fs/btrfs/free-space-cache.c

   1 /*
   2  * Copyright (C) 2008 Red Hat.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/pagemap.h>
  20 #include <linux/sched.h>
  21 #include <linux/slab.h>
  22 #include <linux/math64.h>
  23 #include <linux/ratelimit.h>
  24 #include "ctree.h"
  25 #include "free-space-cache.h"
  26 #include "transaction.h"
  27 #include "disk-io.h"
  28 #include "extent_io.h"
  29 #include "inode-map.h"
  30
  31 #define BITS_PER_BITMAP         (PAGE_CACHE_SIZE * 8)
  32 #define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
  33
  34 static int link_free_space(struct btrfs_free_space_ctl *ctl,
  35                            struct btrfs_free_space *info);
  36 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
  37                               struct btrfs_free_space *info);
  38
  39 static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
  40                                                struct btrfs_path *path,
  41                                                u64 offset)
  42 {
  43         struct btrfs_key key;
  44         struct btrfs_key location;
  45         struct btrfs_disk_key disk_key;
  46         struct btrfs_free_space_header *header;
  47         struct extent_buffer *leaf;
  48         struct inode *inode = NULL;
  49         int ret;
  50
  51         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
  52         key.offset = offset;
  53         key.type = 0;
  54
  55         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  56         if (ret < 0)
  57                 return ERR_PTR(ret);
  58         if (ret > 0) {
  59                 btrfs_release_path(path);
  60                 return ERR_PTR(-ENOENT);
  61         }
  62
  63         leaf = path->nodes[0];
  64         header = btrfs_item_ptr(leaf, path->slots[0],
  65                                 struct btrfs_free_space_header);
  66         btrfs_free_space_key(leaf, header, &disk_key);
  67         btrfs_disk_key_to_cpu(&location, &disk_key);
  68         btrfs_release_path(path);
  69
  70         inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
  71         if (!inode)
  72                 return ERR_PTR(-ENOENT);
  73         if (IS_ERR(inode))
  74                 return inode;
  75         if (is_bad_inode(inode)) {
  76                 iput(inode);
  77                 return ERR_PTR(-ENOENT);
  78         }
  79
  80         mapping_set_gfp_mask(inode->i_mapping,
  81                         mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS);
  82
  83         return inode;
  84 }
  85
  86 struct inode *lookup_free_space_inode(struct btrfs_root *root,
  87                                       struct btrfs_block_group_cache
  88                                       *block_group, struct btrfs_path *path)
  89 {
  90         struct inode *inode = NULL;
  91         u32 flags = BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
  92
  93         spin_lock(&block_group->lock);
  94         if (block_group->inode)
  95                 inode = igrab(block_group->inode);
  96         spin_unlock(&block_group->lock);
  97         if (inode)
  98                 return inode;
  99
 100         inode = __lookup_free_space_inode(root, path,
 101                                           block_group->key.objectid);
 102         if (IS_ERR(inode))
 103                 return inode;
 104
 105         spin_lock(&block_group->lock);
 106         if (!((BTRFS_I(inode)->flags & flags) == flags)) {
 107                 btrfs_info(root->fs_info,
 108                         "Old style space inode found, converting.");
 109                 BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM |
 110                         BTRFS_INODE_NODATACOW;
 111                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 112         }
 113
 114         if (!block_group->iref) {
 115                 block_group->inode = igrab(inode);
 116                 block_group->iref = 1;
 117         }
 118         spin_unlock(&block_group->lock);
 119
 120         return inode;
 121 }
 122
 123 static int __create_free_space_inode(struct btrfs_root *root,
 124                                      struct btrfs_trans_handle *trans,
 125                                      struct btrfs_path *path,
 126                                      u64 ino, u64 offset)
 127 {
 128         struct btrfs_key key;
 129         struct btrfs_disk_key disk_key;
 130         struct btrfs_free_space_header *header;
 131         struct btrfs_inode_item *inode_item;
 132         struct extent_buffer *leaf;
 133         u64 flags = BTRFS_INODE_NOCOMPRESS | BTRFS_INODE_PREALLOC;
 134         int ret;
 135
 136         ret = btrfs_insert_empty_inode(trans, root, path, ino);
 137         if (ret)
 138                 return ret;
 139
 140         /* We inline crc's for the free disk space cache */
 141         if (ino != BTRFS_FREE_INO_OBJECTID)
 142                 flags |= BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
 143
 144         leaf = path->nodes[0];
 145         inode_item = btrfs_item_ptr(leaf, path->slots[0],
 146                                     struct btrfs_inode_item);
 147         btrfs_item_key(leaf, &disk_key, path->slots[0]);
 148         memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
 149                              sizeof(*inode_item));
 150         btrfs_set_inode_generation(leaf, inode_item, trans->transid);
 151         btrfs_set_inode_size(leaf, inode_item, 0);
 152         btrfs_set_inode_nbytes(leaf, inode_item, 0);
 153         btrfs_set_inode_uid(leaf, inode_item, 0);
 154         btrfs_set_inode_gid(leaf, inode_item, 0);
 155         btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
 156         btrfs_set_inode_flags(leaf, inode_item, flags);
 157         btrfs_set_inode_nlink(leaf, inode_item, 1);
 158         btrfs_set_inode_transid(leaf, inode_item, trans->transid);
 159         btrfs_set_inode_block_group(leaf, inode_item, offset);
 160         btrfs_mark_buffer_dirty(leaf);
 161         btrfs_release_path(path);
 162
 163         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 164         key.offset = offset;
 165         key.type = 0;
 166
 167         ret = btrfs_insert_empty_item(trans, root, path, &key,
 168                                       sizeof(struct btrfs_free_space_header));
 169         if (ret < 0) {
 170                 btrfs_release_path(path);
 171                 return ret;
 172         }
 173         leaf = path->nodes[0];
 174         header = btrfs_item_ptr(leaf, path->slots[0],
 175                                 struct btrfs_free_space_header);
 176         memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
 177         btrfs_set_free_space_key(leaf, header, &disk_key);
 178         btrfs_mark_buffer_dirty(leaf);
 179         btrfs_release_path(path);
 180
 181         return 0;
 182 }
 183
 184 int create_free_space_inode(struct btrfs_root *root,
 185                             struct btrfs_trans_handle *trans,
 186                             struct btrfs_block_group_cache *block_group,
 187                             struct btrfs_path *path)
 188 {
 189         int ret;
 190         u64 ino;
 191
 192         ret = btrfs_find_free_objectid(root, &ino);
 193         if (ret < 0)
 194                 return ret;
 195
 196         return __create_free_space_inode(root, trans, path, ino,
 197                                          block_group->key.objectid);
 198 }
 199
 200 int btrfs_check_trunc_cache_free_space(struct btrfs_root *root,
 201                                        struct btrfs_block_rsv *rsv)
 202 {
 203         u64 needed_bytes;
 204         int ret;
 205
 206         /* 1 for slack space, 1 for updating the inode */
 207         needed_bytes = btrfs_calc_trunc_metadata_size(root, 1) +
 208                 btrfs_calc_trans_metadata_size(root, 1);
 209
 210         spin_lock(&rsv->lock);
 211         if (rsv->reserved < needed_bytes)
 212                 ret = -ENOSPC;
 213         else
 214                 ret = 0;
 215         spin_unlock(&rsv->lock);
 216         return ret;
 217 }
 218
 219 int btrfs_truncate_free_space_cache(struct btrfs_root *root,
 220                                     struct btrfs_trans_handle *trans,
 221                                     struct inode *inode)
 222 {
 223         int ret = 0;
 224
 225         btrfs_i_size_write(inode, 0);
 226         truncate_pagecache(inode, 0);
 227
 228         /*
 229          * We don't need an orphan item because truncating the free space cache
 230          * will never be split across transactions.
 231          */
 232         ret = btrfs_truncate_inode_items(trans, root, inode,
 233                                          0, BTRFS_EXTENT_DATA_KEY);
 234         if (ret) {
 235                 btrfs_abort_transaction(trans, root, ret);
 236                 return ret;
 237         }
 238
 239         ret = btrfs_update_inode(trans, root, inode);
 240         if (ret)
 241                 btrfs_abort_transaction(trans, root, ret);
 242
 243         return ret;
 244 }
 245
 246 static int readahead_cache(struct inode *inode)
 247 {
 248         struct file_ra_state *ra;
 249         unsigned long last_index;
 250
 251         ra = kzalloc(sizeof(*ra), GFP_NOFS);
 252         if (!ra)
 253                 return -ENOMEM;
 254
 255         file_ra_state_init(ra, inode->i_mapping);
 256         last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 257
 258         page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
 259
 260         kfree(ra);
 261
 262         return 0;
 263 }
 264
 265 struct io_ctl {
 266         void *cur, *orig;
 267         struct page *page;
 268         struct page **pages;
 269         struct btrfs_root *root;
 270         unsigned long size;
 271         int index;
 272         int num_pages;
 273         unsigned check_crcs:1;
 274 };
 275
 276 static int io_ctl_init(struct io_ctl *io_ctl, struct inode *inode,
 277                        struct btrfs_root *root)
 278 {
 279         memset(io_ctl, 0, sizeof(struct io_ctl));
 280         io_ctl->num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
 281                 PAGE_CACHE_SHIFT;
 282         io_ctl->pages = kzalloc(sizeof(struct page *) * io_ctl->num_pages,
 283                                 GFP_NOFS);
 284         if (!io_ctl->pages)
 285                 return -ENOMEM;
 286         io_ctl->root = root;
 287         if (btrfs_ino(inode) != BTRFS_FREE_INO_OBJECTID)
 288                 io_ctl->check_crcs = 1;
 289         return 0;
 290 }
 291
 292 static void io_ctl_free(struct io_ctl *io_ctl)
 293 {
 294         kfree(io_ctl->pages);
 295 }
 296
 297 static void io_ctl_unmap_page(struct io_ctl *io_ctl)
 298 {
 299         if (io_ctl->cur) {
 300                 kunmap(io_ctl->page);
 301                 io_ctl->cur = NULL;
 302                 io_ctl->orig = NULL;
 303         }
 304 }
 305
 306 static void io_ctl_map_page(struct io_ctl *io_ctl, int clear)
 307 {
 308         ASSERT(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                                 btrfs_err(BTRFS_I(inode)->root->fs_info,
 351                                            "error reading free space cache");
 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         __le64 *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         __le64 *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->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->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 /*
 588  * Since we attach pinned extents after the fact we can have contiguous sections
 589  * of free space that are split up in entries.  This poses a problem with the
 590  * tree logging stuff since it could have allocated across what appears to be 2
 591  * entries since we would have merged the entries when adding the pinned extents
 592  * back to the free space cache.  So run through the space cache that we just
 593  * loaded and merge contiguous entries.  This will make the log replay stuff not
 594  * blow up and it will make for nicer allocator behavior.
 595  */
 596 static void merge_space_tree(struct btrfs_free_space_ctl *ctl)
 597 {
 598         struct btrfs_free_space *e, *prev = NULL;
 599         struct rb_node *n;
 600
 601 again:
 602         spin_lock(&ctl->tree_lock);
 603         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
 604                 e = rb_entry(n, struct btrfs_free_space, offset_index);
 605                 if (!prev)
 606                         goto next;
 607                 if (e->bitmap || prev->bitmap)
 608                         goto next;
 609                 if (prev->offset + prev->bytes == e->offset) {
 610                         unlink_free_space(ctl, prev);
 611                         unlink_free_space(ctl, e);
 612                         prev->bytes += e->bytes;
 613                         kmem_cache_free(btrfs_free_space_cachep, e);
 614                         link_free_space(ctl, prev);
 615                         prev = NULL;
 616                         spin_unlock(&ctl->tree_lock);
 617                         goto again;
 618                 }
 619 next:
 620                 prev = e;
 621         }
 622         spin_unlock(&ctl->tree_lock);
 623 }
 624
 625 static int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 626                                    struct btrfs_free_space_ctl *ctl,
 627                                    struct btrfs_path *path, u64 offset)
 628 {
 629         struct btrfs_free_space_header *header;
 630         struct extent_buffer *leaf;
 631         struct io_ctl io_ctl;
 632         struct btrfs_key key;
 633         struct btrfs_free_space *e, *n;
 634         struct list_head bitmaps;
 635         u64 num_entries;
 636         u64 num_bitmaps;
 637         u64 generation;
 638         u8 type;
 639         int ret = 0;
 640
 641         INIT_LIST_HEAD(&bitmaps);
 642
 643         /* Nothing in the space cache, goodbye */
 644         if (!i_size_read(inode))
 645                 return 0;
 646
 647         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 648         key.offset = offset;
 649         key.type = 0;
 650
 651         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 652         if (ret < 0)
 653                 return 0;
 654         else if (ret > 0) {
 655                 btrfs_release_path(path);
 656                 return 0;
 657         }
 658
 659         ret = -1;
 660
 661         leaf = path->nodes[0];
 662         header = btrfs_item_ptr(leaf, path->slots[0],
 663                                 struct btrfs_free_space_header);
 664         num_entries = btrfs_free_space_entries(leaf, header);
 665         num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
 666         generation = btrfs_free_space_generation(leaf, header);
 667         btrfs_release_path(path);
 668
 669         if (BTRFS_I(inode)->generation != generation) {
 670                 btrfs_err(root->fs_info,
 671                         "free space inode generation (%llu) "
 672                         "did not match free space cache generation (%llu)",
 673                         BTRFS_I(inode)->generation, generation);
 674                 return 0;
 675         }
 676
 677         if (!num_entries)
 678                 return 0;
 679
 680         ret = io_ctl_init(&io_ctl, inode, root);
 681         if (ret)
 682                 return ret;
 683
 684         ret = readahead_cache(inode);
 685         if (ret)
 686                 goto out;
 687
 688         ret = io_ctl_prepare_pages(&io_ctl, inode, 1);
 689         if (ret)
 690                 goto out;
 691
 692         ret = io_ctl_check_crc(&io_ctl, 0);
 693         if (ret)
 694                 goto free_cache;
 695
 696         ret = io_ctl_check_generation(&io_ctl, generation);
 697         if (ret)
 698                 goto free_cache;
 699
 700         while (num_entries) {
 701                 e = kmem_cache_zalloc(btrfs_free_space_cachep,
 702                                       GFP_NOFS);
 703                 if (!e)
 704                         goto free_cache;
 705
 706                 ret = io_ctl_read_entry(&io_ctl, e, &type);
 707                 if (ret) {
 708                         kmem_cache_free(btrfs_free_space_cachep, e);
 709                         goto free_cache;
 710                 }
 711
 712                 if (!e->bytes) {
 713                         kmem_cache_free(btrfs_free_space_cachep, e);
 714                         goto free_cache;
 715                 }
 716
 717                 if (type == BTRFS_FREE_SPACE_EXTENT) {
 718                         spin_lock(&ctl->tree_lock);
 719                         ret = link_free_space(ctl, e);
 720                         spin_unlock(&ctl->tree_lock);
 721                         if (ret) {
 722                                 btrfs_err(root->fs_info,
 723                                         "Duplicate entries in free space cache, dumping");
 724                                 kmem_cache_free(btrfs_free_space_cachep, e);
 725                                 goto free_cache;
 726                         }
 727                 } else {
 728                         ASSERT(num_bitmaps);
 729                         num_bitmaps--;
 730                         e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
 731                         if (!e->bitmap) {
 732                                 kmem_cache_free(
 733                                         btrfs_free_space_cachep, e);
 734                                 goto free_cache;
 735                         }
 736                         spin_lock(&ctl->tree_lock);
 737                         ret = link_free_space(ctl, e);
 738                         ctl->total_bitmaps++;
 739                         ctl->op->recalc_thresholds(ctl);
 740                         spin_unlock(&ctl->tree_lock);
 741                         if (ret) {
 742                                 btrfs_err(root->fs_info,
 743                                         "Duplicate entries in free space cache, dumping");
 744                                 kmem_cache_free(btrfs_free_space_cachep, e);
 745                                 goto free_cache;
 746                         }
 747                         list_add_tail(&e->list, &bitmaps);
 748                 }
 749
 750                 num_entries--;
 751         }
 752
 753         io_ctl_unmap_page(&io_ctl);
 754
 755         /*
 756          * We add the bitmaps at the end of the entries in order that
 757          * the bitmap entries are added to the cache.
 758          */
 759         list_for_each_entry_safe(e, n, &bitmaps, list) {
 760                 list_del_init(&e->list);
 761                 ret = io_ctl_read_bitmap(&io_ctl, e);
 762                 if (ret)
 763                         goto free_cache;
 764         }
 765
 766         io_ctl_drop_pages(&io_ctl);
 767         merge_space_tree(ctl);
 768         ret = 1;
 769 out:
 770         io_ctl_free(&io_ctl);
 771         return ret;
 772 free_cache:
 773         io_ctl_drop_pages(&io_ctl);
 774         __btrfs_remove_free_space_cache(ctl);
 775         goto out;
 776 }
 777
 778 int load_free_space_cache(struct btrfs_fs_info *fs_info,
 779                           struct btrfs_block_group_cache *block_group)
 780 {
 781         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 782         struct btrfs_root *root = fs_info->tree_root;
 783         struct inode *inode;
 784         struct btrfs_path *path;
 785         int ret = 0;
 786         bool matched;
 787         u64 used = btrfs_block_group_used(&block_group->item);
 788
 789         /*
 790          * If this block group has been marked to be cleared for one reason or
 791          * another then we can't trust the on disk cache, so just return.
 792          */
 793         spin_lock(&block_group->lock);
 794         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 795                 spin_unlock(&block_group->lock);
 796                 return 0;
 797         }
 798         spin_unlock(&block_group->lock);
 799
 800         path = btrfs_alloc_path();
 801         if (!path)
 802                 return 0;
 803         path->search_commit_root = 1;
 804         path->skip_locking = 1;
 805
 806         inode = lookup_free_space_inode(root, block_group, path);
 807         if (IS_ERR(inode)) {
 808                 btrfs_free_path(path);
 809                 return 0;
 810         }
 811
 812         /* We may have converted the inode and made the cache invalid. */
 813         spin_lock(&block_group->lock);
 814         if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 815                 spin_unlock(&block_group->lock);
 816                 btrfs_free_path(path);
 817                 goto out;
 818         }
 819         spin_unlock(&block_group->lock);
 820
 821         ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
 822                                       path, block_group->key.objectid);
 823         btrfs_free_path(path);
 824         if (ret <= 0)
 825                 goto out;
 826
 827         spin_lock(&ctl->tree_lock);
 828         matched = (ctl->free_space == (block_group->key.offset - used -
 829                                        block_group->bytes_super));
 830         spin_unlock(&ctl->tree_lock);
 831
 832         if (!matched) {
 833                 __btrfs_remove_free_space_cache(ctl);
 834                 btrfs_warn(fs_info, "block group %llu has wrong amount of free space",
 835                         block_group->key.objectid);
 836                 ret = -1;
 837         }
 838 out:
 839         if (ret < 0) {
 840                 /* This cache is bogus, make sure it gets cleared */
 841                 spin_lock(&block_group->lock);
 842                 block_group->disk_cache_state = BTRFS_DC_CLEAR;
 843                 spin_unlock(&block_group->lock);
 844                 ret = 0;
 845
 846                 btrfs_warn(fs_info, "failed to load free space cache for block group %llu, rebuild it now",
 847                         block_group->key.objectid);
 848         }
 849
 850         iput(inode);
 851         return ret;
 852 }
 853
 854 static noinline_for_stack
 855 int write_cache_extent_entries(struct io_ctl *io_ctl,
 856                               struct btrfs_free_space_ctl *ctl,
 857                               struct btrfs_block_group_cache *block_group,
 858                               int *entries, int *bitmaps,
 859                               struct list_head *bitmap_list)
 860 {
 861         int ret;
 862         struct btrfs_free_cluster *cluster = NULL;
 863         struct rb_node *node = rb_first(&ctl->free_space_offset);
 864
 865         /* Get the cluster for this block_group if it exists */
 866         if (block_group && !list_empty(&block_group->cluster_list)) {
 867                 cluster = list_entry(block_group->cluster_list.next,
 868                                      struct btrfs_free_cluster,
 869                                      block_group_list);
 870         }
 871
 872         if (!node && cluster) {
 873                 node = rb_first(&cluster->root);
 874                 cluster = NULL;
 875         }
 876
 877         /* Write out the extent entries */
 878         while (node) {
 879                 struct btrfs_free_space *e;
 880
 881                 e = rb_entry(node, struct btrfs_free_space, offset_index);
 882                 *entries += 1;
 883
 884                 ret = io_ctl_add_entry(io_ctl, e->offset, e->bytes,
 885                                        e->bitmap);
 886                 if (ret)
 887                         goto fail;
 888
 889                 if (e->bitmap) {
 890                         list_add_tail(&e->list, bitmap_list);
 891                         *bitmaps += 1;
 892                 }
 893                 node = rb_next(node);
 894                 if (!node && cluster) {
 895                         node = rb_first(&cluster->root);
 896                         cluster = NULL;
 897                 }
 898         }
 899         return 0;
 900 fail:
 901         return -ENOSPC;
 902 }
 903
 904 static noinline_for_stack int
 905 update_cache_item(struct btrfs_trans_handle *trans,
 906                   struct btrfs_root *root,
 907                   struct inode *inode,
 908                   struct btrfs_path *path, u64 offset,
 909                   int entries, int bitmaps)
 910 {
 911         struct btrfs_key key;
 912         struct btrfs_free_space_header *header;
 913         struct extent_buffer *leaf;
 914         int ret;
 915
 916         key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 917         key.offset = offset;
 918         key.type = 0;
 919
 920         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
 921         if (ret < 0) {
 922                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
 923                                  EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL,
 924                                  GFP_NOFS);
 925                 goto fail;
 926         }
 927         leaf = path->nodes[0];
 928         if (ret > 0) {
 929                 struct btrfs_key found_key;
 930                 ASSERT(path->slots[0]);
 931                 path->slots[0]--;
 932                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 933                 if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
 934                     found_key.offset != offset) {
 935                         clear_extent_bit(&BTRFS_I(inode)->io_tree, 0,
 936                                          inode->i_size - 1,
 937                                          EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0,
 938                                          NULL, GFP_NOFS);
 939                         btrfs_release_path(path);
 940                         goto fail;
 941                 }
 942         }
 943
 944         BTRFS_I(inode)->generation = trans->transid;
 945         header = btrfs_item_ptr(leaf, path->slots[0],
 946                                 struct btrfs_free_space_header);
 947         btrfs_set_free_space_entries(leaf, header, entries);
 948         btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
 949         btrfs_set_free_space_generation(leaf, header, trans->transid);
 950         btrfs_mark_buffer_dirty(leaf);
 951         btrfs_release_path(path);
 952
 953         return 0;
 954
 955 fail:
 956         return -1;
 957 }
 958
 959 static noinline_for_stack int
 960 add_ioctl_entries(struct btrfs_root *root,
 961                   struct inode *inode,
 962                   struct btrfs_block_group_cache *block_group,
 963                   struct io_ctl *io_ctl,
 964                   struct extent_state **cached_state,
 965                   struct list_head *bitmap_list,
 966                   int *entries)
 967 {
 968         u64 start, extent_start, extent_end, len;
 969         struct list_head *pos, *n;
 970         struct extent_io_tree *unpin = NULL;
 971         int ret;
 972
 973         /*
 974          * We want to add any pinned extents to our free space cache
 975          * so we don't leak the space
 976          *
 977          * We shouldn't have switched the pinned extents yet so this is the
 978          * right one
 979          */
 980         unpin = root->fs_info->pinned_extents;
 981
 982         if (block_group)
 983                 start = block_group->key.objectid;
 984
 985         while (block_group && (start < block_group->key.objectid +
 986                                block_group->key.offset)) {
 987                 ret = find_first_extent_bit(unpin, start,
 988                                             &extent_start, &extent_end,
 989                                             EXTENT_DIRTY, NULL);
 990                 if (ret) {
 991                         ret = 0;
 992                         break;
 993                 }
 994
 995                 /* This pinned extent is out of our range */
 996                 if (extent_start >= block_group->key.objectid +
 997                     block_group->key.offset)
 998                         break;
 999
1000                 extent_start = max(extent_start, start);
1001                 extent_end = min(block_group->key.objectid +
1002                                  block_group->key.offset, extent_end + 1);
1003                 len = extent_end - extent_start;
1004
1005                 *entries += 1;
1006                 ret = io_ctl_add_entry(io_ctl, extent_start, len, NULL);
1007                 if (ret)
1008                         goto out_nospc;
1009
1010                 start = extent_end;
1011         }
1012
1013         /* Write out the bitmaps */
1014         list_for_each_safe(pos, n, bitmap_list) {
1015                 struct btrfs_free_space *entry =
1016                         list_entry(pos, struct btrfs_free_space, list);
1017
1018                 ret = io_ctl_add_bitmap(io_ctl, entry->bitmap);
1019                 if (ret)
1020                         goto out_nospc;
1021                 list_del_init(&entry->list);
1022         }
1023
1024         /* Zero out the rest of the pages just to make sure */
1025         io_ctl_zero_remaining_pages(io_ctl);
1026
1027         ret = btrfs_dirty_pages(root, inode, io_ctl->pages, io_ctl->num_pages,
1028                                 0, i_size_read(inode), cached_state);
1029         io_ctl_drop_pages(io_ctl);
1030         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
1031                              i_size_read(inode) - 1, cached_state, GFP_NOFS);
1032
1033         if (ret)
1034                 goto fail;
1035
1036         ret = btrfs_wait_ordered_range(inode, 0, (u64)-1);
1037         if (ret) {
1038                 clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
1039                                  EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL,
1040                                  GFP_NOFS);
1041                 goto fail;
1042         }
1043         return 0;
1044
1045 fail:
1046         return -1;
1047
1048 out_nospc:
1049         return -ENOSPC;
1050 }
1051
1052 static void noinline_for_stack
1053 cleanup_write_cache_enospc(struct inode *inode,
1054                            struct io_ctl *io_ctl,
1055                            struct extent_state **cached_state,
1056                            struct list_head *bitmap_list)
1057 {
1058         struct list_head *pos, *n;
1059         list_for_each_safe(pos, n, bitmap_list) {
1060                 struct btrfs_free_space *entry =
1061                         list_entry(pos, struct btrfs_free_space, list);
1062                 list_del_init(&entry->list);
1063         }
1064         io_ctl_drop_pages(io_ctl);
1065         unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
1066                              i_size_read(inode) - 1, cached_state,
1067                              GFP_NOFS);
1068 }
1069
1070 /**
1071  * __btrfs_write_out_cache - write out cached info to an inode
1072  * @root - the root the inode belongs to
1073  * @ctl - the free space cache we are going to write out
1074  * @block_group - the block_group for this cache if it belongs to a block_group
1075  * @trans - the trans handle
1076  * @path - the path to use
1077  * @offset - the offset for the key we'll insert
1078  *
1079  * This function writes out a free space cache struct to disk for quick recovery
1080  * on mount.  This will return 0 if it was successfull in writing the cache out,
1081  * and -1 if it was not.
1082  */
1083 static int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
1084                                    struct btrfs_free_space_ctl *ctl,
1085                                    struct btrfs_block_group_cache *block_group,
1086                                    struct btrfs_trans_handle *trans,
1087                                    struct btrfs_path *path, u64 offset)
1088 {
1089         struct extent_state *cached_state = NULL;
1090         struct io_ctl io_ctl;
1091         struct list_head bitmap_list;
1092         int entries = 0;
1093         int bitmaps = 0;
1094         int ret;
1095         int err = -1;
1096
1097         INIT_LIST_HEAD(&bitmap_list);
1098
1099         if (!i_size_read(inode))
1100                 return -1;
1101
1102         ret = io_ctl_init(&io_ctl, inode, root);
1103         if (ret)
1104                 return -1;
1105
1106         /* Lock all pages first so we can lock the extent safely. */
1107         io_ctl_prepare_pages(&io_ctl, inode, 0);
1108
1109         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
1110                          0, &cached_state);
1111
1112
1113         /* Make sure we can fit our crcs into the first page */
1114         if (io_ctl.check_crcs &&
1115             (io_ctl.num_pages * sizeof(u32)) >= PAGE_CACHE_SIZE)
1116                 goto out_nospc;
1117
1118         io_ctl_set_generation(&io_ctl, trans->transid);
1119
1120         ret = write_cache_extent_entries(&io_ctl, ctl,
1121                                          block_group, &entries, &bitmaps,
1122                                          &bitmap_list);
1123         if (ret)
1124                 goto out_nospc;
1125
1126         ret = add_ioctl_entries(root, inode, block_group, &io_ctl,
1127                                 &cached_state, &bitmap_list, &entries);
1128
1129         if (ret == -ENOSPC)
1130                 goto out_nospc;
1131         else if (ret)
1132                 goto out;
1133
1134         err = update_cache_item(trans, root, inode, path, offset,
1135                                 entries, bitmaps);
1136
1137 out:
1138         io_ctl_free(&io_ctl);
1139         if (err) {
1140                 invalidate_inode_pages2(inode->i_mapping);
1141                 BTRFS_I(inode)->generation = 0;
1142         }
1143         btrfs_update_inode(trans, root, inode);
1144         return err;
1145
1146 out_nospc:
1147
1148         cleanup_write_cache_enospc(inode, &io_ctl, &cached_state, &bitmap_list);
1149         goto out;
1150 }
1151
1152 int btrfs_write_out_cache(struct btrfs_root *root,
1153                           struct btrfs_trans_handle *trans,
1154                           struct btrfs_block_group_cache *block_group,
1155                           struct btrfs_path *path)
1156 {
1157         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1158         struct inode *inode;
1159         int ret = 0;
1160
1161         root = root->fs_info->tree_root;
1162
1163         spin_lock(&block_group->lock);
1164         if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
1165                 spin_unlock(&block_group->lock);
1166                 return 0;
1167         }
1168         spin_unlock(&block_group->lock);
1169
1170         inode = lookup_free_space_inode(root, block_group, path);
1171         if (IS_ERR(inode))
1172                 return 0;
1173
1174         ret = __btrfs_write_out_cache(root, inode, ctl, block_group, trans,
1175                                       path, block_group->key.objectid);
1176         if (ret) {
1177                 spin_lock(&block_group->lock);
1178                 block_group->disk_cache_state = BTRFS_DC_ERROR;
1179                 spin_unlock(&block_group->lock);
1180                 ret = 0;
1181 #ifdef DEBUG
1182                 btrfs_err(root->fs_info,
1183                         "failed to write free space cache for block group %llu",
1184                         block_group->key.objectid);
1185 #endif
1186         }
1187
1188         iput(inode);
1189         return ret;
1190 }
1191
1192 static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
1193                                           u64 offset)
1194 {
1195         ASSERT(offset >= bitmap_start);
1196         offset -= bitmap_start;
1197         return (unsigned long)(div_u64(offset, unit));
1198 }
1199
1200 static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
1201 {
1202         return (unsigned long)(div_u64(bytes, unit));
1203 }
1204
1205 static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
1206                                    u64 offset)
1207 {
1208         u64 bitmap_start;
1209         u64 bytes_per_bitmap;
1210
1211         bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
1212         bitmap_start = offset - ctl->start;
1213         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
1214         bitmap_start *= bytes_per_bitmap;
1215         bitmap_start += ctl->start;
1216
1217         return bitmap_start;
1218 }
1219
1220 static int tree_insert_offset(struct rb_root *root, u64 offset,
1221                               struct rb_node *node, int bitmap)
1222 {
1223         struct rb_node **p = &root->rb_node;
1224         struct rb_node *parent = NULL;
1225         struct btrfs_free_space *info;
1226
1227         while (*p) {
1228                 parent = *p;
1229                 info = rb_entry(parent, struct btrfs_free_space, offset_index);
1230
1231                 if (offset < info->offset) {
1232                         p = &(*p)->rb_left;
1233                 } else if (offset > info->offset) {
1234                         p = &(*p)->rb_right;
1235                 } else {
1236                         /*
1237                          * we could have a bitmap entry and an extent entry
1238                          * share the same offset.  If this is the case, we want
1239                          * the extent entry to always be found first if we do a
1240                          * linear search through the tree, since we want to have
1241                          * the quickest allocation time, and allocating from an
1242                          * extent is faster than allocating from a bitmap.  So
1243                          * if we're inserting a bitmap and we find an entry at
1244                          * this offset, we want to go right, or after this entry
1245                          * logically.  If we are inserting an extent and we've
1246                          * found a bitmap, we want to go left, or before
1247                          * logically.
1248                          */
1249                         if (bitmap) {
1250                                 if (info->bitmap) {
1251                                         WARN_ON_ONCE(1);
1252                                         return -EEXIST;
1253                                 }
1254                                 p = &(*p)->rb_right;
1255                         } else {
1256                                 if (!info->bitmap) {
1257                                         WARN_ON_ONCE(1);
1258                                         return -EEXIST;
1259                                 }
1260                                 p = &(*p)->rb_left;
1261                         }
1262                 }
1263         }
1264
1265         rb_link_node(node, parent, p);
1266         rb_insert_color(node, root);
1267
1268         return 0;
1269 }
1270
1271 /*
1272  * searches the tree for the given offset.
1273  *
1274  * fuzzy - If this is set, then we are trying to make an allocation, and we just
1275  * want a section that has at least bytes size and comes at or after the given
1276  * offset.
1277  */
1278 static struct btrfs_free_space *
1279 tree_search_offset(struct btrfs_free_space_ctl *ctl,
1280                    u64 offset, int bitmap_only, int fuzzy)
1281 {
1282         struct rb_node *n = ctl->free_space_offset.rb_node;
1283         struct btrfs_free_space *entry, *prev = NULL;
1284
1285         /* find entry that is closest to the 'offset' */
1286         while (1) {
1287                 if (!n) {
1288                         entry = NULL;
1289                         break;
1290                 }
1291
1292                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1293                 prev = entry;
1294
1295                 if (offset < entry->offset)
1296                         n = n->rb_left;
1297                 else if (offset > entry->offset)
1298                         n = n->rb_right;
1299                 else
1300                         break;
1301         }
1302
1303         if (bitmap_only) {
1304                 if (!entry)
1305                         return NULL;
1306                 if (entry->bitmap)
1307                         return entry;
1308
1309                 /*
1310                  * bitmap entry and extent entry may share same offset,
1311                  * in that case, bitmap entry comes after extent entry.
1312                  */
1313                 n = rb_next(n);
1314                 if (!n)
1315                         return NULL;
1316                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1317                 if (entry->offset != offset)
1318                         return NULL;
1319
1320                 WARN_ON(!entry->bitmap);
1321                 return entry;
1322         } else if (entry) {
1323                 if (entry->bitmap) {
1324                         /*
1325                          * if previous extent entry covers the offset,
1326                          * we should return it instead of the bitmap entry
1327                          */
1328                         n = rb_prev(&entry->offset_index);
1329                         if (n) {
1330                                 prev = rb_entry(n, struct btrfs_free_space,
1331                                                 offset_index);
1332                                 if (!prev->bitmap &&
1333                                     prev->offset + prev->bytes > offset)
1334                                         entry = prev;
1335                         }
1336                 }
1337                 return entry;
1338         }
1339
1340         if (!prev)
1341                 return NULL;
1342
1343         /* find last entry before the 'offset' */
1344         entry = prev;
1345         if (entry->offset > offset) {
1346                 n = rb_prev(&entry->offset_index);
1347                 if (n) {
1348                         entry = rb_entry(n, struct btrfs_free_space,
1349                                         offset_index);
1350                         ASSERT(entry->offset <= offset);
1351                 } else {
1352                         if (fuzzy)
1353                                 return entry;
1354                         else
1355                                 return NULL;
1356                 }
1357         }
1358
1359         if (entry->bitmap) {
1360                 n = rb_prev(&entry->offset_index);
1361                 if (n) {
1362                         prev = rb_entry(n, struct btrfs_free_space,
1363                                         offset_index);
1364                         if (!prev->bitmap &&
1365                             prev->offset + prev->bytes > offset)
1366                                 return prev;
1367                 }
1368                 if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
1369                         return entry;
1370         } else if (entry->offset + entry->bytes > offset)
1371                 return entry;
1372
1373         if (!fuzzy)
1374                 return NULL;
1375
1376         while (1) {
1377                 if (entry->bitmap) {
1378                         if (entry->offset + BITS_PER_BITMAP *
1379                             ctl->unit > offset)
1380                                 break;
1381                 } else {
1382                         if (entry->offset + entry->bytes > offset)
1383                                 break;
1384                 }
1385
1386                 n = rb_next(&entry->offset_index);
1387                 if (!n)
1388                         return NULL;
1389                 entry = rb_entry(n, struct btrfs_free_space, offset_index);
1390         }
1391         return entry;
1392 }
1393
1394 static inline void
1395 __unlink_free_space(struct btrfs_free_space_ctl *ctl,
1396                     struct btrfs_free_space *info)
1397 {
1398         rb_erase(&info->offset_index, &ctl->free_space_offset);
1399         ctl->free_extents--;
1400 }
1401
1402 static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
1403                               struct btrfs_free_space *info)
1404 {
1405         __unlink_free_space(ctl, info);
1406         ctl->free_space -= info->bytes;
1407 }
1408
1409 static int link_free_space(struct btrfs_free_space_ctl *ctl,
1410                            struct btrfs_free_space *info)
1411 {
1412         int ret = 0;
1413
1414         ASSERT(info->bytes || info->bitmap);
1415         ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
1416                                  &info->offset_index, (info->bitmap != NULL));
1417         if (ret)
1418                 return ret;
1419
1420         ctl->free_space += info->bytes;
1421         ctl->free_extents++;
1422         return ret;
1423 }
1424
1425 static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
1426 {
1427         struct btrfs_block_group_cache *block_group = ctl->private;
1428         u64 max_bytes;
1429         u64 bitmap_bytes;
1430         u64 extent_bytes;
1431         u64 size = block_group->key.offset;
1432         u64 bytes_per_bg = BITS_PER_BITMAP * ctl->unit;
1433         int max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
1434
1435         max_bitmaps = max(max_bitmaps, 1);
1436
1437         ASSERT(ctl->total_bitmaps <= max_bitmaps);
1438
1439         /*
1440          * The goal is to keep the total amount of memory used per 1gb of space
1441          * at or below 32k, so we need to adjust how much memory we allow to be
1442          * used by extent based free space tracking
1443          */
1444         if (size < 1024 * 1024 * 1024)
1445                 max_bytes = MAX_CACHE_BYTES_PER_GIG;
1446         else
1447                 max_bytes = MAX_CACHE_BYTES_PER_GIG *
1448                         div64_u64(size, 1024 * 1024 * 1024);
1449
1450         /*
1451          * we want to account for 1 more bitmap than what we have so we can make
1452          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1453          * we add more bitmaps.
1454          */
1455         bitmap_bytes = (ctl->total_bitmaps + 1) * PAGE_CACHE_SIZE;
1456
1457         if (bitmap_bytes >= max_bytes) {
1458                 ctl->extents_thresh = 0;
1459                 return;
1460         }
1461
1462         /*
1463          * we want the extent entry threshold to always be at most 1/2 the maxw
1464          * bytes we can have, or whatever is less than that.
1465          */
1466         extent_bytes = max_bytes - bitmap_bytes;
1467         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
1468
1469         ctl->extents_thresh =
1470                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
1471 }
1472
1473 static inline void __bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1474                                        struct btrfs_free_space *info,
1475                                        u64 offset, u64 bytes)
1476 {
1477         unsigned long start, count;
1478
1479         start = offset_to_bit(info->offset, ctl->unit, offset);
1480         count = bytes_to_bits(bytes, ctl->unit);
1481         ASSERT(start + count <= BITS_PER_BITMAP);
1482
1483         bitmap_clear(info->bitmap, start, count);
1484
1485         info->bytes -= bytes;
1486 }
1487
1488 static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1489                               struct btrfs_free_space *info, u64 offset,
1490                               u64 bytes)
1491 {
1492         __bitmap_clear_bits(ctl, info, offset, bytes);
1493         ctl->free_space -= bytes;
1494 }
1495
1496 static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
1497                             struct btrfs_free_space *info, u64 offset,
1498                             u64 bytes)
1499 {
1500         unsigned long start, count;
1501
1502         start = offset_to_bit(info->offset, ctl->unit, offset);
1503         count = bytes_to_bits(bytes, ctl->unit);
1504         ASSERT(start + count <= BITS_PER_BITMAP);
1505
1506         bitmap_set(info->bitmap, start, count);
1507
1508         info->bytes += bytes;
1509         ctl->free_space += bytes;
1510 }
1511
1512 /*
1513  * If we can not find suitable extent, we will use bytes to record
1514  * the size of the max extent.
1515  */
1516 static int search_bitmap(struct btrfs_free_space_ctl *ctl,
1517                          struct btrfs_free_space *bitmap_info, u64 *offset,
1518                          u64 *bytes)
1519 {
1520         unsigned long found_bits = 0;
1521         unsigned long max_bits = 0;
1522         unsigned long bits, i;
1523         unsigned long next_zero;
1524         unsigned long extent_bits;
1525
1526         i = offset_to_bit(bitmap_info->offset, ctl->unit,
1527                           max_t(u64, *offset, bitmap_info->offset));
1528         bits = bytes_to_bits(*bytes, ctl->unit);
1529
1530         for_each_set_bit_from(i, bitmap_info->bitmap, BITS_PER_BITMAP) {
1531                 next_zero = find_next_zero_bit(bitmap_info->bitmap,
1532                                                BITS_PER_BITMAP, i);
1533                 extent_bits = next_zero - i;
1534                 if (extent_bits >= bits) {
1535                         found_bits = extent_bits;
1536                         break;
1537                 } else if (extent_bits > max_bits) {
1538                         max_bits = extent_bits;
1539                 }
1540                 i = next_zero;
1541         }
1542
1543         if (found_bits) {
1544                 *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
1545                 *bytes = (u64)(found_bits) * ctl->unit;
1546                 return 0;
1547         }
1548
1549         *bytes = (u64)(max_bits) * ctl->unit;
1550         return -1;
1551 }
1552
1553 /* Cache the size of the max extent in bytes */
1554 static struct btrfs_free_space *
1555 find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes,
1556                 unsigned long align, u64 *max_extent_size)
1557 {
1558         struct btrfs_free_space *entry;
1559         struct rb_node *node;
1560         u64 tmp;
1561         u64 align_off;
1562         int ret;
1563
1564         if (!ctl->free_space_offset.rb_node)
1565                 goto out;
1566
1567         entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
1568         if (!entry)
1569                 goto out;
1570
1571         for (node = &entry->offset_index; node; node = rb_next(node)) {
1572                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1573                 if (entry->bytes < *bytes) {
1574                         if (entry->bytes > *max_extent_size)
1575                                 *max_extent_size = entry->bytes;
1576                         continue;
1577                 }
1578
1579                 /* make sure the space returned is big enough
1580                  * to match our requested alignment
1581                  */
1582                 if (*bytes >= align) {
1583                         tmp = entry->offset - ctl->start + align - 1;
1584                         do_div(tmp, align);
1585                         tmp = tmp * align + ctl->start;
1586                         align_off = tmp - entry->offset;
1587                 } else {
1588                         align_off = 0;
1589                         tmp = entry->offset;
1590                 }
1591
1592                 if (entry->bytes < *bytes + align_off) {
1593                         if (entry->bytes > *max_extent_size)
1594                                 *max_extent_size = entry->bytes;
1595                         continue;
1596                 }
1597
1598                 if (entry->bitmap) {
1599                         u64 size = *bytes;
1600
1601                         ret = search_bitmap(ctl, entry, &tmp, &size);
1602                         if (!ret) {
1603                                 *offset = tmp;
1604                                 *bytes = size;
1605                                 return entry;
1606                         } else if (size > *max_extent_size) {
1607                                 *max_extent_size = size;
1608                         }
1609                         continue;
1610                 }
1611
1612                 *offset = tmp;
1613                 *bytes = entry->bytes - align_off;
1614                 return entry;
1615         }
1616 out:
1617         return NULL;
1618 }
1619
1620 static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
1621                            struct btrfs_free_space *info, u64 offset)
1622 {
1623         info->offset = offset_to_bitmap(ctl, offset);
1624         info->bytes = 0;
1625         INIT_LIST_HEAD(&info->list);
1626         link_free_space(ctl, info);
1627         ctl->total_bitmaps++;
1628
1629         ctl->op->recalc_thresholds(ctl);
1630 }
1631
1632 static void free_bitmap(struct btrfs_free_space_ctl *ctl,
1633                         struct btrfs_free_space *bitmap_info)
1634 {
1635         unlink_free_space(ctl, bitmap_info);
1636         kfree(bitmap_info->bitmap);
1637         kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1638         ctl->total_bitmaps--;
1639         ctl->op->recalc_thresholds(ctl);
1640 }
1641
1642 static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
1643                               struct btrfs_free_space *bitmap_info,
1644                               u64 *offset, u64 *bytes)
1645 {
1646         u64 end;
1647         u64 search_start, search_bytes;
1648         int ret;
1649
1650 again:
1651         end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
1652
1653         /*
1654          * We need to search for bits in this bitmap.  We could only cover some
1655          * of the extent in this bitmap thanks to how we add space, so we need
1656          * to search for as much as it as we can and clear that amount, and then
1657          * go searching for the next bit.
1658          */
1659         search_start = *offset;
1660         search_bytes = ctl->unit;
1661         search_bytes = min(search_bytes, end - search_start + 1);
1662         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
1663         if (ret < 0 || search_start != *offset)
1664                 return -EINVAL;
1665
1666         /* We may have found more bits than what we need */
1667         search_bytes = min(search_bytes, *bytes);
1668
1669         /* Cannot clear past the end of the bitmap */
1670         search_bytes = min(search_bytes, end - search_start + 1);
1671
1672         bitmap_clear_bits(ctl, bitmap_info, search_start, search_bytes);
1673         *offset += search_bytes;
1674         *bytes -= search_bytes;
1675
1676         if (*bytes) {
1677                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
1678                 if (!bitmap_info->bytes)
1679                         free_bitmap(ctl, bitmap_info);
1680
1681                 /*
1682                  * no entry after this bitmap, but we still have bytes to
1683                  * remove, so something has gone wrong.
1684                  */
1685                 if (!next)
1686                         return -EINVAL;
1687
1688                 bitmap_info = rb_entry(next, struct btrfs_free_space,
1689                                        offset_index);
1690
1691                 /*
1692                  * if the next entry isn't a bitmap we need to return to let the
1693                  * extent stuff do its work.
1694                  */
1695                 if (!bitmap_info->bitmap)
1696                         return -EAGAIN;
1697
1698                 /*
1699                  * Ok the next item is a bitmap, but it may not actually hold
1700                  * the information for the rest of this free space stuff, so
1701                  * look for it, and if we don't find it return so we can try
1702                  * everything over again.
1703                  */
1704                 search_start = *offset;
1705                 search_bytes = ctl->unit;
1706                 ret = search_bitmap(ctl, bitmap_info, &search_start,
1707                                     &search_bytes);
1708                 if (ret < 0 || search_start != *offset)
1709                         return -EAGAIN;
1710
1711                 goto again;
1712         } else if (!bitmap_info->bytes)
1713                 free_bitmap(ctl, bitmap_info);
1714
1715         return 0;
1716 }
1717
1718 static u64 add_bytes_to_bitmap(struct btrfs_free_space_ctl *ctl,
1719                                struct btrfs_free_space *info, u64 offset,
1720                                u64 bytes)
1721 {
1722         u64 bytes_to_set = 0;
1723         u64 end;
1724
1725         end = info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
1726
1727         bytes_to_set = min(end - offset, bytes);
1728
1729         bitmap_set_bits(ctl, info, offset, bytes_to_set);
1730
1731         return bytes_to_set;
1732
1733 }
1734
1735 static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
1736                       struct btrfs_free_space *info)
1737 {
1738         struct btrfs_block_group_cache *block_group = ctl->private;
1739
1740         /*
1741          * If we are below the extents threshold then we can add this as an
1742          * extent, and don't have to deal with the bitmap
1743          */
1744         if (ctl->free_extents < ctl->extents_thresh) {
1745                 /*
1746                  * If this block group has some small extents we don't want to
1747                  * use up all of our free slots in the cache with them, we want
1748                  * to reserve them to larger extents, however if we have plent
1749                  * of cache left then go ahead an dadd them, no sense in adding
1750                  * the overhead of a bitmap if we don't have to.
1751                  */
1752                 if (info->bytes <= block_group->sectorsize * 4) {
1753                         if (ctl->free_extents * 2 <= ctl->extents_thresh)
1754                                 return false;
1755                 } else {
1756                         return false;
1757                 }
1758         }
1759
1760         /*
1761          * The original block groups from mkfs can be really small, like 8
1762          * megabytes, so don't bother with a bitmap for those entries.  However
1763          * some block groups can be smaller than what a bitmap would cover but
1764          * are still large enough that they could overflow the 32k memory limit,
1765          * so allow those block groups to still be allowed to have a bitmap
1766          * entry.
1767          */
1768         if (((BITS_PER_BITMAP * ctl->unit) >> 1) > block_group->key.offset)
1769                 return false;
1770
1771         return true;
1772 }
1773
1774 static struct btrfs_free_space_op free_space_op = {
1775         .recalc_thresholds      = recalculate_thresholds,
1776         .use_bitmap             = use_bitmap,
1777 };
1778
1779 static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
1780                               struct btrfs_free_space *info)
1781 {
1782         struct btrfs_free_space *bitmap_info;
1783         struct btrfs_block_group_cache *block_group = NULL;
1784         int added = 0;
1785         u64 bytes, offset, bytes_added;
1786         int ret;
1787
1788         bytes = info->bytes;
1789         offset = info->offset;
1790
1791         if (!ctl->op->use_bitmap(ctl, info))
1792                 return 0;
1793
1794         if (ctl->op == &free_space_op)
1795                 block_group = ctl->private;
1796 again:
1797         /*
1798          * Since we link bitmaps right into the cluster we need to see if we
1799          * have a cluster here, and if so and it has our bitmap we need to add
1800          * the free space to that bitmap.
1801          */
1802         if (block_group && !list_empty(&block_group->cluster_list)) {
1803                 struct btrfs_free_cluster *cluster;
1804                 struct rb_node *node;
1805                 struct btrfs_free_space *entry;
1806
1807                 cluster = list_entry(block_group->cluster_list.next,
1808                                      struct btrfs_free_cluster,
1809                                      block_group_list);
1810                 spin_lock(&cluster->lock);
1811                 node = rb_first(&cluster->root);
1812                 if (!node) {
1813                         spin_unlock(&cluster->lock);
1814                         goto no_cluster_bitmap;
1815                 }
1816
1817                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
1818                 if (!entry->bitmap) {
1819                         spin_unlock(&cluster->lock);
1820                         goto no_cluster_bitmap;
1821                 }
1822
1823                 if (entry->offset == offset_to_bitmap(ctl, offset)) {
1824                         bytes_added = add_bytes_to_bitmap(ctl, entry,
1825                                                           offset, bytes);
1826                         bytes -= bytes_added;
1827                         offset += bytes_added;
1828                 }
1829                 spin_unlock(&cluster->lock);
1830                 if (!bytes) {
1831                         ret = 1;
1832                         goto out;
1833                 }
1834         }
1835
1836 no_cluster_bitmap:
1837         bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1838                                          1, 0);
1839         if (!bitmap_info) {
1840                 ASSERT(added == 0);
1841                 goto new_bitmap;
1842         }
1843
1844         bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
1845         bytes -= bytes_added;
1846         offset += bytes_added;
1847         added = 0;
1848
1849         if (!bytes) {
1850                 ret = 1;
1851                 goto out;
1852         } else
1853                 goto again;
1854
1855 new_bitmap:
1856         if (info && info->bitmap) {
1857                 add_new_bitmap(ctl, info, offset);
1858                 added = 1;
1859                 info = NULL;
1860                 goto again;
1861         } else {
1862                 spin_unlock(&ctl->tree_lock);
1863
1864                 /* no pre-allocated info, allocate a new one */
1865                 if (!info) {
1866                         info = kmem_cache_zalloc(btrfs_free_space_cachep,
1867                                                  GFP_NOFS);
1868                         if (!info) {
1869                                 spin_lock(&ctl->tree_lock);
1870                                 ret = -ENOMEM;
1871                                 goto out;
1872                         }
1873                 }
1874
1875                 /* allocate the bitmap */
1876                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
1877                 spin_lock(&ctl->tree_lock);
1878                 if (!info->bitmap) {
1879                         ret = -ENOMEM;
1880                         goto out;
1881                 }
1882                 goto again;
1883         }
1884
1885 out:
1886         if (info) {
1887                 if (info->bitmap)
1888                         kfree(info->bitmap);
1889                 kmem_cache_free(btrfs_free_space_cachep, info);
1890         }
1891
1892         return ret;
1893 }
1894
1895 static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
1896                           struct btrfs_free_space *info, bool update_stat)
1897 {
1898         struct btrfs_free_space *left_info;
1899         struct btrfs_free_space *right_info;
1900         bool merged = false;
1901         u64 offset = info->offset;
1902         u64 bytes = info->bytes;
1903
1904         /*
1905          * first we want to see if there is free space adjacent to the range we
1906          * are adding, if there is remove that struct and add a new one to
1907          * cover the entire range
1908          */
1909         right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
1910         if (right_info && rb_prev(&right_info->offset_index))
1911                 left_info = rb_entry(rb_prev(&right_info->offset_index),
1912                                      struct btrfs_free_space, offset_index);
1913         else
1914                 left_info = tree_search_offset(ctl, offset - 1, 0, 0);
1915
1916         if (right_info && !right_info->bitmap) {
1917                 if (update_stat)
1918                         unlink_free_space(ctl, right_info);
1919                 else
1920                         __unlink_free_space(ctl, right_info);
1921                 info->bytes += right_info->bytes;
1922                 kmem_cache_free(btrfs_free_space_cachep, right_info);
1923                 merged = true;
1924         }
1925
1926         if (left_info && !left_info->bitmap &&
1927             left_info->offset + left_info->bytes == offset) {
1928                 if (update_stat)
1929                         unlink_free_space(ctl, left_info);
1930                 else
1931                         __unlink_free_space(ctl, left_info);
1932                 info->offset = left_info->offset;
1933                 info->bytes += left_info->bytes;
1934                 kmem_cache_free(btrfs_free_space_cachep, left_info);
1935                 merged = true;
1936         }
1937
1938         return merged;
1939 }
1940
1941 int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
1942                            u64 offset, u64 bytes)
1943 {
1944         struct btrfs_free_space *info;
1945         int ret = 0;
1946
1947         info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
1948         if (!info)
1949                 return -ENOMEM;
1950
1951         info->offset = offset;
1952         info->bytes = bytes;
1953
1954         spin_lock(&ctl->tree_lock);
1955
1956         if (try_merge_free_space(ctl, info, true))
1957                 goto link;
1958
1959         /*
1960          * There was no extent directly to the left or right of this new
1961          * extent then we know we're going to have to allocate a new extent, so
1962          * before we do that see if we need to drop this into a bitmap
1963          */
1964         ret = insert_into_bitmap(ctl, info);
1965         if (ret < 0) {
1966                 goto out;
1967         } else if (ret) {
1968                 ret = 0;
1969                 goto out;
1970         }
1971 link:
1972         ret = link_free_space(ctl, info);
1973         if (ret)
1974                 kmem_cache_free(btrfs_free_space_cachep, info);
1975 out:
1976         spin_unlock(&ctl->tree_lock);
1977
1978         if (ret) {
1979                 printk(KERN_CRIT "BTRFS: unable to add free space :%d\n", ret);
1980                 ASSERT(ret != -EEXIST);
1981         }
1982
1983         return ret;
1984 }
1985
1986 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
1987                             u64 offset, u64 bytes)
1988 {
1989         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1990         struct btrfs_free_space *info;
1991         int ret;
1992         bool re_search = false;
1993
1994         spin_lock(&ctl->tree_lock);
1995
1996 again:
1997         ret = 0;
1998         if (!bytes)
1999                 goto out_lock;
2000
2001         info = tree_search_offset(ctl, offset, 0, 0);
2002         if (!info) {
2003                 /*
2004                  * oops didn't find an extent that matched the space we wanted
2005                  * to remove, look for a bitmap instead
2006                  */
2007                 info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
2008                                           1, 0);
2009                 if (!info) {
2010                         /*
2011                          * If we found a partial bit of our free space in a
2012                          * bitmap but then couldn't find the other part this may
2013                          * be a problem, so WARN about it.
2014                          */
2015                         WARN_ON(re_search);
2016                         goto out_lock;
2017                 }
2018         }
2019
2020         re_search = false;
2021         if (!info->bitmap) {
2022                 unlink_free_space(ctl, info);
2023                 if (offset == info->offset) {
2024                         u64 to_free = min(bytes, info->bytes);
2025
2026                         info->bytes -= to_free;
2027                         info->offset += to_free;
2028                         if (info->bytes) {
2029                                 ret = link_free_space(ctl, info);
2030                                 WARN_ON(ret);
2031                         } else {
2032                                 kmem_cache_free(btrfs_free_space_cachep, info);
2033                         }
2034
2035                         offset += to_free;
2036                         bytes -= to_free;
2037                         goto again;
2038                 } else {
2039                         u64 old_end = info->bytes + info->offset;
2040
2041                         info->bytes = offset - info->offset;
2042                         ret = link_free_space(ctl, info);
2043                         WARN_ON(ret);
2044                         if (ret)
2045                                 goto out_lock;
2046
2047                         /* Not enough bytes in this entry to satisfy us */
2048                         if (old_end < offset + bytes) {
2049                                 bytes -= old_end - offset;
2050                                 offset = old_end;
2051                                 goto again;
2052                         } else if (old_end == offset + bytes) {
2053                                 /* all done */
2054                                 goto out_lock;
2055                         }
2056                         spin_unlock(&ctl->tree_lock);
2057
2058                         ret = btrfs_add_free_space(block_group, offset + bytes,
2059                                                    old_end - (offset + bytes));
2060                         WARN_ON(ret);
2061                         goto out;
2062                 }
2063         }
2064
2065         ret = remove_from_bitmap(ctl, info, &offset, &bytes);
2066         if (ret == -EAGAIN) {
2067                 re_search = true;
2068                 goto again;
2069         }
2070 out_lock:
2071         spin_unlock(&ctl->tree_lock);
2072 out:
2073         return ret;
2074 }
2075
2076 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
2077                            u64 bytes)
2078 {
2079         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2080         struct btrfs_free_space *info;
2081         struct rb_node *n;
2082         int count = 0;
2083
2084         for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
2085                 info = rb_entry(n, struct btrfs_free_space, offset_index);
2086                 if (info->bytes >= bytes && !block_group->ro)
2087                         count++;
2088                 btrfs_crit(block_group->fs_info,
2089                            "entry offset %llu, bytes %llu, bitmap %s",
2090                            info->offset, info->bytes,
2091                        (info->bitmap) ? "yes" : "no");
2092         }
2093         btrfs_info(block_group->fs_info, "block group has cluster?: %s",
2094                list_empty(&block_group->cluster_list) ? "no" : "yes");
2095         btrfs_info(block_group->fs_info,
2096                    "%d blocks of free space at or bigger than bytes is", count);
2097 }
2098
2099 void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
2100 {
2101         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2102
2103         spin_lock_init(&ctl->tree_lock);
2104         ctl->unit = block_group->sectorsize;
2105         ctl->start = block_group->key.objectid;
2106         ctl->private = block_group;
2107         ctl->op = &free_space_op;
2108
2109         /*
2110          * we only want to have 32k of ram per block group for keeping
2111          * track of free space, and if we pass 1/2 of that we want to
2112          * start converting things over to using bitmaps
2113          */
2114         ctl->extents_thresh = ((1024 * 32) / 2) /
2115                                 sizeof(struct btrfs_free_space);
2116 }
2117
2118 /*
2119  * for a given cluster, put all of its extents back into the free
2120  * space cache.  If the block group passed doesn't match the block group
2121  * pointed to by the cluster, someone else raced in and freed the
2122  * cluster already.  In that case, we just return without changing anything
2123  */
2124 static int
2125 __btrfs_return_cluster_to_free_space(
2126                              struct btrfs_block_group_cache *block_group,
2127                              struct btrfs_free_cluster *cluster)
2128 {
2129         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2130         struct btrfs_free_space *entry;
2131         struct rb_node *node;
2132
2133         spin_lock(&cluster->lock);
2134         if (cluster->block_group != block_group)
2135                 goto out;
2136
2137         cluster->block_group = NULL;
2138         cluster->window_start = 0;
2139         list_del_init(&cluster->block_group_list);
2140
2141         node = rb_first(&cluster->root);
2142         while (node) {
2143                 bool bitmap;
2144
2145                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2146                 node = rb_next(&entry->offset_index);
2147                 rb_erase(&entry->offset_index, &cluster->root);
2148
2149                 bitmap = (entry->bitmap != NULL);
2150                 if (!bitmap)
2151                         try_merge_free_space(ctl, entry, false);
2152                 tree_insert_offset(&ctl->free_space_offset,
2153                                    entry->offset, &entry->offset_index, bitmap);
2154         }
2155         cluster->root = RB_ROOT;
2156
2157 out:
2158         spin_unlock(&cluster->lock);
2159         btrfs_put_block_group(block_group);
2160         return 0;
2161 }
2162
2163 static void __btrfs_remove_free_space_cache_locked(
2164                                 struct btrfs_free_space_ctl *ctl)
2165 {
2166         struct btrfs_free_space *info;
2167         struct rb_node *node;
2168
2169         while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
2170                 info = rb_entry(node, struct btrfs_free_space, offset_index);
2171                 if (!info->bitmap) {
2172                         unlink_free_space(ctl, info);
2173                         kmem_cache_free(btrfs_free_space_cachep, info);
2174                 } else {
2175                         free_bitmap(ctl, info);
2176                 }
2177                 if (need_resched()) {
2178                         spin_unlock(&ctl->tree_lock);
2179                         cond_resched();
2180                         spin_lock(&ctl->tree_lock);
2181                 }
2182         }
2183 }
2184
2185 void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
2186 {
2187         spin_lock(&ctl->tree_lock);
2188         __btrfs_remove_free_space_cache_locked(ctl);
2189         spin_unlock(&ctl->tree_lock);
2190 }
2191
2192 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
2193 {
2194         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2195         struct btrfs_free_cluster *cluster;
2196         struct list_head *head;
2197
2198         spin_lock(&ctl->tree_lock);
2199         while ((head = block_group->cluster_list.next) !=
2200                &block_group->cluster_list) {
2201                 cluster = list_entry(head, struct btrfs_free_cluster,
2202                                      block_group_list);
2203
2204                 WARN_ON(cluster->block_group != block_group);
2205                 __btrfs_return_cluster_to_free_space(block_group, cluster);
2206                 if (need_resched()) {
2207                         spin_unlock(&ctl->tree_lock);
2208                         cond_resched();
2209                         spin_lock(&ctl->tree_lock);
2210                 }
2211         }
2212         __btrfs_remove_free_space_cache_locked(ctl);
2213         spin_unlock(&ctl->tree_lock);
2214
2215 }
2216
2217 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
2218                                u64 offset, u64 bytes, u64 empty_size,
2219                                u64 *max_extent_size)
2220 {
2221         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2222         struct btrfs_free_space *entry = NULL;
2223         u64 bytes_search = bytes + empty_size;
2224         u64 ret = 0;
2225         u64 align_gap = 0;
2226         u64 align_gap_len = 0;
2227
2228         spin_lock(&ctl->tree_lock);
2229         entry = find_free_space(ctl, &offset, &bytes_search,
2230                                 block_group->full_stripe_len, max_extent_size);
2231         if (!entry)
2232                 goto out;
2233
2234         ret = offset;
2235         if (entry->bitmap) {
2236                 bitmap_clear_bits(ctl, entry, offset, bytes);
2237                 if (!entry->bytes)
2238                         free_bitmap(ctl, entry);
2239         } else {
2240                 unlink_free_space(ctl, entry);
2241                 align_gap_len = offset - entry->offset;
2242                 align_gap = entry->offset;
2243
2244                 entry->offset = offset + bytes;
2245                 WARN_ON(entry->bytes < bytes + align_gap_len);
2246
2247                 entry->bytes -= bytes + align_gap_len;
2248                 if (!entry->bytes)
2249                         kmem_cache_free(btrfs_free_space_cachep, entry);
2250                 else
2251                         link_free_space(ctl, entry);
2252         }
2253 out:
2254         spin_unlock(&ctl->tree_lock);
2255
2256         if (align_gap_len)
2257                 __btrfs_add_free_space(ctl, align_gap, align_gap_len);
2258         return ret;
2259 }
2260
2261 /*
2262  * given a cluster, put all of its extents back into the free space
2263  * cache.  If a block group is passed, this function will only free
2264  * a cluster that belongs to the passed block group.
2265  *
2266  * Otherwise, it'll get a reference on the block group pointed to by the
2267  * cluster and remove the cluster from it.
2268  */
2269 int btrfs_return_cluster_to_free_space(
2270                                struct btrfs_block_group_cache *block_group,
2271                                struct btrfs_free_cluster *cluster)
2272 {
2273         struct btrfs_free_space_ctl *ctl;
2274         int ret;
2275
2276         /* first, get a safe pointer to the block group */
2277         spin_lock(&cluster->lock);
2278         if (!block_group) {
2279                 block_group = cluster->block_group;
2280                 if (!block_group) {
2281                         spin_unlock(&cluster->lock);
2282                         return 0;
2283                 }
2284         } else if (cluster->block_group != block_group) {
2285                 /* someone else has already freed it don't redo their work */
2286                 spin_unlock(&cluster->lock);
2287                 return 0;
2288         }
2289         atomic_inc(&block_group->count);
2290         spin_unlock(&cluster->lock);
2291
2292         ctl = block_group->free_space_ctl;
2293
2294         /* now return any extents the cluster had on it */
2295         spin_lock(&ctl->tree_lock);
2296         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
2297         spin_unlock(&ctl->tree_lock);
2298
2299         /* finally drop our ref */
2300         btrfs_put_block_group(block_group);
2301         return ret;
2302 }
2303
2304 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
2305                                    struct btrfs_free_cluster *cluster,
2306                                    struct btrfs_free_space *entry,
2307                                    u64 bytes, u64 min_start,
2308                                    u64 *max_extent_size)
2309 {
2310         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2311         int err;
2312         u64 search_start = cluster->window_start;
2313         u64 search_bytes = bytes;
2314         u64 ret = 0;
2315
2316         search_start = min_start;
2317         search_bytes = bytes;
2318
2319         err = search_bitmap(ctl, entry, &search_start, &search_bytes);
2320         if (err) {
2321                 if (search_bytes > *max_extent_size)
2322                         *max_extent_size = search_bytes;
2323                 return 0;
2324         }
2325
2326         ret = search_start;
2327         __bitmap_clear_bits(ctl, entry, ret, bytes);
2328
2329         return ret;
2330 }
2331
2332 /*
2333  * given a cluster, try to allocate 'bytes' from it, returns 0
2334  * if it couldn't find anything suitably large, or a logical disk offset
2335  * if things worked out
2336  */
2337 u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
2338                              struct btrfs_free_cluster *cluster, u64 bytes,
2339                              u64 min_start, u64 *max_extent_size)
2340 {
2341         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2342         struct btrfs_free_space *entry = NULL;
2343         struct rb_node *node;
2344         u64 ret = 0;
2345
2346         spin_lock(&cluster->lock);
2347         if (bytes > cluster->max_size)
2348                 goto out;
2349
2350         if (cluster->block_group != block_group)
2351                 goto out;
2352
2353         node = rb_first(&cluster->root);
2354         if (!node)
2355                 goto out;
2356
2357         entry = rb_entry(node, struct btrfs_free_space, offset_index);
2358         while (1) {
2359                 if (entry->bytes < bytes && entry->bytes > *max_extent_size)
2360                         *max_extent_size = entry->bytes;
2361
2362                 if (entry->bytes < bytes ||
2363                     (!entry->bitmap && entry->offset < min_start)) {
2364                         node = rb_next(&entry->offset_index);
2365                         if (!node)
2366                                 break;
2367                         entry = rb_entry(node, struct btrfs_free_space,
2368                                          offset_index);
2369                         continue;
2370                 }
2371
2372                 if (entry->bitmap) {
2373                         ret = btrfs_alloc_from_bitmap(block_group,
2374                                                       cluster, entry, bytes,
2375                                                       cluster->window_start,
2376                                                       max_extent_size);
2377                         if (ret == 0) {
2378                                 node = rb_next(&entry->offset_index);
2379                                 if (!node)
2380                                         break;
2381                                 entry = rb_entry(node, struct btrfs_free_space,
2382                                                  offset_index);
2383                                 continue;
2384                         }
2385                         cluster->window_start += bytes;
2386                 } else {
2387                         ret = entry->offset;
2388
2389                         entry->offset += bytes;
2390                         entry->bytes -= bytes;
2391                 }
2392
2393                 if (entry->bytes == 0)
2394                         rb_erase(&entry->offset_index, &cluster->root);
2395                 break;
2396         }
2397 out:
2398         spin_unlock(&cluster->lock);
2399
2400         if (!ret)
2401                 return 0;
2402
2403         spin_lock(&ctl->tree_lock);
2404
2405         ctl->free_space -= bytes;
2406         if (entry->bytes == 0) {
2407                 ctl->free_extents--;
2408                 if (entry->bitmap) {
2409                         kfree(entry->bitmap);
2410                         ctl->total_bitmaps--;
2411                         ctl->op->recalc_thresholds(ctl);
2412                 }
2413                 kmem_cache_free(btrfs_free_space_cachep, entry);
2414         }
2415
2416         spin_unlock(&ctl->tree_lock);
2417
2418         return ret;
2419 }
2420
2421 static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
2422                                 struct btrfs_free_space *entry,
2423                                 struct btrfs_free_cluster *cluster,
2424                                 u64 offset, u64 bytes,
2425                                 u64 cont1_bytes, u64 min_bytes)
2426 {
2427         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2428         unsigned long next_zero;
2429         unsigned long i;
2430         unsigned long want_bits;
2431         unsigned long min_bits;
2432         unsigned long found_bits;
2433         unsigned long start = 0;
2434         unsigned long total_found = 0;
2435         int ret;
2436
2437         i = offset_to_bit(entry->offset, ctl->unit,
2438                           max_t(u64, offset, entry->offset));
2439         want_bits = bytes_to_bits(bytes, ctl->unit);
2440         min_bits = bytes_to_bits(min_bytes, ctl->unit);
2441
2442 again:
2443         found_bits = 0;
2444         for_each_set_bit_from(i, entry->bitmap, BITS_PER_BITMAP) {
2445                 next_zero = find_next_zero_bit(entry->bitmap,
2446                                                BITS_PER_BITMAP, i);
2447                 if (next_zero - i >= min_bits) {
2448                         found_bits = next_zero - i;
2449                         break;
2450                 }
2451                 i = next_zero;
2452         }
2453
2454         if (!found_bits)
2455                 return -ENOSPC;
2456
2457         if (!total_found) {
2458                 start = i;
2459                 cluster->max_size = 0;
2460         }
2461
2462         total_found += found_bits;
2463
2464         if (cluster->max_size < found_bits * ctl->unit)
2465                 cluster->max_size = found_bits * ctl->unit;
2466
2467         if (total_found < want_bits || cluster->max_size < cont1_bytes) {
2468                 i = next_zero + 1;
2469                 goto again;
2470         }
2471
2472         cluster->window_start = start * ctl->unit + entry->offset;
2473         rb_erase(&entry->offset_index, &ctl->free_space_offset);
2474         ret = tree_insert_offset(&cluster->root, entry->offset,
2475                                  &entry->offset_index, 1);
2476         ASSERT(!ret); /* -EEXIST; Logic error */
2477
2478         trace_btrfs_setup_cluster(block_group, cluster,
2479                                   total_found * ctl->unit, 1);
2480         return 0;
2481 }
2482
2483 /*
2484  * This searches the block group for just extents to fill the cluster with.
2485  * Try to find a cluster with at least bytes total bytes, at least one
2486  * extent of cont1_bytes, and other clusters of at least min_bytes.
2487  */
2488 static noinline int
2489 setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
2490                         struct btrfs_free_cluster *cluster,
2491                         struct list_head *bitmaps, u64 offset, u64 bytes,
2492                         u64 cont1_bytes, u64 min_bytes)
2493 {
2494         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2495         struct btrfs_free_space *first = NULL;
2496         struct btrfs_free_space *entry = NULL;
2497         struct btrfs_free_space *last;
2498         struct rb_node *node;
2499         u64 window_free;
2500         u64 max_extent;
2501         u64 total_size = 0;
2502
2503         entry = tree_search_offset(ctl, offset, 0, 1);
2504         if (!entry)
2505                 return -ENOSPC;
2506
2507         /*
2508          * We don't want bitmaps, so just move along until we find a normal
2509          * extent entry.
2510          */
2511         while (entry->bitmap || entry->bytes < min_bytes) {
2512                 if (entry->bitmap && list_empty(&entry->list))
2513                         list_add_tail(&entry->list, bitmaps);
2514                 node = rb_next(&entry->offset_index);
2515                 if (!node)
2516                         return -ENOSPC;
2517                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2518         }
2519
2520         window_free = entry->bytes;
2521         max_extent = entry->bytes;
2522         first = entry;
2523         last = entry;
2524
2525         for (node = rb_next(&entry->offset_index); node;
2526              node = rb_next(&entry->offset_index)) {
2527                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2528
2529                 if (entry->bitmap) {
2530                         if (list_empty(&entry->list))
2531                                 list_add_tail(&entry->list, bitmaps);
2532                         continue;
2533                 }
2534
2535                 if (entry->bytes < min_bytes)
2536                         continue;
2537
2538                 last = entry;
2539                 window_free += entry->bytes;
2540                 if (entry->bytes > max_extent)
2541                         max_extent = entry->bytes;
2542         }
2543
2544         if (window_free < bytes || max_extent < cont1_bytes)
2545                 return -ENOSPC;
2546
2547         cluster->window_start = first->offset;
2548
2549         node = &first->offset_index;
2550
2551         /*
2552          * now we've found our entries, pull them out of the free space
2553          * cache and put them into the cluster rbtree
2554          */
2555         do {
2556                 int ret;
2557
2558                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
2559                 node = rb_next(&entry->offset_index);
2560                 if (entry->bitmap || entry->bytes < min_bytes)
2561                         continue;
2562
2563                 rb_erase(&entry->offset_index, &ctl->free_space_offset);
2564                 ret = tree_insert_offset(&cluster->root, entry->offset,
2565                                          &entry->offset_index, 0);
2566                 total_size += entry->bytes;
2567                 ASSERT(!ret); /* -EEXIST; Logic error */
2568         } while (node && entry != last);
2569
2570         cluster->max_size = max_extent;
2571         trace_btrfs_setup_cluster(block_group, cluster, total_size, 0);
2572         return 0;
2573 }
2574
2575 /*
2576  * This specifically looks for bitmaps that may work in the cluster, we assume
2577  * that we have already failed to find extents that will work.
2578  */
2579 static noinline int
2580 setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2581                      struct btrfs_free_cluster *cluster,
2582                      struct list_head *bitmaps, u64 offset, u64 bytes,
2583                      u64 cont1_bytes, u64 min_bytes)
2584 {
2585         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2586         struct btrfs_free_space *entry;
2587         int ret = -ENOSPC;
2588         u64 bitmap_offset = offset_to_bitmap(ctl, offset);
2589
2590         if (ctl->total_bitmaps == 0)
2591                 return -ENOSPC;
2592
2593         /*
2594          * The bitmap that covers offset won't be in the list unless offset
2595          * is just its start offset.
2596          */
2597         entry = list_first_entry(bitmaps, struct btrfs_free_space, list);
2598         if (entry->offset != bitmap_offset) {
2599                 entry = tree_search_offset(ctl, bitmap_offset, 1, 0);
2600                 if (entry && list_empty(&entry->list))
2601                         list_add(&entry->list, bitmaps);
2602         }
2603
2604         list_for_each_entry(entry, bitmaps, list) {
2605                 if (entry->bytes < bytes)
2606                         continue;
2607                 ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
2608                                            bytes, cont1_bytes, min_bytes);
2609                 if (!ret)
2610                         return 0;
2611         }
2612
2613         /*
2614          * The bitmaps list has all the bitmaps that record free space
2615          * starting after offset, so no more search is required.
2616          */
2617         return -ENOSPC;
2618 }
2619
2620 /*
2621  * here we try to find a cluster of blocks in a block group.  The goal
2622  * is to find at least bytes+empty_size.
2623  * We might not find them all in one contiguous area.
2624  *
2625  * returns zero and sets up cluster if things worked out, otherwise
2626  * it returns -enospc
2627  */
2628 int btrfs_find_space_cluster(struct btrfs_root *root,
2629                              struct btrfs_block_group_cache *block_group,
2630                              struct btrfs_free_cluster *cluster,
2631                              u64 offset, u64 bytes, u64 empty_size)
2632 {
2633         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2634         struct btrfs_free_space *entry, *tmp;
2635         LIST_HEAD(bitmaps);
2636         u64 min_bytes;
2637         u64 cont1_bytes;
2638         int ret;
2639
2640         /*
2641          * Choose the minimum extent size we'll require for this
2642          * cluster.  For SSD_SPREAD, don't allow any fragmentation.
2643          * For metadata, allow allocates with smaller extents.  For
2644          * data, keep it dense.
2645          */
2646         if (btrfs_test_opt(root, SSD_SPREAD)) {
2647                 cont1_bytes = min_bytes = bytes + empty_size;
2648         } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
2649                 cont1_bytes = bytes;
2650                 min_bytes = block_group->sectorsize;
2651         } else {
2652                 cont1_bytes = max(bytes, (bytes + empty_size) >> 2);
2653                 min_bytes = block_group->sectorsize;
2654         }
2655
2656         spin_lock(&ctl->tree_lock);
2657
2658         /*
2659          * If we know we don't have enough space to make a cluster don't even
2660          * bother doing all the work to try and find one.
2661          */
2662         if (ctl->free_space < bytes) {
2663                 spin_unlock(&ctl->tree_lock);
2664                 return -ENOSPC;
2665         }
2666
2667         spin_lock(&cluster->lock);
2668
2669         /* someone already found a cluster, hooray */
2670         if (cluster->block_group) {
2671                 ret = 0;
2672                 goto out;
2673         }
2674
2675         trace_btrfs_find_cluster(block_group, offset, bytes, empty_size,
2676                                  min_bytes);
2677
2678         INIT_LIST_HEAD(&bitmaps);
2679         ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
2680                                       bytes + empty_size,
2681                                       cont1_bytes, min_bytes);
2682         if (ret)
2683                 ret = setup_cluster_bitmap(block_group, cluster, &bitmaps,
2684                                            offset, bytes + empty_size,
2685                                            cont1_bytes, min_bytes);
2686
2687         /* Clear our temporary list */
2688         list_for_each_entry_safe(entry, tmp, &bitmaps, list)
2689                 list_del_init(&entry->list);
2690
2691         if (!ret) {
2692                 atomic_inc(&block_group->count);
2693                 list_add_tail(&cluster->block_group_list,
2694                               &block_group->cluster_list);
2695                 cluster->block_group = block_group;
2696         } else {
2697                 trace_btrfs_failed_cluster_setup(block_group);
2698         }
2699 out:
2700         spin_unlock(&cluster->lock);
2701         spin_unlock(&ctl->tree_lock);
2702
2703         return ret;
2704 }
2705
2706 /*
2707  * simple code to zero out a cluster
2708  */
2709 void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
2710 {
2711         spin_lock_init(&cluster->lock);
2712         spin_lock_init(&cluster->refill_lock);
2713         cluster->root = RB_ROOT;
2714         cluster->max_size = 0;
2715         INIT_LIST_HEAD(&cluster->block_group_list);
2716         cluster->block_group = NULL;
2717 }
2718
2719 static int do_trimming(struct btrfs_block_group_cache *block_group,
2720                        u64 *total_trimmed, u64 start, u64 bytes,
2721                        u64 reserved_start, u64 reserved_bytes)
2722 {
2723         struct btrfs_space_info *space_info = block_group->space_info;
2724         struct btrfs_fs_info *fs_info = block_group->fs_info;
2725         int ret;
2726         int update = 0;
2727         u64 trimmed = 0;
2728
2729         spin_lock(&space_info->lock);
2730         spin_lock(&block_group->lock);
2731         if (!block_group->ro) {
2732                 block_group->reserved += reserved_bytes;
2733                 space_info->bytes_reserved += reserved_bytes;
2734                 update = 1;
2735         }
2736         spin_unlock(&block_group->lock);
2737         spin_unlock(&space_info->lock);
2738
2739         ret = btrfs_error_discard_extent(fs_info->extent_root,
2740                                          start, bytes, &trimmed);
2741         if (!ret)
2742                 *total_trimmed += trimmed;
2743
2744         btrfs_add_free_space(block_group, reserved_start, reserved_bytes);
2745
2746         if (update) {
2747                 spin_lock(&space_info->lock);
2748                 spin_lock(&block_group->lock);
2749                 if (block_group->ro)
2750                         space_info->bytes_readonly += reserved_bytes;
2751                 block_group->reserved -= reserved_bytes;
2752                 space_info->bytes_reserved -= reserved_bytes;
2753                 spin_unlock(&space_info->lock);
2754                 spin_unlock(&block_group->lock);
2755         }
2756
2757         return ret;
2758 }
2759
2760 static int trim_no_bitmap(struct btrfs_block_group_cache *block_group,
2761                           u64 *total_trimmed, u64 start, u64 end, u64 minlen)
2762 {
2763         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2764         struct btrfs_free_space *entry;
2765         struct rb_node *node;
2766         int ret = 0;
2767         u64 extent_start;
2768         u64 extent_bytes;
2769         u64 bytes;
2770
2771         while (start < end) {
2772                 spin_lock(&ctl->tree_lock);
2773
2774                 if (ctl->free_space < minlen) {
2775                         spin_unlock(&ctl->tree_lock);
2776                         break;
2777                 }
2778
2779                 entry = tree_search_offset(ctl, start, 0, 1);
2780                 if (!entry) {
2781                         spin_unlock(&ctl->tree_lock);
2782                         break;
2783                 }
2784
2785                 /* skip bitmaps */
2786                 while (entry->bitmap) {
2787                         node = rb_next(&entry->offset_index);
2788                         if (!node) {
2789                                 spin_unlock(&ctl->tree_lock);
2790                                 goto out;
2791                         }
2792                         entry = rb_entry(node, struct btrfs_free_space,
2793                                          offset_index);
2794                 }
2795
2796                 if (entry->offset >= end) {
2797                         spin_unlock(&ctl->tree_lock);
2798                         break;
2799                 }
2800
2801                 extent_start = entry->offset;
2802                 extent_bytes = entry->bytes;
2803                 start = max(start, extent_start);
2804                 bytes = min(extent_start + extent_bytes, end) - start;
2805                 if (bytes < minlen) {
2806                         spin_unlock(&ctl->tree_lock);
2807                         goto next;
2808                 }
2809
2810                 unlink_free_space(ctl, entry);
2811                 kmem_cache_free(btrfs_free_space_cachep, entry);
2812
2813                 spin_unlock(&ctl->tree_lock);
2814
2815                 ret = do_trimming(block_group, total_trimmed, start, bytes,
2816                                   extent_start, extent_bytes);
2817                 if (ret)
2818                         break;
2819 next:
2820                 start += bytes;
2821
2822                 if (fatal_signal_pending(current)) {
2823                         ret = -ERESTARTSYS;
2824                         break;
2825                 }
2826
2827                 cond_resched();
2828         }
2829 out:
2830         return ret;
2831 }
2832
2833 static int trim_bitmaps(struct btrfs_block_group_cache *block_group,
2834                         u64 *total_trimmed, u64 start, u64 end, u64 minlen)
2835 {
2836         struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2837         struct btrfs_free_space *entry;
2838         int ret = 0;
2839         int ret2;
2840         u64 bytes;
2841         u64 offset = offset_to_bitmap(ctl, start);
2842
2843         while (offset < end) {
2844                 bool next_bitmap = false;
2845
2846                 spin_lock(&ctl->tree_lock);
2847
2848                 if (ctl->free_space < minlen) {
2849                         spin_unlock(&ctl->tree_lock);
2850                         break;
2851                 }
2852
2853                 entry = tree_search_offset(ctl, offset, 1, 0);
2854                 if (!entry) {
2855                         spin_unlock(&ctl->tree_lock);
2856                         next_bitmap = true;
2857                         goto next;
2858                 }
2859
2860                 bytes = minlen;
2861                 ret2 = search_bitmap(ctl, entry, &start, &bytes);
2862                 if (ret2 || start >= end) {
2863                         spin_unlock(&ctl->tree_lock);
2864                         next_bitmap = true;
2865                         goto next;
2866                 }
2867
2868                 bytes = min(bytes, end - start);
2869                 if (bytes < minlen) {
2870                         spin_unlock(&ctl->tree_lock);
2871                         goto next;
2872                 }
2873
2874                 bitmap_clear_bits(ctl, entry, start, bytes);
2875                 if (entry->bytes == 0)
2876                         free_bitmap(ctl, entry);
2877
2878                 spin_unlock(&ctl->tree_lock);
2879
2880                 ret = do_trimming(block_group, total_trimmed, start, bytes,
2881                                   start, bytes);
2882                 if (ret)
2883                         break;
2884 next:
2885                 if (next_bitmap) {
2886                         offset += BITS_PER_BITMAP * ctl->unit;
2887                 } else {
2888                         start += bytes;
2889                         if (start >= offset + BITS_PER_BITMAP * ctl->unit)
2890                                 offset += BITS_PER_BITMAP * ctl->unit;
2891                 }
2892
2893                 if (fatal_signal_pending(current)) {
2894                         ret = -ERESTARTSYS;
2895                         break;
2896                 }
2897
2898                 cond_resched();
2899         }
2900
2901         return ret;
2902 }
2903
2904 int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
2905                            u64 *trimmed, u64 start, u64 end, u64 minlen)
2906 {
2907         int ret;
2908
2909         *trimmed = 0;
2910
2911         ret = trim_no_bitmap(block_group, trimmed, start, end, minlen);
2912         if (ret)
2913                 return ret;
2914
2915         ret = trim_bitmaps(block_group, trimmed, start, end, minlen);
2916
2917         return ret;
2918 }
2919
2920 /*
2921  * Find the left-most item in the cache tree, and then return the
2922  * smallest inode number in the item.
2923  *
2924  * Note: the returned inode number may not be the smallest one in
2925  * the tree, if the left-most item is a bitmap.
2926  */
2927 u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root)
2928 {
2929         struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl;
2930         struct btrfs_free_space *entry = NULL;
2931         u64 ino = 0;
2932
2933         spin_lock(&ctl->tree_lock);
2934
2935         if (RB_EMPTY_ROOT(&ctl->free_space_offset))
2936                 goto out;
2937
2938         entry = rb_entry(rb_first(&ctl->free_space_offset),
2939                          struct btrfs_free_space, offset_index);
2940
2941         if (!entry->bitmap) {
2942                 ino = entry->offset;
2943
2944                 unlink_free_space(ctl, entry);
2945                 entry->offset++;
2946                 entry->bytes--;
2947                 if (!entry->bytes)
2948                         kmem_cache_free(btrfs_free_space_cachep, entry);
2949                 else
2950                         link_free_space(ctl, entry);
2951         } else {
2952                 u64 offset = 0;
2953                 u64 count = 1;
2954                 int ret;
2955
2956                 ret = search_bitmap(ctl, entry, &offset, &count);
2957                 /* Logic error; Should be empty if it can't find anything */
2958                 ASSERT(!ret);
2959
2960                 ino = offset;
2961                 bitmap_clear_bits(ctl, entry, offset, 1);
2962                 if (entry->bytes == 0)
2963                         free_bitmap(ctl, entry);
2964         }
2965 out:
2966         spin_unlock(&ctl->tree_lock);
2967
2968         return ino;
2969 }
2970
2971 struct inode *lookup_free_ino_inode(struct btrfs_root *root,
2972                                     struct btrfs_path *path)
2973 {
2974         struct inode *inode = NULL;
2975
2976         spin_lock(&root->cache_lock);
2977         if (root->cache_inode)
2978                 inode = igrab(root->cache_inode);
2979         spin_unlock(&root->cache_lock);
2980         if (inode)
2981                 return inode;
2982
2983         inode = __lookup_free_space_inode(root, path, 0);
2984         if (IS_ERR(inode))
2985                 return inode;
2986
2987         spin_lock(&root->cache_lock);
2988         if (!btrfs_fs_closing(root->fs_info))
2989                 root->cache_inode = igrab(inode);
2990         spin_unlock(&root->cache_lock);
2991
2992         return inode;
2993 }
2994
2995 int create_free_ino_inode(struct btrfs_root *root,
2996                           struct btrfs_trans_handle *trans,
2997                           struct btrfs_path *path)
2998 {
2999         return __create_free_space_inode(root, trans, path,
3000                                          BTRFS_FREE_INO_OBJECTID, 0);
3001 }
3002
3003 int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
3004 {
3005         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
3006         struct btrfs_path *path;
3007         struct inode *inode;
3008         int ret = 0;
3009         u64 root_gen = btrfs_root_generation(&root->root_item);
3010
3011         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
3012                 return 0;
3013
3014         /*
3015          * If we're unmounting then just return, since this does a search on the
3016          * normal root and not the commit root and we could deadlock.
3017          */
3018         if (btrfs_fs_closing(fs_info))
3019                 return 0;
3020
3021         path = btrfs_alloc_path();
3022         if (!path)
3023                 return 0;
3024
3025         inode = lookup_free_ino_inode(root, path);
3026         if (IS_ERR(inode))
3027                 goto out;
3028
3029         if (root_gen != BTRFS_I(inode)->generation)
3030                 goto out_put;
3031
3032         ret = __load_free_space_cache(root, inode, ctl, path, 0);
3033
3034         if (ret < 0)
3035                 btrfs_err(fs_info,
3036                         "failed to load free ino cache for root %llu",
3037                         root->root_key.objectid);
3038 out_put:
3039         iput(inode);
3040 out:
3041         btrfs_free_path(path);
3042         return ret;
3043 }
3044
3045 int btrfs_write_out_ino_cache(struct btrfs_root *root,
3046                               struct btrfs_trans_handle *trans,
3047                               struct btrfs_path *path,
3048                               struct inode *inode)
3049 {
3050         struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
3051         int ret;
3052
3053         if (!btrfs_test_opt(root, INODE_MAP_CACHE))
3054                 return 0;
3055
3056         ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);
3057         if (ret) {
3058                 btrfs_delalloc_release_metadata(inode, inode->i_size);
3059 #ifdef DEBUG
3060                 btrfs_err(root->fs_info,
3061                         "failed to write free ino cache for root %llu",
3062                         root->root_key.objectid);
3063 #endif
3064         }
3065
3066         return ret;
3067 }
3068
3069 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
3070 /*
3071  * Use this if you need to make a bitmap or extent entry specifically, it
3072  * doesn't do any of the merging that add_free_space does, this acts a lot like
3073  * how the free space cache loading stuff works, so you can get really weird
3074  * configurations.
3075  */
3076 int test_add_free_space_entry(struct btrfs_block_group_cache *cache,
3077                               u64 offset, u64 bytes, bool bitmap)
3078 {
3079         struct btrfs_free_space_ctl *ctl = cache->free_space_ctl;
3080         struct btrfs_free_space *info = NULL, *bitmap_info;
3081         void *map = NULL;
3082         u64 bytes_added;
3083         int ret;
3084
3085 again:
3086         if (!info) {
3087                 info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
3088                 if (!info)
3089                         return -ENOMEM;
3090         }
3091
3092         if (!bitmap) {
3093                 spin_lock(&ctl->tree_lock);
3094                 info->offset = offset;
3095                 info->bytes = bytes;
3096                 ret = link_free_space(ctl, info);
3097                 spin_unlock(&ctl->tree_lock);
3098                 if (ret)
3099                         kmem_cache_free(btrfs_free_space_cachep, info);
3100                 return ret;
3101         }
3102
3103         if (!map) {
3104                 map = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
3105                 if (!map) {
3106                         kmem_cache_free(btrfs_free_space_cachep, info);
3107                         return -ENOMEM;
3108                 }
3109         }
3110
3111         spin_lock(&ctl->tree_lock);
3112         bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
3113                                          1, 0);
3114         if (!bitmap_info) {
3115                 info->bitmap = map;
3116                 map = NULL;
3117                 add_new_bitmap(ctl, info, offset);
3118                 bitmap_info = info;
3119         }
3120
3121         bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
3122         bytes -= bytes_added;
3123         offset += bytes_added;
3124         spin_unlock(&ctl->tree_lock);
3125
3126         if (bytes)
3127                 goto again;
3128
3129         if (map)
3130                 kfree(map);
3131         return 0;
3132 }
3133
3134 /*
3135  * Checks to see if the given range is in the free space cache.  This is really
3136  * just used to check the absence of space, so if there is free space in the
3137  * range at all we will return 1.
3138  */
3139 int test_check_exists(struct btrfs_block_group_cache *cache,
3140                       u64 offset, u64 bytes)
3141 {
3142         struct btrfs_free_space_ctl *ctl = cache->free_space_ctl;
3143         struct btrfs_free_space *info;
3144         int ret = 0;
3145
3146         spin_lock(&ctl->tree_lock);
3147         info = tree_search_offset(ctl, offset, 0, 0);
3148         if (!info) {
3149                 info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
3150                                           1, 0);
3151                 if (!info)
3152                         goto out;
3153         }
3154
3155 have_info:
3156         if (info->bitmap) {
3157                 u64 bit_off, bit_bytes;
3158                 struct rb_node *n;
3159                 struct btrfs_free_space *tmp;
3160
3161                 bit_off = offset;
3162                 bit_bytes = ctl->unit;
3163                 ret = search_bitmap(ctl, info, &bit_off, &bit_bytes);
3164                 if (!ret) {
3165                         if (bit_off == offset) {
3166                                 ret = 1;
3167                                 goto out;
3168                         } else if (bit_off > offset &&
3169                                    offset + bytes > bit_off) {
3170                                 ret = 1;
3171                                 goto out;
3172                         }
3173                 }
3174
3175                 n = rb_prev(&info->offset_index);
3176                 while (n) {
3177                         tmp = rb_entry(n, struct btrfs_free_space,
3178                                        offset_index);
3179                         if (tmp->offset + tmp->bytes < offset)
3180                                 break;
3181                         if (offset + bytes < tmp->offset) {
3182                                 n = rb_prev(&info->offset_index);
3183                                 continue;
3184                         }
3185                         info = tmp;
3186                         goto have_info;
3187                 }
3188
3189                 n = rb_next(&info->offset_index);
3190                 while (n) {
3191                         tmp = rb_entry(n, struct btrfs_free_space,
3192                                        offset_index);
3193                         if (offset + bytes < tmp->offset)
3194                                 break;
3195                         if (tmp->offset + tmp->bytes < offset) {
3196                                 n = rb_next(&info->offset_index);
3197                                 continue;
3198                         }
3199                         info = tmp;
3200                         goto have_info;
3201                 }
3202
3203                 goto out;
3204         }
3205
3206         if (info->offset == offset) {
3207                 ret = 1;
3208                 goto out;
3209         }
3210
3211         if (offset > info->offset && offset < info->offset + info->bytes)
3212                 ret = 1;
3213 out:
3214         spin_unlock(&ctl->tree_lock);
3215         return ret;
3216 }
3217 #endif /* CONFIG_BTRFS_FS_RUN_SANITY_TESTS */