fs/btrfs/free-space-cache.c

   1 /*
   2  * Copyright (C) 2008 Red Hat.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/pagemap.h>
  20 #include <linux/sched.h>
  21 #include <linux/slab.h>
  22 #include <linux/math64.h>
  23 #include "ctree.h"
  24 #include "free-space-cache.h"
  25 #include "transaction.h"
  26 #include "disk-io.h"
  27 #include "extent_io.h"
  28 #include "inode-map.h"
  29
  30 #define BITS_PER_BITMAP         (PAGE_CACHE_SIZE * 8)
  31 #define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
  32
  33 static int link_free_space(struct btrfs_free_space_ctl *ctl,
  34                            struct btrfs_free_space *info);
  35
  36 static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
  37                                                struct btrfs_path *path,
  38                                                u64 offset)
  39 {
  40         struct btrfs_key key;
  41         struct btrfs_key location;
  42         struct btrfs_disk_key disk_key;
  43         struct btrfs_free_space_header *header;
  44         struct extent_buffer *leaf;
  45         struct inode *inode = NULL;
  46         int ret;
  47
  48         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
  49         key.offset = offset;
  50         key.type = 0;
  51
  52         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  53         if (ret < 0)
  54                 return ERR_PTR(ret);
  55         if (ret > 0) {
  56                 btrfs_release_path(path);
  57                 return ERR_PTR(-ENOENT);
  58         }
  59
  60         leaf = path->nodes[0];
  61         header = btrfs_item_ptr(leaf, path->slots[0],
  62                                 struct btrfs_free_space_header);
  63         btrfs_free_space_key(leaf, header, &disk_key);
  64         btrfs_disk_key_to_cpu(&location, &disk_key);
  65         btrfs_release_path(path);
  66
  67         inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
  68         if (!inode)
  69                 return ERR_PTR(-ENOENT);
  70         if (IS_ERR(inode))
  71                 return inode;
  72         if (is_bad_inode(inode)) {
  73                 iput(inode);
  74                 return ERR_PTR(-ENOENT);
  75         }
  76
  77         inode->i_mapping->flags &= ~__GFP_FS;
  78
  79         return inode;
  80 }
  81
  82 struct inode *lookup_free_space_inode(struct btrfs_root *root,
  83                                       struct btrfs_block_group_cache
  84                                       *block_group, struct btrfs_path *path)
  85 {
  86         struct inode *inode = NULL;
  87
  88         spin_lock(&block_group->lock);
  89         if (block_group->inode)
  90                 inode = igrab(block_group->inode);
  91         spin_unlock(&block_group->lock);
  92         if (inode)
  93                 return inode;
  94
  95         inode = __lookup_free_space_inode(root, path,
  96                                           block_group->key.objectid);
  97         if (IS_ERR(inode))
  98                 return inode;
  99
 100         spin_lock(&block_group->lock);
 101         if (!btrfs_fs_closing(root->fs_info)) {
 102                 block_group->inode = igrab(inode);
 103                 block_group->iref = 1;
 104         }
 105         spin_unlock(&block_group->lock);
 106
 107         return inode;
 108 }
 109
 110 int __create_free_space_inode(struct btrfs_root *root,
 111                               struct btrfs_trans_handle *trans,
 112                               struct btrfs_path *path, u64 ino, u64 offset)
 113 {
 114         struct btrfs_key key;
 115         struct btrfs_disk_key disk_key;
 116         struct btrfs_free_space_header *header;
 117         struct btrfs_inode_item *inode_item;
 118         struct extent_buffer *leaf;
 119         int ret;
 120
 121         ret = btrfs_insert_empty_inode(trans, root, path, ino);
 122         if (ret)
 123                 return ret;
 124
 125         leaf = path->nodes[0];
 126         inode_item = btrfs_item_ptr(leaf, path->slots[0],
 127                                     struct btrfs_inode_item);
 128         btrfs_item_key(leaf, &disk_key, path->slots[0]);
 129         memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
 130                              sizeof(*inode_item));
 131         btrfs_set_inode_generation(leaf, inode_item, trans->transid);
 132         btrfs_set_inode_size(leaf, inode_item, 0);
 133         btrfs_set_inode_nbytes(leaf, inode_item, 0);
 134         btrfs_set_inode_uid(leaf, inode_item, 0);
 135         btrfs_set_inode_gid(leaf, inode_item, 0);
 136         btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
 137         btrfs_set_inode_flags(leaf, inode_item, BTRFS_INODE_NOCOMPRESS |
 138                               BTRFS_INODE_PREALLOC | BTRFS_INODE_NODATASUM);
 139         btrfs_set_inode_nlink(leaf, inode_item, 1);
 140         btrfs_set_inode_transid(leaf, inode_item, trans->transid);
 141         btrfs_set_inode_block_group(leaf, inode_item, offset);
 142         btrfs_mark_buffer_dirty(leaf);
 143         btrfs_release_path(path);
 144
 145         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 146         key.offset = offset;
 147         key.type = 0;
 148
 149         ret = btrfs_insert_empty_item(trans, root, path, &key,
 150                                       sizeof(struct btrfs_free_space_header));
 151         if (ret < 0) {
 152                 btrfs_release_path(path);
 153                 return ret;
 154         }
 155         leaf = path->nodes[0];
 156         header = btrfs_item_ptr(leaf, path->slots[0],
 157                                 struct btrfs_free_space_header);
 158         memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
 159         btrfs_set_free_space_key(leaf, header, &disk_key);
 160         btrfs_mark_buffer_dirty(leaf);
 161         btrfs_release_path(path);
 162
 163         return 0;
 164 }
 165
 166 int create_free_space_inode(struct btrfs_root *root,
 167                             struct btrfs_trans_handle *trans,
 168                             struct btrfs_block_group_cache *block_group,
 169                             struct btrfs_path *path)
 170 {
 171         int ret;
 172         u64 ino;
 173
 174         ret = btrfs_find_free_objectid(root, &ino);
 175         if (ret < 0)
 176                 return ret;
 177
 178         return __create_free_space_inode(root, trans, path, ino,
 179                                          block_group->key.objectid);
 180 }
 181
 182 int btrfs_truncate_free_space_cache(struct btrfs_root *root,
 183                                     struct btrfs_trans_handle *trans,
 184                                     struct btrfs_path *path,
 185                                     struct inode *inode)
 186 {
 187         loff_t oldsize;
 188         int ret = 0;
 189
 190         trans->block_rsv = root->orphan_block_rsv;
 191         ret = btrfs_block_rsv_check(trans, root,
 192                                     root->orphan_block_rsv,
 193                                     0, 5);
 194         if (ret)
 195                 return ret;
 196
 197         oldsize = i_size_read(inode);
 198         btrfs_i_size_write(inode, 0);
 199         truncate_pagecache(inode, oldsize, 0);
 200
 201         /*
 202          * We don't need an orphan item because truncating the free space cache
 203          * will never be split across transactions.
 204          */
 205         ret = btrfs_truncate_inode_items(trans, root, inode,
 206                                          0, BTRFS_EXTENT_DATA_KEY);
 207         if (ret) {
 208                 WARN_ON(1);
 209                 return ret;
 210         }
 211
 212         ret = btrfs_update_inode(trans, root, inode);
 213         return ret;
 214 }
 215
 216 static int readahead_cache(struct inode *inode)
 217 {
 218         struct file_ra_state *ra;
 219         unsigned long last_index;
 220
 221         ra = kzalloc(sizeof(*ra), GFP_NOFS);
 222         if (!ra)
 223                 return -ENOMEM;
 224
 225         file_ra_state_init(ra, inode->i_mapping);
 226         last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 227
 228         page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
 229
 230         kfree(ra);
 231
 232         return 0;
 233 }
 234
 235 int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 236                             struct btrfs_free_space_ctl *ctl,
 237                             struct btrfs_path *path, u64 offset)
 238 {
 239         struct btrfs_free_space_header *header;
 240         struct extent_buffer *leaf;
 241         struct page *page;
 242         u32 *checksums = NULL, *crc;
 243         char *disk_crcs = NULL;
 244         struct btrfs_key key;
 245         struct list_head bitmaps;
 246         u64 num_entries;
 247         u64 num_bitmaps;
 248         u64 generation;
 249         u32 cur_crc = ~(u32)0;
 250         pgoff_t index = 0;
 251         unsigned long first_page_offset;
 252         int num_checksums;
 253         int ret = 0;
 254
 255         INIT_LIST_HEAD(&bitmaps);
 256
 257         /* Nothing in the space cache, goodbye */
 258         if (!i_size_read(inode))
 259                 goto out;
 260
 261         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 262         key.offset = offset;
 263         key.type = 0;
 264
 265         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 266         if (ret < 0)
 267                 goto out;
 268         else if (ret > 0) {
 269                 btrfs_release_path(path);
 270                 ret = 0;
 271                 goto out;
 272         }
 273
 274         ret = -1;
 275
 276         leaf = path->nodes[0];
 277         header = btrfs_item_ptr(leaf, path->slots[0],
 278                                 struct btrfs_free_space_header);
 279         num_entries = btrfs_free_space_entries(leaf, header);
 280         num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
 281         generation = btrfs_free_space_generation(leaf, header);
 282         btrfs_release_path(path);
 283
 284         if (BTRFS_I(inode)->generation != generation) {
 285                 printk(KERN_ERR "btrfs: free space inode generation (%llu) did"
 286                        " not match free space cache generation (%llu)\n",
 287                        (unsigned long long)BTRFS_I(inode)->generation,
 288                        (unsigned long long)generation);
 289                 goto out;
 290         }
 291
 292         if (!num_entries)
 293                 goto out;
 294
 295         /* Setup everything for doing checksumming */
 296         num_checksums = i_size_read(inode) / PAGE_CACHE_SIZE;
 297         checksums = crc = kzalloc(sizeof(u32) * num_checksums, GFP_NOFS);
 298         if (!checksums)
 299                 goto out;
 300         first_page_offset = (sizeof(u32) * num_checksums) + sizeof(u64);
 301         disk_crcs = kzalloc(first_page_offset, GFP_NOFS);
 302         if (!disk_crcs)
 303                 goto out;
 304
 305         ret = readahead_cache(inode);
 306         if (ret)
 307                 goto out;
 308
 309         while (1) {
 310                 struct btrfs_free_space_entry *entry;
 311                 struct btrfs_free_space *e;
 312                 void *addr;
 313                 unsigned long offset = 0;
 314                 unsigned long start_offset = 0;
 315                 int need_loop = 0;
 316
 317                 if (!num_entries && !num_bitmaps)
 318                         break;
 319
 320                 if (index == 0) {
 321                         start_offset = first_page_offset;
 322                         offset = start_offset;
 323                 }
 324
 325                 page = grab_cache_page(inode->i_mapping, index);
 326                 if (!page)
 327                         goto free_cache;
 328
 329                 if (!PageUptodate(page)) {
 330                         btrfs_readpage(NULL, page);
 331                         lock_page(page);
 332                         if (!PageUptodate(page)) {
 333                                 unlock_page(page);
 334                                 page_cache_release(page);
 335                                 printk(KERN_ERR "btrfs: error reading free "
 336                                        "space cache\n");
 337                                 goto free_cache;
 338                         }
 339                 }
 340                 addr = kmap(page);
 341
 342                 if (index == 0) {
 343                         u64 *gen;
 344
 345                         memcpy(disk_crcs, addr, first_page_offset);
 346                         gen = addr + (sizeof(u32) * num_checksums);
 347                         if (*gen != BTRFS_I(inode)->generation) {
 348                                 printk(KERN_ERR "btrfs: space cache generation"
 349                                        " (%llu) does not match inode (%llu)\n",
 350                                        (unsigned long long)*gen,
 351                                        (unsigned long long)
 352                                        BTRFS_I(inode)->generation);
 353                                 kunmap(page);
 354                                 unlock_page(page);
 355                                 page_cache_release(page);
 356                                 goto free_cache;
 357                         }
 358                         crc = (u32 *)disk_crcs;
 359                 }
 360                 entry = addr + start_offset;
 361
 362                 /* First lets check our crc before we do anything fun */
 363                 cur_crc = ~(u32)0;
 364                 cur_crc = btrfs_csum_data(root, addr + start_offset, cur_crc,
 365                                           PAGE_CACHE_SIZE - start_offset);
 366                 btrfs_csum_final(cur_crc, (char *)&cur_crc);
 367                 if (cur_crc != *crc) {
 368                         printk(KERN_ERR "btrfs: crc mismatch for page %lu\n",
 369                                index);
 370                         kunmap(page);
 371                         unlock_page(page);
 372                         page_cache_release(page);
 373                         goto free_cache;
 374                 }
 375                 crc++;
 376
 377                 while (1) {
 378                         if (!num_entries)
 379                                 break;
 380
 381                         need_loop = 1;
 382                         e = kmem_cache_zalloc(btrfs_free_space_cachep,
 383                                               GFP_NOFS);
 384                         if (!e) {
 385                                 kunmap(page);
 386                                 unlock_page(page);
 387                                 page_cache_release(page);
 388                                 goto free_cache;
 389                         }
 390
 391                         e->offset = le64_to_cpu(entry->offset);
 392                         e->bytes = le64_to_cpu(entry->bytes);
 393                         if (!e->bytes) {
 394                                 kunmap(page);
 395                                 kmem_cache_free(btrfs_free_space_cachep, e);
 396                                 unlock_page(page);
 397                                 page_cache_release(page);
 398                                 goto free_cache;
 399                         }
 400
 401                         if (entry->type == BTRFS_FREE_SPACE_EXTENT) {
 402                                 spin_lock(&ctl->tree_lock);
 403                                 ret = link_free_space(ctl, e);
 404                                 spin_unlock(&ctl->tree_lock);
 405                                 if (ret) {
 406                                         printk(KERN_ERR "Duplicate entries in "
 407                                                "free space cache, dumping\n");
 408                                         kunmap(page);
 409                                         unlock_page(page);
 410                                         page_cache_release(page);
 411                                         goto free_cache;
 412                                 }
 413                         } else {
 414                                 e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
 415                                 if (!e->bitmap) {
 416                                         kunmap(page);
 417                                         kmem_cache_free(
 418                                                 btrfs_free_space_cachep, e);
 419                                         unlock_page(page);
 420                                         page_cache_release(page);
 421                                         goto free_cache;
 422                                 }
 423                                 spin_lock(&ctl->tree_lock);
 424                                 ret = link_free_space(ctl, e);
 425                                 ctl->total_bitmaps++;
 426                                 ctl->op->recalc_thresholds(ctl);
 427                                 spin_unlock(&ctl->tree_lock);
 428                                 if (ret) {
 429                                         printk(KERN_ERR "Duplicate entries in "
 430                                                "free space cache, dumping\n");
 431                                         kunmap(page);
 432                                         unlock_page(page);
 433                                         page_cache_release(page);
 434                                         goto free_cache;
 435                                 }
 436                                 list_add_tail(&e->list, &bitmaps);
 437                         }
 438
 439                         num_entries--;
 440                         offset += sizeof(struct btrfs_free_space_entry);
 441                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 442                             PAGE_CACHE_SIZE)
 443                                 break;
 444                         entry++;
 445                 }
 446
 447                 /*
 448                  * We read an entry out of this page, we need to move on to the
 449                  * next page.
 450                  */
 451                 if (need_loop) {
 452                         kunmap(page);
 453                         goto next;
 454                 }
 455
 456                 /*
 457                  * We add the bitmaps at the end of the entries in order that
 458                  * the bitmap entries are added to the cache.
 459                  */
 460                 e = list_entry(bitmaps.next, struct btrfs_free_space, list);
 461                 list_del_init(&e->list);
 462                 memcpy(e->bitmap, addr, PAGE_CACHE_SIZE);
 463                 kunmap(page);
 464                 num_bitmaps--;
 465 next:
 466                 unlock_page(page);
 467                 page_cache_release(page);
 468                 index++;
 469         }
 470
 471         ret = 1;
 472 out:
 473         kfree(checksums);
 474         kfree(disk_crcs);
 475         return ret;
 476 free_cache:
 477         __btrfs_remove_free_space_cache(ctl);
 478         goto out;
 479 }
 480
 481 int load_free_space_cache(struct btrfs_fs_info *fs_info,
 482                           struct btrfs_block_group_cache *block_group)
 483 {
 484         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 485         struct btrfs_root *root = fs_info->tree_root;
 486         struct inode *inode;
 487         struct btrfs_path *path;
 488         int ret;
 489         bool matched;
 490         u64 used = btrfs_block_group_used(&block_group->item);
 491
 492         /*
 493          * If we're unmounting then just return, since this does a search on the
 494          * normal root and not the commit root and we could deadlock.
 495          */
 496         if (btrfs_fs_closing(fs_info))
 497                 return 0;
 498
 499         /*
 500          * If this block group has been marked to be cleared for one reason or
 501          * another then we can't trust the on disk cache, so just return.
 502          */
 503         spin_lock(&block_group->lock);
 504         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 505                 spin_unlock(&block_group->lock);
 506                 return 0;
 507         }
 508         spin_unlock(&block_group->lock);
 509
 510         path = btrfs_alloc_path();
 511         if (!path)
 512                 return 0;
 513
 514         inode = lookup_free_space_inode(root, block_group, path);
 515         if (IS_ERR(inode)) {
 516                 btrfs_free_path(path);
 517                 return 0;
 518         }
 519
 520         ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
 521                                       path, block_group->key.objectid);
 522         btrfs_free_path(path);
 523         if (ret <= 0)
 524                 goto out;
 525
 526         spin_lock(&ctl->tree_lock);
 527         matched = (ctl->free_space == (block_group->key.offset - used -
 528                                        block_group->bytes_super));
 529         spin_unlock(&ctl->tree_lock);
 530
 531         if (!matched) {
 532                 __btrfs_remove_free_space_cache(ctl);
 533                 printk(KERN_ERR "block group %llu has an wrong amount of free "
 534                        "space\n", block_group->key.objectid);
 535                 ret = -1;
 536         }
 537 out:
 538         if (ret < 0) {
 539                 /* This cache is bogus, make sure it gets cleared */
 540                 spin_lock(&block_group->lock);
 541                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 542                 spin_unlock(&block_group->lock);
 543                 ret = 0;
 544
 545                 printk(KERN_ERR "btrfs: failed to load free space cache "
 546                        "for block group %llu\n", block_group->key.objectid);
 547         }
 548
 549         iput(inode);
 550         return ret;
 551 }
 552
 553 int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 554                             struct btrfs_free_space_ctl *ctl,
 555                             struct btrfs_block_group_cache *block_group,
 556                             struct btrfs_trans_handle *trans,
 557                             struct btrfs_path *path, u64 offset)
 558 {
 559         struct btrfs_free_space_header *header;
 560         struct extent_buffer *leaf;
 561         struct rb_node *node;
 562         struct list_head *pos, *n;
 563         struct page **pages;
 564         struct page *page;
 565         struct extent_state *cached_state = NULL;
 566         struct btrfs_free_cluster *cluster = NULL;
 567         struct extent_io_tree *unpin = NULL;
 568         struct list_head bitmap_list;
 569         struct btrfs_key key;
 570         u64 start, end, len;
 571         u64 bytes = 0;
 572         u32 *crc, *checksums;
 573         unsigned long first_page_offset;
 574         int index = 0, num_pages = 0;
 575         int entries = 0;
 576         int bitmaps = 0;
 577         int ret = -1;
 578         bool next_page = false;
 579         bool out_of_space = false;
 580
 581         INIT_LIST_HEAD(&bitmap_list);
 582
 583         node = rb_first(&ctl->free_space_offset);
 584         if (!node)
 585                 return 0;
 586
 587         if (!i_size_read(inode))
 588                 return -1;
 589
 590         num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
 591                 PAGE_CACHE_SHIFT;
 592
 593         /* Since the first page has all of our checksums and our generation we
 594          * need to calculate the offset into the page that we can start writing
 595          * our entries.
 596          */
 597         first_page_offset = (sizeof(u32) * num_pages) + sizeof(u64);
 598
 599         filemap_write_and_wait(inode->i_mapping);
 600         btrfs_wait_ordered_range(inode, inode->i_size &
 601                                  ~(root->sectorsize - 1), (u64)-1);
 602
 603         /* make sure we don't overflow that first page */
 604         if (first_page_offset + sizeof(struct btrfs_free_space_entry) >= PAGE_CACHE_SIZE) {
 605                 /* this is really the same as running out of space, where we also return 0 */
 606                 printk(KERN_CRIT "Btrfs: free space cache was too big for the crc page\n");
 607                 ret = 0;
 608                 goto out_update;
 609         }
 610
 611         /* We need a checksum per page. */
 612         crc = checksums = kzalloc(sizeof(u32) * num_pages, GFP_NOFS);
 613         if (!crc)
 614                 return -1;
 615
 616         pages = kzalloc(sizeof(struct page *) * num_pages, GFP_NOFS);
 617         if (!pages) {
 618                 kfree(crc);
 619                 return -1;
 620         }
 621
 622         /* Get the cluster for this block_group if it exists */
 623         if (block_group && !list_empty(&block_group->cluster_list))
 624                 cluster = list_entry(block_group->cluster_list.next,
 625                                      struct btrfs_free_cluster,
 626                                      block_group_list);
 627
 628         /*
 629          * We shouldn't have switched the pinned extents yet so this is the
 630          * right one
 631          */
 632         unpin = root->fs_info->pinned_extents;
 633
 634         /*
 635          * Lock all pages first so we can lock the extent safely.
 636          *
 637          * NOTE: Because we hold the ref the entire time we're going to write to
 638          * the page find_get_page should never fail, so we don't do a check
 639          * after find_get_page at this point.  Just putting this here so people
 640          * know and don't freak out.
 641          */
 642         while (index < num_pages) {
 643                 page = grab_cache_page(inode->i_mapping, index);
 644                 if (!page) {
 645                         int i;
 646
 647                         for (i = 0; i < num_pages; i++) {
 648                                 unlock_page(pages[i]);
 649                                 page_cache_release(pages[i]);
 650                         }
 651                         goto out_free;
 652                 }
 653                 pages[index] = page;
 654                 index++;
 655         }
 656
 657         index = 0;
 658         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
 659                          0, &cached_state, GFP_NOFS);
 660
 661         /*
 662          * When searching for pinned extents, we need to start at our start
 663          * offset.
 664          */
 665         if (block_group)
 666                 start = block_group->key.objectid;
 667
 668         /* Write out the extent entries */
 669         do {
 670                 struct btrfs_free_space_entry *entry;
 671                 void *addr;
 672                 unsigned long offset = 0;
 673                 unsigned long start_offset = 0;
 674
 675                 next_page = false;
 676
 677                 if (index == 0) {
 678                         start_offset = first_page_offset;
 679                         offset = start_offset;
 680                 }
 681
 682                 if (index >= num_pages) {
 683                         out_of_space = true;
 684                         break;
 685                 }
 686
 687                 page = pages[index];
 688
 689                 addr = kmap(page);
 690                 entry = addr + start_offset;
 691
 692                 memset(addr, 0, PAGE_CACHE_SIZE);
 693                 while (node && !next_page) {
 694                         struct btrfs_free_space *e;
 695
 696                         e = rb_entry(node, struct btrfs_free_space, offset_index);
 697                         entries++;
 698
 699                         entry->offset = cpu_to_le64(e->offset);
 700                         entry->bytes = cpu_to_le64(e->bytes);
 701                         if (e->bitmap) {
 702                                 entry->type = BTRFS_FREE_SPACE_BITMAP;
 703                                 list_add_tail(&e->list, &bitmap_list);
 704                                 bitmaps++;
 705                         } else {
 706                                 entry->type = BTRFS_FREE_SPACE_EXTENT;
 707                         }
 708                         node = rb_next(node);
 709                         if (!node && cluster) {
 710                                 node = rb_first(&cluster->root);
 711                                 cluster = NULL;
 712                         }
 713                         offset += sizeof(struct btrfs_free_space_entry);
 714                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 715                             PAGE_CACHE_SIZE)
 716                                 next_page = true;
 717                         entry++;
 718                 }
 719
 720                 /*
 721                  * We want to add any pinned extents to our free space cache
 722                  * so we don't leak the space
 723                  */
 724                 while (block_group && !next_page &&
 725                        (start < block_group->key.objectid +
 726                         block_group->key.offset)) {
 727                         ret = find_first_extent_bit(unpin, start, &start, &end,
 728                                                     EXTENT_DIRTY);
 729                         if (ret) {
 730                                 ret = 0;
 731                                 break;
 732                         }
 733
 734                         /* This pinned extent is out of our range */
 735                         if (start >= block_group->key.objectid +
 736                             block_group->key.offset)
 737                                 break;
 738
 739                         len = block_group->key.objectid +
 740                                 block_group->key.offset - start;
 741                         len = min(len, end + 1 - start);
 742
 743                         entries++;
 744                         entry->offset = cpu_to_le64(start);
 745                         entry->bytes = cpu_to_le64(len);
 746                         entry->type = BTRFS_FREE_SPACE_EXTENT;
 747
 748                         start = end + 1;
 749                         offset += sizeof(struct btrfs_free_space_entry);
 750                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 751                             PAGE_CACHE_SIZE)
 752                                 next_page = true;
 753                         entry++;
 754                 }
 755                 *crc = ~(u32)0;
 756                 *crc = btrfs_csum_data(root, addr + start_offset, *crc,
 757                                        PAGE_CACHE_SIZE - start_offset);
 758                 kunmap(page);
 759
 760                 btrfs_csum_final(*crc, (char *)crc);
 761                 crc++;
 762
 763                 bytes += PAGE_CACHE_SIZE;
 764
 765                 index++;
 766         } while (node || next_page);
 767
 768         /* Write out the bitmaps */
 769         list_for_each_safe(pos, n, &bitmap_list) {
 770                 void *addr;
 771                 struct btrfs_free_space *entry =
 772                         list_entry(pos, struct btrfs_free_space, list);
 773
 774                 if (index >= num_pages) {
 775                         out_of_space = true;
 776                         break;
 777                 }
 778                 page = pages[index];
 779
 780                 addr = kmap(page);
 781                 memcpy(addr, entry->bitmap, PAGE_CACHE_SIZE);
 782                 *crc = ~(u32)0;
 783                 *crc = btrfs_csum_data(root, addr, *crc, PAGE_CACHE_SIZE);
 784                 kunmap(page);
 785                 btrfs_csum_final(*crc, (char *)crc);
 786                 crc++;
 787                 bytes += PAGE_CACHE_SIZE;
 788
 789                 list_del_init(&entry->list);
 790                 index++;
 791         }
 792
 793         if (out_of_space) {
 794                 btrfs_drop_pages(pages, num_pages);
 795                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 796                                      i_size_read(inode) - 1, &cached_state,
 797                                      GFP_NOFS);
 798                 ret = 0;
 799                 goto out_free;
 800         }
 801
 802         /* Zero out the rest of the pages just to make sure */
 803         while (index < num_pages) {
 804                 void *addr;
 805
 806                 page = pages[index];
 807                 addr = kmap(page);
 808                 memset(addr, 0, PAGE_CACHE_SIZE);
 809                 kunmap(page);
 810                 bytes += PAGE_CACHE_SIZE;
 811                 index++;
 812         }
 813
 814         /* Write the checksums and trans id to the first page */
 815         {
 816                 void *addr;
 817                 u64 *gen;
 818
 819                 page = pages[0];
 820
 821                 addr = kmap(page);
 822                 memcpy(addr, checksums, sizeof(u32) * num_pages);
 823                 gen = addr + (sizeof(u32) * num_pages);
 824                 *gen = trans->transid;
 825                 kunmap(page);
 826         }
 827
 828         ret = btrfs_dirty_pages(root, inode, pages, num_pages, 0,
 829                                             bytes, &cached_state);
 830         btrfs_drop_pages(pages, num_pages);
 831         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 832                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
 833
 834         if (ret) {
 835                 ret = 0;
 836                 goto out_free;
 837         }
 838
 839         BTRFS_I(inode)->generation = trans->transid;
 840
 841         filemap_write_and_wait(inode->i_mapping);
 842
 843         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 844         key.offset = offset;
 845         key.type = 0;
 846
 847         ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
 848         if (ret < 0) {
 849                 ret = -1;
 850                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 851                                  EXTENT_DIRTY | EXTENT_DELALLOC |
 852                                  EXTENT_DO_ACCOUNTING, 0, 0, NULL, GFP_NOFS);
 853                 goto out_free;
 854         }
 855         leaf = path->nodes[0];
 856         if (ret > 0) {
 857                 struct btrfs_key found_key;
 858                 BUG_ON(!path->slots[0]);
 859                 path->slots[0]--;
 860                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 861                 if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
 862                     found_key.offset != offset) {
 863                         ret = -1;
 864                         clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 865                                          EXTENT_DIRTY | EXTENT_DELALLOC |
 866                                          EXTENT_DO_ACCOUNTING, 0, 0, NULL,
 867                                          GFP_NOFS);
 868                         btrfs_release_path(path);
 869                         goto out_free;
 870                 }
 871         }
 872         header = btrfs_item_ptr(leaf, path->slots[0],
 873                                 struct btrfs_free_space_header);
 874         btrfs_set_free_space_entries(leaf, header, entries);
 875         btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
 876         btrfs_set_free_space_generation(leaf, header, trans->transid);
 877         btrfs_mark_buffer_dirty(leaf);
 878         btrfs_release_path(path);
 879
 880         ret = 1;
 881
 882 out_free:
 883         kfree(checksums);
 884         kfree(pages);
 885
 886 out_update:
 887         if (ret != 1) {
 888                 invalidate_inode_pages2_range(inode->i_mapping, 0, index);
 889                 BTRFS_I(inode)->generation = 0;
 890         }
 891         btrfs_update_inode(trans, root, inode);
 892         return ret;
 893 }
 894
 895 int btrfs_write_out_cache(struct btrfs_root *root,
 896                           struct btrfs_trans_handle *trans,
 897                           struct btrfs_block_group_cache *block_group,
 898                           struct btrfs_path *path)
 899 {
 900         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 901         struct inode *inode;
 902         int ret = 0;
 903
 904         root = root->fs_info->tree_root;
 905
 906         spin_lock(&block_group->lock);
 907         if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
 908                 spin_unlock(&block_group->lock);
 909                 return 0;
 910         }
 911         spin_unlock(&block_group->lock);
 912
 913         inode = lookup_free_space_inode(root, block_group, path);
 914         if (IS_ERR(inode))
 915                 return 0;
 916
 917         ret = __btrfs_write_out_cache(root, inode, ctl, block_group, trans,
 918                                       path, block_group->key.objectid);
 919         if (ret < 0) {
 920                 spin_lock(&block_group->lock);
 921                 block_group->disk_cache_state = BTRFS_DC_ERROR;
 922                 spin_unlock(&block_group->lock);
 923                 ret = 0;
 924
 925                 printk(KERN_ERR "btrfs: failed to write free space cace "
 926                        "for block group %llu\n", block_group->key.objectid);
 927         }
 928
 929         iput(inode);
 930         return ret;
 931 }
 932
 933 static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
 934                                           u64 offset)
 935 {
 936         BUG_ON(offset < bitmap_start);
 937         offset -= bitmap_start;
 938         return (unsigned long)(div_u64(offset, unit));
 939 }
 940
 941 static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
 942 {
 943         return (unsigned long)(div_u64(bytes, unit));
 944 }
 945
 946 static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
 947                                    u64 offset)
 948 {
 949         u64 bitmap_start;
 950         u64 bytes_per_bitmap;
 951
 952         bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
 953         bitmap_start = offset - ctl->start;
 954         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
 955         bitmap_start *= bytes_per_bitmap;
 956         bitmap_start += ctl->start;
 957
 958         return bitmap_start;
 959 }
 960
 961 static int tree_insert_offset(struct rb_root *root, u64 offset,
 962                               struct rb_node *node, int bitmap)
 963 {
 964         struct rb_node **p = &root->rb_node;
 965         struct rb_node *parent = NULL;
 966         struct btrfs_free_space *info;
 967
 968         while (*p) {
 969                 parent = *p;
 970                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
 971
 972                 if (offset < info->offset) {
 973                         p = &(*p)->rb_left;
 974                 } else if (offset > info->offset) {
 975                         p = &(*p)->rb_right;
 976                 } else {
 977                         /*
 978                          * we could have a bitmap entry and an extent entry
 979                          * share the same offset.  If this is the case, we want
 980                          * the extent entry to always be found first if we do a
 981                          * linear search through the tree, since we want to have
 982                          * the quickest allocation time, and allocating from an
 983                          * extent is faster than allocating from a bitmap.  So
 984                          * if we're inserting a bitmap and we find an entry at
 985                          * this offset, we want to go right, or after this entry
 986                          * logically.  If we are inserting an extent and we've
 987                          * found a bitmap, we want to go left, or before
 988                          * logically.
 989                          */
 990                         if (bitmap) {
 991                                 if (info->bitmap) {
 992                                         WARN_ON_ONCE(1);
 993                                         return -EEXIST;
 994                                 }
 995                                 p = &(*p)->rb_right;
 996                         } else {
 997                                 if (!info->bitmap) {
 998                                         WARN_ON_ONCE(1);
 999                                         return -EEXIST;
1000                                 }
1001                                 p = &(*p)->rb_left;
1002                         }
1003                 }
1004         }
1005
1006         rb_link_node(node, parent, p);
1007         rb_insert_color(node, root);
1008
1009         return 0;
1010 }
1011
1012 /*
1013  * searches the tree for the given offset.
1014  *
1015  * fuzzy - If this is set, then we are trying to make an allocation, and we just
1016  * want a section that has at least bytes size and comes at or after the given
1017  * offset.
1018  */
1019 static struct btrfs_free_space *
1020 tree_search_offset(struct btrfs_free_space_ctl *ctl,
1021                    u64 offset, int bitmap_only, int fuzzy)
1022 {
1023         struct rb_node *n = ctl->free_space_offset.rb_node;
1024         struct btrfs_free_space *entry, *prev = NULL;
1025
1026         /* find entry that is closest to the 'offset' */
1027         while (1) {
1028                 if (!n) {
1029                         entry = NULL;
1030                         break;
1031                 }
1032
1033                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1034                 prev = entry;
1035
1036                 if (offset < entry->offset)
1037                         n = n->rb_left;
1038                 else if (offset > entry->offset)
1039                         n = n->rb_right;
1040                 else
1041                         break;
1042         }
1043
1044         if (bitmap_only) {
1045                 if (!entry)
1046                         return NULL;
1047                 if (entry->bitmap)
1048                         return entry;
1049
1050                 /*
1051                  * bitmap entry and extent entry may share same offset,
1052                  * in that case, bitmap entry comes after extent entry.
1053                  */
1054                 n = rb_next(n);
1055                 if (!n)
1056                         return NULL;
1057                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1058                 if (entry->offset != offset)
1059                         return NULL;
1060
1061                 WARN_ON(!entry->bitmap);
1062                 return entry;
1063         } else if (entry) {
1064                 if (entry->bitmap) {
1065                         /*
1066                          * if previous extent entry covers the offset,
1067                          * we should return it instead of the bitmap entry
1068                          */
1069                         n = &entry->offset_index;
1070                         while (1) {
1071                                 n = rb_prev(n);
1072                                 if (!n)
1073                                         break;
1074                                 prev = rb_entry(n, struct btrfs_free_space,
1075                                                 offset_index);
1076                                 if (!prev->bitmap) {
1077                                         if (prev->offset + prev->bytes > offset)
1078                                                 entry = prev;
1079                                         break;
1080                                 }
1081                         }
1082                 }
1083                 return entry;
1084         }
1085
1086         if (!prev)
1087                 return NULL;
1088
1089         /* find last entry before the 'offset' */
1090         entry = prev;
1091         if (entry->offset > offset) {
1092                 n = rb_prev(&entry->offset_index);
1093                 if (n) {
1094                         entry = rb_entry(n, struct btrfs_free_space,
1095                                         offset_index);
1096                         BUG_ON(entry->offset > offset);
1097                 } else {
1098                         if (fuzzy)
1099                                 return entry;
1100                         else
1101                                 return NULL;
1102                 }
1103         }
1104
1105         if (entry->bitmap) {
1106                 n = &entry->offset_index;
1107                 while (1) {
1108                         n = rb_prev(n);
1109                         if (!n)
1110                                 break;
1111                         prev = rb_entry(n, struct btrfs_free_space,
1112                                         offset_index);
1113                         if (!prev->bitmap) {
1114                                 if (prev->offset + prev->bytes > offset)
1115                                         return prev;
1116                                 break;
1117                         }
1118                 }
1119                 if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
1120                         return entry;
1121         } else if (entry->offset + entry->bytes > offset)
1122                 return entry;
1123
1124         if (!fuzzy)
1125                 return NULL;
1126
1127         while (1) {
1128                 if (entry->bitmap) {
1129                         if (entry->offset + BITS_PER_BITMAP *
1130                             ctl->unit > offset)
1131                                 break;
1132                 } else {
1133                         if (entry->offset + entry->bytes > offset)
1134                                 break;
1135                 }
1136
1137                 n = rb_next(&entry->offset_index);
1138                 if (!n)
1139                         return NULL;
1140                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1141         }
1142         return entry;
1143 }
1144
1145 static inline void
1146 __unlink_free_space(struct btrfs_free_space_ctl *ctl,
1147                     struct btrfs_free_space *info)
1148 {
1149         rb_erase(&info->offset_index, &ctl->free_space_offset);
1150         ctl->free_extents--;
1151 }
1152
1153 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
1154                               struct btrfs_free_space *info)
1155 {
1156         __unlink_free_space(ctl, info);
1157         ctl->free_space -= info->bytes;
1158 }
1159
1160 static int link_free_space(struct btrfs_free_space_ctl *ctl,
1161                            struct btrfs_free_space *info)
1162 {
1163         int ret = 0;
1164
1165         BUG_ON(!info->bitmap && !info->bytes);
1166         ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
1167                                  &info->offset_index, (info->bitmap != NULL));
1168         if (ret)
1169                 return ret;
1170
1171         ctl->free_space += info->bytes;
1172         ctl->free_extents++;
1173         return ret;
1174 }
1175
1176 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
1177 {
1178         struct btrfs_block_group_cache *block_group = ctl->private;
1179         u64 max_bytes;
1180         u64 bitmap_bytes;
1181         u64 extent_bytes;
1182         u64 size = block_group->key.offset;
1183         u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
1184         int max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
1185
1186         BUG_ON(ctl->total_bitmaps > max_bitmaps);
1187
1188         /*
1189          * The goal is to keep the total amount of memory used per 1gb of space
1190          * at or below 32k, so we need to adjust how much memory we allow to be
1191          * used by extent based free space tracking
1192          */
1193         if (size < 1024 * 1024 * 1024)
1194                 max_bytes = MAX_CACHE_BYTES_PER_GIG;
1195         else
1196                 max_bytes = MAX_CACHE_BYTES_PER_GIG *
1197                         div64_u64(size, 1024 * 1024 * 1024);
1198
1199         /*
1200          * we want to account for 1 more bitmap than what we have so we can make
1201          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1202          * we add more bitmaps.
1203          */
1204         bitmap_bytes = (ctl->total_bitmaps + 1) * PAGE_CACHE_SIZE;
1205
1206         if (bitmap_bytes >= max_bytes) {
1207                 ctl->extents_thresh = 0;
1208                 return;
1209         }
1210
1211         /*
1212          * we want the extent entry threshold to always be at most 1/2 the maxw
1213          * bytes we can have, or whatever is less than that.
1214          */
1215         extent_bytes = max_bytes - bitmap_bytes;
1216         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
1217
1218         ctl->extents_thresh =
1219                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
1220 }
1221
1222 static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1223                               struct btrfs_free_space *info, u64 offset,
1224                               u64 bytes)
1225 {
1226         unsigned long start, count;
1227
1228         start = offset_to_bit(info->offset, ctl->unit, offset);
1229         count = bytes_to_bits(bytes, ctl->unit);
1230         BUG_ON(start + count > BITS_PER_BITMAP);
1231
1232         bitmap_clear(info->bitmap, start, count);
1233
1234         info->bytes -= bytes;
1235         ctl->free_space -= bytes;
1236 }
1237
1238 static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
1239                             struct btrfs_free_space *info, u64 offset,
1240                             u64 bytes)
1241 {
1242         unsigned long start, count;
1243
1244         start = offset_to_bit(info->offset, ctl->unit, offset);
1245         count = bytes_to_bits(bytes, ctl->unit);
1246         BUG_ON(start + count > BITS_PER_BITMAP);
1247
1248         bitmap_set(info->bitmap, start, count);
1249
1250         info->bytes += bytes;
1251         ctl->free_space += bytes;
1252 }
1253
1254 static int search_bitmap(struct btrfs_free_space_ctl *ctl,
1255                          struct btrfs_free_space *bitmap_info, u64 *offset,
1256                          u64 *bytes)
1257 {
1258         unsigned long found_bits = 0;
1259         unsigned long bits, i;
1260         unsigned long next_zero;
1261
1262         i = offset_to_bit(bitmap_info->offset, ctl->unit,
1263                           max_t(u64, *offset, bitmap_info->offset));
1264         bits = bytes_to_bits(*bytes, ctl->unit);
1265
1266         for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
1267              i < BITS_PER_BITMAP;
1268              i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
1269                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
1270                                                BITS_PER_BITMAP, i);
1271                 if ((next_zero - i) >= bits) {
1272                         found_bits = next_zero - i;
1273                         break;
1274                 }
1275                 i = next_zero;
1276         }
1277
1278         if (found_bits) {
1279                 *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
1280                 *bytes = (u64)(found_bits) * ctl->unit;
1281                 return 0;
1282         }
1283
1284         return -1;
1285 }
1286
1287 static struct btrfs_free_space *
1288 find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes)
1289 {
1290         struct btrfs_free_space *entry;
1291         struct rb_node *node;
1292         int ret;
1293
1294         if (!ctl->free_space_offset.rb_node)
1295                 return NULL;
1296
1297         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
1298         if (!entry)
1299                 return NULL;
1300
1301         for (node = &entry->offset_index; node; node = rb_next(node)) {
1302                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1303                 if (entry->bytes < *bytes)
1304                         continue;
1305
1306                 if (entry->bitmap) {
1307                         ret = search_bitmap(ctl, entry, offset, bytes);
1308                         if (!ret)
1309                                 return entry;
1310                         continue;
1311                 }
1312
1313                 *offset = entry->offset;
1314                 *bytes = entry->bytes;
1315                 return entry;
1316         }
1317
1318         return NULL;
1319 }
1320
1321 static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
1322                            struct btrfs_free_space *info, u64 offset)
1323 {
1324         info->offset = offset_to_bitmap(ctl, offset);
1325         info->bytes = 0;
1326         link_free_space(ctl, info);
1327         ctl->total_bitmaps++;
1328
1329         ctl->op->recalc_thresholds(ctl);
1330 }
1331
1332 static void free_bitmap(struct btrfs_free_space_ctl *ctl,
1333                         struct btrfs_free_space *bitmap_info)
1334 {
1335         unlink_free_space(ctl, bitmap_info);
1336         kfree(bitmap_info->bitmap);
1337         kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1338         ctl->total_bitmaps--;
1339         ctl->op->recalc_thresholds(ctl);
1340 }
1341
1342 static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
1343                               struct btrfs_free_space *bitmap_info,
1344                               u64 *offset, u64 *bytes)
1345 {
1346         u64 end;
1347         u64 search_start, search_bytes;
1348         int ret;
1349
1350 again:
1351         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
1352
1353         /*
1354          * XXX - this can go away after a few releases.
1355          *
1356          * since the only user of btrfs_remove_free_space is the tree logging
1357          * stuff, and the only way to test that is under crash conditions, we
1358          * want to have this debug stuff here just in case somethings not
1359          * working.  Search the bitmap for the space we are trying to use to
1360          * make sure its actually there.  If its not there then we need to stop
1361          * because something has gone wrong.
1362          */
1363         search_start = *offset;
1364         search_bytes = *bytes;
1365         search_bytes = min(search_bytes, end - search_start + 1);
1366         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
1367         BUG_ON(ret < 0 || search_start != *offset);
1368
1369         if (*offset > bitmap_info->offset && *offset + *bytes > end) {
1370                 bitmap_clear_bits(ctl, bitmap_info, *offset, end - *offset + 1);
1371                 *bytes -= end - *offset + 1;
1372                 *offset = end + 1;
1373         } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
1374                 bitmap_clear_bits(ctl, bitmap_info, *offset, *bytes);
1375                 *bytes = 0;
1376         }
1377
1378         if (*bytes) {
1379                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
1380                 if (!bitmap_info->bytes)
1381                         free_bitmap(ctl, bitmap_info);
1382
1383                 /*
1384                  * no entry after this bitmap, but we still have bytes to
1385                  * remove, so something has gone wrong.
1386                  */
1387                 if (!next)
1388                         return -EINVAL;
1389
1390                 bitmap_info = rb_entry(next, struct btrfs_free_space,
1391                                        offset_index);
1392
1393                 /*
1394                  * if the next entry isn't a bitmap we need to return to let the
1395                  * extent stuff do its work.
1396                  */
1397                 if (!bitmap_info->bitmap)
1398                         return -EAGAIN;
1399
1400                 /*
1401                  * Ok the next item is a bitmap, but it may not actually hold
1402                  * the information for the rest of this free space stuff, so
1403                  * look for it, and if we don't find it return so we can try
1404                  * everything over again.
1405                  */
1406                 search_start = *offset;
1407                 search_bytes = *bytes;
1408                 ret = search_bitmap(ctl, bitmap_info, &search_start,
1409                                     &search_bytes);
1410                 if (ret < 0 || search_start != *offset)
1411                         return -EAGAIN;
1412
1413                 goto again;
1414         } else if (!bitmap_info->bytes)
1415                 free_bitmap(ctl, bitmap_info);
1416
1417         return 0;
1418 }
1419
1420 static u64 add_bytes_to_bitmap(struct btrfs_free_space_ctl *ctl,
1421                                struct btrfs_free_space *info, u64 offset,
1422                                u64 bytes)
1423 {
1424         u64 bytes_to_set = 0;
1425         u64 end;
1426
1427         end = info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
1428
1429         bytes_to_set = min(end - offset, bytes);
1430
1431         bitmap_set_bits(ctl, info, offset, bytes_to_set);
1432
1433         return bytes_to_set;
1434
1435 }
1436
1437 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
1438                       struct btrfs_free_space *info)
1439 {
1440         struct btrfs_block_group_cache *block_group = ctl->private;
1441
1442         /*
1443          * If we are below the extents threshold then we can add this as an
1444          * extent, and don't have to deal with the bitmap
1445          */
1446         if (ctl->free_extents < ctl->extents_thresh) {
1447                 /*
1448                  * If this block group has some small extents we don't want to
1449                  * use up all of our free slots in the cache with them, we want
1450                  * to reserve them to larger extents, however if we have plent
1451                  * of cache left then go ahead an dadd them, no sense in adding
1452                  * the overhead of a bitmap if we don't have to.
1453                  */
1454                 if (info->bytes <= block_group->sectorsize * 4) {
1455                         if (ctl->free_extents * 2 <= ctl->extents_thresh)
1456                                 return false;
1457                 } else {
1458                         return false;
1459                 }
1460         }
1461
1462         /*
1463          * some block groups are so tiny they can't be enveloped by a bitmap, so
1464          * don't even bother to create a bitmap for this
1465          */
1466         if (BITS_PER_BITMAP * block_group->sectorsize >
1467             block_group->key.offset)
1468                 return false;
1469
1470         return true;
1471 }
1472
1473 static struct btrfs_free_space_op free_space_op = {
1474         .recalc_thresholds      = recalculate_thresholds,
1475         .use_bitmap             = use_bitmap,
1476 };
1477
1478 static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
1479                               struct btrfs_free_space *info)
1480 {
1481         struct btrfs_free_space *bitmap_info;
1482         struct btrfs_block_group_cache *block_group = NULL;
1483         int added = 0;
1484         u64 bytes, offset, bytes_added;
1485         int ret;
1486
1487         bytes = info->bytes;
1488         offset = info->offset;
1489
1490         if (!ctl->op->use_bitmap(ctl, info))
1491                 return 0;
1492
1493         if (ctl->op == &free_space_op)
1494                 block_group = ctl->private;
1495 again:
1496         /*
1497          * Since we link bitmaps right into the cluster we need to see if we
1498          * have a cluster here, and if so and it has our bitmap we need to add
1499          * the free space to that bitmap.
1500          */
1501         if (block_group && !list_empty(&block_group->cluster_list)) {
1502                 struct btrfs_free_cluster *cluster;
1503                 struct rb_node *node;
1504                 struct btrfs_free_space *entry;
1505
1506                 cluster = list_entry(block_group->cluster_list.next,
1507                                      struct btrfs_free_cluster,
1508                                      block_group_list);
1509                 spin_lock(&cluster->lock);
1510                 node = rb_first(&cluster->root);
1511                 if (!node) {
1512                         spin_unlock(&cluster->lock);
1513                         goto no_cluster_bitmap;
1514                 }
1515
1516                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1517                 if (!entry->bitmap) {
1518                         spin_unlock(&cluster->lock);
1519                         goto no_cluster_bitmap;
1520                 }
1521
1522                 if (entry->offset == offset_to_bitmap(ctl, offset)) {
1523                         bytes_added = add_bytes_to_bitmap(ctl, entry,
1524                                                           offset, bytes);
1525                         bytes -= bytes_added;
1526                         offset += bytes_added;
1527                 }
1528                 spin_unlock(&cluster->lock);
1529                 if (!bytes) {
1530                         ret = 1;
1531                         goto out;
1532                 }
1533         }
1534
1535 no_cluster_bitmap:
1536         bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1537                                          1, 0);
1538         if (!bitmap_info) {
1539                 BUG_ON(added);
1540                 goto new_bitmap;
1541         }
1542
1543         bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
1544         bytes -= bytes_added;
1545         offset += bytes_added;
1546         added = 0;
1547
1548         if (!bytes) {
1549                 ret = 1;
1550                 goto out;
1551         } else
1552                 goto again;
1553
1554 new_bitmap:
1555         if (info && info->bitmap) {
1556                 add_new_bitmap(ctl, info, offset);
1557                 added = 1;
1558                 info = NULL;
1559                 goto again;
1560         } else {
1561                 spin_unlock(&ctl->tree_lock);
1562
1563                 /* no pre-allocated info, allocate a new one */
1564                 if (!info) {
1565                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
1566                                                  GFP_NOFS);
1567                         if (!info) {
1568                                 spin_lock(&ctl->tree_lock);
1569                                 ret = -ENOMEM;
1570                                 goto out;
1571                         }
1572                 }
1573
1574                 /* allocate the bitmap */
1575                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
1576                 spin_lock(&ctl->tree_lock);
1577                 if (!info->bitmap) {
1578                         ret = -ENOMEM;
1579                         goto out;
1580                 }
1581                 goto again;
1582         }
1583
1584 out:
1585         if (info) {
1586                 if (info->bitmap)
1587                         kfree(info->bitmap);
1588                 kmem_cache_free(btrfs_free_space_cachep, info);
1589         }
1590
1591         return ret;
1592 }
1593
1594 static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
1595                           struct btrfs_free_space *info, bool update_stat)
1596 {
1597         struct btrfs_free_space *left_info;
1598         struct btrfs_free_space *right_info;
1599         bool merged = false;
1600         u64 offset = info->offset;
1601         u64 bytes = info->bytes;
1602
1603         /*
1604          * first we want to see if there is free space adjacent to the range we
1605          * are adding, if there is remove that struct and add a new one to
1606          * cover the entire range
1607          */
1608         right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
1609         if (right_info && rb_prev(&right_info->offset_index))
1610                 left_info = rb_entry(rb_prev(&right_info->offset_index),
1611                                      struct btrfs_free_space, offset_index);
1612         else
1613                 left_info = tree_search_offset(ctl, offset - 1, 0, 0);
1614
1615         if (right_info && !right_info->bitmap) {
1616                 if (update_stat)
1617                         unlink_free_space(ctl, right_info);
1618                 else
1619                         __unlink_free_space(ctl, right_info);
1620                 info->bytes += right_info->bytes;
1621                 kmem_cache_free(btrfs_free_space_cachep, right_info);
1622                 merged = true;
1623         }
1624
1625         if (left_info && !left_info->bitmap &&
1626             left_info->offset + left_info->bytes == offset) {
1627                 if (update_stat)
1628                         unlink_free_space(ctl, left_info);
1629                 else
1630                         __unlink_free_space(ctl, left_info);
1631                 info->offset = left_info->offset;
1632                 info->bytes += left_info->bytes;
1633                 kmem_cache_free(btrfs_free_space_cachep, left_info);
1634                 merged = true;
1635         }
1636
1637         return merged;
1638 }
1639
1640 int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
1641                            u64 offset, u64 bytes)
1642 {
1643         struct btrfs_free_space *info;
1644         int ret = 0;
1645
1646         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
1647         if (!info)
1648                 return -ENOMEM;
1649
1650         info->offset = offset;
1651         info->bytes = bytes;
1652
1653         spin_lock(&ctl->tree_lock);
1654
1655         if (try_merge_free_space(ctl, info, true))
1656                 goto link;
1657
1658         /*
1659          * There was no extent directly to the left or right of this new
1660          * extent then we know we're going to have to allocate a new extent, so
1661          * before we do that see if we need to drop this into a bitmap
1662          */
1663         ret = insert_into_bitmap(ctl, info);
1664         if (ret < 0) {
1665                 goto out;
1666         } else if (ret) {
1667                 ret = 0;
1668                 goto out;
1669         }
1670 link:
1671         ret = link_free_space(ctl, info);
1672         if (ret)
1673                 kmem_cache_free(btrfs_free_space_cachep, info);
1674 out:
1675         spin_unlock(&ctl->tree_lock);
1676
1677         if (ret) {
1678                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
1679                 BUG_ON(ret == -EEXIST);
1680         }
1681
1682         return ret;
1683 }
1684
1685 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
1686                             u64 offset, u64 bytes)
1687 {
1688         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1689         struct btrfs_free_space *info;
1690         struct btrfs_free_space *next_info = NULL;
1691         int ret = 0;
1692
1693         spin_lock(&ctl->tree_lock);
1694
1695 again:
1696         info = tree_search_offset(ctl, offset, 0, 0);
1697         if (!info) {
1698                 /*
1699                  * oops didn't find an extent that matched the space we wanted
1700                  * to remove, look for a bitmap instead
1701                  */
1702                 info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1703                                           1, 0);
1704                 if (!info) {
1705                         WARN_ON(1);
1706                         goto out_lock;
1707                 }
1708         }
1709
1710         if (info->bytes < bytes && rb_next(&info->offset_index)) {
1711                 u64 end;
1712                 next_info = rb_entry(rb_next(&info->offset_index),
1713                                              struct btrfs_free_space,
1714                                              offset_index);
1715
1716                 if (next_info->bitmap)
1717                         end = next_info->offset +
1718                               BITS_PER_BITMAP * ctl->unit - 1;
1719                 else
1720                         end = next_info->offset + next_info->bytes;
1721
1722                 if (next_info->bytes < bytes ||
1723                     next_info->offset > offset || offset > end) {
1724                         printk(KERN_CRIT "Found free space at %llu, size %llu,"
1725                               " trying to use %llu\n",
1726                               (unsigned long long)info->offset,
1727                               (unsigned long long)info->bytes,
1728                               (unsigned long long)bytes);
1729                         WARN_ON(1);
1730                         ret = -EINVAL;
1731                         goto out_lock;
1732                 }
1733
1734                 info = next_info;
1735         }
1736
1737         if (info->bytes == bytes) {
1738                 unlink_free_space(ctl, info);
1739                 if (info->bitmap) {
1740                         kfree(info->bitmap);
1741                         ctl->total_bitmaps--;
1742                 }
1743                 kmem_cache_free(btrfs_free_space_cachep, info);
1744                 goto out_lock;
1745         }
1746
1747         if (!info->bitmap && info->offset == offset) {
1748                 unlink_free_space(ctl, info);
1749                 info->offset += bytes;
1750                 info->bytes -= bytes;
1751                 link_free_space(ctl, info);
1752                 goto out_lock;
1753         }
1754
1755         if (!info->bitmap && info->offset <= offset &&
1756             info->offset + info->bytes >= offset + bytes) {
1757                 u64 old_start = info->offset;
1758                 /*
1759                  * we're freeing space in the middle of the info,
1760                  * this can happen during tree log replay
1761                  *
1762                  * first unlink the old info and then
1763                  * insert it again after the hole we're creating
1764                  */
1765                 unlink_free_space(ctl, info);
1766                 if (offset + bytes < info->offset + info->bytes) {
1767                         u64 old_end = info->offset + info->bytes;
1768
1769                         info->offset = offset + bytes;
1770                         info->bytes = old_end - info->offset;
1771                         ret = link_free_space(ctl, info);
1772                         WARN_ON(ret);
1773                         if (ret)
1774                                 goto out_lock;
1775                 } else {
1776                         /* the hole we're creating ends at the end
1777                          * of the info struct, just free the info
1778                          */
1779                         kmem_cache_free(btrfs_free_space_cachep, info);
1780                 }
1781                 spin_unlock(&ctl->tree_lock);
1782
1783                 /* step two, insert a new info struct to cover
1784                  * anything before the hole
1785                  */
1786                 ret = btrfs_add_free_space(block_group, old_start,
1787                                            offset - old_start);
1788                 WARN_ON(ret);
1789                 goto out;
1790         }
1791
1792         ret = remove_from_bitmap(ctl, info, &offset, &bytes);
1793         if (ret == -EAGAIN)
1794                 goto again;
1795         BUG_ON(ret);
1796 out_lock:
1797         spin_unlock(&ctl->tree_lock);
1798 out:
1799         return ret;
1800 }
1801
1802 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
1803                            u64 bytes)
1804 {
1805         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1806         struct btrfs_free_space *info;
1807         struct rb_node *n;
1808         int count = 0;
1809
1810         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
1811                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1812                 if (info->bytes >= bytes)
1813                         count++;
1814                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
1815                        (unsigned long long)info->offset,
1816                        (unsigned long long)info->bytes,
1817                        (info->bitmap) ? "yes" : "no");
1818         }
1819         printk(KERN_INFO "block group has cluster?: %s\n",
1820                list_empty(&block_group->cluster_list) ? "no" : "yes");
1821         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
1822                "\n", count);
1823 }
1824
1825 void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
1826 {
1827         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1828
1829         spin_lock_init(&ctl->tree_lock);
1830         ctl->unit = block_group->sectorsize;
1831         ctl->start = block_group->key.objectid;
1832         ctl->private = block_group;
1833         ctl->op = &free_space_op;
1834
1835         /*
1836          * we only want to have 32k of ram per block group for keeping
1837          * track of free space, and if we pass 1/2 of that we want to
1838          * start converting things over to using bitmaps
1839          */
1840         ctl->extents_thresh = ((1024 * 32) / 2) /
1841                                 sizeof(struct btrfs_free_space);
1842 }
1843
1844 /*
1845  * for a given cluster, put all of its extents back into the free
1846  * space cache.  If the block group passed doesn't match the block group
1847  * pointed to by the cluster, someone else raced in and freed the
1848  * cluster already.  In that case, we just return without changing anything
1849  */
1850 static int
1851 __btrfs_return_cluster_to_free_space(
1852                              struct btrfs_block_group_cache *block_group,
1853                              struct btrfs_free_cluster *cluster)
1854 {
1855         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1856         struct btrfs_free_space *entry;
1857         struct rb_node *node;
1858
1859         spin_lock(&cluster->lock);
1860         if (cluster->block_group != block_group)
1861                 goto out;
1862
1863         cluster->block_group = NULL;
1864         cluster->window_start = 0;
1865         list_del_init(&cluster->block_group_list);
1866
1867         node = rb_first(&cluster->root);
1868         while (node) {
1869                 bool bitmap;
1870
1871                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1872                 node = rb_next(&entry->offset_index);
1873                 rb_erase(&entry->offset_index, &cluster->root);
1874
1875                 bitmap = (entry->bitmap != NULL);
1876                 if (!bitmap)
1877                         try_merge_free_space(ctl, entry, false);
1878                 tree_insert_offset(&ctl->free_space_offset,
1879                                    entry->offset, &entry->offset_index, bitmap);
1880         }
1881         cluster->root = RB_ROOT;
1882
1883 out:
1884         spin_unlock(&cluster->lock);
1885         btrfs_put_block_group(block_group);
1886         return 0;
1887 }
1888
1889 void __btrfs_remove_free_space_cache_locked(struct btrfs_free_space_ctl *ctl)
1890 {
1891         struct btrfs_free_space *info;
1892         struct rb_node *node;
1893
1894         while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
1895                 info = rb_entry(node, struct btrfs_free_space, offset_index);
1896                 if (!info->bitmap) {
1897                         unlink_free_space(ctl, info);
1898                         kmem_cache_free(btrfs_free_space_cachep, info);
1899                 } else {
1900                         free_bitmap(ctl, info);
1901                 }
1902                 if (need_resched()) {
1903                         spin_unlock(&ctl->tree_lock);
1904                         cond_resched();
1905                         spin_lock(&ctl->tree_lock);
1906                 }
1907         }
1908 }
1909
1910 void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
1911 {
1912         spin_lock(&ctl->tree_lock);
1913         __btrfs_remove_free_space_cache_locked(ctl);
1914         spin_unlock(&ctl->tree_lock);
1915 }
1916
1917 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
1918 {
1919         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1920         struct btrfs_free_cluster *cluster;
1921         struct list_head *head;
1922
1923         spin_lock(&ctl->tree_lock);
1924         while ((head = block_group->cluster_list.next) !=
1925                &block_group->cluster_list) {
1926                 cluster = list_entry(head, struct btrfs_free_cluster,
1927                                      block_group_list);
1928
1929                 WARN_ON(cluster->block_group != block_group);
1930                 __btrfs_return_cluster_to_free_space(block_group, cluster);
1931                 if (need_resched()) {
1932                         spin_unlock(&ctl->tree_lock);
1933                         cond_resched();
1934                         spin_lock(&ctl->tree_lock);
1935                 }
1936         }
1937         __btrfs_remove_free_space_cache_locked(ctl);
1938         spin_unlock(&ctl->tree_lock);
1939
1940 }
1941
1942 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
1943                                u64 offset, u64 bytes, u64 empty_size)
1944 {
1945         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1946         struct btrfs_free_space *entry = NULL;
1947         u64 bytes_search = bytes + empty_size;
1948         u64 ret = 0;
1949
1950         spin_lock(&ctl->tree_lock);
1951         entry = find_free_space(ctl, &offset, &bytes_search);
1952         if (!entry)
1953                 goto out;
1954
1955         ret = offset;
1956         if (entry->bitmap) {
1957                 bitmap_clear_bits(ctl, entry, offset, bytes);
1958                 if (!entry->bytes)
1959                         free_bitmap(ctl, entry);
1960         } else {
1961                 unlink_free_space(ctl, entry);
1962                 entry->offset += bytes;
1963                 entry->bytes -= bytes;
1964                 if (!entry->bytes)
1965                         kmem_cache_free(btrfs_free_space_cachep, entry);
1966                 else
1967                         link_free_space(ctl, entry);
1968         }
1969
1970 out:
1971         spin_unlock(&ctl->tree_lock);
1972
1973         return ret;
1974 }
1975
1976 /*
1977  * given a cluster, put all of its extents back into the free space
1978  * cache.  If a block group is passed, this function will only free
1979  * a cluster that belongs to the passed block group.
1980  *
1981  * Otherwise, it'll get a reference on the block group pointed to by the
1982  * cluster and remove the cluster from it.
1983  */
1984 int btrfs_return_cluster_to_free_space(
1985                                struct btrfs_block_group_cache *block_group,
1986                                struct btrfs_free_cluster *cluster)
1987 {
1988         struct btrfs_free_space_ctl *ctl;
1989         int ret;
1990
1991         /* first, get a safe pointer to the block group */
1992         spin_lock(&cluster->lock);
1993         if (!block_group) {
1994                 block_group = cluster->block_group;
1995                 if (!block_group) {
1996                         spin_unlock(&cluster->lock);
1997                         return 0;
1998                 }
1999         } else if (cluster->block_group != block_group) {
2000                 /* someone else has already freed it don't redo their work */
2001                 spin_unlock(&cluster->lock);
2002                 return 0;
2003         }
2004         atomic_inc(&block_group->count);
2005         spin_unlock(&cluster->lock);
2006
2007         ctl = block_group->free_space_ctl;
2008
2009         /* now return any extents the cluster had on it */
2010         spin_lock(&ctl->tree_lock);
2011         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
2012         spin_unlock(&ctl->tree_lock);
2013
2014         /* finally drop our ref */
2015         btrfs_put_block_group(block_group);
2016         return ret;
2017 }
2018
2019 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
2020                                    struct btrfs_free_cluster *cluster,
2021                                    struct btrfs_free_space *entry,
2022                                    u64 bytes, u64 min_start)
2023 {
2024         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2025         int err;
2026         u64 search_start = cluster->window_start;
2027         u64 search_bytes = bytes;
2028         u64 ret = 0;
2029
2030         search_start = min_start;
2031         search_bytes = bytes;
2032
2033         err = search_bitmap(ctl, entry, &search_start, &search_bytes);
2034         if (err)
2035                 return 0;
2036
2037         ret = search_start;
2038         bitmap_clear_bits(ctl, entry, ret, bytes);
2039
2040         return ret;
2041 }
2042
2043 /*
2044  * given a cluster, try to allocate 'bytes' from it, returns 0
2045  * if it couldn't find anything suitably large, or a logical disk offset
2046  * if things worked out
2047  */
2048 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
2049                              struct btrfs_free_cluster *cluster, u64 bytes,
2050                              u64 min_start)
2051 {
2052         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2053         struct btrfs_free_space *entry = NULL;
2054         struct rb_node *node;
2055         u64 ret = 0;
2056
2057         spin_lock(&cluster->lock);
2058         if (bytes > cluster->max_size)
2059                 goto out;
2060
2061         if (cluster->block_group != block_group)
2062                 goto out;
2063
2064         node = rb_first(&cluster->root);
2065         if (!node)
2066                 goto out;
2067
2068         entry = rb_entry(node, struct btrfs_free_space, offset_index);
2069         while(1) {
2070                 if (entry->bytes < bytes ||
2071                     (!entry->bitmap && entry->offset < min_start)) {
2072                         node = rb_next(&entry->offset_index);
2073                         if (!node)
2074                                 break;
2075                         entry = rb_entry(node, struct btrfs_free_space,
2076                                          offset_index);
2077                         continue;
2078                 }
2079
2080                 if (entry->bitmap) {
2081                         ret = btrfs_alloc_from_bitmap(block_group,
2082                                                       cluster, entry, bytes,
2083                                                       min_start);
2084                         if (ret == 0) {
2085                                 node = rb_next(&entry->offset_index);
2086                                 if (!node)
2087                                         break;
2088                                 entry = rb_entry(node, struct btrfs_free_space,
2089                                                  offset_index);
2090                                 continue;
2091                         }
2092                 } else {
2093
2094                         ret = entry->offset;
2095
2096                         entry->offset += bytes;
2097                         entry->bytes -= bytes;
2098                 }
2099
2100                 if (entry->bytes == 0)
2101                         rb_erase(&entry->offset_index, &cluster->root);
2102                 break;
2103         }
2104 out:
2105         spin_unlock(&cluster->lock);
2106
2107         if (!ret)
2108                 return 0;
2109
2110         spin_lock(&ctl->tree_lock);
2111
2112         ctl->free_space -= bytes;
2113         if (entry->bytes == 0) {
2114                 ctl->free_extents--;
2115                 if (entry->bitmap) {
2116                         kfree(entry->bitmap);
2117                         ctl->total_bitmaps--;
2118                         ctl->op->recalc_thresholds(ctl);
2119                 }
2120                 kmem_cache_free(btrfs_free_space_cachep, entry);
2121         }
2122
2123         spin_unlock(&ctl->tree_lock);
2124
2125         return ret;
2126 }
2127
2128 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
2129                                 struct btrfs_free_space *entry,
2130                                 struct btrfs_free_cluster *cluster,
2131                                 u64 offset, u64 bytes, u64 min_bytes)
2132 {
2133         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2134         unsigned long next_zero;
2135         unsigned long i;
2136         unsigned long search_bits;
2137         unsigned long total_bits;
2138         unsigned long found_bits;
2139         unsigned long start = 0;
2140         unsigned long total_found = 0;
2141         int ret;
2142         bool found = false;
2143
2144         i = offset_to_bit(entry->offset, block_group->sectorsize,
2145                           max_t(u64, offset, entry->offset));
2146         search_bits = bytes_to_bits(bytes, block_group->sectorsize);
2147         total_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
2148
2149 again:
2150         found_bits = 0;
2151         for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
2152              i < BITS_PER_BITMAP;
2153              i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
2154                 next_zero = find_next_zero_bit(entry->bitmap,
2155                                                BITS_PER_BITMAP, i);
2156                 if (next_zero - i >= search_bits) {
2157                         found_bits = next_zero - i;
2158                         break;
2159                 }
2160                 i = next_zero;
2161         }
2162
2163         if (!found_bits)
2164                 return -ENOSPC;
2165
2166         if (!found) {
2167                 start = i;
2168                 found = true;
2169         }
2170
2171         total_found += found_bits;
2172
2173         if (cluster->max_size < found_bits * block_group->sectorsize)
2174                 cluster->max_size = found_bits * block_group->sectorsize;
2175
2176         if (total_found < total_bits) {
2177                 i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero);
2178                 if (i - start > total_bits * 2) {
2179                         total_found = 0;
2180                         cluster->max_size = 0;
2181                         found = false;
2182                 }
2183                 goto again;
2184         }
2185
2186         cluster->window_start = start * block_group->sectorsize +
2187                 entry->offset;
2188         rb_erase(&entry->offset_index, &ctl->free_space_offset);
2189         ret = tree_insert_offset(&cluster->root, entry->offset,
2190                                  &entry->offset_index, 1);
2191         BUG_ON(ret);
2192
2193         return 0;
2194 }
2195
2196 /*
2197  * This searches the block group for just extents to fill the cluster with.
2198  */
2199 static noinline int
2200 setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
2201                         struct btrfs_free_cluster *cluster,
2202                         struct list_head *bitmaps, u64 offset, u64 bytes,
2203                         u64 min_bytes)
2204 {
2205         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2206         struct btrfs_free_space *first = NULL;
2207         struct btrfs_free_space *entry = NULL;
2208         struct btrfs_free_space *prev = NULL;
2209         struct btrfs_free_space *last;
2210         struct rb_node *node;
2211         u64 window_start;
2212         u64 window_free;
2213         u64 max_extent;
2214         u64 max_gap = 128 * 1024;
2215
2216         entry = tree_search_offset(ctl, offset, 0, 1);
2217         if (!entry)
2218                 return -ENOSPC;
2219
2220         /*
2221          * We don't want bitmaps, so just move along until we find a normal
2222          * extent entry.
2223          */
2224         while (entry->bitmap) {
2225                 if (list_empty(&entry->list))
2226                         list_add_tail(&entry->list, bitmaps);
2227                 node = rb_next(&entry->offset_index);
2228                 if (!node)
2229                         return -ENOSPC;
2230                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2231         }
2232
2233         window_start = entry->offset;
2234         window_free = entry->bytes;
2235         max_extent = entry->bytes;
2236         first = entry;
2237         last = entry;
2238         prev = entry;
2239
2240         while (window_free <= min_bytes) {
2241                 node = rb_next(&entry->offset_index);
2242                 if (!node)
2243                         return -ENOSPC;
2244                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2245
2246                 if (entry->bitmap) {
2247                         if (list_empty(&entry->list))
2248                                 list_add_tail(&entry->list, bitmaps);
2249                         continue;
2250                 }
2251
2252                 /*
2253                  * we haven't filled the empty size and the window is
2254                  * very large.  reset and try again
2255                  */
2256                 if (entry->offset - (prev->offset + prev->bytes) > max_gap ||
2257                     entry->offset - window_start > (min_bytes * 2)) {
2258                         first = entry;
2259                         window_start = entry->offset;
2260                         window_free = entry->bytes;
2261                         last = entry;
2262                         max_extent = entry->bytes;
2263                 } else {
2264                         last = entry;
2265                         window_free += entry->bytes;
2266                         if (entry->bytes > max_extent)
2267                                 max_extent = entry->bytes;
2268                 }
2269                 prev = entry;
2270         }
2271
2272         cluster->window_start = first->offset;
2273
2274         node = &first->offset_index;
2275
2276         /*
2277          * now we've found our entries, pull them out of the free space
2278          * cache and put them into the cluster rbtree
2279          */
2280         do {
2281                 int ret;
2282
2283                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2284                 node = rb_next(&entry->offset_index);
2285                 if (entry->bitmap)
2286                         continue;
2287
2288                 rb_erase(&entry->offset_index, &ctl->free_space_offset);
2289                 ret = tree_insert_offset(&cluster->root, entry->offset,
2290                                          &entry->offset_index, 0);
2291                 BUG_ON(ret);
2292         } while (node && entry != last);
2293
2294         cluster->max_size = max_extent;
2295
2296         return 0;
2297 }
2298
2299 /*
2300  * This specifically looks for bitmaps that may work in the cluster, we assume
2301  * that we have already failed to find extents that will work.
2302  */
2303 static noinline int
2304 setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2305                      struct btrfs_free_cluster *cluster,
2306                      struct list_head *bitmaps, u64 offset, u64 bytes,
2307                      u64 min_bytes)
2308 {
2309         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2310         struct btrfs_free_space *entry;
2311         struct rb_node *node;
2312         int ret = -ENOSPC;
2313
2314         if (ctl->total_bitmaps == 0)
2315                 return -ENOSPC;
2316
2317         /*
2318          * First check our cached list of bitmaps and see if there is an entry
2319          * here that will work.
2320          */
2321         list_for_each_entry(entry, bitmaps, list) {
2322                 if (entry->bytes < min_bytes)
2323                         continue;
2324                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2325                                            bytes, min_bytes);
2326                 if (!ret)
2327                         return 0;
2328         }
2329
2330         /*
2331          * If we do have entries on our list and we are here then we didn't find
2332          * anything, so go ahead and get the next entry after the last entry in
2333          * this list and start the search from there.
2334          */
2335         if (!list_empty(bitmaps)) {
2336                 entry = list_entry(bitmaps->prev, struct btrfs_free_space,
2337                                    list);
2338                 node = rb_next(&entry->offset_index);
2339                 if (!node)
2340                         return -ENOSPC;
2341                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2342                 goto search;
2343         }
2344
2345         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, offset), 0, 1);
2346         if (!entry)
2347                 return -ENOSPC;
2348
2349 search:
2350         node = &entry->offset_index;
2351         do {
2352                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2353                 node = rb_next(&entry->offset_index);
2354                 if (!entry->bitmap)
2355                         continue;
2356                 if (entry->bytes < min_bytes)
2357                         continue;
2358                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2359                                            bytes, min_bytes);
2360         } while (ret && node);
2361
2362         return ret;
2363 }
2364
2365 /*
2366  * here we try to find a cluster of blocks in a block group.  The goal
2367  * is to find at least bytes free and up to empty_size + bytes free.
2368  * We might not find them all in one contiguous area.
2369  *
2370  * returns zero and sets up cluster if things worked out, otherwise
2371  * it returns -enospc
2372  */
2373 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
2374                              struct btrfs_root *root,
2375                              struct btrfs_block_group_cache *block_group,
2376                              struct btrfs_free_cluster *cluster,
2377                              u64 offset, u64 bytes, u64 empty_size)
2378 {
2379         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2380         struct list_head bitmaps;
2381         struct btrfs_free_space *entry, *tmp;
2382         u64 min_bytes;
2383         int ret;
2384
2385         /* for metadata, allow allocates with more holes */
2386         if (btrfs_test_opt(root, SSD_SPREAD)) {
2387                 min_bytes = bytes + empty_size;
2388         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
2389                 /*
2390                  * we want to do larger allocations when we are
2391                  * flushing out the delayed refs, it helps prevent
2392                  * making more work as we go along.
2393                  */
2394                 if (trans->transaction->delayed_refs.flushing)
2395                         min_bytes = max(bytes, (bytes + empty_size) >> 1);
2396                 else
2397                         min_bytes = max(bytes, (bytes + empty_size) >> 4);
2398         } else
2399                 min_bytes = max(bytes, (bytes + empty_size) >> 2);
2400
2401         spin_lock(&ctl->tree_lock);
2402
2403         /*
2404          * If we know we don't have enough space to make a cluster don't even
2405          * bother doing all the work to try and find one.
2406          */
2407         if (ctl->free_space < min_bytes) {
2408                 spin_unlock(&ctl->tree_lock);
2409                 return -ENOSPC;
2410         }
2411
2412         spin_lock(&cluster->lock);
2413
2414         /* someone already found a cluster, hooray */
2415         if (cluster->block_group) {
2416                 ret = 0;
2417                 goto out;
2418         }
2419
2420         INIT_LIST_HEAD(&bitmaps);
2421         ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
2422                                       bytes, min_bytes);
2423         if (ret)
2424                 ret = setup_cluster_bitmap(block_group, cluster, &bitmaps,
2425                                            offset, bytes, min_bytes);
2426
2427         /* Clear our temporary list */
2428         list_for_each_entry_safe(entry, tmp, &bitmaps, list)
2429                 list_del_init(&entry->list);
2430
2431         if (!ret) {
2432                 atomic_inc(&block_group->count);
2433                 list_add_tail(&cluster->block_group_list,
2434                               &block_group->cluster_list);
2435                 cluster->block_group = block_group;
2436         }
2437 out:
2438         spin_unlock(&cluster->lock);
2439         spin_unlock(&ctl->tree_lock);
2440
2441         return ret;
2442 }
2443
2444 /*
2445  * simple code to zero out a cluster
2446  */
2447 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
2448 {
2449         spin_lock_init(&cluster->lock);
2450         spin_lock_init(&cluster->refill_lock);
2451         cluster->root = RB_ROOT;
2452         cluster->max_size = 0;
2453         INIT_LIST_HEAD(&cluster->block_group_list);
2454         cluster->block_group = NULL;
2455 }
2456
2457 int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
2458                            u64 *trimmed, u64 start, u64 end, u64 minlen)
2459 {
2460         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2461         struct btrfs_free_space *entry = NULL;
2462         struct btrfs_fs_info *fs_info = block_group->fs_info;
2463         u64 bytes = 0;
2464         u64 actually_trimmed;
2465         int ret = 0;
2466
2467         *trimmed = 0;
2468
2469         while (start < end) {
2470                 spin_lock(&ctl->tree_lock);
2471
2472                 if (ctl->free_space < minlen) {
2473                         spin_unlock(&ctl->tree_lock);
2474                         break;
2475                 }
2476
2477                 entry = tree_search_offset(ctl, start, 0, 1);
2478                 if (!entry)
2479                         entry = tree_search_offset(ctl,
2480                                                    offset_to_bitmap(ctl, start),
2481                                                    1, 1);
2482
2483                 if (!entry || entry->offset >= end) {
2484                         spin_unlock(&ctl->tree_lock);
2485                         break;
2486                 }
2487
2488                 if (entry->bitmap) {
2489                         ret = search_bitmap(ctl, entry, &start, &bytes);
2490                         if (!ret) {
2491                                 if (start >= end) {
2492                                         spin_unlock(&ctl->tree_lock);
2493                                         break;
2494                                 }
2495                                 bytes = min(bytes, end - start);
2496                                 bitmap_clear_bits(ctl, entry, start, bytes);
2497                                 if (entry->bytes == 0)
2498                                         free_bitmap(ctl, entry);
2499                         } else {
2500                                 start = entry->offset + BITS_PER_BITMAP *
2501                                         block_group->sectorsize;
2502                                 spin_unlock(&ctl->tree_lock);
2503                                 ret = 0;
2504                                 continue;
2505                         }
2506                 } else {
2507                         start = entry->offset;
2508                         bytes = min(entry->bytes, end - start);
2509                         unlink_free_space(ctl, entry);
2510                         kmem_cache_free(btrfs_free_space_cachep, entry);
2511                 }
2512
2513                 spin_unlock(&ctl->tree_lock);
2514
2515                 if (bytes >= minlen) {
2516                         int update_ret;
2517                         update_ret = btrfs_update_reserved_bytes(block_group,
2518                                                                  bytes, 1, 1);
2519
2520                         ret = btrfs_error_discard_extent(fs_info->extent_root,
2521                                                          start,
2522                                                          bytes,
2523                                                          &actually_trimmed);
2524
2525                         btrfs_add_free_space(block_group, start, bytes);
2526                         if (!update_ret)
2527                                 btrfs_update_reserved_bytes(block_group,
2528                                                             bytes, 0, 1);
2529
2530                         if (ret)
2531                                 break;
2532                         *trimmed += actually_trimmed;
2533                 }
2534                 start += bytes;
2535                 bytes = 0;
2536
2537                 if (fatal_signal_pending(current)) {
2538                         ret = -ERESTARTSYS;
2539                         break;
2540                 }
2541
2542                 cond_resched();
2543         }
2544
2545         return ret;
2546 }
2547
2548 /*
2549  * Find the left-most item in the cache tree, and then return the
2550  * smallest inode number in the item.
2551  *
2552  * Note: the returned inode number may not be the smallest one in
2553  * the tree, if the left-most item is a bitmap.
2554  */
2555 u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root)
2556 {
2557         struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl;
2558         struct btrfs_free_space *entry = NULL;
2559         u64 ino = 0;
2560
2561         spin_lock(&ctl->tree_lock);
2562
2563         if (RB_EMPTY_ROOT(&ctl->free_space_offset))
2564                 goto out;
2565
2566         entry = rb_entry(rb_first(&ctl->free_space_offset),
2567                          struct btrfs_free_space, offset_index);
2568
2569         if (!entry->bitmap) {
2570                 ino = entry->offset;
2571
2572                 unlink_free_space(ctl, entry);
2573                 entry->offset++;
2574                 entry->bytes--;
2575                 if (!entry->bytes)
2576                         kmem_cache_free(btrfs_free_space_cachep, entry);
2577                 else
2578                         link_free_space(ctl, entry);
2579         } else {
2580                 u64 offset = 0;
2581                 u64 count = 1;
2582                 int ret;
2583
2584                 ret = search_bitmap(ctl, entry, &offset, &count);
2585                 BUG_ON(ret);
2586
2587                 ino = offset;
2588                 bitmap_clear_bits(ctl, entry, offset, 1);
2589                 if (entry->bytes == 0)
2590                         free_bitmap(ctl, entry);
2591         }
2592 out:
2593         spin_unlock(&ctl->tree_lock);
2594
2595         return ino;
2596 }
2597
2598 struct inode *lookup_free_ino_inode(struct btrfs_root *root,
2599                                     struct btrfs_path *path)
2600 {
2601         struct inode *inode = NULL;
2602
2603         spin_lock(&root->cache_lock);
2604         if (root->cache_inode)
2605                 inode = igrab(root->cache_inode);
2606         spin_unlock(&root->cache_lock);
2607         if (inode)
2608                 return inode;
2609
2610         inode = __lookup_free_space_inode(root, path, 0);
2611         if (IS_ERR(inode))
2612                 return inode;
2613
2614         spin_lock(&root->cache_lock);
2615         if (!btrfs_fs_closing(root->fs_info))
2616                 root->cache_inode = igrab(inode);
2617         spin_unlock(&root->cache_lock);
2618
2619         return inode;
2620 }
2621
2622 int create_free_ino_inode(struct btrfs_root *root,
2623                           struct btrfs_trans_handle *trans,
2624                           struct btrfs_path *path)
2625 {
2626         return __create_free_space_inode(root, trans, path,
2627                                          BTRFS_FREE_INO_OBJECTID, 0);
2628 }
2629
2630 int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
2631 {
2632         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2633         struct btrfs_path *path;
2634         struct inode *inode;
2635         int ret = 0;
2636         u64 root_gen = btrfs_root_generation(&root->root_item);
2637
2638         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
2639                 return 0;
2640
2641         /*
2642          * If we're unmounting then just return, since this does a search on the
2643          * normal root and not the commit root and we could deadlock.
2644          */
2645         if (btrfs_fs_closing(fs_info))
2646                 return 0;
2647
2648         path = btrfs_alloc_path();
2649         if (!path)
2650                 return 0;
2651
2652         inode = lookup_free_ino_inode(root, path);
2653         if (IS_ERR(inode))
2654                 goto out;
2655
2656         if (root_gen != BTRFS_I(inode)->generation)
2657                 goto out_put;
2658
2659         ret = __load_free_space_cache(root, inode, ctl, path, 0);
2660
2661         if (ret < 0)
2662                 printk(KERN_ERR "btrfs: failed to load free ino cache for "
2663                        "root %llu\n", root->root_key.objectid);
2664 out_put:
2665         iput(inode);
2666 out:
2667         btrfs_free_path(path);
2668         return ret;
2669 }
2670
2671 int btrfs_write_out_ino_cache(struct btrfs_root *root,
2672                               struct btrfs_trans_handle *trans,
2673                               struct btrfs_path *path)
2674 {
2675         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2676         struct inode *inode;
2677         int ret;
2678
2679         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
2680                 return 0;
2681
2682         inode = lookup_free_ino_inode(root, path);
2683         if (IS_ERR(inode))
2684                 return 0;
2685
2686         ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);
2687         if (ret < 0)
2688                 printk(KERN_ERR "btrfs: failed to write free ino cache "
2689                        "for root %llu\n", root->root_key.objectid);
2690
2691         iput(inode);
2692         return ret;
2693 }