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(root, 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(root, 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 (!root->fs_info->closing) {
 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(root, 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(root, 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(root, 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         return btrfs_update_inode(trans, root, inode);
 213 }
 214
 215 static int readahead_cache(struct inode *inode)
 216 {
 217         struct file_ra_state *ra;
 218         unsigned long last_index;
 219
 220         ra = kzalloc(sizeof(*ra), GFP_NOFS);
 221         if (!ra)
 222                 return -ENOMEM;
 223
 224         file_ra_state_init(ra, inode->i_mapping);
 225         last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 226
 227         page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
 228
 229         kfree(ra);
 230
 231         return 0;
 232 }
 233
 234 int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 235                             struct btrfs_free_space_ctl *ctl,
 236                             struct btrfs_path *path, u64 offset)
 237 {
 238         struct btrfs_free_space_header *header;
 239         struct extent_buffer *leaf;
 240         struct page *page;
 241         u32 *checksums = NULL, *crc;
 242         char *disk_crcs = NULL;
 243         struct btrfs_key key;
 244         struct list_head bitmaps;
 245         u64 num_entries;
 246         u64 num_bitmaps;
 247         u64 generation;
 248         u32 cur_crc = ~(u32)0;
 249         pgoff_t index = 0;
 250         unsigned long first_page_offset;
 251         int num_checksums;
 252         int ret = 0, ret2;
 253
 254         INIT_LIST_HEAD(&bitmaps);
 255
 256         /* Nothing in the space cache, goodbye */
 257         if (!i_size_read(inode))
 258                 goto out;
 259
 260         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 261         key.offset = offset;
 262         key.type = 0;
 263
 264         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 265         if (ret < 0)
 266                 goto out;
 267         else if (ret > 0) {
 268                 btrfs_release_path(root, path);
 269                 ret = 0;
 270                 goto out;
 271         }
 272
 273         ret = -1;
 274
 275         leaf = path->nodes[0];
 276         header = btrfs_item_ptr(leaf, path->slots[0],
 277                                 struct btrfs_free_space_header);
 278         num_entries = btrfs_free_space_entries(leaf, header);
 279         num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
 280         generation = btrfs_free_space_generation(leaf, header);
 281         btrfs_release_path(root, path);
 282
 283         if (BTRFS_I(inode)->generation != generation) {
 284                 printk(KERN_ERR "btrfs: free space inode generation (%llu) did"
 285                        " not match free space cache generation (%llu)\n",
 286                        (unsigned long long)BTRFS_I(inode)->generation,
 287                        (unsigned long long)generation);
 288                 goto out;
 289         }
 290
 291         if (!num_entries)
 292                 goto out;
 293
 294         /* Setup everything for doing checksumming */
 295         num_checksums = i_size_read(inode) / PAGE_CACHE_SIZE;
 296         checksums = crc = kzalloc(sizeof(u32) * num_checksums, GFP_NOFS);
 297         if (!checksums)
 298                 goto out;
 299         first_page_offset = (sizeof(u32) * num_checksums) + sizeof(u64);
 300         disk_crcs = kzalloc(first_page_offset, GFP_NOFS);
 301         if (!disk_crcs)
 302                 goto out;
 303
 304         ret = readahead_cache(inode);
 305         if (ret)
 306                 goto out;
 307
 308         while (1) {
 309                 struct btrfs_free_space_entry *entry;
 310                 struct btrfs_free_space *e;
 311                 void *addr;
 312                 unsigned long offset = 0;
 313                 unsigned long start_offset = 0;
 314                 int need_loop = 0;
 315
 316                 if (!num_entries && !num_bitmaps)
 317                         break;
 318
 319                 if (index == 0) {
 320                         start_offset = first_page_offset;
 321                         offset = start_offset;
 322                 }
 323
 324                 page = grab_cache_page(inode->i_mapping, index);
 325                 if (!page)
 326                         goto free_cache;
 327
 328                 if (!PageUptodate(page)) {
 329                         btrfs_readpage(NULL, page);
 330                         lock_page(page);
 331                         if (!PageUptodate(page)) {
 332                                 unlock_page(page);
 333                                 page_cache_release(page);
 334                                 printk(KERN_ERR "btrfs: error reading free "
 335                                        "space cache\n");
 336                                 goto free_cache;
 337                         }
 338                 }
 339                 addr = kmap(page);
 340
 341                 if (index == 0) {
 342                         u64 *gen;
 343
 344                         memcpy(disk_crcs, addr, first_page_offset);
 345                         gen = addr + (sizeof(u32) * num_checksums);
 346                         if (*gen != BTRFS_I(inode)->generation) {
 347                                 printk(KERN_ERR "btrfs: space cache generation"
 348                                        " (%llu) does not match inode (%llu)\n",
 349                                        (unsigned long long)*gen,
 350                                        (unsigned long long)
 351                                        BTRFS_I(inode)->generation);
 352                                 kunmap(page);
 353                                 unlock_page(page);
 354                                 page_cache_release(page);
 355                                 goto free_cache;
 356                         }
 357                         crc = (u32 *)disk_crcs;
 358                 }
 359                 entry = addr + start_offset;
 360
 361                 /* First lets check our crc before we do anything fun */
 362                 cur_crc = ~(u32)0;
 363                 cur_crc = btrfs_csum_data(root, addr + start_offset, cur_crc,
 364                                           PAGE_CACHE_SIZE - start_offset);
 365                 btrfs_csum_final(cur_crc, (char *)&cur_crc);
 366                 if (cur_crc != *crc) {
 367                         printk(KERN_ERR "btrfs: crc mismatch for page %lu\n",
 368                                index);
 369                         kunmap(page);
 370                         unlock_page(page);
 371                         page_cache_release(page);
 372                         goto free_cache;
 373                 }
 374                 crc++;
 375
 376                 while (1) {
 377                         if (!num_entries)
 378                                 break;
 379
 380                         need_loop = 1;
 381                         e = kmem_cache_zalloc(btrfs_free_space_cachep,
 382                                               GFP_NOFS);
 383                         if (!e) {
 384                                 kunmap(page);
 385                                 unlock_page(page);
 386                                 page_cache_release(page);
 387                                 goto free_cache;
 388                         }
 389
 390                         e->offset = le64_to_cpu(entry->offset);
 391                         e->bytes = le64_to_cpu(entry->bytes);
 392                         if (!e->bytes) {
 393                                 kunmap(page);
 394                                 kmem_cache_free(btrfs_free_space_cachep, e);
 395                                 unlock_page(page);
 396                                 page_cache_release(page);
 397                                 goto free_cache;
 398                         }
 399
 400                         if (entry->type == BTRFS_FREE_SPACE_EXTENT) {
 401                                 spin_lock(&ctl->tree_lock);
 402                                 ret = link_free_space(ctl, e);
 403                                 spin_unlock(&ctl->tree_lock);
 404                                 BUG_ON(ret);
 405                         } else {
 406                                 e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
 407                                 if (!e->bitmap) {
 408                                         kunmap(page);
 409                                         kmem_cache_free(
 410                                                 btrfs_free_space_cachep, e);
 411                                         unlock_page(page);
 412                                         page_cache_release(page);
 413                                         goto free_cache;
 414                                 }
 415                                 spin_lock(&ctl->tree_lock);
 416                                 ret2 = link_free_space(ctl, e);
 417                                 ctl->total_bitmaps++;
 418                                 ctl->op->recalc_thresholds(ctl);
 419                                 spin_unlock(&ctl->tree_lock);
 420                                 list_add_tail(&e->list, &bitmaps);
 421                         }
 422
 423                         num_entries--;
 424                         offset += sizeof(struct btrfs_free_space_entry);
 425                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 426                             PAGE_CACHE_SIZE)
 427                                 break;
 428                         entry++;
 429                 }
 430
 431                 /*
 432                  * We read an entry out of this page, we need to move on to the
 433                  * next page.
 434                  */
 435                 if (need_loop) {
 436                         kunmap(page);
 437                         goto next;
 438                 }
 439
 440                 /*
 441                  * We add the bitmaps at the end of the entries in order that
 442                  * the bitmap entries are added to the cache.
 443                  */
 444                 e = list_entry(bitmaps.next, struct btrfs_free_space, list);
 445                 list_del_init(&e->list);
 446                 memcpy(e->bitmap, addr, PAGE_CACHE_SIZE);
 447                 kunmap(page);
 448                 num_bitmaps--;
 449 next:
 450                 unlock_page(page);
 451                 page_cache_release(page);
 452                 index++;
 453         }
 454
 455         ret = 1;
 456 out:
 457         kfree(checksums);
 458         kfree(disk_crcs);
 459         return ret;
 460 free_cache:
 461         __btrfs_remove_free_space_cache(ctl);
 462         goto out;
 463 }
 464
 465 int load_free_space_cache(struct btrfs_fs_info *fs_info,
 466                           struct btrfs_block_group_cache *block_group)
 467 {
 468         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 469         struct btrfs_root *root = fs_info->tree_root;
 470         struct inode *inode;
 471         struct btrfs_path *path;
 472         int ret;
 473         bool matched;
 474         u64 used = btrfs_block_group_used(&block_group->item);
 475
 476         /*
 477          * If we're unmounting then just return, since this does a search on the
 478          * normal root and not the commit root and we could deadlock.
 479          */
 480         smp_mb();
 481         if (fs_info->closing)
 482                 return 0;
 483
 484         /*
 485          * If this block group has been marked to be cleared for one reason or
 486          * another then we can't trust the on disk cache, so just return.
 487          */
 488         spin_lock(&block_group->lock);
 489         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 490                 spin_unlock(&block_group->lock);
 491                 return 0;
 492         }
 493         spin_unlock(&block_group->lock);
 494
 495         path = btrfs_alloc_path();
 496         if (!path)
 497                 return 0;
 498
 499         inode = lookup_free_space_inode(root, block_group, path);
 500         if (IS_ERR(inode)) {
 501                 btrfs_free_path(path);
 502                 return 0;
 503         }
 504
 505         ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
 506                                       path, block_group->key.objectid);
 507         btrfs_free_path(path);
 508         if (ret <= 0)
 509                 goto out;
 510
 511         spin_lock(&ctl->tree_lock);
 512         matched = (ctl->free_space == (block_group->key.offset - used -
 513                                        block_group->bytes_super));
 514         spin_unlock(&ctl->tree_lock);
 515
 516         if (!matched) {
 517                 __btrfs_remove_free_space_cache(ctl);
 518                 printk(KERN_ERR "block group %llu has an wrong amount of free "
 519                        "space\n", block_group->key.objectid);
 520                 ret = -1;
 521         }
 522 out:
 523         if (ret < 0) {
 524                 /* This cache is bogus, make sure it gets cleared */
 525                 spin_lock(&block_group->lock);
 526                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 527                 spin_unlock(&block_group->lock);
 528
 529                 printk(KERN_ERR "btrfs: failed to load free space cache "
 530                        "for block group %llu\n", block_group->key.objectid);
 531         }
 532
 533         iput(inode);
 534         return ret;
 535 }
 536
 537 int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 538                             struct btrfs_free_space_ctl *ctl,
 539                             struct btrfs_block_group_cache *block_group,
 540                             struct btrfs_trans_handle *trans,
 541                             struct btrfs_path *path, u64 offset)
 542 {
 543         struct btrfs_free_space_header *header;
 544         struct extent_buffer *leaf;
 545         struct rb_node *node;
 546         struct list_head *pos, *n;
 547         struct page **pages;
 548         struct page *page;
 549         struct extent_state *cached_state = NULL;
 550         struct btrfs_free_cluster *cluster = NULL;
 551         struct extent_io_tree *unpin = NULL;
 552         struct list_head bitmap_list;
 553         struct btrfs_key key;
 554         u64 start, end, len;
 555         u64 bytes = 0;
 556         u32 *crc, *checksums;
 557         unsigned long first_page_offset;
 558         int index = 0, num_pages = 0;
 559         int entries = 0;
 560         int bitmaps = 0;
 561         int ret = -1;
 562         bool next_page = false;
 563         bool out_of_space = false;
 564
 565         INIT_LIST_HEAD(&bitmap_list);
 566
 567         node = rb_first(&ctl->free_space_offset);
 568         if (!node)
 569                 return 0;
 570
 571         if (!i_size_read(inode))
 572                 return -1;
 573
 574         num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
 575                 PAGE_CACHE_SHIFT;
 576         filemap_write_and_wait(inode->i_mapping);
 577         btrfs_wait_ordered_range(inode, inode->i_size &
 578                                  ~(root->sectorsize - 1), (u64)-1);
 579
 580         /* We need a checksum per page. */
 581         crc = checksums = kzalloc(sizeof(u32) * num_pages, GFP_NOFS);
 582         if (!crc)
 583                 return -1;
 584
 585         pages = kzalloc(sizeof(struct page *) * num_pages, GFP_NOFS);
 586         if (!pages) {
 587                 kfree(crc);
 588                 return -1;
 589         }
 590
 591         /* Since the first page has all of our checksums and our generation we
 592          * need to calculate the offset into the page that we can start writing
 593          * our entries.
 594          */
 595         first_page_offset = (sizeof(u32) * num_pages) + sizeof(u64);
 596
 597         /* Get the cluster for this block_group if it exists */
 598         if (block_group && !list_empty(&block_group->cluster_list))
 599                 cluster = list_entry(block_group->cluster_list.next,
 600                                      struct btrfs_free_cluster,
 601                                      block_group_list);
 602
 603         /*
 604          * We shouldn't have switched the pinned extents yet so this is the
 605          * right one
 606          */
 607         unpin = root->fs_info->pinned_extents;
 608
 609         /*
 610          * Lock all pages first so we can lock the extent safely.
 611          *
 612          * NOTE: Because we hold the ref the entire time we're going to write to
 613          * the page find_get_page should never fail, so we don't do a check
 614          * after find_get_page at this point.  Just putting this here so people
 615          * know and don't freak out.
 616          */
 617         while (index < num_pages) {
 618                 page = grab_cache_page(inode->i_mapping, index);
 619                 if (!page) {
 620                         int i;
 621
 622                         for (i = 0; i < num_pages; i++) {
 623                                 unlock_page(pages[i]);
 624                                 page_cache_release(pages[i]);
 625                         }
 626                         goto out_free;
 627                 }
 628                 pages[index] = page;
 629                 index++;
 630         }
 631
 632         index = 0;
 633         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
 634                          0, &cached_state, GFP_NOFS);
 635
 636         /*
 637          * When searching for pinned extents, we need to start at our start
 638          * offset.
 639          */
 640         if (block_group)
 641                 start = block_group->key.objectid;
 642
 643         /* Write out the extent entries */
 644         do {
 645                 struct btrfs_free_space_entry *entry;
 646                 void *addr;
 647                 unsigned long offset = 0;
 648                 unsigned long start_offset = 0;
 649
 650                 next_page = false;
 651
 652                 if (index == 0) {
 653                         start_offset = first_page_offset;
 654                         offset = start_offset;
 655                 }
 656
 657                 if (index >= num_pages) {
 658                         out_of_space = true;
 659                         break;
 660                 }
 661
 662                 page = pages[index];
 663
 664                 addr = kmap(page);
 665                 entry = addr + start_offset;
 666
 667                 memset(addr, 0, PAGE_CACHE_SIZE);
 668                 while (node && !next_page) {
 669                         struct btrfs_free_space *e;
 670
 671                         e = rb_entry(node, struct btrfs_free_space, offset_index);
 672                         entries++;
 673
 674                         entry->offset = cpu_to_le64(e->offset);
 675                         entry->bytes = cpu_to_le64(e->bytes);
 676                         if (e->bitmap) {
 677                                 entry->type = BTRFS_FREE_SPACE_BITMAP;
 678                                 list_add_tail(&e->list, &bitmap_list);
 679                                 bitmaps++;
 680                         } else {
 681                                 entry->type = BTRFS_FREE_SPACE_EXTENT;
 682                         }
 683                         node = rb_next(node);
 684                         if (!node && cluster) {
 685                                 node = rb_first(&cluster->root);
 686                                 cluster = NULL;
 687                         }
 688                         offset += sizeof(struct btrfs_free_space_entry);
 689                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 690                             PAGE_CACHE_SIZE)
 691                                 next_page = true;
 692                         entry++;
 693                 }
 694
 695                 /*
 696                  * We want to add any pinned extents to our free space cache
 697                  * so we don't leak the space
 698                  */
 699                 while (block_group && !next_page &&
 700                        (start < block_group->key.objectid +
 701                         block_group->key.offset)) {
 702                         ret = find_first_extent_bit(unpin, start, &start, &end,
 703                                                     EXTENT_DIRTY);
 704                         if (ret) {
 705                                 ret = 0;
 706                                 break;
 707                         }
 708
 709                         /* This pinned extent is out of our range */
 710                         if (start >= block_group->key.objectid +
 711                             block_group->key.offset)
 712                                 break;
 713
 714                         len = block_group->key.objectid +
 715                                 block_group->key.offset - start;
 716                         len = min(len, end + 1 - start);
 717
 718                         entries++;
 719                         entry->offset = cpu_to_le64(start);
 720                         entry->bytes = cpu_to_le64(len);
 721                         entry->type = BTRFS_FREE_SPACE_EXTENT;
 722
 723                         start = end + 1;
 724                         offset += sizeof(struct btrfs_free_space_entry);
 725                         if (offset + sizeof(struct btrfs_free_space_entry) >=
 726                             PAGE_CACHE_SIZE)
 727                                 next_page = true;
 728                         entry++;
 729                 }
 730                 *crc = ~(u32)0;
 731                 *crc = btrfs_csum_data(root, addr + start_offset, *crc,
 732                                        PAGE_CACHE_SIZE - start_offset);
 733                 kunmap(page);
 734
 735                 btrfs_csum_final(*crc, (char *)crc);
 736                 crc++;
 737
 738                 bytes += PAGE_CACHE_SIZE;
 739
 740                 index++;
 741         } while (node || next_page);
 742
 743         /* Write out the bitmaps */
 744         list_for_each_safe(pos, n, &bitmap_list) {
 745                 void *addr;
 746                 struct btrfs_free_space *entry =
 747                         list_entry(pos, struct btrfs_free_space, list);
 748
 749                 if (index >= num_pages) {
 750                         out_of_space = true;
 751                         break;
 752                 }
 753                 page = pages[index];
 754
 755                 addr = kmap(page);
 756                 memcpy(addr, entry->bitmap, PAGE_CACHE_SIZE);
 757                 *crc = ~(u32)0;
 758                 *crc = btrfs_csum_data(root, addr, *crc, PAGE_CACHE_SIZE);
 759                 kunmap(page);
 760                 btrfs_csum_final(*crc, (char *)crc);
 761                 crc++;
 762                 bytes += PAGE_CACHE_SIZE;
 763
 764                 list_del_init(&entry->list);
 765                 index++;
 766         }
 767
 768         if (out_of_space) {
 769                 btrfs_drop_pages(pages, num_pages);
 770                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 771                                      i_size_read(inode) - 1, &cached_state,
 772                                      GFP_NOFS);
 773                 ret = 0;
 774                 goto out_free;
 775         }
 776
 777         /* Zero out the rest of the pages just to make sure */
 778         while (index < num_pages) {
 779                 void *addr;
 780
 781                 page = pages[index];
 782                 addr = kmap(page);
 783                 memset(addr, 0, PAGE_CACHE_SIZE);
 784                 kunmap(page);
 785                 bytes += PAGE_CACHE_SIZE;
 786                 index++;
 787         }
 788
 789         /* Write the checksums and trans id to the first page */
 790         {
 791                 void *addr;
 792                 u64 *gen;
 793
 794                 page = pages[0];
 795
 796                 addr = kmap(page);
 797                 memcpy(addr, checksums, sizeof(u32) * num_pages);
 798                 gen = addr + (sizeof(u32) * num_pages);
 799                 *gen = trans->transid;
 800                 kunmap(page);
 801         }
 802
 803         ret = btrfs_dirty_pages(root, inode, pages, num_pages, 0,
 804                                             bytes, &cached_state);
 805         btrfs_drop_pages(pages, num_pages);
 806         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 807                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
 808
 809         if (ret) {
 810                 ret = 0;
 811                 goto out_free;
 812         }
 813
 814         BTRFS_I(inode)->generation = trans->transid;
 815
 816         filemap_write_and_wait(inode->i_mapping);
 817
 818         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 819         key.offset = offset;
 820         key.type = 0;
 821
 822         ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
 823         if (ret < 0) {
 824                 ret = -1;
 825                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 826                                  EXTENT_DIRTY | EXTENT_DELALLOC |
 827                                  EXTENT_DO_ACCOUNTING, 0, 0, NULL, GFP_NOFS);
 828                 goto out_free;
 829         }
 830         leaf = path->nodes[0];
 831         if (ret > 0) {
 832                 struct btrfs_key found_key;
 833                 BUG_ON(!path->slots[0]);
 834                 path->slots[0]--;
 835                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 836                 if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
 837                     found_key.offset != offset) {
 838                         ret = -1;
 839                         clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
 840                                          EXTENT_DIRTY | EXTENT_DELALLOC |
 841                                          EXTENT_DO_ACCOUNTING, 0, 0, NULL,
 842                                          GFP_NOFS);
 843                         btrfs_release_path(root, path);
 844                         goto out_free;
 845                 }
 846         }
 847         header = btrfs_item_ptr(leaf, path->slots[0],
 848                                 struct btrfs_free_space_header);
 849         btrfs_set_free_space_entries(leaf, header, entries);
 850         btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
 851         btrfs_set_free_space_generation(leaf, header, trans->transid);
 852         btrfs_mark_buffer_dirty(leaf);
 853         btrfs_release_path(root, path);
 854
 855         ret = 1;
 856
 857 out_free:
 858         if (ret != 1) {
 859                 invalidate_inode_pages2_range(inode->i_mapping, 0, index);
 860                 BTRFS_I(inode)->generation = 0;
 861         }
 862         kfree(checksums);
 863         kfree(pages);
 864         btrfs_update_inode(trans, root, inode);
 865         return ret;
 866 }
 867
 868 int btrfs_write_out_cache(struct btrfs_root *root,
 869                           struct btrfs_trans_handle *trans,
 870                           struct btrfs_block_group_cache *block_group,
 871                           struct btrfs_path *path)
 872 {
 873         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 874         struct inode *inode;
 875         int ret = 0;
 876
 877         root = root->fs_info->tree_root;
 878
 879         spin_lock(&block_group->lock);
 880         if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
 881                 spin_unlock(&block_group->lock);
 882                 return 0;
 883         }
 884         spin_unlock(&block_group->lock);
 885
 886         inode = lookup_free_space_inode(root, block_group, path);
 887         if (IS_ERR(inode))
 888                 return 0;
 889
 890         ret = __btrfs_write_out_cache(root, inode, ctl, block_group, trans,
 891                                       path, block_group->key.objectid);
 892         if (ret < 0) {
 893                 spin_lock(&block_group->lock);
 894                 block_group->disk_cache_state = BTRFS_DC_ERROR;
 895                 spin_unlock(&block_group->lock);
 896
 897                 printk(KERN_ERR "btrfs: failed to write free space cace "
 898                        "for block group %llu\n", block_group->key.objectid);
 899         }
 900
 901         iput(inode);
 902         return ret;
 903 }
 904
 905 static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
 906                                           u64 offset)
 907 {
 908         BUG_ON(offset < bitmap_start);
 909         offset -= bitmap_start;
 910         return (unsigned long)(div_u64(offset, unit));
 911 }
 912
 913 static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
 914 {
 915         return (unsigned long)(div_u64(bytes, unit));
 916 }
 917
 918 static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
 919                                    u64 offset)
 920 {
 921         u64 bitmap_start;
 922         u64 bytes_per_bitmap;
 923
 924         bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
 925         bitmap_start = offset - ctl->start;
 926         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
 927         bitmap_start *= bytes_per_bitmap;
 928         bitmap_start += ctl->start;
 929
 930         return bitmap_start;
 931 }
 932
 933 static int tree_insert_offset(struct rb_root *root, u64 offset,
 934                               struct rb_node *node, int bitmap)
 935 {
 936         struct rb_node **p = &root->rb_node;
 937         struct rb_node *parent = NULL;
 938         struct btrfs_free_space *info;
 939
 940         while (*p) {
 941                 parent = *p;
 942                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
 943
 944                 if (offset < info->offset) {
 945                         p = &(*p)->rb_left;
 946                 } else if (offset > info->offset) {
 947                         p = &(*p)->rb_right;
 948                 } else {
 949                         /*
 950                          * we could have a bitmap entry and an extent entry
 951                          * share the same offset.  If this is the case, we want
 952                          * the extent entry to always be found first if we do a
 953                          * linear search through the tree, since we want to have
 954                          * the quickest allocation time, and allocating from an
 955                          * extent is faster than allocating from a bitmap.  So
 956                          * if we're inserting a bitmap and we find an entry at
 957                          * this offset, we want to go right, or after this entry
 958                          * logically.  If we are inserting an extent and we've
 959                          * found a bitmap, we want to go left, or before
 960                          * logically.
 961                          */
 962                         if (bitmap) {
 963                                 WARN_ON(info->bitmap);
 964                                 p = &(*p)->rb_right;
 965                         } else {
 966                                 WARN_ON(!info->bitmap);
 967                                 p = &(*p)->rb_left;
 968                         }
 969                 }
 970         }
 971
 972         rb_link_node(node, parent, p);
 973         rb_insert_color(node, root);
 974
 975         return 0;
 976 }
 977
 978 /*
 979  * searches the tree for the given offset.
 980  *
 981  * fuzzy - If this is set, then we are trying to make an allocation, and we just
 982  * want a section that has at least bytes size and comes at or after the given
 983  * offset.
 984  */
 985 static struct btrfs_free_space *
 986 tree_search_offset(struct btrfs_free_space_ctl *ctl,
 987                    u64 offset, int bitmap_only, int fuzzy)
 988 {
 989         struct rb_node *n = ctl->free_space_offset.rb_node;
 990         struct btrfs_free_space *entry, *prev = NULL;
 991
 992         /* find entry that is closest to the 'offset' */
 993         while (1) {
 994                 if (!n) {
 995                         entry = NULL;
 996                         break;
 997                 }
 998
 999                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1000                 prev = entry;
1001
1002                 if (offset < entry->offset)
1003                         n = n->rb_left;
1004                 else if (offset > entry->offset)
1005                         n = n->rb_right;
1006                 else
1007                         break;
1008         }
1009
1010         if (bitmap_only) {
1011                 if (!entry)
1012                         return NULL;
1013                 if (entry->bitmap)
1014                         return entry;
1015
1016                 /*
1017                  * bitmap entry and extent entry may share same offset,
1018                  * in that case, bitmap entry comes after extent entry.
1019                  */
1020                 n = rb_next(n);
1021                 if (!n)
1022                         return NULL;
1023                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1024                 if (entry->offset != offset)
1025                         return NULL;
1026
1027                 WARN_ON(!entry->bitmap);
1028                 return entry;
1029         } else if (entry) {
1030                 if (entry->bitmap) {
1031                         /*
1032                          * if previous extent entry covers the offset,
1033                          * we should return it instead of the bitmap entry
1034                          */
1035                         n = &entry->offset_index;
1036                         while (1) {
1037                                 n = rb_prev(n);
1038                                 if (!n)
1039                                         break;
1040                                 prev = rb_entry(n, struct btrfs_free_space,
1041                                                 offset_index);
1042                                 if (!prev->bitmap) {
1043                                         if (prev->offset + prev->bytes > offset)
1044                                                 entry = prev;
1045                                         break;
1046                                 }
1047                         }
1048                 }
1049                 return entry;
1050         }
1051
1052         if (!prev)
1053                 return NULL;
1054
1055         /* find last entry before the 'offset' */
1056         entry = prev;
1057         if (entry->offset > offset) {
1058                 n = rb_prev(&entry->offset_index);
1059                 if (n) {
1060                         entry = rb_entry(n, struct btrfs_free_space,
1061                                         offset_index);
1062                         BUG_ON(entry->offset > offset);
1063                 } else {
1064                         if (fuzzy)
1065                                 return entry;
1066                         else
1067                                 return NULL;
1068                 }
1069         }
1070
1071         if (entry->bitmap) {
1072                 n = &entry->offset_index;
1073                 while (1) {
1074                         n = rb_prev(n);
1075                         if (!n)
1076                                 break;
1077                         prev = rb_entry(n, struct btrfs_free_space,
1078                                         offset_index);
1079                         if (!prev->bitmap) {
1080                                 if (prev->offset + prev->bytes > offset)
1081                                         return prev;
1082                                 break;
1083                         }
1084                 }
1085                 if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
1086                         return entry;
1087         } else if (entry->offset + entry->bytes > offset)
1088                 return entry;
1089
1090         if (!fuzzy)
1091                 return NULL;
1092
1093         while (1) {
1094                 if (entry->bitmap) {
1095                         if (entry->offset + BITS_PER_BITMAP *
1096                             ctl->unit > offset)
1097                                 break;
1098                 } else {
1099                         if (entry->offset + entry->bytes > offset)
1100                                 break;
1101                 }
1102
1103                 n = rb_next(&entry->offset_index);
1104                 if (!n)
1105                         return NULL;
1106                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1107         }
1108         return entry;
1109 }
1110
1111 static inline void
1112 __unlink_free_space(struct btrfs_free_space_ctl *ctl,
1113                     struct btrfs_free_space *info)
1114 {
1115         rb_erase(&info->offset_index, &ctl->free_space_offset);
1116         ctl->free_extents--;
1117 }
1118
1119 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
1120                               struct btrfs_free_space *info)
1121 {
1122         __unlink_free_space(ctl, info);
1123         ctl->free_space -= info->bytes;
1124 }
1125
1126 static int link_free_space(struct btrfs_free_space_ctl *ctl,
1127                            struct btrfs_free_space *info)
1128 {
1129         int ret = 0;
1130
1131         BUG_ON(!info->bitmap && !info->bytes);
1132         ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
1133                                  &info->offset_index, (info->bitmap != NULL));
1134         if (ret)
1135                 return ret;
1136
1137         ctl->free_space += info->bytes;
1138         ctl->free_extents++;
1139         return ret;
1140 }
1141
1142 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
1143 {
1144         struct btrfs_block_group_cache *block_group = ctl->private;
1145         u64 max_bytes;
1146         u64 bitmap_bytes;
1147         u64 extent_bytes;
1148         u64 size = block_group->key.offset;
1149         u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
1150         int max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
1151
1152         BUG_ON(ctl->total_bitmaps > max_bitmaps);
1153
1154         /*
1155          * The goal is to keep the total amount of memory used per 1gb of space
1156          * at or below 32k, so we need to adjust how much memory we allow to be
1157          * used by extent based free space tracking
1158          */
1159         if (size < 1024 * 1024 * 1024)
1160                 max_bytes = MAX_CACHE_BYTES_PER_GIG;
1161         else
1162                 max_bytes = MAX_CACHE_BYTES_PER_GIG *
1163                         div64_u64(size, 1024 * 1024 * 1024);
1164
1165         /*
1166          * we want to account for 1 more bitmap than what we have so we can make
1167          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1168          * we add more bitmaps.
1169          */
1170         bitmap_bytes = (ctl->total_bitmaps + 1) * PAGE_CACHE_SIZE;
1171
1172         if (bitmap_bytes >= max_bytes) {
1173                 ctl->extents_thresh = 0;
1174                 return;
1175         }
1176
1177         /*
1178          * we want the extent entry threshold to always be at most 1/2 the maxw
1179          * bytes we can have, or whatever is less than that.
1180          */
1181         extent_bytes = max_bytes - bitmap_bytes;
1182         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
1183
1184         ctl->extents_thresh =
1185                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
1186 }
1187
1188 static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1189                               struct btrfs_free_space *info, u64 offset,
1190                               u64 bytes)
1191 {
1192         unsigned long start, count;
1193
1194         start = offset_to_bit(info->offset, ctl->unit, offset);
1195         count = bytes_to_bits(bytes, ctl->unit);
1196         BUG_ON(start + count > BITS_PER_BITMAP);
1197
1198         bitmap_clear(info->bitmap, start, count);
1199
1200         info->bytes -= bytes;
1201         ctl->free_space -= bytes;
1202 }
1203
1204 static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
1205                             struct btrfs_free_space *info, u64 offset,
1206                             u64 bytes)
1207 {
1208         unsigned long start, count;
1209
1210         start = offset_to_bit(info->offset, ctl->unit, offset);
1211         count = bytes_to_bits(bytes, ctl->unit);
1212         BUG_ON(start + count > BITS_PER_BITMAP);
1213
1214         bitmap_set(info->bitmap, start, count);
1215
1216         info->bytes += bytes;
1217         ctl->free_space += bytes;
1218 }
1219
1220 static int search_bitmap(struct btrfs_free_space_ctl *ctl,
1221                          struct btrfs_free_space *bitmap_info, u64 *offset,
1222                          u64 *bytes)
1223 {
1224         unsigned long found_bits = 0;
1225         unsigned long bits, i;
1226         unsigned long next_zero;
1227
1228         i = offset_to_bit(bitmap_info->offset, ctl->unit,
1229                           max_t(u64, *offset, bitmap_info->offset));
1230         bits = bytes_to_bits(*bytes, ctl->unit);
1231
1232         for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
1233              i < BITS_PER_BITMAP;
1234              i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
1235                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
1236                                                BITS_PER_BITMAP, i);
1237                 if ((next_zero - i) >= bits) {
1238                         found_bits = next_zero - i;
1239                         break;
1240                 }
1241                 i = next_zero;
1242         }
1243
1244         if (found_bits) {
1245                 *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
1246                 *bytes = (u64)(found_bits) * ctl->unit;
1247                 return 0;
1248         }
1249
1250         return -1;
1251 }
1252
1253 static struct btrfs_free_space *
1254 find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes)
1255 {
1256         struct btrfs_free_space *entry;
1257         struct rb_node *node;
1258         int ret;
1259
1260         if (!ctl->free_space_offset.rb_node)
1261                 return NULL;
1262
1263         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
1264         if (!entry)
1265                 return NULL;
1266
1267         for (node = &entry->offset_index; node; node = rb_next(node)) {
1268                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1269                 if (entry->bytes < *bytes)
1270                         continue;
1271
1272                 if (entry->bitmap) {
1273                         ret = search_bitmap(ctl, entry, offset, bytes);
1274                         if (!ret)
1275                                 return entry;
1276                         continue;
1277                 }
1278
1279                 *offset = entry->offset;
1280                 *bytes = entry->bytes;
1281                 return entry;
1282         }
1283
1284         return NULL;
1285 }
1286
1287 static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
1288                            struct btrfs_free_space *info, u64 offset)
1289 {
1290         info->offset = offset_to_bitmap(ctl, offset);
1291         info->bytes = 0;
1292         link_free_space(ctl, info);
1293         ctl->total_bitmaps++;
1294
1295         ctl->op->recalc_thresholds(ctl);
1296 }
1297
1298 static void free_bitmap(struct btrfs_free_space_ctl *ctl,
1299                         struct btrfs_free_space *bitmap_info)
1300 {
1301         unlink_free_space(ctl, bitmap_info);
1302         kfree(bitmap_info->bitmap);
1303         kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1304         ctl->total_bitmaps--;
1305         ctl->op->recalc_thresholds(ctl);
1306 }
1307
1308 static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
1309                               struct btrfs_free_space *bitmap_info,
1310                               u64 *offset, u64 *bytes)
1311 {
1312         u64 end;
1313         u64 search_start, search_bytes;
1314         int ret;
1315
1316 again:
1317         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
1318
1319         /*
1320          * XXX - this can go away after a few releases.
1321          *
1322          * since the only user of btrfs_remove_free_space is the tree logging
1323          * stuff, and the only way to test that is under crash conditions, we
1324          * want to have this debug stuff here just in case somethings not
1325          * working.  Search the bitmap for the space we are trying to use to
1326          * make sure its actually there.  If its not there then we need to stop
1327          * because something has gone wrong.
1328          */
1329         search_start = *offset;
1330         search_bytes = *bytes;
1331         search_bytes = min(search_bytes, end - search_start + 1);
1332         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
1333         BUG_ON(ret < 0 || search_start != *offset);
1334
1335         if (*offset > bitmap_info->offset && *offset + *bytes > end) {
1336                 bitmap_clear_bits(ctl, bitmap_info, *offset, end - *offset + 1);
1337                 *bytes -= end - *offset + 1;
1338                 *offset = end + 1;
1339         } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
1340                 bitmap_clear_bits(ctl, bitmap_info, *offset, *bytes);
1341                 *bytes = 0;
1342         }
1343
1344         if (*bytes) {
1345                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
1346                 if (!bitmap_info->bytes)
1347                         free_bitmap(ctl, bitmap_info);
1348
1349                 /*
1350                  * no entry after this bitmap, but we still have bytes to
1351                  * remove, so something has gone wrong.
1352                  */
1353                 if (!next)
1354                         return -EINVAL;
1355
1356                 bitmap_info = rb_entry(next, struct btrfs_free_space,
1357                                        offset_index);
1358
1359                 /*
1360                  * if the next entry isn't a bitmap we need to return to let the
1361                  * extent stuff do its work.
1362                  */
1363                 if (!bitmap_info->bitmap)
1364                         return -EAGAIN;
1365
1366                 /*
1367                  * Ok the next item is a bitmap, but it may not actually hold
1368                  * the information for the rest of this free space stuff, so
1369                  * look for it, and if we don't find it return so we can try
1370                  * everything over again.
1371                  */
1372                 search_start = *offset;
1373                 search_bytes = *bytes;
1374                 ret = search_bitmap(ctl, bitmap_info, &search_start,
1375                                     &search_bytes);
1376                 if (ret < 0 || search_start != *offset)
1377                         return -EAGAIN;
1378
1379                 goto again;
1380         } else if (!bitmap_info->bytes)
1381                 free_bitmap(ctl, bitmap_info);
1382
1383         return 0;
1384 }
1385
1386 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
1387                       struct btrfs_free_space *info)
1388 {
1389         struct btrfs_block_group_cache *block_group = ctl->private;
1390
1391         /*
1392          * If we are below the extents threshold then we can add this as an
1393          * extent, and don't have to deal with the bitmap
1394          */
1395         if (ctl->free_extents < ctl->extents_thresh) {
1396                 /*
1397                  * If this block group has some small extents we don't want to
1398                  * use up all of our free slots in the cache with them, we want
1399                  * to reserve them to larger extents, however if we have plent
1400                  * of cache left then go ahead an dadd them, no sense in adding
1401                  * the overhead of a bitmap if we don't have to.
1402                  */
1403                 if (info->bytes <= block_group->sectorsize * 4) {
1404                         if (ctl->free_extents * 2 <= ctl->extents_thresh)
1405                                 return false;
1406                 } else {
1407                         return false;
1408                 }
1409         }
1410
1411         /*
1412          * some block groups are so tiny they can't be enveloped by a bitmap, so
1413          * don't even bother to create a bitmap for this
1414          */
1415         if (BITS_PER_BITMAP * block_group->sectorsize >
1416             block_group->key.offset)
1417                 return false;
1418
1419         return true;
1420 }
1421
1422 static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
1423                               struct btrfs_free_space *info)
1424 {
1425         struct btrfs_free_space *bitmap_info;
1426         int added = 0;
1427         u64 bytes, offset, end;
1428         int ret;
1429
1430         bytes = info->bytes;
1431         offset = info->offset;
1432
1433         if (!ctl->op->use_bitmap(ctl, info))
1434                 return 0;
1435
1436 again:
1437         bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1438                                          1, 0);
1439         if (!bitmap_info) {
1440                 BUG_ON(added);
1441                 goto new_bitmap;
1442         }
1443
1444         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
1445
1446         if (offset >= bitmap_info->offset && offset + bytes > end) {
1447                 bitmap_set_bits(ctl, bitmap_info, offset, end - offset);
1448                 bytes -= end - offset;
1449                 offset = end;
1450                 added = 0;
1451         } else if (offset >= bitmap_info->offset && offset + bytes <= end) {
1452                 bitmap_set_bits(ctl, bitmap_info, offset, bytes);
1453                 bytes = 0;
1454         } else {
1455                 BUG();
1456         }
1457
1458         if (!bytes) {
1459                 ret = 1;
1460                 goto out;
1461         } else
1462                 goto again;
1463
1464 new_bitmap:
1465         if (info && info->bitmap) {
1466                 add_new_bitmap(ctl, info, offset);
1467                 added = 1;
1468                 info = NULL;
1469                 goto again;
1470         } else {
1471                 spin_unlock(&ctl->tree_lock);
1472
1473                 /* no pre-allocated info, allocate a new one */
1474                 if (!info) {
1475                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
1476                                                  GFP_NOFS);
1477                         if (!info) {
1478                                 spin_lock(&ctl->tree_lock);
1479                                 ret = -ENOMEM;
1480                                 goto out;
1481                         }
1482                 }
1483
1484                 /* allocate the bitmap */
1485                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
1486                 spin_lock(&ctl->tree_lock);
1487                 if (!info->bitmap) {
1488                         ret = -ENOMEM;
1489                         goto out;
1490                 }
1491                 goto again;
1492         }
1493
1494 out:
1495         if (info) {
1496                 if (info->bitmap)
1497                         kfree(info->bitmap);
1498                 kmem_cache_free(btrfs_free_space_cachep, info);
1499         }
1500
1501         return ret;
1502 }
1503
1504 bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
1505                           struct btrfs_free_space *info, bool update_stat)
1506 {
1507         struct btrfs_free_space *left_info;
1508         struct btrfs_free_space *right_info;
1509         bool merged = false;
1510         u64 offset = info->offset;
1511         u64 bytes = info->bytes;
1512
1513         /*
1514          * first we want to see if there is free space adjacent to the range we
1515          * are adding, if there is remove that struct and add a new one to
1516          * cover the entire range
1517          */
1518         right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
1519         if (right_info && rb_prev(&right_info->offset_index))
1520                 left_info = rb_entry(rb_prev(&right_info->offset_index),
1521                                      struct btrfs_free_space, offset_index);
1522         else
1523                 left_info = tree_search_offset(ctl, offset - 1, 0, 0);
1524
1525         if (right_info && !right_info->bitmap) {
1526                 if (update_stat)
1527                         unlink_free_space(ctl, right_info);
1528                 else
1529                         __unlink_free_space(ctl, right_info);
1530                 info->bytes += right_info->bytes;
1531                 kmem_cache_free(btrfs_free_space_cachep, right_info);
1532                 merged = true;
1533         }
1534
1535         if (left_info && !left_info->bitmap &&
1536             left_info->offset + left_info->bytes == offset) {
1537                 if (update_stat)
1538                         unlink_free_space(ctl, left_info);
1539                 else
1540                         __unlink_free_space(ctl, left_info);
1541                 info->offset = left_info->offset;
1542                 info->bytes += left_info->bytes;
1543                 kmem_cache_free(btrfs_free_space_cachep, left_info);
1544                 merged = true;
1545         }
1546
1547         return merged;
1548 }
1549
1550 int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
1551                            u64 offset, u64 bytes)
1552 {
1553         struct btrfs_free_space *info;
1554         int ret = 0;
1555
1556         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
1557         if (!info)
1558                 return -ENOMEM;
1559
1560         info->offset = offset;
1561         info->bytes = bytes;
1562
1563         spin_lock(&ctl->tree_lock);
1564
1565         if (try_merge_free_space(ctl, info, true))
1566                 goto link;
1567
1568         /*
1569          * There was no extent directly to the left or right of this new
1570          * extent then we know we're going to have to allocate a new extent, so
1571          * before we do that see if we need to drop this into a bitmap
1572          */
1573         ret = insert_into_bitmap(ctl, info);
1574         if (ret < 0) {
1575                 goto out;
1576         } else if (ret) {
1577                 ret = 0;
1578                 goto out;
1579         }
1580 link:
1581         ret = link_free_space(ctl, info);
1582         if (ret)
1583                 kmem_cache_free(btrfs_free_space_cachep, info);
1584 out:
1585         spin_unlock(&ctl->tree_lock);
1586
1587         if (ret) {
1588                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
1589                 BUG_ON(ret == -EEXIST);
1590         }
1591
1592         return ret;
1593 }
1594
1595 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
1596                             u64 offset, u64 bytes)
1597 {
1598         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1599         struct btrfs_free_space *info;
1600         struct btrfs_free_space *next_info = NULL;
1601         int ret = 0;
1602
1603         spin_lock(&ctl->tree_lock);
1604
1605 again:
1606         info = tree_search_offset(ctl, offset, 0, 0);
1607         if (!info) {
1608                 /*
1609                  * oops didn't find an extent that matched the space we wanted
1610                  * to remove, look for a bitmap instead
1611                  */
1612                 info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1613                                           1, 0);
1614                 if (!info) {
1615                         WARN_ON(1);
1616                         goto out_lock;
1617                 }
1618         }
1619
1620         if (info->bytes < bytes && rb_next(&info->offset_index)) {
1621                 u64 end;
1622                 next_info = rb_entry(rb_next(&info->offset_index),
1623                                              struct btrfs_free_space,
1624                                              offset_index);
1625
1626                 if (next_info->bitmap)
1627                         end = next_info->offset +
1628                               BITS_PER_BITMAP * ctl->unit - 1;
1629                 else
1630                         end = next_info->offset + next_info->bytes;
1631
1632                 if (next_info->bytes < bytes ||
1633                     next_info->offset > offset || offset > end) {
1634                         printk(KERN_CRIT "Found free space at %llu, size %llu,"
1635                               " trying to use %llu\n",
1636                               (unsigned long long)info->offset,
1637                               (unsigned long long)info->bytes,
1638                               (unsigned long long)bytes);
1639                         WARN_ON(1);
1640                         ret = -EINVAL;
1641                         goto out_lock;
1642                 }
1643
1644                 info = next_info;
1645         }
1646
1647         if (info->bytes == bytes) {
1648                 unlink_free_space(ctl, info);
1649                 if (info->bitmap) {
1650                         kfree(info->bitmap);
1651                         ctl->total_bitmaps--;
1652                 }
1653                 kmem_cache_free(btrfs_free_space_cachep, info);
1654                 goto out_lock;
1655         }
1656
1657         if (!info->bitmap && info->offset == offset) {
1658                 unlink_free_space(ctl, info);
1659                 info->offset += bytes;
1660                 info->bytes -= bytes;
1661                 link_free_space(ctl, info);
1662                 goto out_lock;
1663         }
1664
1665         if (!info->bitmap && info->offset <= offset &&
1666             info->offset + info->bytes >= offset + bytes) {
1667                 u64 old_start = info->offset;
1668                 /*
1669                  * we're freeing space in the middle of the info,
1670                  * this can happen during tree log replay
1671                  *
1672                  * first unlink the old info and then
1673                  * insert it again after the hole we're creating
1674                  */
1675                 unlink_free_space(ctl, info);
1676                 if (offset + bytes < info->offset + info->bytes) {
1677                         u64 old_end = info->offset + info->bytes;
1678
1679                         info->offset = offset + bytes;
1680                         info->bytes = old_end - info->offset;
1681                         ret = link_free_space(ctl, info);
1682                         WARN_ON(ret);
1683                         if (ret)
1684                                 goto out_lock;
1685                 } else {
1686                         /* the hole we're creating ends at the end
1687                          * of the info struct, just free the info
1688                          */
1689                         kmem_cache_free(btrfs_free_space_cachep, info);
1690                 }
1691                 spin_unlock(&ctl->tree_lock);
1692
1693                 /* step two, insert a new info struct to cover
1694                  * anything before the hole
1695                  */
1696                 ret = btrfs_add_free_space(block_group, old_start,
1697                                            offset - old_start);
1698                 WARN_ON(ret);
1699                 goto out;
1700         }
1701
1702         ret = remove_from_bitmap(ctl, info, &offset, &bytes);
1703         if (ret == -EAGAIN)
1704                 goto again;
1705         BUG_ON(ret);
1706 out_lock:
1707         spin_unlock(&ctl->tree_lock);
1708 out:
1709         return ret;
1710 }
1711
1712 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
1713                            u64 bytes)
1714 {
1715         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1716         struct btrfs_free_space *info;
1717         struct rb_node *n;
1718         int count = 0;
1719
1720         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
1721                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1722                 if (info->bytes >= bytes)
1723                         count++;
1724                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
1725                        (unsigned long long)info->offset,
1726                        (unsigned long long)info->bytes,
1727                        (info->bitmap) ? "yes" : "no");
1728         }
1729         printk(KERN_INFO "block group has cluster?: %s\n",
1730                list_empty(&block_group->cluster_list) ? "no" : "yes");
1731         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
1732                "\n", count);
1733 }
1734
1735 static struct btrfs_free_space_op free_space_op = {
1736         .recalc_thresholds      = recalculate_thresholds,
1737         .use_bitmap             = use_bitmap,
1738 };
1739
1740 void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
1741 {
1742         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1743
1744         spin_lock_init(&ctl->tree_lock);
1745         ctl->unit = block_group->sectorsize;
1746         ctl->start = block_group->key.objectid;
1747         ctl->private = block_group;
1748         ctl->op = &free_space_op;
1749
1750         /*
1751          * we only want to have 32k of ram per block group for keeping
1752          * track of free space, and if we pass 1/2 of that we want to
1753          * start converting things over to using bitmaps
1754          */
1755         ctl->extents_thresh = ((1024 * 32) / 2) /
1756                                 sizeof(struct btrfs_free_space);
1757 }
1758
1759 /*
1760  * for a given cluster, put all of its extents back into the free
1761  * space cache.  If the block group passed doesn't match the block group
1762  * pointed to by the cluster, someone else raced in and freed the
1763  * cluster already.  In that case, we just return without changing anything
1764  */
1765 static int
1766 __btrfs_return_cluster_to_free_space(
1767                              struct btrfs_block_group_cache *block_group,
1768                              struct btrfs_free_cluster *cluster)
1769 {
1770         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1771         struct btrfs_free_space *entry;
1772         struct rb_node *node;
1773
1774         spin_lock(&cluster->lock);
1775         if (cluster->block_group != block_group)
1776                 goto out;
1777
1778         cluster->block_group = NULL;
1779         cluster->window_start = 0;
1780         list_del_init(&cluster->block_group_list);
1781
1782         node = rb_first(&cluster->root);
1783         while (node) {
1784                 bool bitmap;
1785
1786                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1787                 node = rb_next(&entry->offset_index);
1788                 rb_erase(&entry->offset_index, &cluster->root);
1789
1790                 bitmap = (entry->bitmap != NULL);
1791                 if (!bitmap)
1792                         try_merge_free_space(ctl, entry, false);
1793                 tree_insert_offset(&ctl->free_space_offset,
1794                                    entry->offset, &entry->offset_index, bitmap);
1795         }
1796         cluster->root = RB_ROOT;
1797
1798 out:
1799         spin_unlock(&cluster->lock);
1800         btrfs_put_block_group(block_group);
1801         return 0;
1802 }
1803
1804 void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
1805 {
1806         struct btrfs_free_space *info;
1807         struct rb_node *node;
1808
1809         spin_lock(&ctl->tree_lock);
1810         while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
1811                 info = rb_entry(node, struct btrfs_free_space, offset_index);
1812                 unlink_free_space(ctl, info);
1813                 kfree(info->bitmap);
1814                 kmem_cache_free(btrfs_free_space_cachep, info);
1815                 if (need_resched()) {
1816                         spin_unlock(&ctl->tree_lock);
1817                         cond_resched();
1818                         spin_lock(&ctl->tree_lock);
1819                 }
1820         }
1821         spin_unlock(&ctl->tree_lock);
1822 }
1823
1824 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
1825 {
1826         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1827         struct btrfs_free_cluster *cluster;
1828         struct list_head *head;
1829
1830         spin_lock(&ctl->tree_lock);
1831         while ((head = block_group->cluster_list.next) !=
1832                &block_group->cluster_list) {
1833                 cluster = list_entry(head, struct btrfs_free_cluster,
1834                                      block_group_list);
1835
1836                 WARN_ON(cluster->block_group != block_group);
1837                 __btrfs_return_cluster_to_free_space(block_group, cluster);
1838                 if (need_resched()) {
1839                         spin_unlock(&ctl->tree_lock);
1840                         cond_resched();
1841                         spin_lock(&ctl->tree_lock);
1842                 }
1843         }
1844         spin_unlock(&ctl->tree_lock);
1845
1846         __btrfs_remove_free_space_cache(ctl);
1847 }
1848
1849 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
1850                                u64 offset, u64 bytes, u64 empty_size)
1851 {
1852         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1853         struct btrfs_free_space *entry = NULL;
1854         u64 bytes_search = bytes + empty_size;
1855         u64 ret = 0;
1856
1857         spin_lock(&ctl->tree_lock);
1858         entry = find_free_space(ctl, &offset, &bytes_search);
1859         if (!entry)
1860                 goto out;
1861
1862         ret = offset;
1863         if (entry->bitmap) {
1864                 bitmap_clear_bits(ctl, entry, offset, bytes);
1865                 if (!entry->bytes)
1866                         free_bitmap(ctl, entry);
1867         } else {
1868                 unlink_free_space(ctl, entry);
1869                 entry->offset += bytes;
1870                 entry->bytes -= bytes;
1871                 if (!entry->bytes)
1872                         kmem_cache_free(btrfs_free_space_cachep, entry);
1873                 else
1874                         link_free_space(ctl, entry);
1875         }
1876
1877 out:
1878         spin_unlock(&ctl->tree_lock);
1879
1880         return ret;
1881 }
1882
1883 /*
1884  * given a cluster, put all of its extents back into the free space
1885  * cache.  If a block group is passed, this function will only free
1886  * a cluster that belongs to the passed block group.
1887  *
1888  * Otherwise, it'll get a reference on the block group pointed to by the
1889  * cluster and remove the cluster from it.
1890  */
1891 int btrfs_return_cluster_to_free_space(
1892                                struct btrfs_block_group_cache *block_group,
1893                                struct btrfs_free_cluster *cluster)
1894 {
1895         struct btrfs_free_space_ctl *ctl;
1896         int ret;
1897
1898         /* first, get a safe pointer to the block group */
1899         spin_lock(&cluster->lock);
1900         if (!block_group) {
1901                 block_group = cluster->block_group;
1902                 if (!block_group) {
1903                         spin_unlock(&cluster->lock);
1904                         return 0;
1905                 }
1906         } else if (cluster->block_group != block_group) {
1907                 /* someone else has already freed it don't redo their work */
1908                 spin_unlock(&cluster->lock);
1909                 return 0;
1910         }
1911         atomic_inc(&block_group->count);
1912         spin_unlock(&cluster->lock);
1913
1914         ctl = block_group->free_space_ctl;
1915
1916         /* now return any extents the cluster had on it */
1917         spin_lock(&ctl->tree_lock);
1918         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
1919         spin_unlock(&ctl->tree_lock);
1920
1921         /* finally drop our ref */
1922         btrfs_put_block_group(block_group);
1923         return ret;
1924 }
1925
1926 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
1927                                    struct btrfs_free_cluster *cluster,
1928                                    struct btrfs_free_space *entry,
1929                                    u64 bytes, u64 min_start)
1930 {
1931         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1932         int err;
1933         u64 search_start = cluster->window_start;
1934         u64 search_bytes = bytes;
1935         u64 ret = 0;
1936
1937         search_start = min_start;
1938         search_bytes = bytes;
1939
1940         err = search_bitmap(ctl, entry, &search_start, &search_bytes);
1941         if (err)
1942                 return 0;
1943
1944         ret = search_start;
1945         bitmap_clear_bits(ctl, entry, ret, bytes);
1946
1947         return ret;
1948 }
1949
1950 /*
1951  * given a cluster, try to allocate 'bytes' from it, returns 0
1952  * if it couldn't find anything suitably large, or a logical disk offset
1953  * if things worked out
1954  */
1955 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
1956                              struct btrfs_free_cluster *cluster, u64 bytes,
1957                              u64 min_start)
1958 {
1959         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1960         struct btrfs_free_space *entry = NULL;
1961         struct rb_node *node;
1962         u64 ret = 0;
1963
1964         spin_lock(&cluster->lock);
1965         if (bytes > cluster->max_size)
1966                 goto out;
1967
1968         if (cluster->block_group != block_group)
1969                 goto out;
1970
1971         node = rb_first(&cluster->root);
1972         if (!node)
1973                 goto out;
1974
1975         entry = rb_entry(node, struct btrfs_free_space, offset_index);
1976         while(1) {
1977                 if (entry->bytes < bytes ||
1978                     (!entry->bitmap && entry->offset < min_start)) {
1979                         struct rb_node *node;
1980
1981                         node = rb_next(&entry->offset_index);
1982                         if (!node)
1983                                 break;
1984                         entry = rb_entry(node, struct btrfs_free_space,
1985                                          offset_index);
1986                         continue;
1987                 }
1988
1989                 if (entry->bitmap) {
1990                         ret = btrfs_alloc_from_bitmap(block_group,
1991                                                       cluster, entry, bytes,
1992                                                       min_start);
1993                         if (ret == 0) {
1994                                 struct rb_node *node;
1995                                 node = rb_next(&entry->offset_index);
1996                                 if (!node)
1997                                         break;
1998                                 entry = rb_entry(node, struct btrfs_free_space,
1999                                                  offset_index);
2000                                 continue;
2001                         }
2002                 } else {
2003
2004                         ret = entry->offset;
2005
2006                         entry->offset += bytes;
2007                         entry->bytes -= bytes;
2008                 }
2009
2010                 if (entry->bytes == 0)
2011                         rb_erase(&entry->offset_index, &cluster->root);
2012                 break;
2013         }
2014 out:
2015         spin_unlock(&cluster->lock);
2016
2017         if (!ret)
2018                 return 0;
2019
2020         spin_lock(&ctl->tree_lock);
2021
2022         ctl->free_space -= bytes;
2023         if (entry->bytes == 0) {
2024                 ctl->free_extents--;
2025                 if (entry->bitmap) {
2026                         kfree(entry->bitmap);
2027                         ctl->total_bitmaps--;
2028                         ctl->op->recalc_thresholds(ctl);
2029                 }
2030                 kmem_cache_free(btrfs_free_space_cachep, entry);
2031         }
2032
2033         spin_unlock(&ctl->tree_lock);
2034
2035         return ret;
2036 }
2037
2038 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
2039                                 struct btrfs_free_space *entry,
2040                                 struct btrfs_free_cluster *cluster,
2041                                 u64 offset, u64 bytes, u64 min_bytes)
2042 {
2043         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2044         unsigned long next_zero;
2045         unsigned long i;
2046         unsigned long search_bits;
2047         unsigned long total_bits;
2048         unsigned long found_bits;
2049         unsigned long start = 0;
2050         unsigned long total_found = 0;
2051         int ret;
2052         bool found = false;
2053
2054         i = offset_to_bit(entry->offset, block_group->sectorsize,
2055                           max_t(u64, offset, entry->offset));
2056         search_bits = bytes_to_bits(bytes, block_group->sectorsize);
2057         total_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
2058
2059 again:
2060         found_bits = 0;
2061         for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
2062              i < BITS_PER_BITMAP;
2063              i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
2064                 next_zero = find_next_zero_bit(entry->bitmap,
2065                                                BITS_PER_BITMAP, i);
2066                 if (next_zero - i >= search_bits) {
2067                         found_bits = next_zero - i;
2068                         break;
2069                 }
2070                 i = next_zero;
2071         }
2072
2073         if (!found_bits)
2074                 return -ENOSPC;
2075
2076         if (!found) {
2077                 start = i;
2078                 found = true;
2079         }
2080
2081         total_found += found_bits;
2082
2083         if (cluster->max_size < found_bits * block_group->sectorsize)
2084                 cluster->max_size = found_bits * block_group->sectorsize;
2085
2086         if (total_found < total_bits) {
2087                 i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero);
2088                 if (i - start > total_bits * 2) {
2089                         total_found = 0;
2090                         cluster->max_size = 0;
2091                         found = false;
2092                 }
2093                 goto again;
2094         }
2095
2096         cluster->window_start = start * block_group->sectorsize +
2097                 entry->offset;
2098         rb_erase(&entry->offset_index, &ctl->free_space_offset);
2099         ret = tree_insert_offset(&cluster->root, entry->offset,
2100                                  &entry->offset_index, 1);
2101         BUG_ON(ret);
2102
2103         return 0;
2104 }
2105
2106 /*
2107  * This searches the block group for just extents to fill the cluster with.
2108  */
2109 static int setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
2110                                    struct btrfs_free_cluster *cluster,
2111                                    u64 offset, u64 bytes, u64 min_bytes)
2112 {
2113         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2114         struct btrfs_free_space *first = NULL;
2115         struct btrfs_free_space *entry = NULL;
2116         struct btrfs_free_space *prev = NULL;
2117         struct btrfs_free_space *last;
2118         struct rb_node *node;
2119         u64 window_start;
2120         u64 window_free;
2121         u64 max_extent;
2122         u64 max_gap = 128 * 1024;
2123
2124         entry = tree_search_offset(ctl, offset, 0, 1);
2125         if (!entry)
2126                 return -ENOSPC;
2127
2128         /*
2129          * We don't want bitmaps, so just move along until we find a normal
2130          * extent entry.
2131          */
2132         while (entry->bitmap) {
2133                 node = rb_next(&entry->offset_index);
2134                 if (!node)
2135                         return -ENOSPC;
2136                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2137         }
2138
2139         window_start = entry->offset;
2140         window_free = entry->bytes;
2141         max_extent = entry->bytes;
2142         first = entry;
2143         last = entry;
2144         prev = entry;
2145
2146         while (window_free <= min_bytes) {
2147                 node = rb_next(&entry->offset_index);
2148                 if (!node)
2149                         return -ENOSPC;
2150                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2151
2152                 if (entry->bitmap)
2153                         continue;
2154                 /*
2155                  * we haven't filled the empty size and the window is
2156                  * very large.  reset and try again
2157                  */
2158                 if (entry->offset - (prev->offset + prev->bytes) > max_gap ||
2159                     entry->offset - window_start > (min_bytes * 2)) {
2160                         first = entry;
2161                         window_start = entry->offset;
2162                         window_free = entry->bytes;
2163                         last = entry;
2164                         max_extent = entry->bytes;
2165                 } else {
2166                         last = entry;
2167                         window_free += entry->bytes;
2168                         if (entry->bytes > max_extent)
2169                                 max_extent = entry->bytes;
2170                 }
2171                 prev = entry;
2172         }
2173
2174         cluster->window_start = first->offset;
2175
2176         node = &first->offset_index;
2177
2178         /*
2179          * now we've found our entries, pull them out of the free space
2180          * cache and put them into the cluster rbtree
2181          */
2182         do {
2183                 int ret;
2184
2185                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2186                 node = rb_next(&entry->offset_index);
2187                 if (entry->bitmap)
2188                         continue;
2189
2190                 rb_erase(&entry->offset_index, &ctl->free_space_offset);
2191                 ret = tree_insert_offset(&cluster->root, entry->offset,
2192                                          &entry->offset_index, 0);
2193                 BUG_ON(ret);
2194         } while (node && entry != last);
2195
2196         cluster->max_size = max_extent;
2197
2198         return 0;
2199 }
2200
2201 /*
2202  * This specifically looks for bitmaps that may work in the cluster, we assume
2203  * that we have already failed to find extents that will work.
2204  */
2205 static int setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2206                                 struct btrfs_free_cluster *cluster,
2207                                 u64 offset, u64 bytes, u64 min_bytes)
2208 {
2209         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2210         struct btrfs_free_space *entry;
2211         struct rb_node *node;
2212         int ret = -ENOSPC;
2213
2214         if (ctl->total_bitmaps == 0)
2215                 return -ENOSPC;
2216
2217         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, offset), 0, 1);
2218         if (!entry)
2219                 return -ENOSPC;
2220
2221         node = &entry->offset_index;
2222         do {
2223                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2224                 node = rb_next(&entry->offset_index);
2225                 if (!entry->bitmap)
2226                         continue;
2227                 if (entry->bytes < min_bytes)
2228                         continue;
2229                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2230                                            bytes, min_bytes);
2231         } while (ret && node);
2232
2233         return ret;
2234 }
2235
2236 /*
2237  * here we try to find a cluster of blocks in a block group.  The goal
2238  * is to find at least bytes free and up to empty_size + bytes free.
2239  * We might not find them all in one contiguous area.
2240  *
2241  * returns zero and sets up cluster if things worked out, otherwise
2242  * it returns -enospc
2243  */
2244 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
2245                              struct btrfs_root *root,
2246                              struct btrfs_block_group_cache *block_group,
2247                              struct btrfs_free_cluster *cluster,
2248                              u64 offset, u64 bytes, u64 empty_size)
2249 {
2250         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2251         u64 min_bytes;
2252         int ret;
2253
2254         /* for metadata, allow allocates with more holes */
2255         if (btrfs_test_opt(root, SSD_SPREAD)) {
2256                 min_bytes = bytes + empty_size;
2257         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
2258                 /*
2259                  * we want to do larger allocations when we are
2260                  * flushing out the delayed refs, it helps prevent
2261                  * making more work as we go along.
2262                  */
2263                 if (trans->transaction->delayed_refs.flushing)
2264                         min_bytes = max(bytes, (bytes + empty_size) >> 1);
2265                 else
2266                         min_bytes = max(bytes, (bytes + empty_size) >> 4);
2267         } else
2268                 min_bytes = max(bytes, (bytes + empty_size) >> 2);
2269
2270         spin_lock(&ctl->tree_lock);
2271
2272         /*
2273          * If we know we don't have enough space to make a cluster don't even
2274          * bother doing all the work to try and find one.
2275          */
2276         if (ctl->free_space < min_bytes) {
2277                 spin_unlock(&ctl->tree_lock);
2278                 return -ENOSPC;
2279         }
2280
2281         spin_lock(&cluster->lock);
2282
2283         /* someone already found a cluster, hooray */
2284         if (cluster->block_group) {
2285                 ret = 0;
2286                 goto out;
2287         }
2288
2289         ret = setup_cluster_no_bitmap(block_group, cluster, offset, bytes,
2290                                       min_bytes);
2291         if (ret)
2292                 ret = setup_cluster_bitmap(block_group, cluster, offset,
2293                                            bytes, min_bytes);
2294
2295         if (!ret) {
2296                 atomic_inc(&block_group->count);
2297                 list_add_tail(&cluster->block_group_list,
2298                               &block_group->cluster_list);
2299                 cluster->block_group = block_group;
2300         }
2301 out:
2302         spin_unlock(&cluster->lock);
2303         spin_unlock(&ctl->tree_lock);
2304
2305         return ret;
2306 }
2307
2308 /*
2309  * simple code to zero out a cluster
2310  */
2311 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
2312 {
2313         spin_lock_init(&cluster->lock);
2314         spin_lock_init(&cluster->refill_lock);
2315         cluster->root = RB_ROOT;
2316         cluster->max_size = 0;
2317         INIT_LIST_HEAD(&cluster->block_group_list);
2318         cluster->block_group = NULL;
2319 }
2320
2321 int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
2322                            u64 *trimmed, u64 start, u64 end, u64 minlen)
2323 {
2324         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2325         struct btrfs_free_space *entry = NULL;
2326         struct btrfs_fs_info *fs_info = block_group->fs_info;
2327         u64 bytes = 0;
2328         u64 actually_trimmed;
2329         int ret = 0;
2330
2331         *trimmed = 0;
2332
2333         while (start < end) {
2334                 spin_lock(&ctl->tree_lock);
2335
2336                 if (ctl->free_space < minlen) {
2337                         spin_unlock(&ctl->tree_lock);
2338                         break;
2339                 }
2340
2341                 entry = tree_search_offset(ctl, start, 0, 1);
2342                 if (!entry)
2343                         entry = tree_search_offset(ctl,
2344                                                    offset_to_bitmap(ctl, start),
2345                                                    1, 1);
2346
2347                 if (!entry || entry->offset >= end) {
2348                         spin_unlock(&ctl->tree_lock);
2349                         break;
2350                 }
2351
2352                 if (entry->bitmap) {
2353                         ret = search_bitmap(ctl, entry, &start, &bytes);
2354                         if (!ret) {
2355                                 if (start >= end) {
2356                                         spin_unlock(&ctl->tree_lock);
2357                                         break;
2358                                 }
2359                                 bytes = min(bytes, end - start);
2360                                 bitmap_clear_bits(ctl, entry, start, bytes);
2361                                 if (entry->bytes == 0)
2362                                         free_bitmap(ctl, entry);
2363                         } else {
2364                                 start = entry->offset + BITS_PER_BITMAP *
2365                                         block_group->sectorsize;
2366                                 spin_unlock(&ctl->tree_lock);
2367                                 ret = 0;
2368                                 continue;
2369                         }
2370                 } else {
2371                         start = entry->offset;
2372                         bytes = min(entry->bytes, end - start);
2373                         unlink_free_space(ctl, entry);
2374                         kfree(entry);
2375                 }
2376
2377                 spin_unlock(&ctl->tree_lock);
2378
2379                 if (bytes >= minlen) {
2380                         int update_ret;
2381                         update_ret = btrfs_update_reserved_bytes(block_group,
2382                                                                  bytes, 1, 1);
2383
2384                         ret = btrfs_error_discard_extent(fs_info->extent_root,
2385                                                          start,
2386                                                          bytes,
2387                                                          &actually_trimmed);
2388
2389                         btrfs_add_free_space(block_group, start, bytes);
2390                         if (!update_ret)
2391                                 btrfs_update_reserved_bytes(block_group,
2392                                                             bytes, 0, 1);
2393
2394                         if (ret)
2395                                 break;
2396                         *trimmed += actually_trimmed;
2397                 }
2398                 start += bytes;
2399                 bytes = 0;
2400
2401                 if (fatal_signal_pending(current)) {
2402                         ret = -ERESTARTSYS;
2403                         break;
2404                 }
2405
2406                 cond_resched();
2407         }
2408
2409         return ret;
2410 }
2411
2412 /*
2413  * Find the left-most item in the cache tree, and then return the
2414  * smallest inode number in the item.
2415  *
2416  * Note: the returned inode number may not be the smallest one in
2417  * the tree, if the left-most item is a bitmap.
2418  */
2419 u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root)
2420 {
2421         struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl;
2422         struct btrfs_free_space *entry = NULL;
2423         u64 ino = 0;
2424
2425         spin_lock(&ctl->tree_lock);
2426
2427         if (RB_EMPTY_ROOT(&ctl->free_space_offset))
2428                 goto out;
2429
2430         entry = rb_entry(rb_first(&ctl->free_space_offset),
2431                          struct btrfs_free_space, offset_index);
2432
2433         if (!entry->bitmap) {
2434                 ino = entry->offset;
2435
2436                 unlink_free_space(ctl, entry);
2437                 entry->offset++;
2438                 entry->bytes--;
2439                 if (!entry->bytes)
2440                         kmem_cache_free(btrfs_free_space_cachep, entry);
2441                 else
2442                         link_free_space(ctl, entry);
2443         } else {
2444                 u64 offset = 0;
2445                 u64 count = 1;
2446                 int ret;
2447
2448                 ret = search_bitmap(ctl, entry, &offset, &count);
2449                 BUG_ON(ret);
2450
2451                 ino = offset;
2452                 bitmap_clear_bits(ctl, entry, offset, 1);
2453                 if (entry->bytes == 0)
2454                         free_bitmap(ctl, entry);
2455         }
2456 out:
2457         spin_unlock(&ctl->tree_lock);
2458
2459         return ino;
2460 }