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