 for slack space, 1 for updating the inode */
 212         needed_bytes = btrfs_calc_trunc_metadata_size(root, 1) +
 213                 btrfs_calc_trans_metadata_size(root, 1);
 214
 215         spin_lock(&trans->block_rsv->lock);
 216         if (trans->block_rsv->reserved < needed_bytes) {
 217                 spin_unlock(&trans->block_rsv->lock);
 218                 trans->block_rsv = rsv;
 219                 return -ENOSPC;
 220         }
 221         spin_unlock(&trans->block_rsv->lock);
 222
 223         oldsize = i_size_read(inode);
 224         btrfs_i_size_write(inode, 0);
 225         truncate_pagecache(inode, oldsize, 0);
 226
 227         /*
 228          * We don't need an orphan item because truncating the free space cache
 229          * will never be split across transactions.
 230          */
 231         ret = btrfs_truncate_inode_items(trans, root, inode,
 232                                          0, BTRFS_EXTENT_DATA_KEY);
 233
 234         if (ret) {
 235                 trans->block_rsv = rsv;
 236                 btrfs_abort_transaction(trans, root, ret);
 237                 return ret;
 238         }
 239
 240         ret = btrfs_update_inode(trans, root, inode);
 241         if (ret)
 242                 btrfs_abort_transaction(trans, root, ret);
 243         trans->block_rsv = rsv;
 244
 245         return ret;
 246 }
 247
 248 static int readahead_cache(struct inode *inode)
 249 {
 250         struct file_ra_state *ra;
 251         unsigned long last_index;
 252
 253         ra = kzalloc(sizeof(*ra), GFP_NOFS);
 254         if (!ra)
 255                 return -ENOMEM;
 256
 257         file_ra_state_init(ra, inode->i_mapping);
 258         last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 259
 260         page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
 261
 262         kfree(ra);
 263
 264         return 0;
 265 }
 266
 267 struct io_ctl {
 268         void *cur, *orig;
 269         struct page *page;
 270         struct page **pages;
 271         struct btrfs_root *root;
 272         unsigned long size;
 273         int index;
 274         int num_pages;
 275         unsigned check_crcs:1;
 276 };
 277
 278 static int io_ctl_init(struct io_ctl *io_ctl, struct inode *inode,
 279                        struct btrfs_root *root)
 280 {
 281         memset(io_ctl, 0, sizeof(struct io_ctl));
 282         io_ctl->num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
 283                 PAGE_CACHE_SHIFT;
 284         io_ctl->pages = kzalloc(sizeof(struct page *) * io_ctl->num_pages,
 285                                 GFP_NOFS);
 286         if (!io_ctl->pages)
 287                 return -ENOMEM;
 288         io_ctl->root = root;
 289         if (btrfs_ino(inode) != BTRFS_FREE_INO_OBJECTID)
 290                 io_ctl->check_crcs = 1;
 291         return 0;
 292 }
 293
 294 static void io_ctl_free(struct io_ctl *io_ctl)
 295 {
 296         kfree(io_ctl->pages);
 297 }
 298
 299 static void io_ctl_unmap_page(struct io_ctl *io_ctl)
 300 {
 301         if (io_ctl->cur) {
 302                 kunmap(io_ctl->page);
 303                 io_ctl->cur = NULL;
 304                 io_ctl->orig = NULL;
 305         }
 306 }
 307
 308 static void io_ctl_map_page(struct io_ctl *io_ctl, int clear)
 309 {
 310         BUG_ON(io_ctl->index >= io_ctl->num_pages);
 311         io_ctl->page = io_ctl->pages[io_ctl->index++];
 312         io_ctl->cur = kmap(io_ctl->page);
 313         io_ctl->orig = io_ctl->cur;
 314         io_ctl->size = PAGE_CACHE_SIZE;
 315         if (clear)
 316                 memset(io_ctl->cur, 0, PAGE_CACHE_SIZE);
 317 }
 318
 319 static void io_ctl_drop_pages(struct io_ctl *io_ctl)
 320 {
 321         int i;
 322
 323         io_ctl_unmap_page(io_ctl);
 324
 325         for (i = 0; i < io_ctl->num_pages; i++) {
 326                 if (io_ctl->pages[i]) {
 327                         ClearPageChecked(io_ctl->pages[i]);
 328                         unlock_page(io_ctl->pages[i]);
 329                         page_cache_release(io_ctl->pages[i]);
 330                 }
 331         }
 332 }
 333
 334 static int io_ctl_prepare_pages(struct io_ctl *io_ctl, struct inode *inode,
 335                                 int uptodate)
 336 {
 337         struct page *page;
 338         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
 339         int i;
 340
 341         for (i = 0; i < io_ctl->num_pages; i++) {
 342                 page = find_or_create_page(inode->i_mapping, i, mask);
 343                 if (!page) {
 344                         io_ctl_drop_pages(io_ctl);
 345                         return -ENOMEM;
 346                 }
 347                 io_ctl->pages[i] = page;
 348                 if (uptodate && !PageUptodate(page)) {
 349                         btrfs_readpage(NULL, page);
 350                         lock_page(page);
 351                         if (!PageUptodate(page)) {
 352                                 printk(KERN_ERR "btrfs: error reading free "
 353                                        "space cache\n");
 354                                 io_ctl_drop_pages(io_ctl);
 355                                 return -EIO;
 356                         }
 357                 }
 358         }
 359
 360         for (i = 0; i < io_ctl->num_pages; i++) {
 361                 clear_page_dirty_for_io(io_ctl->pages[i]);
 362                 set_page_extent_mapped(io_ctl->pages[i]);
 363         }
 364
 365         return 0;
 366 }
 367
 368 static void io_ctl_set_generation(struct io_ctl *io_ctl, u64 generation)
 369 {
 370         __le64 *val;
 371
 372         io_ctl_map_page(io_ctl, 1);
 373
 374         /*
 375          * Skip the csum areas.  If we don't check crcs then we just have a
 376          * 64bit chunk at the front of the first page.
 377          */
 378         if (io_ctl->check_crcs) {
 379                 io_ctl->cur += (sizeof(u32) * io_ctl->num_pages);
 380                 io_ctl->size -= sizeof(u64) + (sizeof(u32) * io_ctl->num_pages);
 381         } else {
 382                 io_ctl->cur += sizeof(u64);
 383                 io_ctl->size -= sizeof(u64) * 2;
 384         }
 385
 386         val = io_ctl->cur;
 387         *val = cpu_to_le64(generation);
 388         io_ctl->cur += sizeof(u64);
 389 }
 390
 391 static int io_ctl_check_generation(struct io_ctl *io_ctl, u64 generation)
 392 {
 393         __le64 *gen;
 394
 395         /*
 396          * Skip the crc area.  If we don't check crcs then we just have a 64bit
 397          * chunk at the front of the first page.
 398          */
 399         if (io_ctl->check_crcs) {
 400                 io_ctl->cur += sizeof(u32) * io_ctl->num_pages;
 401                 io_ctl->size -= sizeof(u64) +
 402                         (sizeof(u32) * io_ctl->num_pages);
 403         } else {
 404                 io_ctl->cur += sizeof(u64);
 405                 io_ctl->size -= sizeof(u64) * 2;
 406         }
 407
 408         gen = io_ctl->cur;
 409         if (le64_to_cpu(*gen) != generation) {
 410                 printk_ratelimited(KERN_ERR "btrfs: space cache generation "
 411                                    "(%Lu) does not match inode (%Lu)\n", *gen,
 412                                    generation);
 413                 io_ctl_unmap_page(io_ctl);
 414                 return -EIO;
 415         }
 416         io_ctl->cur += sizeof(u64);
 417         return 0;
 418 }
 419
 420 static void io_ctl_set_crc(struct io_ctl *io_ctl, int index)
 421 {
 422         u32 *tmp;
 423         u32 crc = ~(u32)0;
 424         unsigned offset = 0;
 425
 426         if (!io_ctl->check_crcs) {
 427                 io_ctl_unmap_page(io_ctl);
 428                 return;
 429         }
 430
 431         if (index == 0)
 432                 offset = sizeof(u32) * io_ctl->num_pages;
 433
 434         crc = btrfs_csum_data(io_ctl->root, io_ctl->orig + offset, crc,
 435                               PAGE_CACHE_SIZE - offset);
 436         btrfs_csum_final(crc, (char *)&crc);
 437         io_ctl_unmap_page(io_ctl);
 438         tmp = kmap(io_ctl->pages[0]);
 439         tmp += index;
 440         *tmp = crc;
 441         kunmap(io_ctl->pages[0]);
 442 }
 443
 444 static int io_ctl_check_crc(struct io_ctl *io_ctl, int index)
 445 {
 446         u32 *tmp, val;
 447         u32 crc = ~(u32)0;
 448         unsigned offset = 0;
 449
 450         if (!io_ctl->check_crcs) {
 451                 io_ctl_map_page(io_ctl, 0);
 452                 return 0;
 453         }
 454
 455         if (index == 0)
 456                 offset = sizeof(u32) * io_ctl->num_pages;
 457
 458         tmp = kmap(io_ctl->pages[0]);
 459         tmp += index;
 460         val = *tmp;
 461         kunmap(io_ctl->pages[0]);
 462
 463         io_ctl_map_page(io_ctl, 0);
 464         crc = btrfs_csum_data(io_ctl->root, io_ctl->orig + offset, crc,
 465                               PAGE_CACHE_SIZE - offset);
 466         btrfs_csum_final(crc, (char *)&crc);
 467         if (val != crc) {
 468                 printk_ratelimited(KERN_ERR "btrfs: csum mismatch on free "
 469                                    "space cache\n");
 470                 io_ctl_unmap_page(io_ctl);
 471                 return -EIO;
 472         }
 473
 474         return 0;
 475 }
 476
 477 static int io_ctl_add_entry(struct io_ctl *io_ctl, u64 offset, u64 bytes,
 478                             void *bitmap)
 479 {
 480         struct btrfs_free_space_entry *entry;
 481
 482         if (!io_ctl->cur)
 483                 return -ENOSPC;
 484
 485         entry = io_ctl->cur;
 486         entry->offset = cpu_to_le64(offset);
 487         entry->bytes = cpu_to_le64(bytes);
 488         entry->type = (bitmap) ? BTRFS_FREE_SPACE_BITMAP :
 489                 BTRFS_FREE_SPACE_EXTENT;
 490         io_ctl->cur += sizeof(struct btrfs_free_space_entry);
 491         io_ctl->size -= sizeof(struct btrfs_free_space_entry);
 492
 493         if (io_ctl->size >= sizeof(struct btrfs_free_space_entry))
 494                 return 0;
 495
 496         io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 497
 498         /* No more pages to map */
 499         if (io_ctl->index >= io_ctl->num_pages)
 500                 return 0;
 501
 502         /* map the next page */
 503         io_ctl_map_page(io_ctl, 1);
 504         return 0;
 505 }
 506
 507 static int io_ctl_add_bitmap(struct io_ctl *io_ctl, void *bitmap)
 508 {
 509         if (!io_ctl->cur)
 510                 return -ENOSPC;
 511
 512         /*
 513          * If we aren't at the start of the current page, unmap this one and
 514          * map the next one if there is any left.
 515          */
 516         if (io_ctl->cur != io_ctl->orig) {
 517                 io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 518                 if (io_ctl->index >= io_ctl->num_pages)
 519                         return -ENOSPC;
 520                 io_ctl_map_page(io_ctl, 0);
 521         }
 522
 523         memcpy(io_ctl->cur, bitmap, PAGE_CACHE_SIZE);
 524         io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 525         if (io_ctl->index < io_ctl->num_pages)
 526                 io_ctl_map_page(io_ctl, 0);
 527         return 0;
 528 }
 529
 530 static void io_ctl_zero_remaining_pages(struct io_ctl *io_ctl)
 531 {
 532         /*
 533          * If we're not on the boundary we know we've modified the page and we
 534          * need to crc the page.
 535          */
 536         if (io_ctl->cur != io_ctl->orig)
 537                 io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 538         else
 539                 io_ctl_unmap_page(io_ctl);
 540
 541         while (io_ctl->index < io_ctl->num_pages) {
 542                 io_ctl_map_page(io_ctl, 1);
 543                 io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 544         }
 545 }
 546
 547 static int io_ctl_read_entry(struct io_ctl *io_ctl,
 548                             struct btrfs_free_space *entry, u8 *type)
 549 {
 550         struct btrfs_free_space_entry *e;
 551         int ret;
 552
 553         if (!io_ctl->cur) {
 554                 ret = io_ctl_check_crc(io_ctl, io_ctl->index);
 555                 if (ret)
 556                         return ret;
 557         }
 558
 559         e = io_ctl->cur;
 560         entry->offset = le64_to_cpu(e->offset);
 561         entry->bytes = le64_to_cpu(e->bytes);
 562         *type = e->type;
 563         io_ctl->cur += sizeof(struct btrfs_free_space_entry);
 564         io_ctl->size -= sizeof(struct btrfs_free_space_entry);
 565
 566         if (io_ctl->size >= sizeof(struct btrfs_free_space_entry))
 567                 return 0;
 568
 569         io_ctl_unmap_page(io_ctl);
 570
 571         return 0;
 572 }
 573
 574 static int io_ctl_read_bitmap(struct io_ctl *io_ctl,
 575                               struct btrfs_free_space *entry)
 576 {
 577         int ret;
 578
 579         ret = io_ctl_check_crc(io_ctl, io_ctl->index);
 580         if (ret)
 581                 return ret;
 582
 583         memcpy(entry->bitmap, io_ctl->cur, PAGE_CACHE_SIZE);
 584         io_ctl_unmap_page(io_ctl);
 585
 586         return 0;
 587 }
 588
 589 /*
 590  * Since we attach pinned extents after the fact we can have contiguous sections
 591  * of free space that are split up in entries.  This poses a problem with the
 592  * tree logging stuff since it could have allocated across what appears to be 2
 593  * entries since we would have merged the entries when adding the pinned extents
 594  * back to the free space cache.  So run through the space cache that we just
 595  * loaded and merge contiguous entries.  This will make the log replay stuff not
 596  * blow up and it will make for nicer allocator behavior.
 597  */
 598 static void merge_space_tree(struct btrfs_free_space_ctl *ctl)
 599 {
 600         struct btrfs_free_space *e, *prev = NULL;
 601         struct rb_node *n;
 602
 603 again:
 604         spin_lock(&ctl->tree_lock);
 605         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
 606                 e = rb_entry(n, struct btrfs_free_space, offset_index);
 607                 if (!prev)
 608                         goto next;
 609                 if (e->bitmap || prev->bitmap)
 610                         goto next;
 611                 if (prev->offset + prev->bytes == e->offset) {
 612                         unlink_free_space(ctl, prev);
 613                         unlink_free_space(ctl, e);
 614                         prev->bytes += e->bytes;
 615                         kmem_cache_free(btrfs_free_space_cachep, e);
 616                         link_free_space(ctl, prev);
 617                         prev = NULL;
 618                         spin_unlock(&ctl->tree_lock);
 619                         goto again;
 620                 }
 621 next:
 622                 prev = e;
 623         }
 624         spin_unlock(&ctl->tree_lock);
 625 }
 626
 627 int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 628                             struct btrfs_free_space_ctl *ctl,
 629                             struct btrfs_path *path, u64 offset)
 630 {
 631         struct btrfs_free_space_header *header;
 632         struct extent_buffer *leaf;
 633         struct io_ctl io_ctl;
 634         struct btrfs_key key;
 635         struct btrfs_free_space *e, *n;
 636         struct list_head bitmaps;
 637         u64 num_entries;
 638         u64 num_bitmaps;
 639         u64 generation;
 640         u8 type;
 641         int ret = 0;
 642
 643         INIT_LIST_HEAD(&bitmaps);
 644
 645         /* Nothing in the space cache, goodbye */
 646         if (!i_size_read(inode))
 647                 return 0;
 648
 649         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 650         key.offset = offset;
 651         key.type = 0;
 652
 653         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 654         if (ret < 0)
 655                 return 0;
 656         else if (ret > 0) {
 657                 btrfs_release_path(path);
 658                 return 0;
 659         }
 660
 661         ret = -1;
 662
 663         leaf = path->nodes[0];
 664         header = btrfs_item_ptr(leaf, path->slots[0],
 665                                 struct btrfs_free_space_header);
 666         num_entries = btrfs_free_space_entries(leaf, header);
 667         num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
 668         generation = btrfs_free_space_generation(leaf, header);
 669         btrfs_release_path(path);
 670
 671         if (BTRFS_I(inode)->generation != generation) {
 672                 printk(KERN_ERR "btrfs: free space inode generation (%llu) did"
 673                        " not match free space cache generation (%llu)\n",
 674                        (unsigned long long)BTRFS_I(inode)->generation,
 675                        (unsigned long long)generation);
 676                 return 0;
 677         }
 678
 679         if (!num_entries)
 680                 return 0;
 681
 682         ret = io_ctl_init(&io_ctl, inode, root);
 683         if (ret)
 684                 return ret;
 685
 686         ret = readahead_cache(inode);
 687         if (ret)
 688                 goto out;
 689
 690         ret = io_ctl_prepare_pages(&io_ctl, inode, 1);
 691         if (ret)
 692                 goto out;
 693
 694         ret = io_ctl_check_crc(&io_ctl, 0);
 695         if (ret)
 696                 goto free_cache;
 697
 698         ret = io_ctl_check_generation(&io_ctl, generation);
 699         if (ret)
 700                 goto free_cache;
 701
 702         while (num_entries) {
 703                 e = kmem_cache_zalloc(btrfs_free_space_cachep,
 704                                       GFP_NOFS);
 705                 if (!e)
 706                         goto free_cache;
 707
 708                 ret = io_ctl_read_entry(&io_ctl, e, &type);
 709                 if (ret) {
 710                         kmem_cache_free(btrfs_free_space_cachep, e);
 711                         goto free_cache;
 712                 }
 713
 714                 if (!e->bytes) {
 715                         kmem_cache_free(btrfs_free_space_cachep, e);
 716                         goto free_cache;
 717                 }
 718
 719                 if (type == BTRFS_FREE_SPACE_EXTENT) {
 720                         spin_lock(&ctl->tree_lock);
 721                         ret = link_free_space(ctl, e);
 722                         spin_unlock(&ctl->tree_lock);
 723                         if (ret) {
 724                                 printk(KERN_ERR "Duplicate entries in "
 725                                        "free space cache, dumping\n");
 726                                 kmem_cache_free(btrfs_free_space_cachep, e);
 727                                 goto free_cache;
 728                         }
 729                 } else {
 730                         BUG_ON(!num_bitmaps);
 731                         num_bitmaps--;
 732                         e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
 733                         if (!e->bitmap) {
 734                                 kmem_cache_free(
 735                                         btrfs_free_space_cachep, e);
 736                                 goto free_cache;
 737                         }
 738                         spin_lock(&ctl->tree_lock);
 739                         ret = link_free_space(ctl, e);
 740                         ctl->total_bitmaps++;
 741                         ctl->op->recalc_thresholds(ctl);
 742                         spin_unlock(&ctl->tree_lock);
 743                         if (ret) {
 744                                 printk(KERN_ERR "Duplicate entries in "
 745                                        "free space cache, dumping\n");
 746                                 kmem_cache_free(btrfs_free_space_cachep, e);
 747                                 goto free_cache;
 748                         }
 749                         list_add_tail(&e->list, &bitmaps);
 750                 }
 751
 752                 num_entries--;
 753         }
 754
 755         io_ctl_unmap_page(&io_ctl);
 756
 757         /*
 758          * We add the bitmaps at the end of the entries in order that
 759          * the bitmap entries are added to the cache.
 760          */
 761         list_for_each_entry_safe(e, n, &bitmaps, list) {
 762                 list_del_init(&e->list);
 763                 ret = io_ctl_read_bitmap(&io_ctl, e);
 764                 if (ret)
 765                         goto free_cache;
 766         }
 767
 768         io_ctl_drop_pages(&io_ctl);
 769         merge_space_tree(ctl);
 770         ret = 1;
 771 out:
 772         io_ctl_free(&io_ctl);
 773         return ret;
 774 free_cache:
 775         io_ctl_drop_pages(&io_ctl);
 776         __btrfs_remove_free_space_cache(ctl);
 777         goto out;
 778 }
 779
 780 int load_free_space_cache(struct btrfs_fs_info *fs_info,
 781                           struct btrfs_block_group_cache *block_group)
 782 {
 783         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 784         struct btrfs_root *root = fs_info->tree_root;
 785         struct inode *inode;
 786         struct btrfs_path *path;
 787         int ret = 0;
 788         bool matched;
 789         u64 used = btrfs_block_group_used(&block_group->item);
 790
 791         /*
 792          * If this block group has been marked to be cleared for one reason or
 793          * another then we can't trust the on disk cache, so just return.
 794          */
 795         spin_lock(&block_group->lock);
 796         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 797                 spin_unlock(&block_group->lock);
 798                 return 0;
 799         }
 800         spin_unlock(&block_group->lock);
 801
 802         path = btrfs_alloc_path();
 803         if (!path)
 804                 return 0;
 805         path->search_commit_root = 1;
 806         path->skip_locking = 1;
 807
 808         inode = lookup_free_space_inode(root, block_group, path);
 809         if (IS_ERR(inode)) {
 810                 btrfs_free_path(path);
 811                 return 0;
 812         }
 813
 814         /* We may have converted the inode and made the cache invalid. */
 815         spin_lock(&block_group->lock);
 816         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 817                 spin_unlock(&block_group->lock);
 818                 btrfs_free_path(path);
 819                 goto out;
 820         }
 821         spin_unlock(&block_group->lock);
 822
 823         ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
 824                                       path, block_group->key.objectid);
 825         btrfs_free_path(path);
 826         if (ret <= 0)
 827                 goto out;
 828
 829         spin_lock(&ctl->tree_lock);
 830         matched = (ctl->free_space == (block_group->key.offset - used -
 831                                        block_group->bytes_super));
 832         spin_unlock(&ctl->tree_lock);
 833
 834         if (!matched) {
 835                 __btrfs_remove_free_space_cache(ctl);
 836                 printk(KERN_ERR "block group %llu has an wrong amount of free "
 837                        "space\n", block_group->key.objectid);
 838                 ret = -1;
 839         }
 840 out:
 841         if (ret < 0) {
 842                 /* This cache is bogus, make sure it gets cleared */
 843                 spin_lock(&block_group->lock);
 844                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 845                 spin_unlock(&block_group->lock);
 846                 ret = 0;
 847
 848                 printk(KERN_ERR "btrfs: failed to load free space cache "
 849                        "for block group %llu\n", block_group->key.objectid);
 850         }
 851
 852         iput(inode);
 853         return ret;
 854 }
 855
 856 /**
 857  * __btrfs_write_out_cache - write out cached info to an inode
 858  * @root - the root the inode belongs to
 859  * @ctl - the free space cache we are going to write out
 860  * @block_group - the block_group for this cache if it belongs to a block_group
 861  * @trans - the trans handle
 862  * @path - the path to use
 863  * @offset - the offset for the key we'll insert
 864  *
 865  * This function writes out a free space cache struct to disk for quick recovery
 866  * on mount.  This will return 0 if it was successfull in writing the cache out,
 867  * and -1 if it was not.
 868  */
 869 int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 870                             struct btrfs_free_space_ctl *ctl,
 871                             struct btrfs_block_group_cache *block_group,
 872                             struct btrfs_trans_handle *trans,
 873                             struct btrfs_path *path, u64 offset)
 874 {
 875         struct btrfs_free_space_header *header;
 876         struct extent_buffer *leaf;
 877         struct rb_node *node;
 878         struct list_head *pos, *n;
 879         struct extent_state *cached_state = NULL;
 880         struct btrfs_free_cluster *cluster = NULL;
 881         struct extent_io_tree *unpin = NULL;
 882         struct io_ctl io_ctl;
 883         struct list_head bitmap_list;
 884         struct btrfs_key key;
 885         u64 start, extent_start, extent_end, len;
 886         int entries = 0;
 887         int bitmaps = 0;
 888         int ret;
 889         int err = -1;
 890
 891         INIT_LIST_HEAD(&bitmap_list);
 892
 893         if (!i_size_read(inode))
 894                 return -1;
 895
 896         ret = io_ctl_init(&io_ctl, inode, root);
 897         if (ret)
 898                 return -1;
 899
 900         /* Get the cluster for this block_group if it exists */
 901         if (block_group && !list_empty(&block_group->cluster_list))
 902                 cluster = list_entry(block_group->cluster_list.next,
 903                                      struct btrfs_free_cluster,
 904                                      block_group_list);
 905
 906         /* Lock all pages first so we can lock the extent safely. */
 907         io_ctl_prepare_pages(&io_ctl, inode, 0);
 908
 909         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
 910                          0, &cached_state);
 911
 912         node = rb_first(&ctl->free_space_offset);
 913         if (!node && cluster) {
 914                 node = rb_first(&cluster->root);
 915                 cluster = NULL;
 916         }
 917
 918         /* Make sure we can fit our crcs into the first page */
 919         if (io_ctl.check_crcs &&
 920             (io_ctl.num_pages * sizeof(u32)) >= PAGE_CACHE_SIZE) {
 921                 WARN_ON(1);
 922                 goto out_nospc;
 923         }
 924
 925         io_ctl_set_generation(&io_ctl, trans->transid);
 926
 927         /* Write out the extent entries */
 928         while (node) {
 929                 struct btrfs_free_space *e;
 930
 931                 e = rb_entry(node, struct btrfs_free_space, offset_index);
 932                 entries++;
 933
 934                 ret = io_ctl_add_entry(&io_ctl, e->offset, e->bytes,
 935                                        e->bitmap);
 936                 if (ret)
 937                         goto out_nospc;
 938
 939                 if (e->bitmap) {
 940                         list_add_tail(&e->list, &bitmap_list);
 941                         bitmaps++;
 942                 }
 943                 node = rb_next(node);
 944                 if (!node && cluster) {
 945                         node = rb_first(&cluster->root);
 946                         cluster = NULL;
 947                 }
 948         }
 949
 950         /*
 951          * We want to add any pinned extents to our free space cache
 952          * so we don't leak the space
 953          */
 954
 955         /*
 956          * We shouldn't have switched the pinned extents yet so this is the
 957          * right one
 958          */
 959         unpin = root->fs_info->pinned_extents;
 960
 961         if (block_group)
 962                 start = block_group->key.objectid;
 963
 964         while (block_group && (start < block_group->key.objectid +
 965                                block_group->key.offset)) {
 966                 ret = find_first_extent_bit(unpin, start,
 967                                             &extent_start, &extent_end,
 968                                             EXTENT_DIRTY, NULL);
 969                 if (ret) {
 970                         ret = 0;
 971                         break;
 972                 }
 973
 974                 /* This pinned extent is out of our range */
 975                 if (extent_start >= block_group->key.objectid +
 976                     block_group->key.offset)
 977                         break;
 978
 979                 extent_start = max(extent_start, start);
 980                 extent_end = min(block_group->key.objectid +
 981                                  block_group->key.offset, extent_end + 1);
 982                 len = extent_end - extent_start;
 983
 984                 entries++;
 985                 ret = io_ctl_add_entry(&io_ctl, extent_start, len, NULL);
 986                 if (ret)
 987                         goto out_nospc;
 988
 989                 start = extent_end;
 990         }
 991
 992         /* Write out the bitmaps */
 993         list_for_each_safe(pos, n, &bitmap_list) {
 994                 struct btrfs_free_space *entry =
 995                         list_entry(pos, struct btrfs_free_space, list);
 996
 997                 ret = io_ctl_add_bitmap(&io_ctl, entry->bitmap);
 998                 if (ret)
 999                         goto out_nospc;
1000                 list_del_init(&entry->list);
1001         }
1002
1003         /* Zero out the rest of the pages just to make sure */
1004         io_ctl_zero_remaining_pages(&io_ctl);
1005
1006         ret = btrfs_dirty_pages(root, inode, io_ctl.pages, io_ctl.num_pages,
1007                                 0, i_size_read(inode), &cached_state);
1008         io_ctl_drop_pages(&io_ctl);
1009         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
1010                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
1011
1012         if (ret)
1013                 goto out;
1014
1015
1016         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1017
1018         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
1019         key.offset = offset;
1020         key.type = 0;
1021
1022         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
1023         if (ret < 0) {
1024                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
1025                                  EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL,
1026                                  GFP_NOFS);
1027                 goto out;
1028         }
1029         leaf = path->nodes[0];
1030         if (ret > 0) {
1031                 struct btrfs_key found_key;
1032                 BUG_ON(!path->slots[0]);
1033                 path->slots[0]--;
1034                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1035                 if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
1036                     found_key.offset != offset) {
1037                         clear_extent_bit(&BTRFS_I(inode)->io_tree, 0,
1038                                          inode->i_size - 1,
1039                                          EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0,
1040                                          NULL, GFP_NOFS);
1041                         btrfs_release_path(path);
1042                         goto out;
1043                 }
1044         }
1045
1046         BTRFS_I(inode)->generation = trans->transid;
1047         header = btrfs_item_ptr(leaf, path->slots[0],
1048                                 struct btrfs_free_space_header);
1049         btrfs_set_free_space_entries(leaf, header, entries);
1050         btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
1051         btrfs_set_free_space_generation(leaf, header, trans->transid);
1052         btrfs_mark_buffer_dirty(leaf);
1053         btrfs_release_path(path);
1054
1055         err = 0;
1056 out:
1057         io_ctl_free(&io_ctl);
1058         if (err) {
1059                 invalidate_inode_pages2(inode->i_mapping);
1060                 BTRFS_I(inode)->generation = 0;
1061         }
1062         btrfs_update_inode(trans, root, inode);
1063         return err;
1064
1065 out_nospc:
1066         list_for_each_safe(pos, n, &bitmap_list) {
1067                 struct btrfs_free_space *entry =
1068                         list_entry(pos, struct btrfs_free_space, list);
1069                 list_del_init(&entry->list);
1070         }
1071         io_ctl_drop_pages(&io_ctl);
1072         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
1073                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
1074         goto out;
1075 }
1076
1077 int btrfs_write_out_cache(struct btrfs_root *root,
1078                           struct btrfs_trans_handle *trans,
1079                           struct btrfs_block_group_cache *block_group,
1080                           struct btrfs_path *path)
1081 {
1082         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1083         struct inode *inode;
1084         int ret = 0;
1085
1086         root = root->fs_info->tree_root;
1087
1088         spin_lock(&block_group->lock);
1089         if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
1090                 spin_unlock(&block_group->lock);
1091                 return 0;
1092         }
1093         spin_unlock(&block_group->lock);
1094
1095         inode = lookup_free_space_inode(root, block_group, path);
1096         if (IS_ERR(inode))
1097                 return 0;
1098
1099         ret = __btrfs_write_out_cache(root, inode, ctl, block_group, trans,
1100                                       path, block_group->key.objectid);
1101         if (ret) {
1102                 spin_lock(&block_group->lock);
1103                 block_group->disk_cache_state = BTRFS_DC_ERROR;
1104                 spin_unlock(&block_group->lock);
1105                 ret = 0;
1106 #ifdef DEBUG
1107                 printk(KERN_ERR "btrfs: failed to write free space cache "
1108                        "for block group %llu\n", block_group->key.objectid);
1109 #endif
1110         }
1111
1112         iput(inode);
1113         return ret;
1114 }
1115
1116 static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
1117                                           u64 offset)
1118 {
1119         BUG_ON(offset < bitmap_start);
1120         offset -= bitmap_start;
1121         return (unsigned long)(div_u64(offset, unit));
1122 }
1123
1124 static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
1125 {
1126         return (unsigned long)(div_u64(bytes, unit));
1127 }
1128
1129 static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
1130                                    u64 offset)
1131 {
1132         u64 bitmap_start;
1133         u64 bytes_per_bitmap;
1134
1135         bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
1136         bitmap_start = offset - ctl->start;
1137         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
1138         bitmap_start *= bytes_per_bitmap;
1139         bitmap_start += ctl->start;
1140
1141         return bitmap_start;
1142 }
1143
1144 static int tree_insert_offset(struct rb_root *root, u64 offset,
1145                               struct rb_node *node, int bitmap)
1146 {
1147         struct rb_node **p = &root->rb_node;
1148         struct rb_node *parent = NULL;
1149         struct btrfs_free_space *info;
1150
1151         while (*p) {
1152                 parent = *p;
1153                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
1154
1155                 if (offset < info->offset) {
1156                         p = &(*p)->rb_left;
1157                 } else if (offset > info->offset) {
1158                         p = &(*p)->rb_right;
1159                 } else {
1160                         /*
1161                          * we could have a bitmap entry and an extent entry
1162                          * share the same offset.  If this is the case, we want
1163                          * the extent entry to always be found first if we do a
1164                          * linear search through the tree, since we want to have
1165                          * the quickest allocation time, and allocating from an
1166                          * extent is faster than allocating from a bitmap.  So
1167                          * if we're inserting a bitmap and we find an entry at
1168                          * this offset, we want to go right, or after this entry
1169                          * logically.  If we are inserting an extent and we've
1170                          * found a bitmap, we want to go left, or before
1171                          * logically.
1172                          */
1173                         if (bitmap) {
1174                                 if (info->bitmap) {
1175                                         WARN_ON_ONCE(1);
1176                                         return -EEXIST;
1177                                 }
1178                                 p = &(*p)->rb_right;
1179                         } else {
1180                                 if (!info->bitmap) {
1181                                         WARN_ON_ONCE(1);
1182                                         return -EEXIST;
1183                                 }
1184                                 p = &(*p)->rb_left;
1185                         }
1186                 }
1187         }
1188
1189         rb_link_node(node, parent, p);
1190         rb_insert_color(node, root);
1191
1192         return 0;
1193 }
1194
1195 /*
1196  * searches the tree for the given offset.
1197  *
1198  * fuzzy - If this is set, then we are trying to make an allocation, and we just
1199  * want a section that has at least bytes size and comes at or after the given
1200  * offset.
1201  */
1202 static struct btrfs_free_space *
1203 tree_search_offset(struct btrfs_free_space_ctl *ctl,
1204                    u64 offset, int bitmap_only, int fuzzy)
1205 {
1206         struct rb_node *n = ctl->free_space_offset.rb_node;
1207         struct btrfs_free_space *entry, *prev = NULL;
1208
1209         /* find entry that is closest to the 'offset' */
1210         while (1) {
1211                 if (!n) {
1212                         entry = NULL;
1213                         break;
1214                 }
1215
1216                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1217                 prev = entry;
1218
1219                 if (offset < entry->offset)
1220                         n = n->rb_left;
1221                 else if (offset > entry->offset)
1222                         n = n->rb_right;
1223                 else
1224                         break;
1225         }
1226
1227         if (bitmap_only) {
1228                 if (!entry)
1229                         return NULL;
1230                 if (entry->bitmap)
1231                         return entry;
1232
1233                 /*
1234                  * bitmap entry and extent entry may share same offset,
1235                  * in that case, bitmap entry comes after extent entry.
1236                  */
1237                 n = rb_next(n);
1238                 if (!n)
1239                         return NULL;
1240                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1241                 if (entry->offset != offset)
1242                         return NULL;
1243
1244                 WARN_ON(!entry->bitmap);
1245                 return entry;
1246         } else if (entry) {
1247                 if (entry->bitmap) {
1248                         /*
1249                          * if previous extent entry covers the offset,
1250                          * we should return it instead of the bitmap entry
1251                          */
1252                         n = rb_prev(&entry->offset_index);
1253                         if (n) {
1254                                 prev = rb_entry(n, struct btrfs_free_space,
1255                                                 offset_index);
1256                                 if (!prev->bitmap &&
1257                                     prev->offset + prev->bytes > offset)
1258                                         entry = prev;
1259                         }
1260                 }
1261                 return entry;
1262         }
1263
1264         if (!prev)
1265                 return NULL;
1266
1267         /* find last entry before the 'offset' */
1268         entry = prev;
1269         if (entry->offset > offset) {
1270                 n = rb_prev(&entry->offset_index);
1271                 if (n) {
1272                         entry = rb_entry(n, struct btrfs_free_space,
1273                                         offset_index);
1274                         BUG_ON(entry->offset > offset);
1275                 } else {
1276                         if (fuzzy)
1277                                 return entry;
1278                         else
1279                                 return NULL;
1280                 }
1281         }
1282
1283         if (entry->bitmap) {
1284                 n = rb_prev(&entry->offset_index);
1285                 if (n) {
1286                         prev = rb_entry(n, struct btrfs_free_space,
1287                                         offset_index);
1288                         if (!prev->bitmap &&
1289                             prev->offset + prev->bytes > offset)
1290                                 return prev;
1291                 }
1292                 if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
1293                         return entry;
1294         } else if (entry->offset + entry->bytes > offset)
1295                 return entry;
1296
1297         if (!fuzzy)
1298                 return NULL;
1299
1300         while (1) {
1301                 if (entry->bitmap) {
1302                         if (entry->offset + BITS_PER_BITMAP *
1303                             ctl->unit > offset)
1304                                 break;
1305                 } else {
1306                         if (entry->offset + entry->bytes > offset)
1307                                 break;
1308                 }
1309
1310                 n = rb_next(&entry->offset_index);
1311                 if (!n)
1312                         return NULL;
1313                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1314         }
1315         return entry;
1316 }
1317
1318 static inline void
1319 __unlink_free_space(struct btrfs_free_space_ctl *ctl,
1320                     struct btrfs_free_space *info)
1321 {
1322         rb_erase(&info->offset_index, &ctl->free_space_offset);
1323         ctl->free_extents--;
1324 }
1325
1326 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
1327                               struct btrfs_free_space *info)
1328 {
1329         __unlink_free_space(ctl, info);
1330         ctl->free_space -= info->bytes;
1331 }
1332
1333 static int link_free_space(struct btrfs_free_space_ctl *ctl,
1334                            struct btrfs_free_space *info)
1335 {
1336         int ret = 0;
1337
1338         BUG_ON(!info->bitmap && !info->bytes);
1339         ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
1340                                  &info->offset_index, (info->bitmap != NULL));
1341         if (ret)
1342                 return ret;
1343
1344         ctl->free_space += info->bytes;
1345         ctl->free_extents++;
1346         return ret;
1347 }
1348
1349 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
1350 {
1351         struct btrfs_block_group_cache *block_group = ctl->private;
1352         u64 max_bytes;
1353         u64 bitmap_bytes;
1354         u64 extent_bytes;
1355         u64 size = block_group->key.offset;
1356         u64 bytes_per_bg = BITS_PER_BITMAP * ctl->unit;
1357         int max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
1358
1359         max_bitmaps = max(max_bitmaps, 1);
1360
1361         BUG_ON(ctl->total_bitmaps > max_bitmaps);
1362
1363         /*
1364          * The goal is to keep the total amount of memory used per 1gb of space
1365          * at or below 32k, so we need to adjust how much memory we allow to be
1366          * used by extent based free space tracking
1367          */
1368         if (size < 1024 * 1024 * 1024)
1369                 max_bytes = MAX_CACHE_BYTES_PER_GIG;
1370         else
1371                 max_bytes = MAX_CACHE_BYTES_PER_GIG *
1372                         div64_u64(size, 1024 * 1024 * 1024);
1373
1374         /*
1375          * we want to account for 1 more bitmap than what we have so we can make
1376          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1377          * we add more bitmaps.
1378          */
1379         bitmap_bytes = (ctl->total_bitmaps + 1) * PAGE_CACHE_SIZE;
1380
1381         if (bitmap_bytes >= max_bytes) {
1382                 ctl->extents_thresh = 0;
1383                 return;
1384         }
1385
1386         /*
1387          * we want the extent entry threshold to always be at most 1/2 the maxw
1388          * bytes we can have, or whatever is less than that.
1389          */
1390         extent_bytes = max_bytes - bitmap_bytes;
1391         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
1392
1393         ctl->extents_thresh =
1394                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
1395 }
1396
1397 static inline void __bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1398                                        struct btrfs_free_space *info,
1399                                        u64 offset, u64 bytes)
1400 {
1401         unsigned long start, count;
1402
1403         start = offset_to_bit(info->offset, ctl->unit, offset);
1404         count = bytes_to_bits(bytes, ctl->unit);
1405         BUG_ON(start + count > BITS_PER_BITMAP);
1406
1407         bitmap_clear(info->bitmap, start, count);
1408
1409         info->bytes -= bytes;
1410 }
1411
1412 static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1413                               struct btrfs_free_space *info, u64 offset,
1414                               u64 bytes)
1415 {
1416         __bitmap_clear_bits(ctl, info, offset, bytes);
1417         ctl->free_space -= bytes;
1418 }
1419
1420 static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
1421                             struct btrfs_free_space *info, u64 offset,
1422                             u64 bytes)
1423 {
1424         unsigned long start, count;
1425
1426         start = offset_to_bit(info->offset, ctl->unit, offset);
1427         count = bytes_to_bits(bytes, ctl->unit);
1428         BUG_ON(start + count > BITS_PER_BITMAP);
1429
1430         bitmap_set(info->bitmap, start, count);
1431
1432         info->bytes += bytes;
1433         ctl->free_space += bytes;
1434 }
1435
1436 static int search_bitmap(struct btrfs_free_space_ctl *ctl,
1437                          struct btrfs_free_space *bitmap_info, u64 *offset,
1438                          u64 *bytes)
1439 {
1440         unsigned long found_bits = 0;
1441         unsigned long bits, i;
1442         unsigned long next_zero;
1443
1444         i = offset_to_bit(bitmap_info->offset, ctl->unit,
1445                           max_t(u64, *offset, bitmap_info->offset));
1446         bits = bytes_to_bits(*bytes, ctl->unit);
1447
1448         for_each_set_bit_from(i, bitmap_info->bitmap, BITS_PER_BITMAP) {
1449                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
1450                                                BITS_PER_BITMAP, i);
1451                 if ((next_zero - i) >= bits) {
1452                         found_bits = next_zero - i;
1453                         break;
1454                 }
1455                 i = next_zero;
1456         }
1457
1458         if (found_bits) {
1459                 *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
1460                 *bytes = (u64)(found_bits) * ctl->unit;
1461                 return 0;
1462         }
1463
1464         return -1;
1465 }
1466
1467 static struct btrfs_free_space *
1468 find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes,
1469                 unsigned long align)
1470 {
1471         struct btrfs_free_space *entry;
1472         struct rb_node *node;
1473         u64 ctl_off;
1474         u64 tmp;
1475         u64 align_off;
1476         int ret;
1477
1478         if (!ctl->free_space_offset.rb_node)
1479                 return NULL;
1480
1481         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
1482         if (!entry)
1483                 return NULL;
1484
1485         for (node = &entry->offset_index; node; node = rb_next(node)) {
1486                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1487                 if (entry->bytes < *bytes)
1488                         continue;
1489
1490                 /* make sure the space returned is big enough
1491                  * to match our requested alignment
1492                  */
1493                 if (*bytes >= align) {
1494                         ctl_off = entry->offset - ctl->start;
1495                         tmp = ctl_off + align - 1;;
1496                         do_div(tmp, align);
1497                         tmp = tmp * align + ctl->start;
1498                         align_off = tmp - entry->offset;
1499                 } else {
1500                         align_off = 0;
1501                         tmp = entry->offset;
1502                 }
1503
1504                 if (entry->bytes < *bytes + align_off)
1505                         continue;
1506
1507                 if (entry->bitmap) {
1508                         ret = search_bitmap(ctl, entry, &tmp, bytes);
1509                         if (!ret) {
1510                                 *offset = tmp;
1511                                 return entry;
1512                         }
1513                         continue;
1514                 }
1515
1516                 *offset = tmp;
1517                 *bytes = entry->bytes - align_off;
1518                 return entry;
1519         }
1520
1521         return NULL;
1522 }
1523
1524 static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
1525                            struct btrfs_free_space *info, u64 offset)
1526 {
1527         info->offset = offset_to_bitmap(ctl, offset);
1528         info->bytes = 0;
1529         INIT_LIST_HEAD(&info->list);
1530         link_free_space(ctl, info);
1531         ctl->total_bitmaps++;
1532
1533         ctl->op->recalc_thresholds(ctl);
1534 }
1535
1536 static void free_bitmap(struct btrfs_free_space_ctl *ctl,
1537                         struct btrfs_free_space *bitmap_info)
1538 {
1539         unlink_free_space(ctl, bitmap_info);
1540         kfree(bitmap_info->bitmap);
1541         kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1542         ctl->total_bitmaps--;
1543         ctl->op->recalc_thresholds(ctl);
1544 }
1545
1546 static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
1547                               struct btrfs_free_space *bitmap_info,
1548                               u64 *offset, u64 *bytes)
1549 {
1550         u64 end;
1551         u64 search_start, search_bytes;
1552         int ret;
1553
1554 again:
1555         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
1556
1557         /*
1558          * We need to search for bits in this bitmap.  We could only cover some
1559          * of the extent in this bitmap thanks to how we add space, so we need
1560          * to search for as much as it as we can and clear that amount, and then
1561          * go searching for the next bit.
1562          */
1563         search_start = *offset;
1564         search_bytes = ctl->unit;
1565         search_bytes = min(search_bytes, end - search_start + 1);
1566         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
1567         BUG_ON(ret < 0 || search_start != *offset);
1568
1569         /* We may have found more bits than what we need */
1570         search_bytes = min(search_bytes, *bytes);
1571
1572         /* Cannot clear past the end of the bitmap */
1573         search_bytes = min(search_bytes, end - search_start + 1);
1574
1575         bitmap_clear_bits(ctl, bitmap_info, search_start, search_bytes);
1576         *offset += search_bytes;
1577         *bytes -= search_bytes;
1578
1579         if (*bytes) {
1580                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
1581                 if (!bitmap_info->bytes)
1582                         free_bitmap(ctl, bitmap_info);
1583
1584                 /*
1585                  * no entry after this bitmap, but we still have bytes to
1586                  * remove, so something has gone wrong.
1587                  */
1588                 if (!next)
1589                         return -EINVAL;
1590
1591                 bitmap_info = rb_entry(next, struct btrfs_free_space,
1592                                        offset_index);
1593
1594                 /*
1595                  * if the next entry isn't a bitmap we need to return to let the
1596                  * extent stuff do its work.
1597                  */
1598                 if (!bitmap_info->bitmap)
1599                         return -EAGAIN;
1600
1601                 /*
1602                  * Ok the next item is a bitmap, but it may not actually hold
1603                  * the information for the rest of this free space stuff, so
1604                  * look for it, and if we don't find it return so we can try
1605                  * everything over again.
1606                  */
1607                 search_start = *offset;
1608                 search_bytes = ctl->unit;
1609                 ret = search_bitmap(ctl, bitmap_info, &search_start,
1610                                     &search_bytes);
1611                 if (ret < 0 || search_start != *offset)
1612                         return -EAGAIN;
1613
1614                 goto again;
1615         } else if (!bitmap_info->bytes)
1616                 free_bitmap(ctl, bitmap_info);
1617
1618         return 0;
1619 }
1620
1621 static u64 add_bytes_to_bitmap(struct btrfs_free_space_ctl *ctl,
1622                                struct btrfs_free_space *info, u64 offset,
1623                                u64 bytes)
1624 {
1625         u64 bytes_to_set = 0;
1626         u64 end;
1627
1628         end = info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
1629
1630         bytes_to_set = min(end - offset, bytes);
1631
1632         bitmap_set_bits(ctl, info, offset, bytes_to_set);
1633
1634         return bytes_to_set;
1635
1636 }
1637
1638 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
1639                       struct btrfs_free_space *info)
1640 {
1641         struct btrfs_block_group_cache *block_group = ctl->private;
1642
1643         /*
1644          * If we are below the extents threshold then we can add this as an
1645          * extent, and don't have to deal with the bitmap
1646          */
1647         if (ctl->free_extents < ctl->extents_thresh) {
1648                 /*
1649                  * If this block group has some small extents we don't want to
1650                  * use up all of our free slots in the cache with them, we want
1651                  * to reserve them to larger extents, however if we have plent
1652                  * of cache left then go ahead an dadd them, no sense in adding
1653                  * the overhead of a bitmap if we don't have to.
1654                  */
1655                 if (info->bytes <= block_group->sectorsize * 4) {
1656                         if (ctl->free_extents * 2 <= ctl->extents_thresh)
1657                                 return false;
1658                 } else {
1659                         return false;
1660                 }
1661         }
1662
1663         /*
1664          * The original block groups from mkfs can be really small, like 8
1665          * megabytes, so don't bother with a bitmap for those entries.  However
1666          * some block groups can be smaller than what a bitmap would cover but
1667          * are still large enough that they could overflow the 32k memory limit,
1668          * so allow those block groups to still be allowed to have a bitmap
1669          * entry.
1670          */
1671         if (((BITS_PER_BITMAP * ctl->unit) >> 1) > block_group->key.offset)
1672                 return false;
1673
1674         return true;
1675 }
1676
1677 static struct btrfs_free_space_op free_space_op = {
1678         .recalc_thresholds      = recalculate_thresholds,
1679         .use_bitmap             = use_bitmap,
1680 };
1681
1682 static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
1683                               struct btrfs_free_space *info)
1684 {
1685         struct btrfs_free_space *bitmap_info;
1686         struct btrfs_block_group_cache *block_group = NULL;
1687         int added = 0;
1688         u64 bytes, offset, bytes_added;
1689         int ret;
1690
1691         bytes = info->bytes;
1692         offset = info->offset;
1693
1694         if (!ctl->op->use_bitmap(ctl, info))
1695                 return 0;
1696
1697         if (ctl->op == &free_space_op)
1698                 block_group = ctl->private;
1699 again:
1700         /*
1701          * Since we link bitmaps right into the cluster we need to see if we
1702          * have a cluster here, and if so and it has our bitmap we need to add
1703          * the free space to that bitmap.
1704          */
1705         if (block_group && !list_empty(&block_group->cluster_list)) {
1706                 struct btrfs_free_cluster *cluster;
1707                 struct rb_node *node;
1708                 struct btrfs_free_space *entry;
1709
1710                 cluster = list_entry(block_group->cluster_list.next,
1711                                      struct btrfs_free_cluster,
1712                                      block_group_list);
1713                 spin_lock(&cluster->lock);
1714                 node = rb_first(&cluster->root);
1715                 if (!node) {
1716                         spin_unlock(&cluster->lock);
1717                         goto no_cluster_bitmap;
1718                 }
1719
1720                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1721                 if (!entry->bitmap) {
1722                         spin_unlock(&cluster->lock);
1723                         goto no_cluster_bitmap;
1724                 }
1725
1726                 if (entry->offset == offset_to_bitmap(ctl, offset)) {
1727                         bytes_added = add_bytes_to_bitmap(ctl, entry,
1728                                                           offset, bytes);
1729                         bytes -= bytes_added;
1730                         offset += bytes_added;
1731                 }
1732                 spin_unlock(&cluster->lock);
1733                 if (!bytes) {
1734                         ret = 1;
1735                         goto out;
1736                 }
1737         }
1738
1739 no_cluster_bitmap:
1740         bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1741                                          1, 0);
1742         if (!bitmap_info) {
1743                 BUG_ON(added);
1744                 goto new_bitmap;
1745         }
1746
1747         bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
1748         bytes -= bytes_added;
1749         offset += bytes_added;
1750         added = 0;
1751
1752         if (!bytes) {
1753                 ret = 1;
1754                 goto out;
1755         } else
1756                 goto again;
1757
1758 new_bitmap:
1759         if (info && info->bitmap) {
1760                 add_new_bitmap(ctl, info, offset);
1761                 added = 1;
1762                 info = NULL;
1763                 goto again;
1764         } else {
1765                 spin_unlock(&ctl->tree_lock);
1766
1767                 /* no pre-allocated info, allocate a new one */
1768                 if (!info) {
1769                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
1770                                                  GFP_NOFS);
1771                         if (!info) {
1772                                 spin_lock(&ctl->tree_lock);
1773                                 ret = -ENOMEM;
1774                                 goto out;
1775                         }
1776                 }
1777
1778                 /* allocate the bitmap */
1779                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
1780                 spin_lock(&ctl->tree_lock);
1781                 if (!info->bitmap) {
1782                         ret = -ENOMEM;
1783                         goto out;
1784                 }
1785                 goto again;
1786         }
1787
1788 out:
1789         if (info) {
1790                 if (info->bitmap)
1791                         kfree(info->bitmap);
1792                 kmem_cache_free(btrfs_free_space_cachep, info);
1793         }
1794
1795         return ret;
1796 }
1797
1798 static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
1799                           struct btrfs_free_space *info, bool update_stat)
1800 {
1801         struct btrfs_free_space *left_info;
1802         struct btrfs_free_space *right_info;
1803         bool merged = false;
1804         u64 offset = info->offset;
1805         u64 bytes = info->bytes;
1806
1807         /*
1808          * first we want to see if there is free space adjacent to the range we
1809          * are adding, if there is remove that struct and add a new one to
1810          * cover the entire range
1811          */
1812         right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
1813         if (right_info && rb_prev(&right_info->offset_index))
1814                 left_info = rb_entry(rb_prev(&right_info->offset_index),
1815                                      struct btrfs_free_space, offset_index);
1816         else
1817                 left_info = tree_search_offset(ctl, offset - 1, 0, 0);
1818
1819         if (right_info && !right_info->bitmap) {
1820                 if (update_stat)
1821                         unlink_free_space(ctl, right_info);
1822                 else
1823                         __unlink_free_space(ctl, right_info);
1824                 info->bytes += right_info->bytes;
1825                 kmem_cache_free(btrfs_free_space_cachep, right_info);
1826                 merged = true;
1827         }
1828
1829         if (left_info && !left_info->bitmap &&
1830             left_info->offset + left_info->bytes == offset) {
1831                 if (update_stat)
1832                         unlink_free_space(ctl, left_info);
1833                 else
1834                         __unlink_free_space(ctl, left_info);
1835                 info->offset = left_info->offset;
1836                 info->bytes += left_info->bytes;
1837                 kmem_cache_free(btrfs_free_space_cachep, left_info);
1838                 merged = true;
1839         }
1840
1841         return merged;
1842 }
1843
1844 int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
1845                            u64 offset, u64 bytes)
1846 {
1847         struct btrfs_free_space *info;
1848         int ret = 0;
1849
1850         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
1851         if (!info)
1852                 return -ENOMEM;
1853
1854         info->offset = offset;
1855         info->bytes = bytes;
1856
1857         spin_lock(&ctl->tree_lock);
1858
1859         if (try_merge_free_space(ctl, info, true))
1860                 goto link;
1861
1862         /*
1863          * There was no extent directly to the left or right of this new
1864          * extent then we know we're going to have to allocate a new extent, so
1865          * before we do that see if we need to drop this into a bitmap
1866          */
1867         ret = insert_into_bitmap(ctl, info);
1868         if (ret < 0) {
1869                 goto out;
1870         } else if (ret) {
1871                 ret = 0;
1872                 goto out;
1873         }
1874 link:
1875         ret = link_free_space(ctl, info);
1876         if (ret)
1877                 kmem_cache_free(btrfs_free_space_cachep, info);
1878 out:
1879         spin_unlock(&ctl->tree_lock);
1880
1881         if (ret) {
1882                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
1883                 BUG_ON(ret == -EEXIST);
1884         }
1885
1886         return ret;
1887 }
1888
1889 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
1890                             u64 offset, u64 bytes)
1891 {
1892         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1893         struct btrfs_free_space *info;
1894         int ret;
1895         bool re_search = false;
1896
1897         spin_lock(&ctl->tree_lock);
1898
1899 again:
1900         ret = 0;
1901         if (!bytes)
1902                 goto out_lock;
1903
1904         info = tree_search_offset(ctl, offset, 0, 0);
1905         if (!info) {
1906                 /*
1907                  * oops didn't find an extent that matched the space we wanted
1908                  * to remove, look for a bitmap instead
1909                  */
1910                 info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1911                                           1, 0);
1912                 if (!info) {
1913                         /*
1914                          * If we found a partial bit of our free space in a
1915                          * bitmap but then couldn't find the other part this may
1916                          * be a problem, so WARN about it.
1917                          */
1918                         WARN_ON(re_search);
1919                         goto out_lock;
1920                 }
1921         }
1922
1923         re_search = false;
1924         if (!info->bitmap) {
1925                 unlink_free_space(ctl, info);
1926                 if (offset == info->offset) {
1927                         u64 to_free = min(bytes, info->bytes);
1928
1929                         info->bytes -= to_free;
1930                         info->offset += to_free;
1931                         if (info->bytes) {
1932                                 ret = link_free_space(ctl, info);
1933                                 WARN_ON(ret);
1934                         } else {
1935                                 kmem_cache_free(btrfs_free_space_cachep, info);
1936                         }
1937
1938                         offset += to_free;
1939                         bytes -= to_free;
1940                         goto again;
1941                 } else {
1942                         u64 old_end = info->bytes + info->offset;
1943
1944                         info->bytes = offset - info->offset;
1945                         ret = link_free_space(ctl, info);
1946                         WARN_ON(ret);
1947                         if (ret)
1948                                 goto out_lock;
1949
1950                         /* Not enough bytes in this entry to satisfy us */
1951                         if (old_end < offset + bytes) {
1952                                 bytes -= old_end - offset;
1953                                 offset = old_end;
1954                                 goto again;
1955                         } else if (old_end == offset + bytes) {
1956                                 /* all done */
1957                                 goto out_lock;
1958                         }
1959                         spin_unlock(&ctl->tree_lock);
1960
1961                         ret = btrfs_add_free_space(block_group, offset + bytes,
1962                                                    old_end - (offset + bytes));
1963                         WARN_ON(ret);
1964                         goto out;
1965                 }
1966         }
1967
1968         ret = remove_from_bitmap(ctl, info, &offset, &bytes);
1969         if (ret == -EAGAIN) {
1970                 re_search = true;
1971                 goto again;
1972         }
1973         BUG_ON(ret); /* logic error */
1974 out_lock:
1975         spin_unlock(&ctl->tree_lock);
1976 out:
1977         return ret;
1978 }
1979
1980 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
1981                            u64 bytes)
1982 {
1983         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1984         struct btrfs_free_space *info;
1985         struct rb_node *n;
1986         int count = 0;
1987
1988         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
1989                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1990                 if (info->bytes >= bytes && !block_group->ro)
1991                         count++;
1992                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
1993                        (unsigned long long)info->offset,
1994                        (unsigned long long)info->bytes,
1995                        (info->bitmap) ? "yes" : "no");
1996         }
1997         printk(KERN_INFO "block group has cluster?: %s\n",
1998                list_empty(&block_group->cluster_list) ? "no" : "yes");
1999         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
2000                "\n", count);
2001 }
2002
2003 void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
2004 {
2005         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2006
2007         spin_lock_init(&ctl->tree_lock);
2008         ctl->unit = block_group->sectorsize;
2009         ctl->start = block_group->key.objectid;
2010         ctl->private = block_group;
2011         ctl->op = &free_space_op;
2012
2013         /*
2014          * we only want to have 32k of ram per block group for keeping
2015          * track of free space, and if we pass 1/2 of that we want to
2016          * start converting things over to using bitmaps
2017          */
2018         ctl->extents_thresh = ((1024 * 32) / 2) /
2019                                 sizeof(struct btrfs_free_space);
2020 }
2021
2022 /*
2023  * for a given cluster, put all of its extents back into the free
2024  * space cache.  If the block group passed doesn't match the block group
2025  * pointed to by the cluster, someone else raced in and freed the
2026  * cluster already.  In that case, we just return without changing anything
2027  */
2028 static int
2029 __btrfs_return_cluster_to_free_space(
2030                              struct btrfs_block_group_cache *block_group,
2031                              struct btrfs_free_cluster *cluster)
2032 {
2033         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2034         struct btrfs_free_space *entry;
2035         struct rb_node *node;
2036
2037         spin_lock(&cluster->lock);
2038         if (cluster->block_group != block_group)
2039                 goto out;
2040
2041         cluster->block_group = NULL;
2042         cluster->window_start = 0;
2043         list_del_init(&cluster->block_group_list);
2044
2045         node = rb_first(&cluster->root);
2046         while (node) {
2047                 bool bitmap;
2048
2049                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2050                 node = rb_next(&entry->offset_index);
2051                 rb_erase(&entry->offset_index, &cluster->root);
2052
2053                 bitmap = (entry->bitmap != NULL);
2054                 if (!bitmap)
2055                         try_merge_free_space(ctl, entry, false);
2056                 tree_insert_offset(&ctl->free_space_offset,
2057                                    entry->offset, &entry->offset_index, bitmap);
2058         }
2059         cluster->root = RB_ROOT;
2060
2061 out:
2062         spin_unlock(&cluster->lock);
2063         btrfs_put_block_group(block_group);
2064         return 0;
2065 }
2066
2067 void __btrfs_remove_free_space_cache_locked(struct btrfs_free_space_ctl *ctl)
2068 {
2069         struct btrfs_free_space *info;
2070         struct rb_node *node;
2071
2072         while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
2073                 info = rb_entry(node, struct btrfs_free_space, offset_index);
2074                 if (!info->bitmap) {
2075                         unlink_free_space(ctl, info);
2076                         kmem_cache_free(btrfs_free_space_cachep, info);
2077                 } else {
2078                         free_bitmap(ctl, info);
2079                 }
2080                 if (need_resched()) {
2081                         spin_unlock(&ctl->tree_lock);
2082                         cond_resched();
2083                         spin_lock(&ctl->tree_lock);
2084                 }
2085         }
2086 }
2087
2088 void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
2089 {
2090         spin_lock(&ctl->tree_lock);
2091         __btrfs_remove_free_space_cache_locked(ctl);
2092         spin_unlock(&ctl->tree_lock);
2093 }
2094
2095 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
2096 {
2097         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2098         struct btrfs_free_cluster *cluster;
2099         struct list_head *head;
2100
2101         spin_lock(&ctl->tree_lock);
2102         while ((head = block_group->cluster_list.next) !=
2103                &block_group->cluster_list) {
2104                 cluster = list_entry(head, struct btrfs_free_cluster,
2105                                      block_group_list);
2106
2107                 WARN_ON(cluster->block_group != block_group);
2108                 __btrfs_return_cluster_to_free_space(block_group, cluster);
2109                 if (need_resched()) {
2110                         spin_unlock(&ctl->tree_lock);
2111                         cond_resched();
2112                         spin_lock(&ctl->tree_lock);
2113                 }
2114         }
2115         __btrfs_remove_free_space_cache_locked(ctl);
2116         spin_unlock(&ctl->tree_lock);
2117
2118 }
2119
2120 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
2121                                u64 offset, u64 bytes, u64 empty_size)
2122 {
2123         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2124         struct btrfs_free_space *entry = NULL;
2125         u64 bytes_search = bytes + empty_size;
2126         u64 ret = 0;
2127         u64 align_gap = 0;
2128         u64 align_gap_len = 0;
2129
2130         spin_lock(&ctl->tree_lock);
2131         entry = find_free_space(ctl, &offset, &bytes_search,
2132                                 block_group->full_stripe_len);
2133         if (!entry)
2134                 goto out;
2135
2136         ret = offset;
2137         if (entry->bitmap) {
2138                 bitmap_clear_bits(ctl, entry, offset, bytes);
2139                 if (!entry->bytes)
2140                         free_bitmap(ctl, entry);
2141         } else {
2142
2143                 unlink_free_space(ctl, entry);
2144                 align_gap_len = offset - entry->offset;
2145                 align_gap = entry->offset;
2146
2147                 entry->offset = offset + bytes;
2148                 WARN_ON(entry->bytes < bytes + align_gap_len);
2149
2150                 entry->bytes -= bytes + align_gap_len;
2151                 if (!entry->bytes)
2152                         kmem_cache_free(btrfs_free_space_cachep, entry);
2153                 else
2154                         link_free_space(ctl, entry);
2155         }
2156
2157 out:
2158         spin_unlock(&ctl->tree_lock);
2159
2160         if (align_gap_len)
2161                 __btrfs_add_free_space(ctl, align_gap, align_gap_len);
2162         return ret;
2163 }
2164
2165 /*
2166  * given a cluster, put all of its extents back into the free space
2167  * cache.  If a block group is passed, this function will only free
2168  * a cluster that belongs to the passed block group.
2169  *
2170  * Otherwise, it'll get a reference on the block group pointed to by the
2171  * cluster and remove the cluster from it.
2172  */
2173 int btrfs_return_cluster_to_free_space(
2174                                struct btrfs_block_group_cache *block_group,
2175                                struct btrfs_free_cluster *cluster)
2176 {
2177         struct btrfs_free_space_ctl *ctl;
2178         int ret;
2179
2180         /* first, get a safe pointer to the block group */
2181         spin_lock(&cluster->lock);
2182         if (!block_group) {
2183                 block_group = cluster->block_group;
2184                 if (!block_group) {
2185                         spin_unlock(&cluster->lock);
2186                         return 0;
2187                 }
2188         } else if (cluster->block_group != block_group) {
2189                 /* someone else has already freed it don't redo their work */
2190                 spin_unlock(&cluster->lock);
2191                 return 0;
2192         }
2193         atomic_inc(&block_group->count);
2194         spin_unlock(&cluster->lock);
2195
2196         ctl = block_group->free_space_ctl;
2197
2198         /* now return any extents the cluster had on it */
2199         spin_lock(&ctl->tree_lock);
2200         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
2201         spin_unlock(&ctl->tree_lock);
2202
2203         /* finally drop our ref */
2204         btrfs_put_block_group(block_group);
2205         return ret;
2206 }
2207
2208 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
2209                                    struct btrfs_free_cluster *cluster,
2210                                    struct btrfs_free_space *entry,
2211                                    u64 bytes, u64 min_start)
2212 {
2213         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2214         int err;
2215         u64 search_start = cluster->window_start;
2216         u64 search_bytes = bytes;
2217         u64 ret = 0;
2218
2219         search_start = min_start;
2220         search_bytes = bytes;
2221
2222         err = search_bitmap(ctl, entry, &search_start, &search_bytes);
2223         if (err)
2224                 return 0;
2225
2226         ret = search_start;
2227         __bitmap_clear_bits(ctl, entry, ret, bytes);
2228
2229         return ret;
2230 }
2231
2232 /*
2233  * given a cluster, try to allocate 'bytes' from it, returns 0
2234  * if it couldn't find anything suitably large, or a logical disk offset
2235  * if things worked out
2236  */
2237 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
2238                              struct btrfs_free_cluster *cluster, u64 bytes,
2239                              u64 min_start)
2240 {
2241         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2242         struct btrfs_free_space *entry = NULL;
2243         struct rb_node *node;
2244         u64 ret = 0;
2245
2246         spin_lock(&cluster->lock);
2247         if (bytes > cluster->max_size)
2248                 goto out;
2249
2250         if (cluster->block_group != block_group)
2251                 goto out;
2252
2253         node = rb_first(&cluster->root);
2254         if (!node)
2255                 goto out;
2256
2257         entry = rb_entry(node, struct btrfs_free_space, offset_index);
2258         while(1) {
2259                 if (entry->bytes < bytes ||
2260                     (!entry->bitmap && entry->offset < min_start)) {
2261                         node = rb_next(&entry->offset_index);
2262                         if (!node)
2263                                 break;
2264                         entry = rb_entry(node, struct btrfs_free_space,
2265                                          offset_index);
2266                         continue;
2267                 }
2268
2269                 if (entry->bitmap) {
2270                         ret = btrfs_alloc_from_bitmap(block_group,
2271                                                       cluster, entry, bytes,
2272                                                       cluster->window_start);
2273                         if (ret == 0) {
2274                                 node = rb_next(&entry->offset_index);
2275                                 if (!node)
2276                                         break;
2277                                 entry = rb_entry(node, struct btrfs_free_space,
2278                                                  offset_index);
2279                                 continue;
2280                         }
2281                         cluster->window_start += bytes;
2282                 } else {
2283                         ret = entry->offset;
2284
2285                         entry->offset += bytes;
2286                         entry->bytes -= bytes;
2287                 }
2288
2289                 if (entry->bytes == 0)
2290                         rb_erase(&entry->offset_index, &cluster->root);
2291                 break;
2292         }
2293 out:
2294         spin_unlock(&cluster->lock);
2295
2296         if (!ret)
2297                 return 0;
2298
2299         spin_lock(&ctl->tree_lock);
2300
2301         ctl->free_space -= bytes;
2302         if (entry->bytes == 0) {
2303                 ctl->free_extents--;
2304                 if (entry->bitmap) {
2305                         kfree(entry->bitmap);
2306                         ctl->total_bitmaps--;
2307                         ctl->op->recalc_thresholds(ctl);
2308                 }
2309                 kmem_cache_free(btrfs_free_space_cachep, entry);
2310         }
2311
2312         spin_unlock(&ctl->tree_lock);
2313
2314         return ret;
2315 }
2316
2317 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
2318                                 struct btrfs_free_space *entry,
2319                                 struct btrfs_free_cluster *cluster,
2320                                 u64 offset, u64 bytes,
2321                                 u64 cont1_bytes, u64 min_bytes)
2322 {
2323         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2324         unsigned long next_zero;
2325         unsigned long i;
2326         unsigned long want_bits;
2327         unsigned long min_bits;
2328         unsigned long found_bits;
2329         unsigned long start = 0;
2330         unsigned long total_found = 0;
2331         int ret;
2332
2333         i = offset_to_bit(entry->offset, ctl->unit,
2334                           max_t(u64, offset, entry->offset));
2335         want_bits = bytes_to_bits(bytes, ctl->unit);
2336         min_bits = bytes_to_bits(min_bytes, ctl->unit);
2337
2338 again:
2339         found_bits = 0;
2340         for_each_set_bit_from(i, entry->bitmap, BITS_PER_BITMAP) {
2341                 next_zero = find_next_zero_bit(entry->bitmap,
2342                                                BITS_PER_BITMAP, i);
2343                 if (next_zero - i >= min_bits) {
2344                         found_bits = next_zero - i;
2345                         break;
2346                 }
2347                 i = next_zero;
2348         }
2349
2350         if (!found_bits)
2351                 return -ENOSPC;
2352
2353         if (!total_found) {
2354                 start = i;
2355                 cluster->max_size = 0;
2356         }
2357
2358         total_found += found_bits;
2359
2360         if (cluster->max_size < found_bits * ctl->unit)
2361                 cluster->max_size = found_bits * ctl->unit;
2362
2363         if (total_found < want_bits || cluster->max_size < cont1_bytes) {
2364                 i = next_zero + 1;
2365                 goto again;
2366         }
2367
2368         cluster->window_start = start * ctl->unit + entry->offset;
2369         rb_erase(&entry->offset_index, &ctl->free_space_offset);
2370         ret = tree_insert_offset(&cluster->root, entry->offset,
2371                                  &entry->offset_index, 1);
2372         BUG_ON(ret); /* -EEXIST; Logic error */
2373
2374         trace_btrfs_setup_cluster(block_group, cluster,
2375                                   total_found * ctl->unit, 1);
2376         return 0;
2377 }
2378
2379 /*
2380  * This searches the block group for just extents to fill the cluster with.
2381  * Try to find a cluster with at least bytes total bytes, at least one
2382  * extent of cont1_bytes, and other clusters of at least min_bytes.
2383  */
2384 static noinline int
2385 setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
2386                         struct btrfs_free_cluster *cluster,
2387                         struct list_head *bitmaps, u64 offset, u64 bytes,
2388                         u64 cont1_bytes, u64 min_bytes)
2389 {
2390         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2391         struct btrfs_free_space *first = NULL;
2392         struct btrfs_free_space *entry = NULL;
2393         struct btrfs_free_space *last;
2394         struct rb_node *node;
2395         u64 window_start;
2396         u64 window_free;
2397         u64 max_extent;
2398         u64 total_size = 0;
2399
2400         entry = tree_search_offset(ctl, offset, 0, 1);
2401         if (!entry)
2402                 return -ENOSPC;
2403
2404         /*
2405          * We don't want bitmaps, so just move along until we find a normal
2406          * extent entry.
2407          */
2408         while (entry->bitmap || entry->bytes < min_bytes) {
2409                 if (entry->bitmap && list_empty(&entry->list))
2410                         list_add_tail(&entry->list, bitmaps);
2411                 node = rb_next(&entry->offset_index);
2412                 if (!node)
2413                         return -ENOSPC;
2414                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2415         }
2416
2417         window_start = entry->offset;
2418         window_free = entry->bytes;
2419         max_extent = entry->bytes;
2420         first = entry;
2421         last = entry;
2422
2423         for (node = rb_next(&entry->offset_index); node;
2424              node = rb_next(&entry->offset_index)) {
2425                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2426
2427                 if (entry->bitmap) {
2428                         if (list_empty(&entry->list))
2429                                 list_add_tail(&entry->list, bitmaps);
2430                         continue;
2431                 }
2432
2433                 if (entry->bytes < min_bytes)
2434                         continue;
2435
2436                 last = entry;
2437                 window_free += entry->bytes;
2438                 if (entry->bytes > max_extent)
2439                         max_extent = entry->bytes;
2440         }
2441
2442         if (window_free < bytes || max_extent < cont1_bytes)
2443                 return -ENOSPC;
2444
2445         cluster->window_start = first->offset;
2446
2447         node = &first->offset_index;
2448
2449         /*
2450          * now we've found our entries, pull them out of the free space
2451          * cache and put them into the cluster rbtree
2452          */
2453         do {
2454                 int ret;
2455
2456                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2457                 node = rb_next(&entry->offset_index);
2458                 if (entry->bitmap || entry->bytes < min_bytes)
2459                         continue;
2460
2461                 rb_erase(&entry->offset_index, &ctl->free_space_offset);
2462                 ret = tree_insert_offset(&cluster->root, entry->offset,
2463                                          &entry->offset_index, 0);
2464                 total_size += entry->bytes;
2465                 BUG_ON(ret); /* -EEXIST; Logic error */
2466         } while (node && entry != last);
2467
2468         cluster->max_size = max_extent;
2469         trace_btrfs_setup_cluster(block_group, cluster, total_size, 0);
2470         return 0;
2471 }
2472
2473 /*
2474  * This specifically looks for bitmaps that may work in the cluster, we assume
2475  * that we have already failed to find extents that will work.
2476  */
2477 static noinline int
2478 setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2479                      struct btrfs_free_cluster *cluster,
2480                      struct list_head *bitmaps, u64 offset, u64 bytes,
2481                      u64 cont1_bytes, u64 min_bytes)
2482 {
2483         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2484         struct btrfs_free_space *entry;
2485         int ret = -ENOSPC;
2486         u64 bitmap_offset = offset_to_bitmap(ctl, offset);
2487
2488         if (ctl->total_bitmaps == 0)
2489                 return -ENOSPC;
2490
2491         /*
2492          * The bitmap that covers offset won't be in the list unless offset
2493          * is just its start offset.
2494          */
2495         entry = list_first_entry(bitmaps, struct btrfs_free_space, list);
2496         if (entry->offset != bitmap_offset) {
2497                 entry = tree_search_offset(ctl, bitmap_offset, 1, 0);
2498                 if (entry && list_empty(&entry->list))
2499                         list_add(&entry->list, bitmaps);
2500         }
2501
2502         list_for_each_entry(entry, bitmaps, list) {
2503                 if (entry->bytes < bytes)
2504                         continue;
2505                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2506                                            bytes, cont1_bytes, min_bytes);
2507                 if (!ret)
2508                         return 0;
2509         }
2510
2511         /*
2512          * The bitmaps list has all the bitmaps that record free space
2513          * starting after offset, so no more search is required.
2514          */
2515         return -ENOSPC;
2516 }
2517
2518 /*
2519  * here we try to find a cluster of blocks in a block group.  The goal
2520  * is to find at least bytes+empty_size.
2521  * We might not find them all in one contiguous area.
2522  *
2523  * returns zero and sets up cluster if things worked out, otherwise
2524  * it returns -enospc
2525  */
2526 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
2527                              struct btrfs_root *root,
2528                              struct btrfs_block_group_cache *block_group,
2529                              struct btrfs_free_cluster *cluster,
2530                              u64 offset, u64 bytes, u64 empty_size)
2531 {
2532         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2533         struct btrfs_free_space *entry, *tmp;
2534         LIST_HEAD(bitmaps);
2535         u64 min_bytes;
2536         u64 cont1_bytes;
2537         int ret;
2538
2539         /*
2540          * Choose the minimum extent size we'll require for this
2541          * cluster.  For SSD_SPREAD, don't allow any fragmentation.
2542          * For metadata, allow allocates with smaller extents.  For
2543          * data, keep it dense.
2544          */
2545         if (btrfs_test_opt(root, SSD_SPREAD)) {
2546                 cont1_bytes = min_bytes = bytes + empty_size;
2547         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
2548                 cont1_bytes = bytes;
2549                 min_bytes = block_group->sectorsize;
2550         } else {
2551                 cont1_bytes = max(bytes, (bytes + empty_size) >> 2);
2552                 min_bytes = block_group->sectorsize;
2553         }
2554
2555         spin_lock(&ctl->tree_lock);
2556
2557         /*
2558          * If we know we don't have enough space to make a cluster don't even
2559          * bother doing all the work to try and find one.
2560          */
2561         if (ctl->free_space < bytes) {
2562                 spin_unlock(&ctl->tree_lock);
2563                 return -ENOSPC;
2564         }
2565
2566         spin_lock(&cluster->lock);
2567
2568         /* someone already found a cluster, hooray */
2569         if (cluster->block_group) {
2570                 ret = 0;
2571                 goto out;
2572         }
2573
2574         trace_btrfs_find_cluster(block_group, offset, bytes, empty_size,
2575                                  min_bytes);
2576
2577         INIT_LIST_HEAD(&bitmaps);
2578         ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
2579                                       bytes + empty_size,
2580                                       cont1_bytes, min_bytes);
2581         if (ret)
2582                 ret = setup_cluster_bitmap(block_group, cluster, &bitmaps,
2583                                            offset, bytes + empty_size,
2584                                            cont1_bytes, min_bytes);
2585
2586         /* Clear our temporary list */
2587         list_for_each_entry_safe(entry, tmp, &bitmaps, list)
2588                 list_del_init(&entry->list);
2589
2590         if (!ret) {
2591                 atomic_inc(&block_group->count);
2592                 list_add_tail(&cluster->block_group_list,
2593                               &block_group->cluster_list);
2594                 cluster->block_group = block_group;
2595         } else {
2596                 trace_btrfs_failed_cluster_setup(block_group);
2597         }
2598 out:
2599         spin_unlock(&cluster->lock);
2600         spin_unlock(&ctl->tree_lock);
2601
2602         return ret;
2603 }
2604
2605 /*
2606  * simple code to zero out a cluster
2607  */
2608 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
2609 {
2610         spin_lock_init(&cluster->lock);
2611         spin_lock_init(&cluster->refill_lock);
2612         cluster->root = RB_ROOT;
2613         cluster->max_size = 0;
2614         INIT_LIST_HEAD(&cluster->block_group_list);
2615         cluster->block_group = NULL;
2616 }
2617
2618 static int do_trimming(struct btrfs_block_group_cache *block_group,
2619                        u64 *total_trimmed, u64 start, u64 bytes,
2620                        u64 reserved_start, u64 reserved_bytes)
2621 {
2622         struct btrfs_space_info *space_info = block_group->space_info;
2623         struct btrfs_fs_info *fs_info = block_group->fs_info;
2624         int ret;
2625         int update = 0;
2626         u64 trimmed = 0;
2627
2628         spin_lock(&space_info->lock);
2629         spin_lock(&block_group->lock);
2630         if (!block_group->ro) {
2631                 block_group->reserved += reserved_bytes;
2632                 space_info->bytes_reserved += reserved_bytes;
2633                 update = 1;
2634         }
2635         spin_unlock(&block_group->lock);
2636         spin_unlock(&space_info->lock);
2637
2638         ret = btrfs_error_discard_extent(fs_info->extent_root,
2639                                          start, bytes, &trimmed);
2640         if (!ret)
2641                 *total_trimmed += trimmed;
2642
2643         btrfs_add_free_space(block_group, reserved_start, reserved_bytes);
2644
2645         if (update) {
2646                 spin_lock(&space_info->lock);
2647                 spin_lock(&block_group->lock);
2648                 if (block_group->ro)
2649                         space_info->bytes_readonly += reserved_bytes;
2650                 block_group->reserved -= reserved_bytes;
2651                 space_info->bytes_reserved -= reserved_bytes;
2652                 spin_unlock(&space_info->lock);
2653                 spin_unlock(&block_group->lock);
2654         }
2655
2656         return ret;
2657 }
2658
2659 static int trim_no_bitmap(struct btrfs_block_group_cache *block_group,
2660                           u64 *total_trimmed, u64 start, u64 end, u64 minlen)
2661 {
2662         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2663         struct btrfs_free_space *entry;
2664         struct rb_node *node;
2665         int ret = 0;
2666         u64 extent_start;
2667         u64 extent_bytes;
2668         u64 bytes;
2669
2670         while (start < end) {
2671                 spin_lock(&ctl->tree_lock);
2672
2673                 if (ctl->free_space < minlen) {
2674                         spin_unlock(&ctl->tree_lock);
2675                         break;
2676                 }
2677
2678                 entry = tree_search_offset(ctl, start, 0, 1);
2679                 if (!entry) {
2680                         spin_unlock(&ctl->tree_lock);
2681                         break;
2682                 }
2683
2684                 /* skip bitmaps */
2685                 while (entry->bitmap) {
2686                         node = rb_next(&entry->offset_index);
2687                         if (!node) {
2688                                 spin_unlock(&ctl->tree_lock);
2689                                 goto out;
2690                         }
2691                         entry = rb_entry(node, struct btrfs_free_space,
2692                                          offset_index);
2693                 }
2694
2695                 if (entry->offset >= end) {
2696                         spin_unlock(&ctl->tree_lock);
2697                         break;
2698                 }
2699
2700                 extent_start = entry->offset;
2701                 extent_bytes = entry->bytes;
2702                 start = max(start, extent_start);
2703                 bytes = min(extent_start + extent_bytes, end) - start;
2704                 if (bytes < minlen) {
2705                         spin_unlock(&ctl->tree_lock);
2706                         goto next;
2707                 }
2708
2709                 unlink_free_space(ctl, entry);
2710                 kmem_cache_free(btrfs_free_space_cachep, entry);
2711
2712                 spin_unlock(&ctl->tree_lock);
2713
2714                 ret = do_trimming(block_group, total_trimmed, start, bytes,
2715                                   extent_start, extent_bytes);
2716                 if (ret)
2717                         break;
2718 next:
2719                 start += bytes;
2720
2721                 if (fatal_signal_pending(current)) {
2722                         ret = -ERESTARTSYS;
2723                         break;
2724                 }
2725
2726                 cond_resched();
2727         }
2728 out:
2729         return ret;
2730 }
2731
2732 static int trim_bitmaps(struct btrfs_block_group_cache *block_group,
2733                         u64 *total_trimmed, u64 start, u64 end, u64 minlen)
2734 {
2735         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2736         struct btrfs_free_space *entry;
2737         int ret = 0;
2738         int ret2;
2739         u64 bytes;
2740         u64 offset = offset_to_bitmap(ctl, start);
2741
2742         while (offset < end) {
2743                 bool next_bitmap = false;
2744
2745                 spin_lock(&ctl->tree_lock);
2746
2747                 if (ctl->free_space < minlen) {
2748                         spin_unlock(&ctl->tree_lock);
2749                         break;
2750                 }
2751
2752                 entry = tree_search_offset(ctl, offset, 1, 0);
2753                 if (!entry) {
2754                         spin_unlock(&ctl->tree_lock);
2755                         next_bitmap = true;
2756                         goto next;
2757                 }
2758
2759                 bytes = minlen;
2760                 ret2 = search_bitmap(ctl, entry, &start, &bytes);
2761                 if (ret2 || start >= end) {
2762                         spin_unlock(&ctl->tree_lock);
2763                         next_bitmap = true;
2764                         goto next;
2765                 }
2766
2767                 bytes = min(bytes, end - start);
2768                 if (bytes < minlen) {
2769                         spin_unlock(&ctl->tree_lock);
2770                         goto next;
2771                 }
2772
2773                 bitmap_clear_bits(ctl, entry, start, bytes);
2774                 if (entry->bytes == 0)
2775                         free_bitmap(ctl, entry);
2776
2777                 spin_unlock(&ctl->tree_lock);
2778
2779                 ret = do_trimming(block_group, total_trimmed, start, bytes,
2780                                   start, bytes);
2781                 if (ret)
2782                         break;
2783 next:
2784                 if (next_bitmap) {
2785                         offset += BITS_PER_BITMAP * ctl->unit;
2786                 } else {
2787                         start += bytes;
2788                         if (start >= offset + BITS_PER_BITMAP * ctl->unit)
2789                                 offset += BITS_PER_BITMAP * ctl->unit;
2790                 }
2791
2792                 if (fatal_signal_pending(current)) {
2793                         ret = -ERESTARTSYS;
2794                         break;
2795                 }
2796
2797                 cond_resched();
2798         }
2799
2800         return ret;
2801 }
2802
2803 int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
2804                            u64 *trimmed, u64 start, u64 end, u64 minlen)
2805 {
2806         int ret;
2807
2808         *trimmed = 0;
2809
2810         ret = trim_no_bitmap(block_group, trimmed, start, end, minlen);
2811         if (ret)
2812                 return ret;
2813
2814         ret = trim_bitmaps(block_group, trimmed, start, end, minlen);
2815
2816         return ret;
2817 }
2818
2819 /*
2820  * Find the left-most item in the cache tree, and then return the
2821  * smallest inode number in the item.
2822  *
2823  * Note: the returned inode number may not be the smallest one in
2824  * the tree, if the left-most item is a bitmap.
2825  */
2826 u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root)
2827 {
2828         struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl;
2829         struct btrfs_free_space *entry = NULL;
2830         u64 ino = 0;
2831
2832         spin_lock(&ctl->tree_lock);
2833
2834         if (RB_EMPTY_ROOT(&ctl->free_space_offset))
2835                 goto out;
2836
2837         entry = rb_entry(rb_first(&ctl->free_space_offset),
2838                          struct btrfs_free_space, offset_index);
2839
2840         if (!entry->bitmap) {
2841                 ino = entry->offset;
2842
2843                 unlink_free_space(ctl, entry);
2844                 entry->offset++;
2845                 entry->bytes--;
2846                 if (!entry->bytes)
2847                         kmem_cache_free(btrfs_free_space_cachep, entry);
2848                 else
2849                         link_free_space(ctl, entry);
2850         } else {
2851                 u64 offset = 0;
2852                 u64 count = 1;
2853                 int ret;
2854
2855                 ret = search_bitmap(ctl, entry, &offset, &count);
2856                 /* Logic error; Should be empty if it can't find anything */
2857                 BUG_ON(ret);
2858
2859                 ino = offset;
2860                 bitmap_clear_bits(ctl, entry, offset, 1);
2861                 if (entry->bytes == 0)
2862                         free_bitmap(ctl, entry);
2863         }
2864 out:
2865         spin_unlock(&ctl->tree_lock);
2866
2867         return ino;
2868 }
2869
2870 struct inode *lookup_free_ino_inode(struct btrfs_root *root,
2871                                     struct btrfs_path *path)
2872 {
2873         struct inode *inode = NULL;
2874
2875         spin_lock(&root->cache_lock);
2876         if (root->cache_inode)
2877                 inode = igrab(root->cache_inode);
2878         spin_unlock(&root->cache_lock);
2879         if (inode)
2880                 return inode;
2881
2882         inode = __lookup_free_space_inode(root, path, 0);
2883         if (IS_ERR(inode))
2884                 return inode;
2885
2886         spin_lock(&root->cache_lock);
2887         if (!btrfs_fs_closing(root->fs_info))
2888                 root->cache_inode = igrab(inode);
2889         spin_unlock(&root->cache_lock);
2890
2891         return inode;
2892 }
2893
2894 int create_free_ino_inode(struct btrfs_root *root,
2895                           struct btrfs_trans_handle *trans,
2896                           struct btrfs_path *path)
2897 {
2898         return __create_free_space_inode(root, trans, path,
2899                                          BTRFS_FREE_INO_OBJECTID, 0);
2900 }
2901
2902 int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
2903 {
2904         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2905         struct btrfs_path *path;
2906         struct inode *inode;
2907         int ret = 0;
2908         u64 root_gen = btrfs_root_generation(&root->root_item);
2909
2910         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
2911                 return 0;
2912
2913         /*
2914          * If we're unmounting then just return, since this does a search on the
2915          * normal root and not the commit root and we could deadlock.
2916          */
2917         if (btrfs_fs_closing(fs_info))
2918                 return 0;
2919
2920         path = btrfs_alloc_path();
2921         if (!path)
2922                 return 0;
2923
2924         inode = lookup_free_ino_inode(root, path);
2925         if (IS_ERR(inode))
2926                 goto out;
2927
2928         if (root_gen != BTRFS_I(inode)->generation)
2929                 goto out_put;
2930
2931         ret = __load_free_space_cache(root, inode, ctl, path, 0);
2932
2933         if (ret < 0)
2934                 printk(KERN_ERR "btrfs: failed to load free ino cache for "
2935                        "root %llu\n", root->root_key.objectid);
2936 out_put:
2937         iput(inode);
2938 out:
2939         btrfs_free_path(path);
2940         return ret;
2941 }
2942
2943 int btrfs_write_out_ino_cache(struct btrfs_root *root,
2944                               struct btrfs_trans_handle *trans,
2945                               struct btrfs_path *path)
2946 {
2947         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2948         struct inode *inode;
2949         int ret;
2950
2951         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
2952                 return 0;
2953
2954         inode = lookup_free_ino_inode(root, path);
2955         if (IS_ERR(inode))
2956                 return 0;
2957
2958         ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);
2959         if (ret) {
2960                 btrfs_delalloc_release_metadata(inode, inode->i_size);
2961 #ifdef DEBUG
2962                 printk(KERN_ERR "btrfs: failed to write free ino cache "
2963                        "for root %llu\n", root->root_key.objectid);
2964 #endif
2965         }
2966
2967         iput(inode);
2968         return ret;
2969 }