fs/btrfs/free-space-cache.c

   1 /*
   2  * Copyright (C) 2008 Red Hat.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/pagemap.h>
  20 #include <linux/sched.h>
  21 #include <linux/slab.h>
  22 #include <linux/math64.h>
  23 #include <linux/ratelimit.h>
  24 #include "ctree.h"
  25 #include "free-space-cache.h"
  26 #include "transaction.h"
  27 #include "disk-io.h"
  28 #include "extent_io.h"
  29 #include "inode-map.h"
  30
  31 #define BITS_PER_BITMAP         (PAGE_CACHE_SIZE * 8)
  32 #define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
  33
  34 static int link_free_space(struct btrfs_free_space_ctl *ctl,
  35                            struct btrfs_free_space *info);
  36
  37 static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
  38                                                struct btrfs_path *path,
  39                                                u64 offset)
  40 {
  41         struct btrfs_key key;
  42         struct btrfs_key location;
  43         struct btrfs_disk_key disk_key;
  44         struct btrfs_free_space_header *header;
  45         struct extent_buffer *leaf;
  46         struct inode *inode = NULL;
  47         int ret;
  48
  49         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
  50         key.offset = offset;
  51         key.type = 0;
  52
  53         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  54         if (ret < 0)
  55                 return ERR_PTR(ret);
  56         if (ret > 0) {
  57                 btrfs_release_path(path);
  58                 return ERR_PTR(-ENOENT);
  59         }
  60
  61         leaf = path->nodes[0];
  62         header = btrfs_item_ptr(leaf, path->slots[0],
  63                                 struct btrfs_free_space_header);
  64         btrfs_free_space_key(leaf, header, &disk_key);
  65         btrfs_disk_key_to_cpu(&location, &disk_key);
  66         btrfs_release_path(path);
  67
  68         inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
  69         if (!inode)
  70                 return ERR_PTR(-ENOENT);
  71         if (IS_ERR(inode))
  72                 return inode;
  73         if (is_bad_inode(inode)) {
  74                 iput(inode);
  75                 return ERR_PTR(-ENOENT);
  76         }
  77
  78         inode->i_mapping->flags &= ~__GFP_FS;
  79
  80         return inode;
  81 }
  82
  83 struct inode *lookup_free_space_inode(struct btrfs_root *root,
  84                                       struct btrfs_block_group_cache
  85                                       *block_group, struct btrfs_path *path)
  86 {
  87         struct inode *inode = NULL;
  88         u32 flags = BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
  89
  90         spin_lock(&block_group->lock);
  91         if (block_group->inode)
  92                 inode = igrab(block_group->inode);
  93         spin_unlock(&block_group->lock);
  94         if (inode)
  95                 return inode;
  96
  97         inode = __lookup_free_space_inode(root, path,
  98                                           block_group->key.objectid);
  99         if (IS_ERR(inode))
 100                 return inode;
 101
 102         spin_lock(&block_group->lock);
 103         if (!((BTRFS_I(inode)->flags & flags) == flags)) {
 104                 printk(KERN_INFO "Old style space inode found, converting.\n");
 105                 BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM |
 106                         BTRFS_INODE_NODATACOW;
 107                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 108         }
 109
 110         if (!block_group->iref) {
 111                 block_group->inode = igrab(inode);
 112                 block_group->iref = 1;
 113         }
 114         spin_unlock(&block_group->lock);
 115
 116         return inode;
 117 }
 118
 119 int __create_free_space_inode(struct btrfs_root *root,
 120                               struct btrfs_trans_handle *trans,
 121                               struct btrfs_path *path, u64 ino, u64 offset)
 122 {
 123         struct btrfs_key key;
 124         struct btrfs_disk_key disk_key;
 125         struct btrfs_free_space_header *header;
 126         struct btrfs_inode_item *inode_item;
 127         struct extent_buffer *leaf;
 128         u64 flags = BTRFS_INODE_NOCOMPRESS | BTRFS_INODE_PREALLOC;
 129         int ret;
 130
 131         ret = btrfs_insert_empty_inode(trans, root, path, ino);
 132         if (ret)
 133                 return ret;
 134
 135         /* We inline crc's for the free disk space cache */
 136         if (ino != BTRFS_FREE_INO_OBJECTID)
 137                 flags |= BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
 138
 139         leaf = path->nodes[0];
 140         inode_item = btrfs_item_ptr(leaf, path->slots[0],
 141                                     struct btrfs_inode_item);
 142         btrfs_item_key(leaf, &disk_key, path->slots[0]);
 143         memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
 144                              sizeof(*inode_item));
 145         btrfs_set_inode_generation(leaf, inode_item, trans->transid);
 146         btrfs_set_inode_size(leaf, inode_item, 0);
 147         btrfs_set_inode_nbytes(leaf, inode_item, 0);
 148         btrfs_set_inode_uid(leaf, inode_item, 0);
 149         btrfs_set_inode_gid(leaf, inode_item, 0);
 150         btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
 151         btrfs_set_inode_flags(leaf, inode_item, flags);
 152         btrfs_set_inode_nlink(leaf, inode_item, 1);
 153         btrfs_set_inode_transid(leaf, inode_item, trans->transid);
 154         btrfs_set_inode_block_group(leaf, inode_item, offset);
 155         btrfs_mark_buffer_dirty(leaf);
 156         btrfs_release_path(path);
 157
 158         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 159         key.offset = offset;
 160         key.type = 0;
 161
 162         ret = btrfs_insert_empty_item(trans, root, path, &key,
 163                                       sizeof(struct btrfs_free_space_header));
 164         if (ret < 0) {
 165                 btrfs_release_path(path);
 166                 return ret;
 167         }
 168         leaf = path->nodes[0];
 169         header = btrfs_item_ptr(leaf, path->slots[0],
 170                                 struct btrfs_free_space_header);
 171         memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
 172         btrfs_set_free_space_key(leaf, header, &disk_key);
 173         btrfs_mark_buffer_dirty(leaf);
 174         btrfs_release_path(path);
 175
 176         return 0;
 177 }
 178
 179 int create_free_space_inode(struct btrfs_root *root,
 180                             struct btrfs_trans_handle *trans,
 181                             struct btrfs_block_group_cache *block_group,
 182                             struct btrfs_path *path)
 183 {
 184         int ret;
 185         u64 ino;
 186
 187         ret = btrfs_find_free_objectid(root, &ino);
 188         if (ret < 0)
 189                 return ret;
 190
 191         return __create_free_space_inode(root, trans, path, ino,
 192                                          block_group->key.objectid);
 193 }
 194
 195 int btrfs_truncate_free_space_cache(struct btrfs_root *root,
 196                                     struct btrfs_trans_handle *trans,
 197                                     struct btrfs_path *path,
 198                                     struct inode *inode)
 199 {
 200         struct btrfs_block_rsv *rsv;
 201         u64 needed_bytes;
 202         loff_t oldsize;
 203         int ret = 0;
 204
 205         rsv = trans->block_rsv;
 206         trans->block_rsv = &root->fs_info->global_block_rsv;
 207
 208         /* 1 for slack space, 1 for updating the inode */
 209         needed_bytes = btrfs_calc_trunc_metadata_size(root, 1) +
 210                 btrfs_calc_trans_metadata_size(root, 1);
 211
 212         spin_lock(&trans->block_rsv->lock);
 213         if (trans->block_rsv->reserved < needed_bytes) {
 214                 spin_unlock(&trans->block_rsv->lock);
 215                 trans->block_rsv = rsv;
 216                 return -ENOSPC;
 217         }
 218         spin_unlock(&trans->block_rsv->lock);
 219
 220         oldsize = i_size_read(inode);
 221         btrfs_i_size_write(inode, 0);
 222         truncate_pagecache(inode, oldsize, 0);
 223
 224         /*
 225          * We don't need an orphan item because truncating the free space cache
 226          * will never be split across transactions.
 227          */
 228         ret = btrfs_truncate_inode_items(trans, root, inode,
 229                                          0, BTRFS_EXTENT_DATA_KEY);
 230
 231         if (ret) {
 232                 trans->block_rsv = rsv;
 233                 btrfs_abort_transaction(trans, root, ret);
 234                 return ret;
 235         }
 236
 237         ret = btrfs_update_inode(trans, root, inode);
 238         if (ret)
 239                 btrfs_abort_transaction(trans, root, ret);
 240         trans->block_rsv = rsv;
 241
 242         return ret;
 243 }
 244
 245 static int readahead_cache(struct inode *inode)
 246 {
 247         struct file_ra_state *ra;
 248         unsigned long last_index;
 249
 250         ra = kzalloc(sizeof(*ra), GFP_NOFS);
 251         if (!ra)
 252                 return -ENOMEM;
 253
 254         file_ra_state_init(ra, inode->i_mapping);
 255         last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 256
 257         page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
 258
 259         kfree(ra);
 260
 261         return 0;
 262 }
 263
 264 struct io_ctl {
 265         void *cur, *orig;
 266         struct page *page;
 267         struct page **pages;
 268         struct btrfs_root *root;
 269         unsigned long size;
 270         int index;
 271         int num_pages;
 272         unsigned check_crcs:1;
 273 };
 274
 275 static int io_ctl_init(struct io_ctl *io_ctl, struct inode *inode,
 276                        struct btrfs_root *root)
 277 {
 278         memset(io_ctl, 0, sizeof(struct io_ctl));
 279         io_ctl->num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
 280                 PAGE_CACHE_SHIFT;
 281         io_ctl->pages = kzalloc(sizeof(struct page *) * io_ctl->num_pages,
 282                                 GFP_NOFS);
 283         if (!io_ctl->pages)
 284                 return -ENOMEM;
 285         io_ctl->root = root;
 286         if (btrfs_ino(inode) != BTRFS_FREE_INO_OBJECTID)
 287                 io_ctl->check_crcs = 1;
 288         return 0;
 289 }
 290
 291 static void io_ctl_free(struct io_ctl *io_ctl)
 292 {
 293         kfree(io_ctl->pages);
 294 }
 295
 296 static void io_ctl_unmap_page(struct io_ctl *io_ctl)
 297 {
 298         if (io_ctl->cur) {
 299                 kunmap(io_ctl->page);
 300                 io_ctl->cur = NULL;
 301                 io_ctl->orig = NULL;
 302         }
 303 }
 304
 305 static void io_ctl_map_page(struct io_ctl *io_ctl, int clear)
 306 {
 307         WARN_ON(io_ctl->cur);
 308         BUG_ON(io_ctl->index >= io_ctl->num_pages);
 309         io_ctl->page = io_ctl->pages[io_ctl->index++];
 310         io_ctl->cur = kmap(io_ctl->page);
 311         io_ctl->orig = io_ctl->cur;
 312         io_ctl->size = PAGE_CACHE_SIZE;
 313         if (clear)
 314                 memset(io_ctl->cur, 0, PAGE_CACHE_SIZE);
 315 }
 316
 317 static void io_ctl_drop_pages(struct io_ctl *io_ctl)
 318 {
 319         int i;
 320
 321         io_ctl_unmap_page(io_ctl);
 322
 323         for (i = 0; i < io_ctl->num_pages; i++) {
 324                 if (io_ctl->pages[i]) {
 325                         ClearPageChecked(io_ctl->pages[i]);
 326                         unlock_page(io_ctl->pages[i]);
 327                         page_cache_release(io_ctl->pages[i]);
 328                 }
 329         }
 330 }
 331
 332 static int io_ctl_prepare_pages(struct io_ctl *io_ctl, struct inode *inode,
 333                                 int uptodate)
 334 {
 335         struct page *page;
 336         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
 337         int i;
 338
 339         for (i = 0; i < io_ctl->num_pages; i++) {
 340                 page = find_or_create_page(inode->i_mapping, i, mask);
 341                 if (!page) {
 342                         io_ctl_drop_pages(io_ctl);
 343                         return -ENOMEM;
 344                 }
 345                 io_ctl->pages[i] = page;
 346                 if (uptodate && !PageUptodate(page)) {
 347                         btrfs_readpage(NULL, page);
 348                         lock_page(page);
 349                         if (!PageUptodate(page)) {
 350                                 printk(KERN_ERR "btrfs: error reading free "
 351                                        "space cache\n");
 352                                 io_ctl_drop_pages(io_ctl);
 353                                 return -EIO;
 354                         }
 355                 }
 356         }
 357
 358         for (i = 0; i < io_ctl->num_pages; i++) {
 359                 clear_page_dirty_for_io(io_ctl->pages[i]);
 360                 set_page_extent_mapped(io_ctl->pages[i]);
 361         }
 362
 363         return 0;
 364 }
 365
 366 static void io_ctl_set_generation(struct io_ctl *io_ctl, u64 generation)
 367 {
 368         u64 *val;
 369
 370         io_ctl_map_page(io_ctl, 1);
 371
 372         /*
 373          * Skip the csum areas.  If we don't check crcs then we just have a
 374          * 64bit chunk at the front of the first page.
 375          */
 376         if (io_ctl->check_crcs) {
 377                 io_ctl->cur += (sizeof(u32) * io_ctl->num_pages);
 378                 io_ctl->size -= sizeof(u64) + (sizeof(u32) * io_ctl->num_pages);
 379         } else {
 380                 io_ctl->cur += sizeof(u64);
 381                 io_ctl->size -= sizeof(u64) * 2;
 382         }
 383
 384         val = io_ctl->cur;
 385         *val = cpu_to_le64(generation);
 386         io_ctl->cur += sizeof(u64);
 387 }
 388
 389 static int io_ctl_check_generation(struct io_ctl *io_ctl, u64 generation)
 390 {
 391         u64 *gen;
 392
 393         /*
 394          * Skip the crc area.  If we don't check crcs then we just have a 64bit
 395          * chunk at the front of the first page.
 396          */
 397         if (io_ctl->check_crcs) {
 398                 io_ctl->cur += sizeof(u32) * io_ctl->num_pages;
 399                 io_ctl->size -= sizeof(u64) +
 400                         (sizeof(u32) * io_ctl->num_pages);
 401         } else {
 402                 io_ctl->cur += sizeof(u64);
 403                 io_ctl->size -= sizeof(u64) * 2;
 404         }
 405
 406         gen = io_ctl->cur;
 407         if (le64_to_cpu(*gen) != generation) {
 408                 printk_ratelimited(KERN_ERR "btrfs: space cache generation "
 409                                    "(%Lu) does not match inode (%Lu)\n", *gen,
 410                                    generation);
 411                 io_ctl_unmap_page(io_ctl);
 412                 return -EIO;
 413         }
 414         io_ctl->cur += sizeof(u64);
 415         return 0;
 416 }
 417
 418 static void io_ctl_set_crc(struct io_ctl *io_ctl, int index)
 419 {
 420         u32 *tmp;
 421         u32 crc = ~(u32)0;
 422         unsigned offset = 0;
 423
 424         if (!io_ctl->check_crcs) {
 425                 io_ctl_unmap_page(io_ctl);
 426                 return;
 427         }
 428
 429         if (index == 0)
 430                 offset = sizeof(u32) * io_ctl->num_pages;
 431
 432         crc = btrfs_csum_data(io_ctl->root, io_ctl->orig + offset, crc,
 433                               PAGE_CACHE_SIZE - offset);
 434         btrfs_csum_final(crc, (char *)&crc);
 435         io_ctl_unmap_page(io_ctl);
 436         tmp = kmap(io_ctl->pages[0]);
 437         tmp += index;
 438         *tmp = crc;
 439         kunmap(io_ctl->pages[0]);
 440 }
 441
 442 static int io_ctl_check_crc(struct io_ctl *io_ctl, int index)
 443 {
 444         u32 *tmp, val;
 445         u32 crc = ~(u32)0;
 446         unsigned offset = 0;
 447
 448         if (!io_ctl->check_crcs) {
 449                 io_ctl_map_page(io_ctl, 0);
 450                 return 0;
 451         }
 452
 453         if (index == 0)
 454                 offset = sizeof(u32) * io_ctl->num_pages;
 455
 456         tmp = kmap(io_ctl->pages[0]);
 457         tmp += index;
 458         val = *tmp;
 459         kunmap(io_ctl->pages[0]);
 460
 461         io_ctl_map_page(io_ctl, 0);
 462         crc = btrfs_csum_data(io_ctl->root, io_ctl->orig + offset, crc,
 463                               PAGE_CACHE_SIZE - offset);
 464         btrfs_csum_final(crc, (char *)&crc);
 465         if (val != crc) {
 466                 printk_ratelimited(KERN_ERR "btrfs: csum mismatch on free "
 467                                    "space cache\n");
 468                 io_ctl_unmap_page(io_ctl);
 469                 return -EIO;
 470         }
 471
 472         return 0;
 473 }
 474
 475 static int io_ctl_add_entry(struct io_ctl *io_ctl, u64 offset, u64 bytes,
 476                             void *bitmap)
 477 {
 478         struct btrfs_free_space_entry *entry;
 479
 480         if (!io_ctl->cur)
 481                 return -ENOSPC;
 482
 483         entry = io_ctl->cur;
 484         entry->offset = cpu_to_le64(offset);
 485         entry->bytes = cpu_to_le64(bytes);
 486         entry->type = (bitmap) ? BTRFS_FREE_SPACE_BITMAP :
 487                 BTRFS_FREE_SPACE_EXTENT;
 488         io_ctl->cur += sizeof(struct btrfs_free_space_entry);
 489         io_ctl->size -= sizeof(struct btrfs_free_space_entry);
 490
 491         if (io_ctl->size >= sizeof(struct btrfs_free_space_entry))
 492                 return 0;
 493
 494         io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 495
 496         /* No more pages to map */
 497         if (io_ctl->index >= io_ctl->num_pages)
 498                 return 0;
 499
 500         /* map the next page */
 501         io_ctl_map_page(io_ctl, 1);
 502         return 0;
 503 }
 504
 505 static int io_ctl_add_bitmap(struct io_ctl *io_ctl, void *bitmap)
 506 {
 507         if (!io_ctl->cur)
 508                 return -ENOSPC;
 509
 510         /*
 511          * If we aren't at the start of the current page, unmap this one and
 512          * map the next one if there is any left.
 513          */
 514         if (io_ctl->cur != io_ctl->orig) {
 515                 io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 516                 if (io_ctl->index >= io_ctl->num_pages)
 517                         return -ENOSPC;
 518                 io_ctl_map_page(io_ctl, 0);
 519         }
 520
 521         memcpy(io_ctl->cur, bitmap, PAGE_CACHE_SIZE);
 522         io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 523         if (io_ctl->index < io_ctl->num_pages)
 524                 io_ctl_map_page(io_ctl, 0);
 525         return 0;
 526 }
 527
 528 static void io_ctl_zero_remaining_pages(struct io_ctl *io_ctl)
 529 {
 530         /*
 531          * If we're not on the boundary we know we've modified the page and we
 532          * need to crc the page.
 533          */
 534         if (io_ctl->cur != io_ctl->orig)
 535                 io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 536         else
 537                 io_ctl_unmap_page(io_ctl);
 538
 539         while (io_ctl->index < io_ctl->num_pages) {
 540                 io_ctl_map_page(io_ctl, 1);
 541                 io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 542         }
 543 }
 544
 545 static int io_ctl_read_entry(struct io_ctl *io_ctl,
 546                             struct btrfs_free_space *entry, u8 *type)
 547 {
 548         struct btrfs_free_space_entry *e;
 549         int ret;
 550
 551         if (!io_ctl->cur) {
 552                 ret = io_ctl_check_crc(io_ctl, io_ctl->index);
 553                 if (ret)
 554                         return ret;
 555         }
 556
 557         e = io_ctl->cur;
 558         entry->offset = le64_to_cpu(e->offset);
 559         entry->bytes = le64_to_cpu(e->bytes);
 560         *type = e->type;
 561         io_ctl->cur += sizeof(struct btrfs_free_space_entry);
 562         io_ctl->size -= sizeof(struct btrfs_free_space_entry);
 563
 564         if (io_ctl->size >= sizeof(struct btrfs_free_space_entry))
 565                 return 0;
 566
 567         io_ctl_unmap_page(io_ctl);
 568
 569         return 0;
 570 }
 571
 572 static int io_ctl_read_bitmap(struct io_ctl *io_ctl,
 573                               struct btrfs_free_space *entry)
 574 {
 575         int ret;
 576
 577         ret = io_ctl_check_crc(io_ctl, io_ctl->index);
 578         if (ret)
 579                 return ret;
 580
 581         memcpy(entry->bitmap, io_ctl->cur, PAGE_CACHE_SIZE);
 582         io_ctl_unmap_page(io_ctl);
 583
 584         return 0;
 585 }
 586
 587 int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 588                             struct btrfs_free_space_ctl *ctl,
 589                             struct btrfs_path *path, u64 offset)
 590 {
 591         struct btrfs_free_space_header *header;
 592         struct extent_buffer *leaf;
 593         struct io_ctl io_ctl;
 594         struct btrfs_key key;
 595         struct btrfs_free_space *e, *n;
 596         struct list_head bitmaps;
 597         u64 num_entries;
 598         u64 num_bitmaps;
 599         u64 generation;
 600         u8 type;
 601         int ret = 0;
 602
 603         INIT_LIST_HEAD(&bitmaps);
 604
 605         /* Nothing in the space cache, goodbye */
 606         if (!i_size_read(inode))
 607                 return 0;
 608
 609         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 610         key.offset = offset;
 611         key.type = 0;
 612
 613         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 614         if (ret < 0)
 615                 return 0;
 616         else if (ret > 0) {
 617                 btrfs_release_path(path);
 618                 return 0;
 619         }
 620
 621         ret = -1;
 622
 623         leaf = path->nodes[0];
 624         header = btrfs_item_ptr(leaf, path->slots[0],
 625                                 struct btrfs_free_space_header);
 626         num_entries = btrfs_free_space_entries(leaf, header);
 627         num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
 628         generation = btrfs_free_space_generation(leaf, header);
 629         btrfs_release_path(path);
 630
 631         if (BTRFS_I(inode)->generation != generation) {
 632                 printk(KERN_ERR "btrfs: free space inode generation (%llu) did"
 633                        " not match free space cache generation (%llu)\n",
 634                        (unsigned long long)BTRFS_I(inode)->generation,
 635                        (unsigned long long)generation);
 636                 return 0;
 637         }
 638
 639         if (!num_entries)
 640                 return 0;
 641
 642         ret = io_ctl_init(&io_ctl, inode, root);
 643         if (ret)
 644                 return ret;
 645
 646         ret = readahead_cache(inode);
 647         if (ret)
 648                 goto out;
 649
 650         ret = io_ctl_prepare_pages(&io_ctl, inode, 1);
 651         if (ret)
 652                 goto out;
 653
 654         ret = io_ctl_check_crc(&io_ctl, 0);
 655         if (ret)
 656                 goto free_cache;
 657
 658         ret = io_ctl_check_generation(&io_ctl, generation);
 659         if (ret)
 660                 goto free_cache;
 661
 662         while (num_entries) {
 663                 e = kmem_cache_zalloc(btrfs_free_space_cachep,
 664                                       GFP_NOFS);
 665                 if (!e)
 666                         goto free_cache;
 667
 668                 ret = io_ctl_read_entry(&io_ctl, e, &type);
 669                 if (ret) {
 670                         kmem_cache_free(btrfs_free_space_cachep, e);
 671                         goto free_cache;
 672                 }
 673
 674                 if (!e->bytes) {
 675                         kmem_cache_free(btrfs_free_space_cachep, e);
 676                         goto free_cache;
 677                 }
 678
 679                 if (type == BTRFS_FREE_SPACE_EXTENT) {
 680                         spin_lock(&ctl->tree_lock);
 681                         ret = link_free_space(ctl, e);
 682                         spin_unlock(&ctl->tree_lock);
 683                         if (ret) {
 684                                 printk(KERN_ERR "Duplicate entries in "
 685                                        "free space cache, dumping\n");
 686                                 kmem_cache_free(btrfs_free_space_cachep, e);
 687                                 goto free_cache;
 688                         }
 689                 } else {
 690                         BUG_ON(!num_bitmaps);
 691                         num_bitmaps--;
 692                         e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
 693                         if (!e->bitmap) {
 694                                 kmem_cache_free(
 695                                         btrfs_free_space_cachep, e);
 696                                 goto free_cache;
 697                         }
 698                         spin_lock(&ctl->tree_lock);
 699                         ret = link_free_space(ctl, e);
 700                         ctl->total_bitmaps++;
 701                         ctl->op->recalc_thresholds(ctl);
 702                         spin_unlock(&ctl->tree_lock);
 703                         if (ret) {
 704                                 printk(KERN_ERR "Duplicate entries in "
 705                                        "free space cache, dumping\n");
 706                                 kmem_cache_free(btrfs_free_space_cachep, e);
 707                                 goto free_cache;
 708                         }
 709                         list_add_tail(&e->list, &bitmaps);
 710                 }
 711
 712                 num_entries--;
 713         }
 714
 715         io_ctl_unmap_page(&io_ctl);
 716
 717         /*
 718          * We add the bitmaps at the end of the entries in order that
 719          * the bitmap entries are added to the cache.
 720          */
 721         list_for_each_entry_safe(e, n, &bitmaps, list) {
 722                 list_del_init(&e->list);
 723                 ret = io_ctl_read_bitmap(&io_ctl, e);
 724                 if (ret)
 725                         goto free_cache;
 726         }
 727
 728         io_ctl_drop_pages(&io_ctl);
 729         ret = 1;
 730 out:
 731         io_ctl_free(&io_ctl);
 732         return ret;
 733 free_cache:
 734         io_ctl_drop_pages(&io_ctl);
 735         __btrfs_remove_free_space_cache(ctl);
 736         goto out;
 737 }
 738
 739 int load_free_space_cache(struct btrfs_fs_info *fs_info,
 740                           struct btrfs_block_group_cache *block_group)
 741 {
 742         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 743         struct btrfs_root *root = fs_info->tree_root;
 744         struct inode *inode;
 745         struct btrfs_path *path;
 746         int ret = 0;
 747         bool matched;
 748         u64 used = btrfs_block_group_used(&block_group->item);
 749
 750         /*
 751          * If this block group has been marked to be cleared for one reason or
 752          * another then we can't trust the on disk cache, so just return.
 753          */
 754         spin_lock(&block_group->lock);
 755         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 756                 spin_unlock(&block_group->lock);
 757                 return 0;
 758         }
 759         spin_unlock(&block_group->lock);
 760
 761         path = btrfs_alloc_path();
 762         if (!path)
 763                 return 0;
 764         path->search_commit_root = 1;
 765         path->skip_locking = 1;
 766
 767         inode = lookup_free_space_inode(root, block_group, path);
 768         if (IS_ERR(inode)) {
 769                 btrfs_free_path(path);
 770                 return 0;
 771         }
 772
 773         /* We may have converted the inode and made the cache invalid. */
 774         spin_lock(&block_group->lock);
 775         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 776                 spin_unlock(&block_group->lock);
 777                 btrfs_free_path(path);
 778                 goto out;
 779         }
 780         spin_unlock(&block_group->lock);
 781
 782         ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
 783                                       path, block_group->key.objectid);
 784         btrfs_free_path(path);
 785         if (ret <= 0)
 786                 goto out;
 787
 788         spin_lock(&ctl->tree_lock);
 789         matched = (ctl->free_space == (block_group->key.offset - used -
 790                                        block_group->bytes_super));
 791         spin_unlock(&ctl->tree_lock);
 792
 793         if (!matched) {
 794                 __btrfs_remove_free_space_cache(ctl);
 795                 printk(KERN_ERR "block group %llu has an wrong amount of free "
 796                        "space\n", block_group->key.objectid);
 797                 ret = -1;
 798         }
 799 out:
 800         if (ret < 0) {
 801                 /* This cache is bogus, make sure it gets cleared */
 802                 spin_lock(&block_group->lock);
 803                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 804                 spin_unlock(&block_group->lock);
 805                 ret = 0;
 806
 807                 printk(KERN_ERR "btrfs: failed to load free space cache "
 808                        "for block group %llu\n", block_group->key.objectid);
 809         }
 810
 811         iput(inode);
 812         return ret;
 813 }
 814
 815 /**
 816  * __btrfs_write_out_cache - write out cached info to an inode
 817  * @root - the root the inode belongs to
 818  * @ctl - the free space cache we are going to write out
 819  * @block_group - the block_group for this cache if it belongs to a block_group
 820  * @trans - the trans handle
 821  * @path - the path to use
 822  * @offset - the offset for the key we'll insert
 823  *
 824  * This function writes out a free space cache struct to disk for quick recovery
 825  * on mount.  This will return 0 if it was successfull in writing the cache out,
 826  * and -1 if it was not.
 827  */
 828 int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
 829                             struct btrfs_free_space_ctl *ctl,
 830                             struct btrfs_block_group_cache *block_group,
 831                             struct btrfs_trans_handle *trans,
 832                             struct btrfs_path *path, u64 offset)
 833 {
 834         struct btrfs_free_space_header *header;
 835         struct extent_buffer *leaf;
 836         struct rb_node *node;
 837         struct list_head *pos, *n;
 838         struct extent_state *cached_state = NULL;
 839         struct btrfs_free_cluster *cluster = NULL;
 840         struct extent_io_tree *unpin = NULL;
 841         struct io_ctl io_ctl;
 842         struct list_head bitmap_list;
 843         struct btrfs_key key;
 844         u64 start, extent_start, extent_end, len;
 845         int entries = 0;
 846         int bitmaps = 0;
 847         int ret;
 848         int err = -1;
 849
 850         INIT_LIST_HEAD(&bitmap_list);
 851
 852         if (!i_size_read(inode))
 853                 return -1;
 854
 855         ret = io_ctl_init(&io_ctl, inode, root);
 856         if (ret)
 857                 return -1;
 858
 859         /* Get the cluster for this block_group if it exists */
 860         if (block_group && !list_empty(&block_group->cluster_list))
 861                 cluster = list_entry(block_group->cluster_list.next,
 862                                      struct btrfs_free_cluster,
 863                                      block_group_list);
 864
 865         /* Lock all pages first so we can lock the extent safely. */
 866         io_ctl_prepare_pages(&io_ctl, inode, 0);
 867
 868         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
 869                          0, &cached_state);
 870
 871         node = rb_first(&ctl->free_space_offset);
 872         if (!node && cluster) {
 873                 node = rb_first(&cluster->root);
 874                 cluster = NULL;
 875         }
 876
 877         /* Make sure we can fit our crcs into the first page */
 878         if (io_ctl.check_crcs &&
 879             (io_ctl.num_pages * sizeof(u32)) >= PAGE_CACHE_SIZE) {
 880                 WARN_ON(1);
 881                 goto out_nospc;
 882         }
 883
 884         io_ctl_set_generation(&io_ctl, trans->transid);
 885
 886         /* Write out the extent entries */
 887         while (node) {
 888                 struct btrfs_free_space *e;
 889
 890                 e = rb_entry(node, struct btrfs_free_space, offset_index);
 891                 entries++;
 892
 893                 ret = io_ctl_add_entry(&io_ctl, e->offset, e->bytes,
 894                                        e->bitmap);
 895                 if (ret)
 896                         goto out_nospc;
 897
 898                 if (e->bitmap) {
 899                         list_add_tail(&e->list, &bitmap_list);
 900                         bitmaps++;
 901                 }
 902                 node = rb_next(node);
 903                 if (!node && cluster) {
 904                         node = rb_first(&cluster->root);
 905                         cluster = NULL;
 906                 }
 907         }
 908
 909         /*
 910          * We want to add any pinned extents to our free space cache
 911          * so we don't leak the space
 912          */
 913
 914         /*
 915          * We shouldn't have switched the pinned extents yet so this is the
 916          * right one
 917          */
 918         unpin = root->fs_info->pinned_extents;
 919
 920         if (block_group)
 921                 start = block_group->key.objectid;
 922
 923         while (block_group && (start < block_group->key.objectid +
 924                                block_group->key.offset)) {
 925                 ret = find_first_extent_bit(unpin, start,
 926                                             &extent_start, &extent_end,
 927                                             EXTENT_DIRTY);
 928                 if (ret) {
 929                         ret = 0;
 930                         break;
 931                 }
 932
 933                 /* This pinned extent is out of our range */
 934                 if (extent_start >= block_group->key.objectid +
 935                     block_group->key.offset)
 936                         break;
 937
 938                 extent_start = max(extent_start, start);
 939                 extent_end = min(block_group->key.objectid +
 940                                  block_group->key.offset, extent_end + 1);
 941                 len = extent_end - extent_start;
 942
 943                 entries++;
 944                 ret = io_ctl_add_entry(&io_ctl, extent_start, len, NULL);
 945                 if (ret)
 946                         goto out_nospc;
 947
 948                 start = extent_end;
 949         }
 950
 951         /* Write out the bitmaps */
 952         list_for_each_safe(pos, n, &bitmap_list) {
 953                 struct btrfs_free_space *entry =
 954                         list_entry(pos, struct btrfs_free_space, list);
 955
 956                 ret = io_ctl_add_bitmap(&io_ctl, entry->bitmap);
 957                 if (ret)
 958                         goto out_nospc;
 959                 list_del_init(&entry->list);
 960         }
 961
 962         /* Zero out the rest of the pages just to make sure */
 963         io_ctl_zero_remaining_pages(&io_ctl);
 964
 965         ret = btrfs_dirty_pages(root, inode, io_ctl.pages, io_ctl.num_pages,
 966                                 0, i_size_read(inode), &cached_state);
 967         io_ctl_drop_pages(&io_ctl);
 968         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
 969                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
 970
 971         if (ret)
 972                 goto out;
 973
 974
 975         ret = filemap_write_and_wait(inode->i_mapping);
 976         if (ret)
 977                 goto out;
 978
 979         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 980         key.offset = offset;
 981         key.type = 0;
 982
 983         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
 984         if (ret < 0) {
 985                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
 986                                  EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL,
 987                                  GFP_NOFS);
 988                 goto out;
 989         }
 990         leaf = path->nodes[0];
 991         if (ret > 0) {
 992                 struct btrfs_key found_key;
 993                 BUG_ON(!path->slots[0]);
 994                 path->slots[0]--;
 995                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 996                 if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
 997                     found_key.offset != offset) {
 998                         clear_extent_bit(&BTRFS_I(inode)->io_tree, 0,
 999                                          inode->i_size - 1,
1000                                          EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0,
1001                                          NULL, GFP_NOFS);
1002                         btrfs_release_path(path);
1003                         goto out;
1004                 }
1005         }
1006
1007         BTRFS_I(inode)->generation = trans->transid;
1008         header = btrfs_item_ptr(leaf, path->slots[0],
1009                                 struct btrfs_free_space_header);
1010         btrfs_set_free_space_entries(leaf, header, entries);
1011         btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
1012         btrfs_set_free_space_generation(leaf, header, trans->transid);
1013         btrfs_mark_buffer_dirty(leaf);
1014         btrfs_release_path(path);
1015
1016         err = 0;
1017 out:
1018         io_ctl_free(&io_ctl);
1019         if (err) {
1020                 invalidate_inode_pages2(inode->i_mapping);
1021                 BTRFS_I(inode)->generation = 0;
1022         }
1023         btrfs_update_inode(trans, root, inode);
1024         return err;
1025
1026 out_nospc:
1027         list_for_each_safe(pos, n, &bitmap_list) {
1028                 struct btrfs_free_space *entry =
1029                         list_entry(pos, struct btrfs_free_space, list);
1030                 list_del_init(&entry->list);
1031         }
1032         io_ctl_drop_pages(&io_ctl);
1033         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
1034                              i_size_read(inode) - 1, &cached_state, GFP_NOFS);
1035         goto out;
1036 }
1037
1038 int btrfs_write_out_cache(struct btrfs_root *root,
1039                           struct btrfs_trans_handle *trans,
1040                           struct btrfs_block_group_cache *block_group,
1041                           struct btrfs_path *path)
1042 {
1043         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1044         struct inode *inode;
1045         int ret = 0;
1046
1047         root = root->fs_info->tree_root;
1048
1049         spin_lock(&block_group->lock);
1050         if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
1051                 spin_unlock(&block_group->lock);
1052                 return 0;
1053         }
1054         spin_unlock(&block_group->lock);
1055
1056         inode = lookup_free_space_inode(root, block_group, path);
1057         if (IS_ERR(inode))
1058                 return 0;
1059
1060         ret = __btrfs_write_out_cache(root, inode, ctl, block_group, trans,
1061                                       path, block_group->key.objectid);
1062         if (ret) {
1063                 spin_lock(&block_group->lock);
1064                 block_group->disk_cache_state = BTRFS_DC_ERROR;
1065                 spin_unlock(&block_group->lock);
1066                 ret = 0;
1067 #ifdef DEBUG
1068                 printk(KERN_ERR "btrfs: failed to write free space cache "
1069                        "for block group %llu\n", block_group->key.objectid);
1070 #endif
1071         }
1072
1073         iput(inode);
1074         return ret;
1075 }
1076
1077 static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
1078                                           u64 offset)
1079 {
1080         BUG_ON(offset < bitmap_start);
1081         offset -= bitmap_start;
1082         return (unsigned long)(div_u64(offset, unit));
1083 }
1084
1085 static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
1086 {
1087         return (unsigned long)(div_u64(bytes, unit));
1088 }
1089
1090 static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
1091                                    u64 offset)
1092 {
1093         u64 bitmap_start;
1094         u64 bytes_per_bitmap;
1095
1096         bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
1097         bitmap_start = offset - ctl->start;
1098         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
1099         bitmap_start *= bytes_per_bitmap;
1100         bitmap_start += ctl->start;
1101
1102         return bitmap_start;
1103 }
1104
1105 static int tree_insert_offset(struct rb_root *root, u64 offset,
1106                               struct rb_node *node, int bitmap)
1107 {
1108         struct rb_node **p = &root->rb_node;
1109         struct rb_node *parent = NULL;
1110         struct btrfs_free_space *info;
1111
1112         while (*p) {
1113                 parent = *p;
1114                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
1115
1116                 if (offset < info->offset) {
1117                         p = &(*p)->rb_left;
1118                 } else if (offset > info->offset) {
1119                         p = &(*p)->rb_right;
1120                 } else {
1121                         /*
1122                          * we could have a bitmap entry and an extent entry
1123                          * share the same offset.  If this is the case, we want
1124                          * the extent entry to always be found first if we do a
1125                          * linear search through the tree, since we want to have
1126                          * the quickest allocation time, and allocating from an
1127                          * extent is faster than allocating from a bitmap.  So
1128                          * if we're inserting a bitmap and we find an entry at
1129                          * this offset, we want to go right, or after this entry
1130                          * logically.  If we are inserting an extent and we've
1131                          * found a bitmap, we want to go left, or before
1132                          * logically.
1133                          */
1134                         if (bitmap) {
1135                                 if (info->bitmap) {
1136                                         WARN_ON_ONCE(1);
1137                                         return -EEXIST;
1138                                 }
1139                                 p = &(*p)->rb_right;
1140                         } else {
1141                                 if (!info->bitmap) {
1142                                         WARN_ON_ONCE(1);
1143                                         return -EEXIST;
1144                                 }
1145                                 p = &(*p)->rb_left;
1146                         }
1147                 }
1148         }
1149
1150         rb_link_node(node, parent, p);
1151         rb_insert_color(node, root);
1152
1153         return 0;
1154 }
1155
1156 /*
1157  * searches the tree for the given offset.
1158  *
1159  * fuzzy - If this is set, then we are trying to make an allocation, and we just
1160  * want a section that has at least bytes size and comes at or after the given
1161  * offset.
1162  */
1163 static struct btrfs_free_space *
1164 tree_search_offset(struct btrfs_free_space_ctl *ctl,
1165                    u64 offset, int bitmap_only, int fuzzy)
1166 {
1167         struct rb_node *n = ctl->free_space_offset.rb_node;
1168         struct btrfs_free_space *entry, *prev = NULL;
1169
1170         /* find entry that is closest to the 'offset' */
1171         while (1) {
1172                 if (!n) {
1173                         entry = NULL;
1174                         break;
1175                 }
1176
1177                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1178                 prev = entry;
1179
1180                 if (offset < entry->offset)
1181                         n = n->rb_left;
1182                 else if (offset > entry->offset)
1183                         n = n->rb_right;
1184                 else
1185                         break;
1186         }
1187
1188         if (bitmap_only) {
1189                 if (!entry)
1190                         return NULL;
1191                 if (entry->bitmap)
1192                         return entry;
1193
1194                 /*
1195                  * bitmap entry and extent entry may share same offset,
1196                  * in that case, bitmap entry comes after extent entry.
1197                  */
1198                 n = rb_next(n);
1199                 if (!n)
1200                         return NULL;
1201                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1202                 if (entry->offset != offset)
1203                         return NULL;
1204
1205                 WARN_ON(!entry->bitmap);
1206                 return entry;
1207         } else if (entry) {
1208                 if (entry->bitmap) {
1209                         /*
1210                          * if previous extent entry covers the offset,
1211                          * we should return it instead of the bitmap entry
1212                          */
1213                         n = &entry->offset_index;
1214                         while (1) {
1215                                 n = rb_prev(n);
1216                                 if (!n)
1217                                         break;
1218                                 prev = rb_entry(n, struct btrfs_free_space,
1219                                                 offset_index);
1220                                 if (!prev->bitmap) {
1221                                         if (prev->offset + prev->bytes > offset)
1222                                                 entry = prev;
1223                                         break;
1224                                 }
1225                         }
1226                 }
1227                 return entry;
1228         }
1229
1230         if (!prev)
1231                 return NULL;
1232
1233         /* find last entry before the 'offset' */
1234         entry = prev;
1235         if (entry->offset > offset) {
1236                 n = rb_prev(&entry->offset_index);
1237                 if (n) {
1238                         entry = rb_entry(n, struct btrfs_free_space,
1239                                         offset_index);
1240                         BUG_ON(entry->offset > offset);
1241                 } else {
1242                         if (fuzzy)
1243                                 return entry;
1244                         else
1245                                 return NULL;
1246                 }
1247         }
1248
1249         if (entry->bitmap) {
1250                 n = &entry->offset_index;
1251                 while (1) {
1252                         n = rb_prev(n);
1253                         if (!n)
1254                                 break;
1255                         prev = rb_entry(n, struct btrfs_free_space,
1256                                         offset_index);
1257                         if (!prev->bitmap) {
1258                                 if (prev->offset + prev->bytes > offset)
1259                                         return prev;
1260                                 break;
1261                         }
1262                 }
1263                 if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
1264                         return entry;
1265         } else if (entry->offset + entry->bytes > offset)
1266                 return entry;
1267
1268         if (!fuzzy)
1269                 return NULL;
1270
1271         while (1) {
1272                 if (entry->bitmap) {
1273                         if (entry->offset + BITS_PER_BITMAP *
1274                             ctl->unit > offset)
1275                                 break;
1276                 } else {
1277                         if (entry->offset + entry->bytes > offset)
1278                                 break;
1279                 }
1280
1281                 n = rb_next(&entry->offset_index);
1282                 if (!n)
1283                         return NULL;
1284                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1285         }
1286         return entry;
1287 }
1288
1289 static inline void
1290 __unlink_free_space(struct btrfs_free_space_ctl *ctl,
1291                     struct btrfs_free_space *info)
1292 {
1293         rb_erase(&info->offset_index, &ctl->free_space_offset);
1294         ctl->free_extents--;
1295 }
1296
1297 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
1298                               struct btrfs_free_space *info)
1299 {
1300         __unlink_free_space(ctl, info);
1301         ctl->free_space -= info->bytes;
1302 }
1303
1304 static int link_free_space(struct btrfs_free_space_ctl *ctl,
1305                            struct btrfs_free_space *info)
1306 {
1307         int ret = 0;
1308
1309         BUG_ON(!info->bitmap && !info->bytes);
1310         ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
1311                                  &info->offset_index, (info->bitmap != NULL));
1312         if (ret)
1313                 return ret;
1314
1315         ctl->free_space += info->bytes;
1316         ctl->free_extents++;
1317         return ret;
1318 }
1319
1320 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
1321 {
1322         struct btrfs_block_group_cache *block_group = ctl->private;
1323         u64 max_bytes;
1324         u64 bitmap_bytes;
1325         u64 extent_bytes;
1326         u64 size = block_group->key.offset;
1327         u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
1328         int max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
1329
1330         BUG_ON(ctl->total_bitmaps > max_bitmaps);
1331
1332         /*
1333          * The goal is to keep the total amount of memory used per 1gb of space
1334          * at or below 32k, so we need to adjust how much memory we allow to be
1335          * used by extent based free space tracking
1336          */
1337         if (size < 1024 * 1024 * 1024)
1338                 max_bytes = MAX_CACHE_BYTES_PER_GIG;
1339         else
1340                 max_bytes = MAX_CACHE_BYTES_PER_GIG *
1341                         div64_u64(size, 1024 * 1024 * 1024);
1342
1343         /*
1344          * we want to account for 1 more bitmap than what we have so we can make
1345          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1346          * we add more bitmaps.
1347          */
1348         bitmap_bytes = (ctl->total_bitmaps + 1) * PAGE_CACHE_SIZE;
1349
1350         if (bitmap_bytes >= max_bytes) {
1351                 ctl->extents_thresh = 0;
1352                 return;
1353         }
1354
1355         /*
1356          * we want the extent entry threshold to always be at most 1/2 the maxw
1357          * bytes we can have, or whatever is less than that.
1358          */
1359         extent_bytes = max_bytes - bitmap_bytes;
1360         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
1361
1362         ctl->extents_thresh =
1363                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
1364 }
1365
1366 static inline void __bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1367                                        struct btrfs_free_space *info,
1368                                        u64 offset, u64 bytes)
1369 {
1370         unsigned long start, count;
1371
1372         start = offset_to_bit(info->offset, ctl->unit, offset);
1373         count = bytes_to_bits(bytes, ctl->unit);
1374         BUG_ON(start + count > BITS_PER_BITMAP);
1375
1376         bitmap_clear(info->bitmap, start, count);
1377
1378         info->bytes -= bytes;
1379 }
1380
1381 static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1382                               struct btrfs_free_space *info, u64 offset,
1383                               u64 bytes)
1384 {
1385         __bitmap_clear_bits(ctl, info, offset, bytes);
1386         ctl->free_space -= bytes;
1387 }
1388
1389 static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
1390                             struct btrfs_free_space *info, u64 offset,
1391                             u64 bytes)
1392 {
1393         unsigned long start, count;
1394
1395         start = offset_to_bit(info->offset, ctl->unit, offset);
1396         count = bytes_to_bits(bytes, ctl->unit);
1397         BUG_ON(start + count > BITS_PER_BITMAP);
1398
1399         bitmap_set(info->bitmap, start, count);
1400
1401         info->bytes += bytes;
1402         ctl->free_space += bytes;
1403 }
1404
1405 static int search_bitmap(struct btrfs_free_space_ctl *ctl,
1406                          struct btrfs_free_space *bitmap_info, u64 *offset,
1407                          u64 *bytes)
1408 {
1409         unsigned long found_bits = 0;
1410         unsigned long bits, i;
1411         unsigned long next_zero;
1412
1413         i = offset_to_bit(bitmap_info->offset, ctl->unit,
1414                           max_t(u64, *offset, bitmap_info->offset));
1415         bits = bytes_to_bits(*bytes, ctl->unit);
1416
1417         for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
1418              i < BITS_PER_BITMAP;
1419              i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
1420                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
1421                                                BITS_PER_BITMAP, i);
1422                 if ((next_zero - i) >= bits) {
1423                         found_bits = next_zero - i;
1424                         break;
1425                 }
1426                 i = next_zero;
1427         }
1428
1429         if (found_bits) {
1430                 *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
1431                 *bytes = (u64)(found_bits) * ctl->unit;
1432                 return 0;
1433         }
1434
1435         return -1;
1436 }
1437
1438 static struct btrfs_free_space *
1439 find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes)
1440 {
1441         struct btrfs_free_space *entry;
1442         struct rb_node *node;
1443         int ret;
1444
1445         if (!ctl->free_space_offset.rb_node)
1446                 return NULL;
1447
1448         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
1449         if (!entry)
1450                 return NULL;
1451
1452         for (node = &entry->offset_index; node; node = rb_next(node)) {
1453                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1454                 if (entry->bytes < *bytes)
1455                         continue;
1456
1457                 if (entry->bitmap) {
1458                         ret = search_bitmap(ctl, entry, offset, bytes);
1459                         if (!ret)
1460                                 return entry;
1461                         continue;
1462                 }
1463
1464                 *offset = entry->offset;
1465                 *bytes = entry->bytes;
1466                 return entry;
1467         }
1468
1469         return NULL;
1470 }
1471
1472 static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
1473                            struct btrfs_free_space *info, u64 offset)
1474 {
1475         info->offset = offset_to_bitmap(ctl, offset);
1476         info->bytes = 0;
1477         INIT_LIST_HEAD(&info->list);
1478         link_free_space(ctl, info);
1479         ctl->total_bitmaps++;
1480
1481         ctl->op->recalc_thresholds(ctl);
1482 }
1483
1484 static void free_bitmap(struct btrfs_free_space_ctl *ctl,
1485                         struct btrfs_free_space *bitmap_info)
1486 {
1487         unlink_free_space(ctl, bitmap_info);
1488         kfree(bitmap_info->bitmap);
1489         kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1490         ctl->total_bitmaps--;
1491         ctl->op->recalc_thresholds(ctl);
1492 }
1493
1494 static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
1495                               struct btrfs_free_space *bitmap_info,
1496                               u64 *offset, u64 *bytes)
1497 {
1498         u64 end;
1499         u64 search_start, search_bytes;
1500         int ret;
1501
1502 again:
1503         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
1504
1505         /*
1506          * XXX - this can go away after a few releases.
1507          *
1508          * since the only user of btrfs_remove_free_space is the tree logging
1509          * stuff, and the only way to test that is under crash conditions, we
1510          * want to have this debug stuff here just in case somethings not
1511          * working.  Search the bitmap for the space we are trying to use to
1512          * make sure its actually there.  If its not there then we need to stop
1513          * because something has gone wrong.
1514          */
1515         search_start = *offset;
1516         search_bytes = *bytes;
1517         search_bytes = min(search_bytes, end - search_start + 1);
1518         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
1519         BUG_ON(ret < 0 || search_start != *offset);
1520
1521         if (*offset > bitmap_info->offset && *offset + *bytes > end) {
1522                 bitmap_clear_bits(ctl, bitmap_info, *offset, end - *offset + 1);
1523                 *bytes -= end - *offset + 1;
1524                 *offset = end + 1;
1525         } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
1526                 bitmap_clear_bits(ctl, bitmap_info, *offset, *bytes);
1527                 *bytes = 0;
1528         }
1529
1530         if (*bytes) {
1531                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
1532                 if (!bitmap_info->bytes)
1533                         free_bitmap(ctl, bitmap_info);
1534
1535                 /*
1536                  * no entry after this bitmap, but we still have bytes to
1537                  * remove, so something has gone wrong.
1538                  */
1539                 if (!next)
1540                         return -EINVAL;
1541
1542                 bitmap_info = rb_entry(next, struct btrfs_free_space,
1543                                        offset_index);
1544
1545                 /*
1546                  * if the next entry isn't a bitmap we need to return to let the
1547                  * extent stuff do its work.
1548                  */
1549                 if (!bitmap_info->bitmap)
1550                         return -EAGAIN;
1551
1552                 /*
1553                  * Ok the next item is a bitmap, but it may not actually hold
1554                  * the information for the rest of this free space stuff, so
1555                  * look for it, and if we don't find it return so we can try
1556                  * everything over again.
1557                  */
1558                 search_start = *offset;
1559                 search_bytes = *bytes;
1560                 ret = search_bitmap(ctl, bitmap_info, &search_start,
1561                                     &search_bytes);
1562                 if (ret < 0 || search_start != *offset)
1563                         return -EAGAIN;
1564
1565                 goto again;
1566         } else if (!bitmap_info->bytes)
1567                 free_bitmap(ctl, bitmap_info);
1568
1569         return 0;
1570 }
1571
1572 static u64 add_bytes_to_bitmap(struct btrfs_free_space_ctl *ctl,
1573                                struct btrfs_free_space *info, u64 offset,
1574                                u64 bytes)
1575 {
1576         u64 bytes_to_set = 0;
1577         u64 end;
1578
1579         end = info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
1580
1581         bytes_to_set = min(end - offset, bytes);
1582
1583         bitmap_set_bits(ctl, info, offset, bytes_to_set);
1584
1585         return bytes_to_set;
1586
1587 }
1588
1589 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
1590                       struct btrfs_free_space *info)
1591 {
1592         struct btrfs_block_group_cache *block_group = ctl->private;
1593
1594         /*
1595          * If we are below the extents threshold then we can add this as an
1596          * extent, and don't have to deal with the bitmap
1597          */
1598         if (ctl->free_extents < ctl->extents_thresh) {
1599                 /*
1600                  * If this block group has some small extents we don't want to
1601                  * use up all of our free slots in the cache with them, we want
1602                  * to reserve them to larger extents, however if we have plent
1603                  * of cache left then go ahead an dadd them, no sense in adding
1604                  * the overhead of a bitmap if we don't have to.
1605                  */
1606                 if (info->bytes <= block_group->sectorsize * 4) {
1607                         if (ctl->free_extents * 2 <= ctl->extents_thresh)
1608                                 return false;
1609                 } else {
1610                         return false;
1611                 }
1612         }
1613
1614         /*
1615          * some block groups are so tiny they can't be enveloped by a bitmap, so
1616          * don't even bother to create a bitmap for this
1617          */
1618         if (BITS_PER_BITMAP * block_group->sectorsize >
1619             block_group->key.offset)
1620                 return false;
1621
1622         return true;
1623 }
1624
1625 static struct btrfs_free_space_op free_space_op = {
1626         .recalc_thresholds      = recalculate_thresholds,
1627         .use_bitmap             = use_bitmap,
1628 };
1629
1630 static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
1631                               struct btrfs_free_space *info)
1632 {
1633         struct btrfs_free_space *bitmap_info;
1634         struct btrfs_block_group_cache *block_group = NULL;
1635         int added = 0;
1636         u64 bytes, offset, bytes_added;
1637         int ret;
1638
1639         bytes = info->bytes;
1640         offset = info->offset;
1641
1642         if (!ctl->op->use_bitmap(ctl, info))
1643                 return 0;
1644
1645         if (ctl->op == &free_space_op)
1646                 block_group = ctl->private;
1647 again:
1648         /*
1649          * Since we link bitmaps right into the cluster we need to see if we
1650          * have a cluster here, and if so and it has our bitmap we need to add
1651          * the free space to that bitmap.
1652          */
1653         if (block_group && !list_empty(&block_group->cluster_list)) {
1654                 struct btrfs_free_cluster *cluster;
1655                 struct rb_node *node;
1656                 struct btrfs_free_space *entry;
1657
1658                 cluster = list_entry(block_group->cluster_list.next,
1659                                      struct btrfs_free_cluster,
1660                                      block_group_list);
1661                 spin_lock(&cluster->lock);
1662                 node = rb_first(&cluster->root);
1663                 if (!node) {
1664                         spin_unlock(&cluster->lock);
1665                         goto no_cluster_bitmap;
1666                 }
1667
1668                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1669                 if (!entry->bitmap) {
1670                         spin_unlock(&cluster->lock);
1671                         goto no_cluster_bitmap;
1672                 }
1673
1674                 if (entry->offset == offset_to_bitmap(ctl, offset)) {
1675                         bytes_added = add_bytes_to_bitmap(ctl, entry,
1676                                                           offset, bytes);
1677                         bytes -= bytes_added;
1678                         offset += bytes_added;
1679                 }
1680                 spin_unlock(&cluster->lock);
1681                 if (!bytes) {
1682                         ret = 1;
1683                         goto out;
1684                 }
1685         }
1686
1687 no_cluster_bitmap:
1688         bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1689                                          1, 0);
1690         if (!bitmap_info) {
1691                 BUG_ON(added);
1692                 goto new_bitmap;
1693         }
1694
1695         bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
1696         bytes -= bytes_added;
1697         offset += bytes_added;
1698         added = 0;
1699
1700         if (!bytes) {
1701                 ret = 1;
1702                 goto out;
1703         } else
1704                 goto again;
1705
1706 new_bitmap:
1707         if (info && info->bitmap) {
1708                 add_new_bitmap(ctl, info, offset);
1709                 added = 1;
1710                 info = NULL;
1711                 goto again;
1712         } else {
1713                 spin_unlock(&ctl->tree_lock);
1714
1715                 /* no pre-allocated info, allocate a new one */
1716                 if (!info) {
1717                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
1718                                                  GFP_NOFS);
1719                         if (!info) {
1720                                 spin_lock(&ctl->tree_lock);
1721                                 ret = -ENOMEM;
1722                                 goto out;
1723                         }
1724                 }
1725
1726                 /* allocate the bitmap */
1727                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
1728                 spin_lock(&ctl->tree_lock);
1729                 if (!info->bitmap) {
1730                         ret = -ENOMEM;
1731                         goto out;
1732                 }
1733                 goto again;
1734         }
1735
1736 out:
1737         if (info) {
1738                 if (info->bitmap)
1739                         kfree(info->bitmap);
1740                 kmem_cache_free(btrfs_free_space_cachep, info);
1741         }
1742
1743         return ret;
1744 }
1745
1746 static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
1747                           struct btrfs_free_space *info, bool update_stat)
1748 {
1749         struct btrfs_free_space *left_info;
1750         struct btrfs_free_space *right_info;
1751         bool merged = false;
1752         u64 offset = info->offset;
1753         u64 bytes = info->bytes;
1754
1755         /*
1756          * first we want to see if there is free space adjacent to the range we
1757          * are adding, if there is remove that struct and add a new one to
1758          * cover the entire range
1759          */
1760         right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
1761         if (right_info && rb_prev(&right_info->offset_index))
1762                 left_info = rb_entry(rb_prev(&right_info->offset_index),
1763                                      struct btrfs_free_space, offset_index);
1764         else
1765                 left_info = tree_search_offset(ctl, offset - 1, 0, 0);
1766
1767         if (right_info && !right_info->bitmap) {
1768                 if (update_stat)
1769                         unlink_free_space(ctl, right_info);
1770                 else
1771                         __unlink_free_space(ctl, right_info);
1772                 info->bytes += right_info->bytes;
1773                 kmem_cache_free(btrfs_free_space_cachep, right_info);
1774                 merged = true;
1775         }
1776
1777         if (left_info && !left_info->bitmap &&
1778             left_info->offset + left_info->bytes == offset) {
1779                 if (update_stat)
1780                         unlink_free_space(ctl, left_info);
1781                 else
1782                         __unlink_free_space(ctl, left_info);
1783                 info->offset = left_info->offset;
1784                 info->bytes += left_info->bytes;
1785                 kmem_cache_free(btrfs_free_space_cachep, left_info);
1786                 merged = true;
1787         }
1788
1789         return merged;
1790 }
1791
1792 int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
1793                            u64 offset, u64 bytes)
1794 {
1795         struct btrfs_free_space *info;
1796         int ret = 0;
1797
1798         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
1799         if (!info)
1800                 return -ENOMEM;
1801
1802         info->offset = offset;
1803         info->bytes = bytes;
1804
1805         spin_lock(&ctl->tree_lock);
1806
1807         if (try_merge_free_space(ctl, info, true))
1808                 goto link;
1809
1810         /*
1811          * There was no extent directly to the left or right of this new
1812          * extent then we know we're going to have to allocate a new extent, so
1813          * before we do that see if we need to drop this into a bitmap
1814          */
1815         ret = insert_into_bitmap(ctl, info);
1816         if (ret < 0) {
1817                 goto out;
1818         } else if (ret) {
1819                 ret = 0;
1820                 goto out;
1821         }
1822 link:
1823         ret = link_free_space(ctl, info);
1824         if (ret)
1825                 kmem_cache_free(btrfs_free_space_cachep, info);
1826 out:
1827         spin_unlock(&ctl->tree_lock);
1828
1829         if (ret) {
1830                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
1831                 BUG_ON(ret == -EEXIST);
1832         }
1833
1834         return ret;
1835 }
1836
1837 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
1838                             u64 offset, u64 bytes)
1839 {
1840         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1841         struct btrfs_free_space *info;
1842         struct btrfs_free_space *next_info = NULL;
1843         int ret = 0;
1844
1845         spin_lock(&ctl->tree_lock);
1846
1847 again:
1848         info = tree_search_offset(ctl, offset, 0, 0);
1849         if (!info) {
1850                 /*
1851                  * oops didn't find an extent that matched the space we wanted
1852                  * to remove, look for a bitmap instead
1853                  */
1854                 info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1855                                           1, 0);
1856                 if (!info) {
1857                         /* the tree logging code might be calling us before we
1858                          * have fully loaded the free space rbtree for this
1859                          * block group.  So it is possible the entry won't
1860                          * be in the rbtree yet at all.  The caching code
1861                          * will make sure not to put it in the rbtree if
1862                          * the logging code has pinned it.
1863                          */
1864                         goto out_lock;
1865                 }
1866         }
1867
1868         if (info->bytes < bytes && rb_next(&info->offset_index)) {
1869                 u64 end;
1870                 next_info = rb_entry(rb_next(&info->offset_index),
1871                                              struct btrfs_free_space,
1872                                              offset_index);
1873
1874                 if (next_info->bitmap)
1875                         end = next_info->offset +
1876                               BITS_PER_BITMAP * ctl->unit - 1;
1877                 else
1878                         end = next_info->offset + next_info->bytes;
1879
1880                 if (next_info->bytes < bytes ||
1881                     next_info->offset > offset || offset > end) {
1882                         printk(KERN_CRIT "Found free space at %llu, size %llu,"
1883                               " trying to use %llu\n",
1884                               (unsigned long long)info->offset,
1885                               (unsigned long long)info->bytes,
1886                               (unsigned long long)bytes);
1887                         WARN_ON(1);
1888                         ret = -EINVAL;
1889                         goto out_lock;
1890                 }
1891
1892                 info = next_info;
1893         }
1894
1895         if (info->bytes == bytes) {
1896                 unlink_free_space(ctl, info);
1897                 if (info->bitmap) {
1898                         kfree(info->bitmap);
1899                         ctl->total_bitmaps--;
1900                 }
1901                 kmem_cache_free(btrfs_free_space_cachep, info);
1902                 ret = 0;
1903                 goto out_lock;
1904         }
1905
1906         if (!info->bitmap && info->offset == offset) {
1907                 unlink_free_space(ctl, info);
1908                 info->offset += bytes;
1909                 info->bytes -= bytes;
1910                 ret = link_free_space(ctl, info);
1911                 WARN_ON(ret);
1912                 goto out_lock;
1913         }
1914
1915         if (!info->bitmap && info->offset <= offset &&
1916             info->offset + info->bytes >= offset + bytes) {
1917                 u64 old_start = info->offset;
1918                 /*
1919                  * we're freeing space in the middle of the info,
1920                  * this can happen during tree log replay
1921                  *
1922                  * first unlink the old info and then
1923                  * insert it again after the hole we're creating
1924                  */
1925                 unlink_free_space(ctl, info);
1926                 if (offset + bytes < info->offset + info->bytes) {
1927                         u64 old_end = info->offset + info->bytes;
1928
1929                         info->offset = offset + bytes;
1930                         info->bytes = old_end - info->offset;
1931                         ret = link_free_space(ctl, info);
1932                         WARN_ON(ret);
1933                         if (ret)
1934                                 goto out_lock;
1935                 } else {
1936                         /* the hole we're creating ends at the end
1937                          * of the info struct, just free the info
1938                          */
1939                         kmem_cache_free(btrfs_free_space_cachep, info);
1940                 }
1941                 spin_unlock(&ctl->tree_lock);
1942
1943                 /* step two, insert a new info struct to cover
1944                  * anything before the hole
1945                  */
1946                 ret = btrfs_add_free_space(block_group, old_start,
1947                                            offset - old_start);
1948                 WARN_ON(ret); /* -ENOMEM */
1949                 goto out;
1950         }
1951
1952         ret = remove_from_bitmap(ctl, info, &offset, &bytes);
1953         if (ret == -EAGAIN)
1954                 goto again;
1955         BUG_ON(ret); /* logic error */
1956 out_lock:
1957         spin_unlock(&ctl->tree_lock);
1958 out:
1959         return ret;
1960 }
1961
1962 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
1963                            u64 bytes)
1964 {
1965         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1966         struct btrfs_free_space *info;
1967         struct rb_node *n;
1968         int count = 0;
1969
1970         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
1971                 info = rb_entry(n, struct btrfs_free_space, offset_index);
1972                 if (info->bytes >= bytes)
1973                         count++;
1974                 printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
1975                        (unsigned long long)info->offset,
1976                        (unsigned long long)info->bytes,
1977                        (info->bitmap) ? "yes" : "no");
1978         }
1979         printk(KERN_INFO "block group has cluster?: %s\n",
1980                list_empty(&block_group->cluster_list) ? "no" : "yes");
1981         printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
1982                "\n", count);
1983 }
1984
1985 void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
1986 {
1987         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1988
1989         spin_lock_init(&ctl->tree_lock);
1990         ctl->unit = block_group->sectorsize;
1991         ctl->start = block_group->key.objectid;
1992         ctl->private = block_group;
1993         ctl->op = &free_space_op;
1994
1995         /*
1996          * we only want to have 32k of ram per block group for keeping
1997          * track of free space, and if we pass 1/2 of that we want to
1998          * start converting things over to using bitmaps
1999          */
2000         ctl->extents_thresh = ((1024 * 32) / 2) /
2001                                 sizeof(struct btrfs_free_space);
2002 }
2003
2004 /*
2005  * for a given cluster, put all of its extents back into the free
2006  * space cache.  If the block group passed doesn't match the block group
2007  * pointed to by the cluster, someone else raced in and freed the
2008  * cluster already.  In that case, we just return without changing anything
2009  */
2010 static int
2011 __btrfs_return_cluster_to_free_space(
2012                              struct btrfs_block_group_cache *block_group,
2013                              struct btrfs_free_cluster *cluster)
2014 {
2015         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2016         struct btrfs_free_space *entry;
2017         struct rb_node *node;
2018
2019         spin_lock(&cluster->lock);
2020         if (cluster->block_group != block_group)
2021                 goto out;
2022
2023         cluster->block_group = NULL;
2024         cluster->window_start = 0;
2025         list_del_init(&cluster->block_group_list);
2026
2027         node = rb_first(&cluster->root);
2028         while (node) {
2029                 bool bitmap;
2030
2031                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2032                 node = rb_next(&entry->offset_index);
2033                 rb_erase(&entry->offset_index, &cluster->root);
2034
2035                 bitmap = (entry->bitmap != NULL);
2036                 if (!bitmap)
2037                         try_merge_free_space(ctl, entry, false);
2038                 tree_insert_offset(&ctl->free_space_offset,
2039                                    entry->offset, &entry->offset_index, bitmap);
2040         }
2041         cluster->root = RB_ROOT;
2042
2043 out:
2044         spin_unlock(&cluster->lock);
2045         btrfs_put_block_group(block_group);
2046         return 0;
2047 }
2048
2049 void __btrfs_remove_free_space_cache_locked(struct btrfs_free_space_ctl *ctl)
2050 {
2051         struct btrfs_free_space *info;
2052         struct rb_node *node;
2053
2054         while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
2055                 info = rb_entry(node, struct btrfs_free_space, offset_index);
2056                 if (!info->bitmap) {
2057                         unlink_free_space(ctl, info);
2058                         kmem_cache_free(btrfs_free_space_cachep, info);
2059                 } else {
2060                         free_bitmap(ctl, info);
2061                 }
2062                 if (need_resched()) {
2063                         spin_unlock(&ctl->tree_lock);
2064                         cond_resched();
2065                         spin_lock(&ctl->tree_lock);
2066                 }
2067         }
2068 }
2069
2070 void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
2071 {
2072         spin_lock(&ctl->tree_lock);
2073         __btrfs_remove_free_space_cache_locked(ctl);
2074         spin_unlock(&ctl->tree_lock);
2075 }
2076
2077 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
2078 {
2079         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2080         struct btrfs_free_cluster *cluster;
2081         struct list_head *head;
2082
2083         spin_lock(&ctl->tree_lock);
2084         while ((head = block_group->cluster_list.next) !=
2085                &block_group->cluster_list) {
2086                 cluster = list_entry(head, struct btrfs_free_cluster,
2087                                      block_group_list);
2088
2089                 WARN_ON(cluster->block_group != block_group);
2090                 __btrfs_return_cluster_to_free_space(block_group, cluster);
2091                 if (need_resched()) {
2092                         spin_unlock(&ctl->tree_lock);
2093                         cond_resched();
2094                         spin_lock(&ctl->tree_lock);
2095                 }
2096         }
2097         __btrfs_remove_free_space_cache_locked(ctl);
2098         spin_unlock(&ctl->tree_lock);
2099
2100 }
2101
2102 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
2103                                u64 offset, u64 bytes, u64 empty_size)
2104 {
2105         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2106         struct btrfs_free_space *entry = NULL;
2107         u64 bytes_search = bytes + empty_size;
2108         u64 ret = 0;
2109
2110         spin_lock(&ctl->tree_lock);
2111         entry = find_free_space(ctl, &offset, &bytes_search);
2112         if (!entry)
2113                 goto out;
2114
2115         ret = offset;
2116         if (entry->bitmap) {
2117                 bitmap_clear_bits(ctl, entry, offset, bytes);
2118                 if (!entry->bytes)
2119                         free_bitmap(ctl, entry);
2120         } else {
2121                 unlink_free_space(ctl, entry);
2122                 entry->offset += bytes;
2123                 entry->bytes -= bytes;
2124                 if (!entry->bytes)
2125                         kmem_cache_free(btrfs_free_space_cachep, entry);
2126                 else
2127                         link_free_space(ctl, entry);
2128         }
2129
2130 out:
2131         spin_unlock(&ctl->tree_lock);
2132
2133         return ret;
2134 }
2135
2136 /*
2137  * given a cluster, put all of its extents back into the free space
2138  * cache.  If a block group is passed, this function will only free
2139  * a cluster that belongs to the passed block group.
2140  *
2141  * Otherwise, it'll get a reference on the block group pointed to by the
2142  * cluster and remove the cluster from it.
2143  */
2144 int btrfs_return_cluster_to_free_space(
2145                                struct btrfs_block_group_cache *block_group,
2146                                struct btrfs_free_cluster *cluster)
2147 {
2148         struct btrfs_free_space_ctl *ctl;
2149         int ret;
2150
2151         /* first, get a safe pointer to the block group */
2152         spin_lock(&cluster->lock);
2153         if (!block_group) {
2154                 block_group = cluster->block_group;
2155                 if (!block_group) {
2156                         spin_unlock(&cluster->lock);
2157                         return 0;
2158                 }
2159         } else if (cluster->block_group != block_group) {
2160                 /* someone else has already freed it don't redo their work */
2161                 spin_unlock(&cluster->lock);
2162                 return 0;
2163         }
2164         atomic_inc(&block_group->count);
2165         spin_unlock(&cluster->lock);
2166
2167         ctl = block_group->free_space_ctl;
2168
2169         /* now return any extents the cluster had on it */
2170         spin_lock(&ctl->tree_lock);
2171         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
2172         spin_unlock(&ctl->tree_lock);
2173
2174         /* finally drop our ref */
2175         btrfs_put_block_group(block_group);
2176         return ret;
2177 }
2178
2179 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
2180                                    struct btrfs_free_cluster *cluster,
2181                                    struct btrfs_free_space *entry,
2182                                    u64 bytes, u64 min_start)
2183 {
2184         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2185         int err;
2186         u64 search_start = cluster->window_start;
2187         u64 search_bytes = bytes;
2188         u64 ret = 0;
2189
2190         search_start = min_start;
2191         search_bytes = bytes;
2192
2193         err = search_bitmap(ctl, entry, &search_start, &search_bytes);
2194         if (err)
2195                 return 0;
2196
2197         ret = search_start;
2198         __bitmap_clear_bits(ctl, entry, ret, bytes);
2199
2200         return ret;
2201 }
2202
2203 /*
2204  * given a cluster, try to allocate 'bytes' from it, returns 0
2205  * if it couldn't find anything suitably large, or a logical disk offset
2206  * if things worked out
2207  */
2208 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
2209                              struct btrfs_free_cluster *cluster, u64 bytes,
2210                              u64 min_start)
2211 {
2212         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2213         struct btrfs_free_space *entry = NULL;
2214         struct rb_node *node;
2215         u64 ret = 0;
2216
2217         spin_lock(&cluster->lock);
2218         if (bytes > cluster->max_size)
2219                 goto out;
2220
2221         if (cluster->block_group != block_group)
2222                 goto out;
2223
2224         node = rb_first(&cluster->root);
2225         if (!node)
2226                 goto out;
2227
2228         entry = rb_entry(node, struct btrfs_free_space, offset_index);
2229         while(1) {
2230                 if (entry->bytes < bytes ||
2231                     (!entry->bitmap && entry->offset < min_start)) {
2232                         node = rb_next(&entry->offset_index);
2233                         if (!node)
2234                                 break;
2235                         entry = rb_entry(node, struct btrfs_free_space,
2236                                          offset_index);
2237                         continue;
2238                 }
2239
2240                 if (entry->bitmap) {
2241                         ret = btrfs_alloc_from_bitmap(block_group,
2242                                                       cluster, entry, bytes,
2243                                                       cluster->window_start);
2244                         if (ret == 0) {
2245                                 node = rb_next(&entry->offset_index);
2246                                 if (!node)
2247                                         break;
2248                                 entry = rb_entry(node, struct btrfs_free_space,
2249                                                  offset_index);
2250                                 continue;
2251                         }
2252                         cluster->window_start += bytes;
2253                 } else {
2254                         ret = entry->offset;
2255
2256                         entry->offset += bytes;
2257                         entry->bytes -= bytes;
2258                 }
2259
2260                 if (entry->bytes == 0)
2261                         rb_erase(&entry->offset_index, &cluster->root);
2262                 break;
2263         }
2264 out:
2265         spin_unlock(&cluster->lock);
2266
2267         if (!ret)
2268                 return 0;
2269
2270         spin_lock(&ctl->tree_lock);
2271
2272         ctl->free_space -= bytes;
2273         if (entry->bytes == 0) {
2274                 ctl->free_extents--;
2275                 if (entry->bitmap) {
2276                         kfree(entry->bitmap);
2277                         ctl->total_bitmaps--;
2278                         ctl->op->recalc_thresholds(ctl);
2279                 }
2280                 kmem_cache_free(btrfs_free_space_cachep, entry);
2281         }
2282
2283         spin_unlock(&ctl->tree_lock);
2284
2285         return ret;
2286 }
2287
2288 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
2289                                 struct btrfs_free_space *entry,
2290                                 struct btrfs_free_cluster *cluster,
2291                                 u64 offset, u64 bytes,
2292                                 u64 cont1_bytes, u64 min_bytes)
2293 {
2294         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2295         unsigned long next_zero;
2296         unsigned long i;
2297         unsigned long want_bits;
2298         unsigned long min_bits;
2299         unsigned long found_bits;
2300         unsigned long start = 0;
2301         unsigned long total_found = 0;
2302         int ret;
2303
2304         i = offset_to_bit(entry->offset, block_group->sectorsize,
2305                           max_t(u64, offset, entry->offset));
2306         want_bits = bytes_to_bits(bytes, block_group->sectorsize);
2307         min_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
2308
2309 again:
2310         found_bits = 0;
2311         for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
2312              i < BITS_PER_BITMAP;
2313              i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
2314                 next_zero = find_next_zero_bit(entry->bitmap,
2315                                                BITS_PER_BITMAP, i);
2316                 if (next_zero - i >= min_bits) {
2317                         found_bits = next_zero - i;
2318                         break;
2319                 }
2320                 i = next_zero;
2321         }
2322
2323         if (!found_bits)
2324                 return -ENOSPC;
2325
2326         if (!total_found) {
2327                 start = i;
2328                 cluster->max_size = 0;
2329         }
2330
2331         total_found += found_bits;
2332
2333         if (cluster->max_size < found_bits * block_group->sectorsize)
2334                 cluster->max_size = found_bits * block_group->sectorsize;
2335
2336         if (total_found < want_bits || cluster->max_size < cont1_bytes) {
2337                 i = next_zero + 1;
2338                 goto again;
2339         }
2340
2341         cluster->window_start = start * block_group->sectorsize +
2342                 entry->offset;
2343         rb_erase(&entry->offset_index, &ctl->free_space_offset);
2344         ret = tree_insert_offset(&cluster->root, entry->offset,
2345                                  &entry->offset_index, 1);
2346         BUG_ON(ret); /* -EEXIST; Logic error */
2347
2348         trace_btrfs_setup_cluster(block_group, cluster,
2349                                   total_found * block_group->sectorsize, 1);
2350         return 0;
2351 }
2352
2353 /*
2354  * This searches the block group for just extents to fill the cluster with.
2355  * Try to find a cluster with at least bytes total bytes, at least one
2356  * extent of cont1_bytes, and other clusters of at least min_bytes.
2357  */
2358 static noinline int
2359 setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
2360                         struct btrfs_free_cluster *cluster,
2361                         struct list_head *bitmaps, u64 offset, u64 bytes,
2362                         u64 cont1_bytes, u64 min_bytes)
2363 {
2364         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2365         struct btrfs_free_space *first = NULL;
2366         struct btrfs_free_space *entry = NULL;
2367         struct btrfs_free_space *last;
2368         struct rb_node *node;
2369         u64 window_start;
2370         u64 window_free;
2371         u64 max_extent;
2372         u64 total_size = 0;
2373
2374         entry = tree_search_offset(ctl, offset, 0, 1);
2375         if (!entry)
2376                 return -ENOSPC;
2377
2378         /*
2379          * We don't want bitmaps, so just move along until we find a normal
2380          * extent entry.
2381          */
2382         while (entry->bitmap || entry->bytes < min_bytes) {
2383                 if (entry->bitmap && list_empty(&entry->list))
2384                         list_add_tail(&entry->list, bitmaps);
2385                 node = rb_next(&entry->offset_index);
2386                 if (!node)
2387                         return -ENOSPC;
2388                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2389         }
2390
2391         window_start = entry->offset;
2392         window_free = entry->bytes;
2393         max_extent = entry->bytes;
2394         first = entry;
2395         last = entry;
2396
2397         for (node = rb_next(&entry->offset_index); node;
2398              node = rb_next(&entry->offset_index)) {
2399                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2400
2401                 if (entry->bitmap) {
2402                         if (list_empty(&entry->list))
2403                                 list_add_tail(&entry->list, bitmaps);
2404                         continue;
2405                 }
2406
2407                 if (entry->bytes < min_bytes)
2408                         continue;
2409
2410                 last = entry;
2411                 window_free += entry->bytes;
2412                 if (entry->bytes > max_extent)
2413                         max_extent = entry->bytes;
2414         }
2415
2416         if (window_free < bytes || max_extent < cont1_bytes)
2417                 return -ENOSPC;
2418
2419         cluster->window_start = first->offset;
2420
2421         node = &first->offset_index;
2422
2423         /*
2424          * now we've found our entries, pull them out of the free space
2425          * cache and put them into the cluster rbtree
2426          */
2427         do {
2428                 int ret;
2429
2430                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2431                 node = rb_next(&entry->offset_index);
2432                 if (entry->bitmap || entry->bytes < min_bytes)
2433                         continue;
2434
2435                 rb_erase(&entry->offset_index, &ctl->free_space_offset);
2436                 ret = tree_insert_offset(&cluster->root, entry->offset,
2437                                          &entry->offset_index, 0);
2438                 total_size += entry->bytes;
2439                 BUG_ON(ret); /* -EEXIST; Logic error */
2440         } while (node && entry != last);
2441
2442         cluster->max_size = max_extent;
2443         trace_btrfs_setup_cluster(block_group, cluster, total_size, 0);
2444         return 0;
2445 }
2446
2447 /*
2448  * This specifically looks for bitmaps that may work in the cluster, we assume
2449  * that we have already failed to find extents that will work.
2450  */
2451 static noinline int
2452 setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2453                      struct btrfs_free_cluster *cluster,
2454                      struct list_head *bitmaps, u64 offset, u64 bytes,
2455                      u64 cont1_bytes, u64 min_bytes)
2456 {
2457         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2458         struct btrfs_free_space *entry;
2459         int ret = -ENOSPC;
2460         u64 bitmap_offset = offset_to_bitmap(ctl, offset);
2461
2462         if (ctl->total_bitmaps == 0)
2463                 return -ENOSPC;
2464
2465         /*
2466          * The bitmap that covers offset won't be in the list unless offset
2467          * is just its start offset.
2468          */
2469         entry = list_first_entry(bitmaps, struct btrfs_free_space, list);
2470         if (entry->offset != bitmap_offset) {
2471                 entry = tree_search_offset(ctl, bitmap_offset, 1, 0);
2472                 if (entry && list_empty(&entry->list))
2473                         list_add(&entry->list, bitmaps);
2474         }
2475
2476         list_for_each_entry(entry, bitmaps, list) {
2477                 if (entry->bytes < bytes)
2478                         continue;
2479                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2480                                            bytes, cont1_bytes, min_bytes);
2481                 if (!ret)
2482                         return 0;
2483         }
2484
2485         /*
2486          * The bitmaps list has all the bitmaps that record free space
2487          * starting after offset, so no more search is required.
2488          */
2489         return -ENOSPC;
2490 }
2491
2492 /*
2493  * here we try to find a cluster of blocks in a block group.  The goal
2494  * is to find at least bytes+empty_size.
2495  * We might not find them all in one contiguous area.
2496  *
2497  * returns zero and sets up cluster if things worked out, otherwise
2498  * it returns -enospc
2499  */
2500 int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
2501                              struct btrfs_root *root,
2502                              struct btrfs_block_group_cache *block_group,
2503                              struct btrfs_free_cluster *cluster,
2504                              u64 offset, u64 bytes, u64 empty_size)
2505 {
2506         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2507         struct btrfs_free_space *entry, *tmp;
2508         LIST_HEAD(bitmaps);
2509         u64 min_bytes;
2510         u64 cont1_bytes;
2511         int ret;
2512
2513         /*
2514          * Choose the minimum extent size we'll require for this
2515          * cluster.  For SSD_SPREAD, don't allow any fragmentation.
2516          * For metadata, allow allocates with smaller extents.  For
2517          * data, keep it dense.
2518          */
2519         if (btrfs_test_opt(root, SSD_SPREAD)) {
2520                 cont1_bytes = min_bytes = bytes + empty_size;
2521         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
2522                 cont1_bytes = bytes;
2523                 min_bytes = block_group->sectorsize;
2524         } else {
2525                 cont1_bytes = max(bytes, (bytes + empty_size) >> 2);
2526                 min_bytes = block_group->sectorsize;
2527         }
2528
2529         spin_lock(&ctl->tree_lock);
2530
2531         /*
2532          * If we know we don't have enough space to make a cluster don't even
2533          * bother doing all the work to try and find one.
2534          */
2535         if (ctl->free_space < bytes) {
2536                 spin_unlock(&ctl->tree_lock);
2537                 return -ENOSPC;
2538         }
2539
2540         spin_lock(&cluster->lock);
2541
2542         /* someone already found a cluster, hooray */
2543         if (cluster->block_group) {
2544                 ret = 0;
2545                 goto out;
2546         }
2547
2548         trace_btrfs_find_cluster(block_group, offset, bytes, empty_size,
2549                                  min_bytes);
2550
2551         INIT_LIST_HEAD(&bitmaps);
2552         ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
2553                                       bytes + empty_size,
2554                                       cont1_bytes, min_bytes);
2555         if (ret)
2556                 ret = setup_cluster_bitmap(block_group, cluster, &bitmaps,
2557                                            offset, bytes + empty_size,
2558                                            cont1_bytes, min_bytes);
2559
2560         /* Clear our temporary list */
2561         list_for_each_entry_safe(entry, tmp, &bitmaps, list)
2562                 list_del_init(&entry->list);
2563
2564         if (!ret) {
2565                 atomic_inc(&block_group->count);
2566                 list_add_tail(&cluster->block_group_list,
2567                               &block_group->cluster_list);
2568                 cluster->block_group = block_group;
2569         } else {
2570                 trace_btrfs_failed_cluster_setup(block_group);
2571         }
2572 out:
2573         spin_unlock(&cluster->lock);
2574         spin_unlock(&ctl->tree_lock);
2575
2576         return ret;
2577 }
2578
2579 /*
2580  * simple code to zero out a cluster
2581  */
2582 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
2583 {
2584         spin_lock_init(&cluster->lock);
2585         spin_lock_init(&cluster->refill_lock);
2586         cluster->root = RB_ROOT;
2587         cluster->max_size = 0;
2588         INIT_LIST_HEAD(&cluster->block_group_list);
2589         cluster->block_group = NULL;
2590 }
2591
2592 static int do_trimming(struct btrfs_block_group_cache *block_group,
2593                        u64 *total_trimmed, u64 start, u64 bytes,
2594                        u64 reserved_start, u64 reserved_bytes)
2595 {
2596         struct btrfs_space_info *space_info = block_group->space_info;
2597         struct btrfs_fs_info *fs_info = block_group->fs_info;
2598         int ret;
2599         int update = 0;
2600         u64 trimmed = 0;
2601
2602         spin_lock(&space_info->lock);
2603         spin_lock(&block_group->lock);
2604         if (!block_group->ro) {
2605                 block_group->reserved += reserved_bytes;
2606                 space_info->bytes_reserved += reserved_bytes;
2607                 update = 1;
2608         }
2609         spin_unlock(&block_group->lock);
2610         spin_unlock(&space_info->lock);
2611
2612         ret = btrfs_error_discard_extent(fs_info->extent_root,
2613                                          start, bytes, &trimmed);
2614         if (!ret)
2615                 *total_trimmed += trimmed;
2616
2617         btrfs_add_free_space(block_group, reserved_start, reserved_bytes);
2618
2619         if (update) {
2620                 spin_lock(&space_info->lock);
2621                 spin_lock(&block_group->lock);
2622                 if (block_group->ro)
2623                         space_info->bytes_readonly += reserved_bytes;
2624                 block_group->reserved -= reserved_bytes;
2625                 space_info->bytes_reserved -= reserved_bytes;
2626                 spin_unlock(&space_info->lock);
2627                 spin_unlock(&block_group->lock);
2628         }
2629
2630         return ret;
2631 }
2632
2633 static int trim_no_bitmap(struct btrfs_block_group_cache *block_group,
2634                           u64 *total_trimmed, u64 start, u64 end, u64 minlen)
2635 {
2636         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2637         struct btrfs_free_space *entry;
2638         struct rb_node *node;
2639         int ret = 0;
2640         u64 extent_start;
2641         u64 extent_bytes;
2642         u64 bytes;
2643
2644         while (start < end) {
2645                 spin_lock(&ctl->tree_lock);
2646
2647                 if (ctl->free_space < minlen) {
2648                         spin_unlock(&ctl->tree_lock);
2649                         break;
2650                 }
2651
2652                 entry = tree_search_offset(ctl, start, 0, 1);
2653                 if (!entry) {
2654                         spin_unlock(&ctl->tree_lock);
2655                         break;
2656                 }
2657
2658                 /* skip bitmaps */
2659                 while (entry->bitmap) {
2660                         node = rb_next(&entry->offset_index);
2661                         if (!node) {
2662                                 spin_unlock(&ctl->tree_lock);
2663                                 goto out;
2664                         }
2665                         entry = rb_entry(node, struct btrfs_free_space,
2666                                          offset_index);
2667                 }
2668
2669                 if (entry->offset >= end) {
2670                         spin_unlock(&ctl->tree_lock);
2671                         break;
2672                 }
2673
2674                 extent_start = entry->offset;
2675                 extent_bytes = entry->bytes;
2676                 start = max(start, extent_start);
2677                 bytes = min(extent_start + extent_bytes, end) - start;
2678                 if (bytes < minlen) {
2679                         spin_unlock(&ctl->tree_lock);
2680                         goto next;
2681                 }
2682
2683                 unlink_free_space(ctl, entry);
2684                 kmem_cache_free(btrfs_free_space_cachep, entry);
2685
2686                 spin_unlock(&ctl->tree_lock);
2687
2688                 ret = do_trimming(block_group, total_trimmed, start, bytes,
2689                                   extent_start, extent_bytes);
2690                 if (ret)
2691                         break;
2692 next:
2693                 start += bytes;
2694
2695                 if (fatal_signal_pending(current)) {
2696                         ret = -ERESTARTSYS;
2697                         break;
2698                 }
2699
2700                 cond_resched();
2701         }
2702 out:
2703         return ret;
2704 }
2705
2706 static int trim_bitmaps(struct btrfs_block_group_cache *block_group,
2707                         u64 *total_trimmed, u64 start, u64 end, u64 minlen)
2708 {
2709         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2710         struct btrfs_free_space *entry;
2711         int ret = 0;
2712         int ret2;
2713         u64 bytes;
2714         u64 offset = offset_to_bitmap(ctl, start);
2715
2716         while (offset < end) {
2717                 bool next_bitmap = false;
2718
2719                 spin_lock(&ctl->tree_lock);
2720
2721                 if (ctl->free_space < minlen) {
2722                         spin_unlock(&ctl->tree_lock);
2723                         break;
2724                 }
2725
2726                 entry = tree_search_offset(ctl, offset, 1, 0);
2727                 if (!entry) {
2728                         spin_unlock(&ctl->tree_lock);
2729                         next_bitmap = true;
2730                         goto next;
2731                 }
2732
2733                 bytes = minlen;
2734                 ret2 = search_bitmap(ctl, entry, &start, &bytes);
2735                 if (ret2 || start >= end) {
2736                         spin_unlock(&ctl->tree_lock);
2737                         next_bitmap = true;
2738                         goto next;
2739                 }
2740
2741                 bytes = min(bytes, end - start);
2742                 if (bytes < minlen) {
2743                         spin_unlock(&ctl->tree_lock);
2744                         goto next;
2745                 }
2746
2747                 bitmap_clear_bits(ctl, entry, start, bytes);
2748                 if (entry->bytes == 0)
2749                         free_bitmap(ctl, entry);
2750
2751                 spin_unlock(&ctl->tree_lock);
2752
2753                 ret = do_trimming(block_group, total_trimmed, start, bytes,
2754                                   start, bytes);
2755                 if (ret)
2756                         break;
2757 next:
2758                 if (next_bitmap) {
2759                         offset += BITS_PER_BITMAP * ctl->unit;
2760                 } else {
2761                         start += bytes;
2762                         if (start >= offset + BITS_PER_BITMAP * ctl->unit)
2763                                 offset += BITS_PER_BITMAP * ctl->unit;
2764                 }
2765
2766                 if (fatal_signal_pending(current)) {
2767                         ret = -ERESTARTSYS;
2768                         break;
2769                 }
2770
2771                 cond_resched();
2772         }
2773
2774         return ret;
2775 }
2776
2777 int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
2778                            u64 *trimmed, u64 start, u64 end, u64 minlen)
2779 {
2780         int ret;
2781
2782         *trimmed = 0;
2783
2784         ret = trim_no_bitmap(block_group, trimmed, start, end, minlen);
2785         if (ret)
2786                 return ret;
2787
2788         ret = trim_bitmaps(block_group, trimmed, start, end, minlen);
2789
2790         return ret;
2791 }
2792
2793 /*
2794  * Find the left-most item in the cache tree, and then return the
2795  * smallest inode number in the item.
2796  *
2797  * Note: the returned inode number may not be the smallest one in
2798  * the tree, if the left-most item is a bitmap.
2799  */
2800 u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root)
2801 {
2802         struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl;
2803         struct btrfs_free_space *entry = NULL;
2804         u64 ino = 0;
2805
2806         spin_lock(&ctl->tree_lock);
2807
2808         if (RB_EMPTY_ROOT(&ctl->free_space_offset))
2809                 goto out;
2810
2811         entry = rb_entry(rb_first(&ctl->free_space_offset),
2812                          struct btrfs_free_space, offset_index);
2813
2814         if (!entry->bitmap) {
2815                 ino = entry->offset;
2816
2817                 unlink_free_space(ctl, entry);
2818                 entry->offset++;
2819                 entry->bytes--;
2820                 if (!entry->bytes)
2821                         kmem_cache_free(btrfs_free_space_cachep, entry);
2822                 else
2823                         link_free_space(ctl, entry);
2824         } else {
2825                 u64 offset = 0;
2826                 u64 count = 1;
2827                 int ret;
2828
2829                 ret = search_bitmap(ctl, entry, &offset, &count);
2830                 /* Logic error; Should be empty if it can't find anything */
2831                 BUG_ON(ret);
2832
2833                 ino = offset;
2834                 bitmap_clear_bits(ctl, entry, offset, 1);
2835                 if (entry->bytes == 0)
2836                         free_bitmap(ctl, entry);
2837         }
2838 out:
2839         spin_unlock(&ctl->tree_lock);
2840
2841         return ino;
2842 }
2843
2844 struct inode *lookup_free_ino_inode(struct btrfs_root *root,
2845                                     struct btrfs_path *path)
2846 {
2847         struct inode *inode = NULL;
2848
2849         spin_lock(&root->cache_lock);
2850         if (root->cache_inode)
2851                 inode = igrab(root->cache_inode);
2852         spin_unlock(&root->cache_lock);
2853         if (inode)
2854                 return inode;
2855
2856         inode = __lookup_free_space_inode(root, path, 0);
2857         if (IS_ERR(inode))
2858                 return inode;
2859
2860         spin_lock(&root->cache_lock);
2861         if (!btrfs_fs_closing(root->fs_info))
2862                 root->cache_inode = igrab(inode);
2863         spin_unlock(&root->cache_lock);
2864
2865         return inode;
2866 }
2867
2868 int create_free_ino_inode(struct btrfs_root *root,
2869                           struct btrfs_trans_handle *trans,
2870                           struct btrfs_path *path)
2871 {
2872         return __create_free_space_inode(root, trans, path,
2873                                          BTRFS_FREE_INO_OBJECTID, 0);
2874 }
2875
2876 int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
2877 {
2878         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2879         struct btrfs_path *path;
2880         struct inode *inode;
2881         int ret = 0;
2882         u64 root_gen = btrfs_root_generation(&root->root_item);
2883
2884         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
2885                 return 0;
2886
2887         /*
2888          * If we're unmounting then just return, since this does a search on the
2889          * normal root and not the commit root and we could deadlock.
2890          */
2891         if (btrfs_fs_closing(fs_info))
2892                 return 0;
2893
2894         path = btrfs_alloc_path();
2895         if (!path)
2896                 return 0;
2897
2898         inode = lookup_free_ino_inode(root, path);
2899         if (IS_ERR(inode))
2900                 goto out;
2901
2902         if (root_gen != BTRFS_I(inode)->generation)
2903                 goto out_put;
2904
2905         ret = __load_free_space_cache(root, inode, ctl, path, 0);
2906
2907         if (ret < 0)
2908                 printk(KERN_ERR "btrfs: failed to load free ino cache for "
2909                        "root %llu\n", root->root_key.objectid);
2910 out_put:
2911         iput(inode);
2912 out:
2913         btrfs_free_path(path);
2914         return ret;
2915 }
2916
2917 int btrfs_write_out_ino_cache(struct btrfs_root *root,
2918                               struct btrfs_trans_handle *trans,
2919                               struct btrfs_path *path)
2920 {
2921         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
2922         struct inode *inode;
2923         int ret;
2924
2925         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
2926                 return 0;
2927
2928         inode = lookup_free_ino_inode(root, path);
2929         if (IS_ERR(inode))
2930                 return 0;
2931
2932         ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);
2933         if (ret) {
2934                 btrfs_delalloc_release_metadata(inode, inode->i_size);
2935 #ifdef DEBUG
2936                 printk(KERN_ERR "btrfs: failed to write free ino cache "
2937                        "for root %llu\n", root->root_key.objectid);
2938 #endif
2939         }
2940
2941         iput(inode);
2942         return ret;
2943 }