fs/btrfs/free-space-cache.c

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