linux/fs/btrfs/free-space-cache.c
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   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/sched/signal.h>
  22#include <linux/slab.h>
  23#include <linux/math64.h>
  24#include <linux/ratelimit.h>
  25#include "ctree.h"
  26#include "free-space-cache.h"
  27#include "transaction.h"
  28#include "disk-io.h"
  29#include "extent_io.h"
  30#include "inode-map.h"
  31#include "volumes.h"
  32
  33#define BITS_PER_BITMAP         (PAGE_SIZE * 8UL)
  34#define MAX_CACHE_BYTES_PER_GIG SZ_32K
  35
  36struct btrfs_trim_range {
  37        u64 start;
  38        u64 bytes;
  39        struct list_head list;
  40};
  41
  42static int link_free_space(struct btrfs_free_space_ctl *ctl,
  43                           struct btrfs_free_space *info);
  44static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
  45                              struct btrfs_free_space *info);
  46static int btrfs_wait_cache_io_root(struct btrfs_root *root,
  47                             struct btrfs_trans_handle *trans,
  48                             struct btrfs_io_ctl *io_ctl,
  49                             struct btrfs_path *path);
  50
  51static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
  52                                               struct btrfs_path *path,
  53                                               u64 offset)
  54{
  55        struct btrfs_fs_info *fs_info = root->fs_info;
  56        struct btrfs_key key;
  57        struct btrfs_key location;
  58        struct btrfs_disk_key disk_key;
  59        struct btrfs_free_space_header *header;
  60        struct extent_buffer *leaf;
  61        struct inode *inode = NULL;
  62        int ret;
  63
  64        key.objectid = BTRFS_FREE_SPACE_OBJECTID;
  65        key.offset = offset;
  66        key.type = 0;
  67
  68        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  69        if (ret < 0)
  70                return ERR_PTR(ret);
  71        if (ret > 0) {
  72                btrfs_release_path(path);
  73                return ERR_PTR(-ENOENT);
  74        }
  75
  76        leaf = path->nodes[0];
  77        header = btrfs_item_ptr(leaf, path->slots[0],
  78                                struct btrfs_free_space_header);
  79        btrfs_free_space_key(leaf, header, &disk_key);
  80        btrfs_disk_key_to_cpu(&location, &disk_key);
  81        btrfs_release_path(path);
  82
  83        inode = btrfs_iget(fs_info->sb, &location, root, NULL);
  84        if (IS_ERR(inode))
  85                return inode;
  86        if (is_bad_inode(inode)) {
  87                iput(inode);
  88                return ERR_PTR(-ENOENT);
  89        }
  90
  91        mapping_set_gfp_mask(inode->i_mapping,
  92                        mapping_gfp_constraint(inode->i_mapping,
  93                        ~(__GFP_FS | __GFP_HIGHMEM)));
  94
  95        return inode;
  96}
  97
  98struct inode *lookup_free_space_inode(struct btrfs_fs_info *fs_info,
  99                                      struct btrfs_block_group_cache
 100                                      *block_group, struct btrfs_path *path)
 101{
 102        struct inode *inode = NULL;
 103        u32 flags = BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
 104
 105        spin_lock(&block_group->lock);
 106        if (block_group->inode)
 107                inode = igrab(block_group->inode);
 108        spin_unlock(&block_group->lock);
 109        if (inode)
 110                return inode;
 111
 112        inode = __lookup_free_space_inode(fs_info->tree_root, path,
 113                                          block_group->key.objectid);
 114        if (IS_ERR(inode))
 115                return inode;
 116
 117        spin_lock(&block_group->lock);
 118        if (!((BTRFS_I(inode)->flags & flags) == flags)) {
 119                btrfs_info(fs_info, "Old style space inode found, converting.");
 120                BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM |
 121                        BTRFS_INODE_NODATACOW;
 122                block_group->disk_cache_state = BTRFS_DC_CLEAR;
 123        }
 124
 125        if (!block_group->iref) {
 126                block_group->inode = igrab(inode);
 127                block_group->iref = 1;
 128        }
 129        spin_unlock(&block_group->lock);
 130
 131        return inode;
 132}
 133
 134static int __create_free_space_inode(struct btrfs_root *root,
 135                                     struct btrfs_trans_handle *trans,
 136                                     struct btrfs_path *path,
 137                                     u64 ino, u64 offset)
 138{
 139        struct btrfs_key key;
 140        struct btrfs_disk_key disk_key;
 141        struct btrfs_free_space_header *header;
 142        struct btrfs_inode_item *inode_item;
 143        struct extent_buffer *leaf;
 144        u64 flags = BTRFS_INODE_NOCOMPRESS | BTRFS_INODE_PREALLOC;
 145        int ret;
 146
 147        ret = btrfs_insert_empty_inode(trans, root, path, ino);
 148        if (ret)
 149                return ret;
 150
 151        /* We inline crc's for the free disk space cache */
 152        if (ino != BTRFS_FREE_INO_OBJECTID)
 153                flags |= BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
 154
 155        leaf = path->nodes[0];
 156        inode_item = btrfs_item_ptr(leaf, path->slots[0],
 157                                    struct btrfs_inode_item);
 158        btrfs_item_key(leaf, &disk_key, path->slots[0]);
 159        memzero_extent_buffer(leaf, (unsigned long)inode_item,
 160                             sizeof(*inode_item));
 161        btrfs_set_inode_generation(leaf, inode_item, trans->transid);
 162        btrfs_set_inode_size(leaf, inode_item, 0);
 163        btrfs_set_inode_nbytes(leaf, inode_item, 0);
 164        btrfs_set_inode_uid(leaf, inode_item, 0);
 165        btrfs_set_inode_gid(leaf, inode_item, 0);
 166        btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
 167        btrfs_set_inode_flags(leaf, inode_item, flags);
 168        btrfs_set_inode_nlink(leaf, inode_item, 1);
 169        btrfs_set_inode_transid(leaf, inode_item, trans->transid);
 170        btrfs_set_inode_block_group(leaf, inode_item, offset);
 171        btrfs_mark_buffer_dirty(leaf);
 172        btrfs_release_path(path);
 173
 174        key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 175        key.offset = offset;
 176        key.type = 0;
 177        ret = btrfs_insert_empty_item(trans, root, path, &key,
 178                                      sizeof(struct btrfs_free_space_header));
 179        if (ret < 0) {
 180                btrfs_release_path(path);
 181                return ret;
 182        }
 183
 184        leaf = path->nodes[0];
 185        header = btrfs_item_ptr(leaf, path->slots[0],
 186                                struct btrfs_free_space_header);
 187        memzero_extent_buffer(leaf, (unsigned long)header, sizeof(*header));
 188        btrfs_set_free_space_key(leaf, header, &disk_key);
 189        btrfs_mark_buffer_dirty(leaf);
 190        btrfs_release_path(path);
 191
 192        return 0;
 193}
 194
 195int create_free_space_inode(struct btrfs_fs_info *fs_info,
 196                            struct btrfs_trans_handle *trans,
 197                            struct btrfs_block_group_cache *block_group,
 198                            struct btrfs_path *path)
 199{
 200        int ret;
 201        u64 ino;
 202
 203        ret = btrfs_find_free_objectid(fs_info->tree_root, &ino);
 204        if (ret < 0)
 205                return ret;
 206
 207        return __create_free_space_inode(fs_info->tree_root, trans, path, ino,
 208                                         block_group->key.objectid);
 209}
 210
 211int btrfs_check_trunc_cache_free_space(struct btrfs_fs_info *fs_info,
 212                                       struct btrfs_block_rsv *rsv)
 213{
 214        u64 needed_bytes;
 215        int ret;
 216
 217        /* 1 for slack space, 1 for updating the inode */
 218        needed_bytes = btrfs_calc_trunc_metadata_size(fs_info, 1) +
 219                btrfs_calc_trans_metadata_size(fs_info, 1);
 220
 221        spin_lock(&rsv->lock);
 222        if (rsv->reserved < needed_bytes)
 223                ret = -ENOSPC;
 224        else
 225                ret = 0;
 226        spin_unlock(&rsv->lock);
 227        return ret;
 228}
 229
 230int btrfs_truncate_free_space_cache(struct btrfs_trans_handle *trans,
 231                                    struct btrfs_block_group_cache *block_group,
 232                                    struct inode *inode)
 233{
 234        struct btrfs_root *root = BTRFS_I(inode)->root;
 235        int ret = 0;
 236        bool locked = false;
 237
 238        if (block_group) {
 239                struct btrfs_path *path = btrfs_alloc_path();
 240
 241                if (!path) {
 242                        ret = -ENOMEM;
 243                        goto fail;
 244                }
 245                locked = true;
 246                mutex_lock(&trans->transaction->cache_write_mutex);
 247                if (!list_empty(&block_group->io_list)) {
 248                        list_del_init(&block_group->io_list);
 249
 250                        btrfs_wait_cache_io(trans, block_group, path);
 251                        btrfs_put_block_group(block_group);
 252                }
 253
 254                /*
 255                 * now that we've truncated the cache away, its no longer
 256                 * setup or written
 257                 */
 258                spin_lock(&block_group->lock);
 259                block_group->disk_cache_state = BTRFS_DC_CLEAR;
 260                spin_unlock(&block_group->lock);
 261                btrfs_free_path(path);
 262        }
 263
 264        btrfs_i_size_write(BTRFS_I(inode), 0);
 265        truncate_pagecache(inode, 0);
 266
 267        /*
 268         * We don't need an orphan item because truncating the free space cache
 269         * will never be split across transactions.
 270         * We don't need to check for -EAGAIN because we're a free space
 271         * cache inode
 272         */
 273        ret = btrfs_truncate_inode_items(trans, root, inode,
 274                                         0, BTRFS_EXTENT_DATA_KEY);
 275        if (ret)
 276                goto fail;
 277
 278        ret = btrfs_update_inode(trans, root, inode);
 279
 280fail:
 281        if (locked)
 282                mutex_unlock(&trans->transaction->cache_write_mutex);
 283        if (ret)
 284                btrfs_abort_transaction(trans, ret);
 285
 286        return ret;
 287}
 288
 289static void readahead_cache(struct inode *inode)
 290{
 291        struct file_ra_state *ra;
 292        unsigned long last_index;
 293
 294        ra = kzalloc(sizeof(*ra), GFP_NOFS);
 295        if (!ra)
 296                return;
 297
 298        file_ra_state_init(ra, inode->i_mapping);
 299        last_index = (i_size_read(inode) - 1) >> PAGE_SHIFT;
 300
 301        page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
 302
 303        kfree(ra);
 304}
 305
 306static int io_ctl_init(struct btrfs_io_ctl *io_ctl, struct inode *inode,
 307                       int write)
 308{
 309        int num_pages;
 310        int check_crcs = 0;
 311
 312        num_pages = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
 313
 314        if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FREE_INO_OBJECTID)
 315                check_crcs = 1;
 316
 317        /* Make sure we can fit our crcs into the first page */
 318        if (write && check_crcs &&
 319            (num_pages * sizeof(u32)) >= PAGE_SIZE)
 320                return -ENOSPC;
 321
 322        memset(io_ctl, 0, sizeof(struct btrfs_io_ctl));
 323
 324        io_ctl->pages = kcalloc(num_pages, sizeof(struct page *), GFP_NOFS);
 325        if (!io_ctl->pages)
 326                return -ENOMEM;
 327
 328        io_ctl->num_pages = num_pages;
 329        io_ctl->fs_info = btrfs_sb(inode->i_sb);
 330        io_ctl->check_crcs = check_crcs;
 331        io_ctl->inode = inode;
 332
 333        return 0;
 334}
 335
 336static void io_ctl_free(struct btrfs_io_ctl *io_ctl)
 337{
 338        kfree(io_ctl->pages);
 339        io_ctl->pages = NULL;
 340}
 341
 342static void io_ctl_unmap_page(struct btrfs_io_ctl *io_ctl)
 343{
 344        if (io_ctl->cur) {
 345                io_ctl->cur = NULL;
 346                io_ctl->orig = NULL;
 347        }
 348}
 349
 350static void io_ctl_map_page(struct btrfs_io_ctl *io_ctl, int clear)
 351{
 352        ASSERT(io_ctl->index < io_ctl->num_pages);
 353        io_ctl->page = io_ctl->pages[io_ctl->index++];
 354        io_ctl->cur = page_address(io_ctl->page);
 355        io_ctl->orig = io_ctl->cur;
 356        io_ctl->size = PAGE_SIZE;
 357        if (clear)
 358                clear_page(io_ctl->cur);
 359}
 360
 361static void io_ctl_drop_pages(struct btrfs_io_ctl *io_ctl)
 362{
 363        int i;
 364
 365        io_ctl_unmap_page(io_ctl);
 366
 367        for (i = 0; i < io_ctl->num_pages; i++) {
 368                if (io_ctl->pages[i]) {
 369                        ClearPageChecked(io_ctl->pages[i]);
 370                        unlock_page(io_ctl->pages[i]);
 371                        put_page(io_ctl->pages[i]);
 372                }
 373        }
 374}
 375
 376static int io_ctl_prepare_pages(struct btrfs_io_ctl *io_ctl, struct inode *inode,
 377                                int uptodate)
 378{
 379        struct page *page;
 380        gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
 381        int i;
 382
 383        for (i = 0; i < io_ctl->num_pages; i++) {
 384                page = find_or_create_page(inode->i_mapping, i, mask);
 385                if (!page) {
 386                        io_ctl_drop_pages(io_ctl);
 387                        return -ENOMEM;
 388                }
 389                io_ctl->pages[i] = page;
 390                if (uptodate && !PageUptodate(page)) {
 391                        btrfs_readpage(NULL, page);
 392                        lock_page(page);
 393                        if (!PageUptodate(page)) {
 394                                btrfs_err(BTRFS_I(inode)->root->fs_info,
 395                                           "error reading free space cache");
 396                                io_ctl_drop_pages(io_ctl);
 397                                return -EIO;
 398                        }
 399                }
 400        }
 401
 402        for (i = 0; i < io_ctl->num_pages; i++) {
 403                clear_page_dirty_for_io(io_ctl->pages[i]);
 404                set_page_extent_mapped(io_ctl->pages[i]);
 405        }
 406
 407        return 0;
 408}
 409
 410static void io_ctl_set_generation(struct btrfs_io_ctl *io_ctl, u64 generation)
 411{
 412        __le64 *val;
 413
 414        io_ctl_map_page(io_ctl, 1);
 415
 416        /*
 417         * Skip the csum areas.  If we don't check crcs then we just have a
 418         * 64bit chunk at the front of the first page.
 419         */
 420        if (io_ctl->check_crcs) {
 421                io_ctl->cur += (sizeof(u32) * io_ctl->num_pages);
 422                io_ctl->size -= sizeof(u64) + (sizeof(u32) * io_ctl->num_pages);
 423        } else {
 424                io_ctl->cur += sizeof(u64);
 425                io_ctl->size -= sizeof(u64) * 2;
 426        }
 427
 428        val = io_ctl->cur;
 429        *val = cpu_to_le64(generation);
 430        io_ctl->cur += sizeof(u64);
 431}
 432
 433static int io_ctl_check_generation(struct btrfs_io_ctl *io_ctl, u64 generation)
 434{
 435        __le64 *gen;
 436
 437        /*
 438         * Skip the crc area.  If we don't check crcs then we just have a 64bit
 439         * chunk at the front of the first page.
 440         */
 441        if (io_ctl->check_crcs) {
 442                io_ctl->cur += sizeof(u32) * io_ctl->num_pages;
 443                io_ctl->size -= sizeof(u64) +
 444                        (sizeof(u32) * io_ctl->num_pages);
 445        } else {
 446                io_ctl->cur += sizeof(u64);
 447                io_ctl->size -= sizeof(u64) * 2;
 448        }
 449
 450        gen = io_ctl->cur;
 451        if (le64_to_cpu(*gen) != generation) {
 452                btrfs_err_rl(io_ctl->fs_info,
 453                        "space cache generation (%llu) does not match inode (%llu)",
 454                                *gen, generation);
 455                io_ctl_unmap_page(io_ctl);
 456                return -EIO;
 457        }
 458        io_ctl->cur += sizeof(u64);
 459        return 0;
 460}
 461
 462static void io_ctl_set_crc(struct btrfs_io_ctl *io_ctl, int index)
 463{
 464        u32 *tmp;
 465        u32 crc = ~(u32)0;
 466        unsigned offset = 0;
 467
 468        if (!io_ctl->check_crcs) {
 469                io_ctl_unmap_page(io_ctl);
 470                return;
 471        }
 472
 473        if (index == 0)
 474                offset = sizeof(u32) * io_ctl->num_pages;
 475
 476        crc = btrfs_csum_data(io_ctl->orig + offset, crc,
 477                              PAGE_SIZE - offset);
 478        btrfs_csum_final(crc, (u8 *)&crc);
 479        io_ctl_unmap_page(io_ctl);
 480        tmp = page_address(io_ctl->pages[0]);
 481        tmp += index;
 482        *tmp = crc;
 483}
 484
 485static int io_ctl_check_crc(struct btrfs_io_ctl *io_ctl, int index)
 486{
 487        u32 *tmp, val;
 488        u32 crc = ~(u32)0;
 489        unsigned offset = 0;
 490
 491        if (!io_ctl->check_crcs) {
 492                io_ctl_map_page(io_ctl, 0);
 493                return 0;
 494        }
 495
 496        if (index == 0)
 497                offset = sizeof(u32) * io_ctl->num_pages;
 498
 499        tmp = page_address(io_ctl->pages[0]);
 500        tmp += index;
 501        val = *tmp;
 502
 503        io_ctl_map_page(io_ctl, 0);
 504        crc = btrfs_csum_data(io_ctl->orig + offset, crc,
 505                              PAGE_SIZE - offset);
 506        btrfs_csum_final(crc, (u8 *)&crc);
 507        if (val != crc) {
 508                btrfs_err_rl(io_ctl->fs_info,
 509                        "csum mismatch on free space cache");
 510                io_ctl_unmap_page(io_ctl);
 511                return -EIO;
 512        }
 513
 514        return 0;
 515}
 516
 517static int io_ctl_add_entry(struct btrfs_io_ctl *io_ctl, u64 offset, u64 bytes,
 518                            void *bitmap)
 519{
 520        struct btrfs_free_space_entry *entry;
 521
 522        if (!io_ctl->cur)
 523                return -ENOSPC;
 524
 525        entry = io_ctl->cur;
 526        entry->offset = cpu_to_le64(offset);
 527        entry->bytes = cpu_to_le64(bytes);
 528        entry->type = (bitmap) ? BTRFS_FREE_SPACE_BITMAP :
 529                BTRFS_FREE_SPACE_EXTENT;
 530        io_ctl->cur += sizeof(struct btrfs_free_space_entry);
 531        io_ctl->size -= sizeof(struct btrfs_free_space_entry);
 532
 533        if (io_ctl->size >= sizeof(struct btrfs_free_space_entry))
 534                return 0;
 535
 536        io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 537
 538        /* No more pages to map */
 539        if (io_ctl->index >= io_ctl->num_pages)
 540                return 0;
 541
 542        /* map the next page */
 543        io_ctl_map_page(io_ctl, 1);
 544        return 0;
 545}
 546
 547static int io_ctl_add_bitmap(struct btrfs_io_ctl *io_ctl, void *bitmap)
 548{
 549        if (!io_ctl->cur)
 550                return -ENOSPC;
 551
 552        /*
 553         * If we aren't at the start of the current page, unmap this one and
 554         * map the next one if there is any left.
 555         */
 556        if (io_ctl->cur != io_ctl->orig) {
 557                io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 558                if (io_ctl->index >= io_ctl->num_pages)
 559                        return -ENOSPC;
 560                io_ctl_map_page(io_ctl, 0);
 561        }
 562
 563        memcpy(io_ctl->cur, bitmap, PAGE_SIZE);
 564        io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 565        if (io_ctl->index < io_ctl->num_pages)
 566                io_ctl_map_page(io_ctl, 0);
 567        return 0;
 568}
 569
 570static void io_ctl_zero_remaining_pages(struct btrfs_io_ctl *io_ctl)
 571{
 572        /*
 573         * If we're not on the boundary we know we've modified the page and we
 574         * need to crc the page.
 575         */
 576        if (io_ctl->cur != io_ctl->orig)
 577                io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 578        else
 579                io_ctl_unmap_page(io_ctl);
 580
 581        while (io_ctl->index < io_ctl->num_pages) {
 582                io_ctl_map_page(io_ctl, 1);
 583                io_ctl_set_crc(io_ctl, io_ctl->index - 1);
 584        }
 585}
 586
 587static int io_ctl_read_entry(struct btrfs_io_ctl *io_ctl,
 588                            struct btrfs_free_space *entry, u8 *type)
 589{
 590        struct btrfs_free_space_entry *e;
 591        int ret;
 592
 593        if (!io_ctl->cur) {
 594                ret = io_ctl_check_crc(io_ctl, io_ctl->index);
 595                if (ret)
 596                        return ret;
 597        }
 598
 599        e = io_ctl->cur;
 600        entry->offset = le64_to_cpu(e->offset);
 601        entry->bytes = le64_to_cpu(e->bytes);
 602        *type = e->type;
 603        io_ctl->cur += sizeof(struct btrfs_free_space_entry);
 604        io_ctl->size -= sizeof(struct btrfs_free_space_entry);
 605
 606        if (io_ctl->size >= sizeof(struct btrfs_free_space_entry))
 607                return 0;
 608
 609        io_ctl_unmap_page(io_ctl);
 610
 611        return 0;
 612}
 613
 614static int io_ctl_read_bitmap(struct btrfs_io_ctl *io_ctl,
 615                              struct btrfs_free_space *entry)
 616{
 617        int ret;
 618
 619        ret = io_ctl_check_crc(io_ctl, io_ctl->index);
 620        if (ret)
 621                return ret;
 622
 623        memcpy(entry->bitmap, io_ctl->cur, PAGE_SIZE);
 624        io_ctl_unmap_page(io_ctl);
 625
 626        return 0;
 627}
 628
 629/*
 630 * Since we attach pinned extents after the fact we can have contiguous sections
 631 * of free space that are split up in entries.  This poses a problem with the
 632 * tree logging stuff since it could have allocated across what appears to be 2
 633 * entries since we would have merged the entries when adding the pinned extents
 634 * back to the free space cache.  So run through the space cache that we just
 635 * loaded and merge contiguous entries.  This will make the log replay stuff not
 636 * blow up and it will make for nicer allocator behavior.
 637 */
 638static void merge_space_tree(struct btrfs_free_space_ctl *ctl)
 639{
 640        struct btrfs_free_space *e, *prev = NULL;
 641        struct rb_node *n;
 642
 643again:
 644        spin_lock(&ctl->tree_lock);
 645        for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
 646                e = rb_entry(n, struct btrfs_free_space, offset_index);
 647                if (!prev)
 648                        goto next;
 649                if (e->bitmap || prev->bitmap)
 650                        goto next;
 651                if (prev->offset + prev->bytes == e->offset) {
 652                        unlink_free_space(ctl, prev);
 653                        unlink_free_space(ctl, e);
 654                        prev->bytes += e->bytes;
 655                        kmem_cache_free(btrfs_free_space_cachep, e);
 656                        link_free_space(ctl, prev);
 657                        prev = NULL;
 658                        spin_unlock(&ctl->tree_lock);
 659                        goto again;
 660                }
 661next:
 662                prev = e;
 663        }
 664        spin_unlock(&ctl->tree_lock);
 665}
 666
 667static int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
 668                                   struct btrfs_free_space_ctl *ctl,
 669                                   struct btrfs_path *path, u64 offset)
 670{
 671        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 672        struct btrfs_free_space_header *header;
 673        struct extent_buffer *leaf;
 674        struct btrfs_io_ctl io_ctl;
 675        struct btrfs_key key;
 676        struct btrfs_free_space *e, *n;
 677        LIST_HEAD(bitmaps);
 678        u64 num_entries;
 679        u64 num_bitmaps;
 680        u64 generation;
 681        u8 type;
 682        int ret = 0;
 683
 684        /* Nothing in the space cache, goodbye */
 685        if (!i_size_read(inode))
 686                return 0;
 687
 688        key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 689        key.offset = offset;
 690        key.type = 0;
 691
 692        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 693        if (ret < 0)
 694                return 0;
 695        else if (ret > 0) {
 696                btrfs_release_path(path);
 697                return 0;
 698        }
 699
 700        ret = -1;
 701
 702        leaf = path->nodes[0];
 703        header = btrfs_item_ptr(leaf, path->slots[0],
 704                                struct btrfs_free_space_header);
 705        num_entries = btrfs_free_space_entries(leaf, header);
 706        num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
 707        generation = btrfs_free_space_generation(leaf, header);
 708        btrfs_release_path(path);
 709
 710        if (!BTRFS_I(inode)->generation) {
 711                btrfs_info(fs_info,
 712                           "the free space cache file (%llu) is invalid, skip it",
 713                           offset);
 714                return 0;
 715        }
 716
 717        if (BTRFS_I(inode)->generation != generation) {
 718                btrfs_err(fs_info,
 719                          "free space inode generation (%llu) did not match free space cache generation (%llu)",
 720                          BTRFS_I(inode)->generation, generation);
 721                return 0;
 722        }
 723
 724        if (!num_entries)
 725                return 0;
 726
 727        ret = io_ctl_init(&io_ctl, inode, 0);
 728        if (ret)
 729                return ret;
 730
 731        readahead_cache(inode);
 732
 733        ret = io_ctl_prepare_pages(&io_ctl, inode, 1);
 734        if (ret)
 735                goto out;
 736
 737        ret = io_ctl_check_crc(&io_ctl, 0);
 738        if (ret)
 739                goto free_cache;
 740
 741        ret = io_ctl_check_generation(&io_ctl, generation);
 742        if (ret)
 743                goto free_cache;
 744
 745        while (num_entries) {
 746                e = kmem_cache_zalloc(btrfs_free_space_cachep,
 747                                      GFP_NOFS);
 748                if (!e)
 749                        goto free_cache;
 750
 751                ret = io_ctl_read_entry(&io_ctl, e, &type);
 752                if (ret) {
 753                        kmem_cache_free(btrfs_free_space_cachep, e);
 754                        goto free_cache;
 755                }
 756
 757                if (!e->bytes) {
 758                        kmem_cache_free(btrfs_free_space_cachep, e);
 759                        goto free_cache;
 760                }
 761
 762                if (type == BTRFS_FREE_SPACE_EXTENT) {
 763                        spin_lock(&ctl->tree_lock);
 764                        ret = link_free_space(ctl, e);
 765                        spin_unlock(&ctl->tree_lock);
 766                        if (ret) {
 767                                btrfs_err(fs_info,
 768                                        "Duplicate entries in free space cache, dumping");
 769                                kmem_cache_free(btrfs_free_space_cachep, e);
 770                                goto free_cache;
 771                        }
 772                } else {
 773                        ASSERT(num_bitmaps);
 774                        num_bitmaps--;
 775                        e->bitmap = kzalloc(PAGE_SIZE, GFP_NOFS);
 776                        if (!e->bitmap) {
 777                                kmem_cache_free(
 778                                        btrfs_free_space_cachep, e);
 779                                goto free_cache;
 780                        }
 781                        spin_lock(&ctl->tree_lock);
 782                        ret = link_free_space(ctl, e);
 783                        ctl->total_bitmaps++;
 784                        ctl->op->recalc_thresholds(ctl);
 785                        spin_unlock(&ctl->tree_lock);
 786                        if (ret) {
 787                                btrfs_err(fs_info,
 788                                        "Duplicate entries in free space cache, dumping");
 789                                kmem_cache_free(btrfs_free_space_cachep, e);
 790                                goto free_cache;
 791                        }
 792                        list_add_tail(&e->list, &bitmaps);
 793                }
 794
 795                num_entries--;
 796        }
 797
 798        io_ctl_unmap_page(&io_ctl);
 799
 800        /*
 801         * We add the bitmaps at the end of the entries in order that
 802         * the bitmap entries are added to the cache.
 803         */
 804        list_for_each_entry_safe(e, n, &bitmaps, list) {
 805                list_del_init(&e->list);
 806                ret = io_ctl_read_bitmap(&io_ctl, e);
 807                if (ret)
 808                        goto free_cache;
 809        }
 810
 811        io_ctl_drop_pages(&io_ctl);
 812        merge_space_tree(ctl);
 813        ret = 1;
 814out:
 815        io_ctl_free(&io_ctl);
 816        return ret;
 817free_cache:
 818        io_ctl_drop_pages(&io_ctl);
 819        __btrfs_remove_free_space_cache(ctl);
 820        goto out;
 821}
 822
 823int load_free_space_cache(struct btrfs_fs_info *fs_info,
 824                          struct btrfs_block_group_cache *block_group)
 825{
 826        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 827        struct inode *inode;
 828        struct btrfs_path *path;
 829        int ret = 0;
 830        bool matched;
 831        u64 used = btrfs_block_group_used(&block_group->item);
 832
 833        /*
 834         * If this block group has been marked to be cleared for one reason or
 835         * another then we can't trust the on disk cache, so just return.
 836         */
 837        spin_lock(&block_group->lock);
 838        if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 839                spin_unlock(&block_group->lock);
 840                return 0;
 841        }
 842        spin_unlock(&block_group->lock);
 843
 844        path = btrfs_alloc_path();
 845        if (!path)
 846                return 0;
 847        path->search_commit_root = 1;
 848        path->skip_locking = 1;
 849
 850        inode = lookup_free_space_inode(fs_info, block_group, path);
 851        if (IS_ERR(inode)) {
 852                btrfs_free_path(path);
 853                return 0;
 854        }
 855
 856        /* We may have converted the inode and made the cache invalid. */
 857        spin_lock(&block_group->lock);
 858        if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
 859                spin_unlock(&block_group->lock);
 860                btrfs_free_path(path);
 861                goto out;
 862        }
 863        spin_unlock(&block_group->lock);
 864
 865        ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
 866                                      path, block_group->key.objectid);
 867        btrfs_free_path(path);
 868        if (ret <= 0)
 869                goto out;
 870
 871        spin_lock(&ctl->tree_lock);
 872        matched = (ctl->free_space == (block_group->key.offset - used -
 873                                       block_group->bytes_super));
 874        spin_unlock(&ctl->tree_lock);
 875
 876        if (!matched) {
 877                __btrfs_remove_free_space_cache(ctl);
 878                btrfs_warn(fs_info,
 879                           "block group %llu has wrong amount of free space",
 880                           block_group->key.objectid);
 881                ret = -1;
 882        }
 883out:
 884        if (ret < 0) {
 885                /* This cache is bogus, make sure it gets cleared */
 886                spin_lock(&block_group->lock);
 887                block_group->disk_cache_state = BTRFS_DC_CLEAR;
 888                spin_unlock(&block_group->lock);
 889                ret = 0;
 890
 891                btrfs_warn(fs_info,
 892                           "failed to load free space cache for block group %llu, rebuilding it now",
 893                           block_group->key.objectid);
 894        }
 895
 896        iput(inode);
 897        return ret;
 898}
 899
 900static noinline_for_stack
 901int write_cache_extent_entries(struct btrfs_io_ctl *io_ctl,
 902                              struct btrfs_free_space_ctl *ctl,
 903                              struct btrfs_block_group_cache *block_group,
 904                              int *entries, int *bitmaps,
 905                              struct list_head *bitmap_list)
 906{
 907        int ret;
 908        struct btrfs_free_cluster *cluster = NULL;
 909        struct btrfs_free_cluster *cluster_locked = NULL;
 910        struct rb_node *node = rb_first(&ctl->free_space_offset);
 911        struct btrfs_trim_range *trim_entry;
 912
 913        /* Get the cluster for this block_group if it exists */
 914        if (block_group && !list_empty(&block_group->cluster_list)) {
 915                cluster = list_entry(block_group->cluster_list.next,
 916                                     struct btrfs_free_cluster,
 917                                     block_group_list);
 918        }
 919
 920        if (!node && cluster) {
 921                cluster_locked = cluster;
 922                spin_lock(&cluster_locked->lock);
 923                node = rb_first(&cluster->root);
 924                cluster = NULL;
 925        }
 926
 927        /* Write out the extent entries */
 928        while (node) {
 929                struct btrfs_free_space *e;
 930
 931                e = rb_entry(node, struct btrfs_free_space, offset_index);
 932                *entries += 1;
 933
 934                ret = io_ctl_add_entry(io_ctl, e->offset, e->bytes,
 935                                       e->bitmap);
 936                if (ret)
 937                        goto fail;
 938
 939                if (e->bitmap) {
 940                        list_add_tail(&e->list, bitmap_list);
 941                        *bitmaps += 1;
 942                }
 943                node = rb_next(node);
 944                if (!node && cluster) {
 945                        node = rb_first(&cluster->root);
 946                        cluster_locked = cluster;
 947                        spin_lock(&cluster_locked->lock);
 948                        cluster = NULL;
 949                }
 950        }
 951        if (cluster_locked) {
 952                spin_unlock(&cluster_locked->lock);
 953                cluster_locked = NULL;
 954        }
 955
 956        /*
 957         * Make sure we don't miss any range that was removed from our rbtree
 958         * because trimming is running. Otherwise after a umount+mount (or crash
 959         * after committing the transaction) we would leak free space and get
 960         * an inconsistent free space cache report from fsck.
 961         */
 962        list_for_each_entry(trim_entry, &ctl->trimming_ranges, list) {
 963                ret = io_ctl_add_entry(io_ctl, trim_entry->start,
 964                                       trim_entry->bytes, NULL);
 965                if (ret)
 966                        goto fail;
 967                *entries += 1;
 968        }
 969
 970        return 0;
 971fail:
 972        if (cluster_locked)
 973                spin_unlock(&cluster_locked->lock);
 974        return -ENOSPC;
 975}
 976
 977static noinline_for_stack int
 978update_cache_item(struct btrfs_trans_handle *trans,
 979                  struct btrfs_root *root,
 980                  struct inode *inode,
 981                  struct btrfs_path *path, u64 offset,
 982                  int entries, int bitmaps)
 983{
 984        struct btrfs_key key;
 985        struct btrfs_free_space_header *header;
 986        struct extent_buffer *leaf;
 987        int ret;
 988
 989        key.objectid = BTRFS_FREE_SPACE_OBJECTID;
 990        key.offset = offset;
 991        key.type = 0;
 992
 993        ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
 994        if (ret < 0) {
 995                clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
 996                                 EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL,
 997                                 GFP_NOFS);
 998                goto fail;
 999        }
1000        leaf = path->nodes[0];
1001        if (ret > 0) {
1002                struct btrfs_key found_key;
1003                ASSERT(path->slots[0]);
1004                path->slots[0]--;
1005                btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1006                if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
1007                    found_key.offset != offset) {
1008                        clear_extent_bit(&BTRFS_I(inode)->io_tree, 0,
1009                                         inode->i_size - 1,
1010                                         EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0,
1011                                         NULL, GFP_NOFS);
1012                        btrfs_release_path(path);
1013                        goto fail;
1014                }
1015        }
1016
1017        BTRFS_I(inode)->generation = trans->transid;
1018        header = btrfs_item_ptr(leaf, path->slots[0],
1019                                struct btrfs_free_space_header);
1020        btrfs_set_free_space_entries(leaf, header, entries);
1021        btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
1022        btrfs_set_free_space_generation(leaf, header, trans->transid);
1023        btrfs_mark_buffer_dirty(leaf);
1024        btrfs_release_path(path);
1025
1026        return 0;
1027
1028fail:
1029        return -1;
1030}
1031
1032static noinline_for_stack int
1033write_pinned_extent_entries(struct btrfs_fs_info *fs_info,
1034                            struct btrfs_block_group_cache *block_group,
1035                            struct btrfs_io_ctl *io_ctl,
1036                            int *entries)
1037{
1038        u64 start, extent_start, extent_end, len;
1039        struct extent_io_tree *unpin = NULL;
1040        int ret;
1041
1042        if (!block_group)
1043                return 0;
1044
1045        /*
1046         * We want to add any pinned extents to our free space cache
1047         * so we don't leak the space
1048         *
1049         * We shouldn't have switched the pinned extents yet so this is the
1050         * right one
1051         */
1052        unpin = fs_info->pinned_extents;
1053
1054        start = block_group->key.objectid;
1055
1056        while (start < block_group->key.objectid + block_group->key.offset) {
1057                ret = find_first_extent_bit(unpin, start,
1058                                            &extent_start, &extent_end,
1059                                            EXTENT_DIRTY, NULL);
1060                if (ret)
1061                        return 0;
1062
1063                /* This pinned extent is out of our range */
1064                if (extent_start >= block_group->key.objectid +
1065                    block_group->key.offset)
1066                        return 0;
1067
1068                extent_start = max(extent_start, start);
1069                extent_end = min(block_group->key.objectid +
1070                                 block_group->key.offset, extent_end + 1);
1071                len = extent_end - extent_start;
1072
1073                *entries += 1;
1074                ret = io_ctl_add_entry(io_ctl, extent_start, len, NULL);
1075                if (ret)
1076                        return -ENOSPC;
1077
1078                start = extent_end;
1079        }
1080
1081        return 0;
1082}
1083
1084static noinline_for_stack int
1085write_bitmap_entries(struct btrfs_io_ctl *io_ctl, struct list_head *bitmap_list)
1086{
1087        struct btrfs_free_space *entry, *next;
1088        int ret;
1089
1090        /* Write out the bitmaps */
1091        list_for_each_entry_safe(entry, next, bitmap_list, list) {
1092                ret = io_ctl_add_bitmap(io_ctl, entry->bitmap);
1093                if (ret)
1094                        return -ENOSPC;
1095                list_del_init(&entry->list);
1096        }
1097
1098        return 0;
1099}
1100
1101static int flush_dirty_cache(struct inode *inode)
1102{
1103        int ret;
1104
1105        ret = btrfs_wait_ordered_range(inode, 0, (u64)-1);
1106        if (ret)
1107                clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
1108                                 EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL,
1109                                 GFP_NOFS);
1110
1111        return ret;
1112}
1113
1114static void noinline_for_stack
1115cleanup_bitmap_list(struct list_head *bitmap_list)
1116{
1117        struct btrfs_free_space *entry, *next;
1118
1119        list_for_each_entry_safe(entry, next, bitmap_list, list)
1120                list_del_init(&entry->list);
1121}
1122
1123static void noinline_for_stack
1124cleanup_write_cache_enospc(struct inode *inode,
1125                           struct btrfs_io_ctl *io_ctl,
1126                           struct extent_state **cached_state)
1127{
1128        io_ctl_drop_pages(io_ctl);
1129        unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
1130                             i_size_read(inode) - 1, cached_state,
1131                             GFP_NOFS);
1132}
1133
1134static int __btrfs_wait_cache_io(struct btrfs_root *root,
1135                                 struct btrfs_trans_handle *trans,
1136                                 struct btrfs_block_group_cache *block_group,
1137                                 struct btrfs_io_ctl *io_ctl,
1138                                 struct btrfs_path *path, u64 offset)
1139{
1140        int ret;
1141        struct inode *inode = io_ctl->inode;
1142        struct btrfs_fs_info *fs_info;
1143
1144        if (!inode)
1145                return 0;
1146
1147        fs_info = btrfs_sb(inode->i_sb);
1148
1149        /* Flush the dirty pages in the cache file. */
1150        ret = flush_dirty_cache(inode);
1151        if (ret)
1152                goto out;
1153
1154        /* Update the cache item to tell everyone this cache file is valid. */
1155        ret = update_cache_item(trans, root, inode, path, offset,
1156                                io_ctl->entries, io_ctl->bitmaps);
1157out:
1158        io_ctl_free(io_ctl);
1159        if (ret) {
1160                invalidate_inode_pages2(inode->i_mapping);
1161                BTRFS_I(inode)->generation = 0;
1162                if (block_group) {
1163#ifdef DEBUG
1164                        btrfs_err(fs_info,
1165                                  "failed to write free space cache for block group %llu",
1166                                  block_group->key.objectid);
1167#endif
1168                }
1169        }
1170        btrfs_update_inode(trans, root, inode);
1171
1172        if (block_group) {
1173                /* the dirty list is protected by the dirty_bgs_lock */
1174                spin_lock(&trans->transaction->dirty_bgs_lock);
1175
1176                /* the disk_cache_state is protected by the block group lock */
1177                spin_lock(&block_group->lock);
1178
1179                /*
1180                 * only mark this as written if we didn't get put back on
1181                 * the dirty list while waiting for IO.   Otherwise our
1182                 * cache state won't be right, and we won't get written again
1183                 */
1184                if (!ret && list_empty(&block_group->dirty_list))
1185                        block_group->disk_cache_state = BTRFS_DC_WRITTEN;
1186                else if (ret)
1187                        block_group->disk_cache_state = BTRFS_DC_ERROR;
1188
1189                spin_unlock(&block_group->lock);
1190                spin_unlock(&trans->transaction->dirty_bgs_lock);
1191                io_ctl->inode = NULL;
1192                iput(inode);
1193        }
1194
1195        return ret;
1196
1197}
1198
1199static int btrfs_wait_cache_io_root(struct btrfs_root *root,
1200                                    struct btrfs_trans_handle *trans,
1201                                    struct btrfs_io_ctl *io_ctl,
1202                                    struct btrfs_path *path)
1203{
1204        return __btrfs_wait_cache_io(root, trans, NULL, io_ctl, path, 0);
1205}
1206
1207int btrfs_wait_cache_io(struct btrfs_trans_handle *trans,
1208                        struct btrfs_block_group_cache *block_group,
1209                        struct btrfs_path *path)
1210{
1211        return __btrfs_wait_cache_io(block_group->fs_info->tree_root, trans,
1212                                     block_group, &block_group->io_ctl,
1213                                     path, block_group->key.objectid);
1214}
1215
1216/**
1217 * __btrfs_write_out_cache - write out cached info to an inode
1218 * @root - the root the inode belongs to
1219 * @ctl - the free space cache we are going to write out
1220 * @block_group - the block_group for this cache if it belongs to a block_group
1221 * @trans - the trans handle
1222 *
1223 * This function writes out a free space cache struct to disk for quick recovery
1224 * on mount.  This will return 0 if it was successful in writing the cache out,
1225 * or an errno if it was not.
1226 */
1227static int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
1228                                   struct btrfs_free_space_ctl *ctl,
1229                                   struct btrfs_block_group_cache *block_group,
1230                                   struct btrfs_io_ctl *io_ctl,
1231                                   struct btrfs_trans_handle *trans)
1232{
1233        struct btrfs_fs_info *fs_info = root->fs_info;
1234        struct extent_state *cached_state = NULL;
1235        LIST_HEAD(bitmap_list);
1236        int entries = 0;
1237        int bitmaps = 0;
1238        int ret;
1239        int must_iput = 0;
1240
1241        if (!i_size_read(inode))
1242                return -EIO;
1243
1244        WARN_ON(io_ctl->pages);
1245        ret = io_ctl_init(io_ctl, inode, 1);
1246        if (ret)
1247                return ret;
1248
1249        if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA)) {
1250                down_write(&block_group->data_rwsem);
1251                spin_lock(&block_group->lock);
1252                if (block_group->delalloc_bytes) {
1253                        block_group->disk_cache_state = BTRFS_DC_WRITTEN;
1254                        spin_unlock(&block_group->lock);
1255                        up_write(&block_group->data_rwsem);
1256                        BTRFS_I(inode)->generation = 0;
1257                        ret = 0;
1258                        must_iput = 1;
1259                        goto out;
1260                }
1261                spin_unlock(&block_group->lock);
1262        }
1263
1264        /* Lock all pages first so we can lock the extent safely. */
1265        ret = io_ctl_prepare_pages(io_ctl, inode, 0);
1266        if (ret)
1267                goto out;
1268
1269        lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
1270                         &cached_state);
1271
1272        io_ctl_set_generation(io_ctl, trans->transid);
1273
1274        mutex_lock(&ctl->cache_writeout_mutex);
1275        /* Write out the extent entries in the free space cache */
1276        spin_lock(&ctl->tree_lock);
1277        ret = write_cache_extent_entries(io_ctl, ctl,
1278                                         block_group, &entries, &bitmaps,
1279                                         &bitmap_list);
1280        if (ret)
1281                goto out_nospc_locked;
1282
1283        /*
1284         * Some spaces that are freed in the current transaction are pinned,
1285         * they will be added into free space cache after the transaction is
1286         * committed, we shouldn't lose them.
1287         *
1288         * If this changes while we are working we'll get added back to
1289         * the dirty list and redo it.  No locking needed
1290         */
1291        ret = write_pinned_extent_entries(fs_info, block_group,
1292                                          io_ctl, &entries);
1293        if (ret)
1294                goto out_nospc_locked;
1295
1296        /*
1297         * At last, we write out all the bitmaps and keep cache_writeout_mutex
1298         * locked while doing it because a concurrent trim can be manipulating
1299         * or freeing the bitmap.
1300         */
1301        ret = write_bitmap_entries(io_ctl, &bitmap_list);
1302        spin_unlock(&ctl->tree_lock);
1303        mutex_unlock(&ctl->cache_writeout_mutex);
1304        if (ret)
1305                goto out_nospc;
1306
1307        /* Zero out the rest of the pages just to make sure */
1308        io_ctl_zero_remaining_pages(io_ctl);
1309
1310        /* Everything is written out, now we dirty the pages in the file. */
1311        ret = btrfs_dirty_pages(inode, io_ctl->pages, io_ctl->num_pages, 0,
1312                                i_size_read(inode), &cached_state);
1313        if (ret)
1314                goto out_nospc;
1315
1316        if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA))
1317                up_write(&block_group->data_rwsem);
1318        /*
1319         * Release the pages and unlock the extent, we will flush
1320         * them out later
1321         */
1322        io_ctl_drop_pages(io_ctl);
1323
1324        unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
1325                             i_size_read(inode) - 1, &cached_state, GFP_NOFS);
1326
1327        /*
1328         * at this point the pages are under IO and we're happy,
1329         * The caller is responsible for waiting on them and updating the
1330         * the cache and the inode
1331         */
1332        io_ctl->entries = entries;
1333        io_ctl->bitmaps = bitmaps;
1334
1335        ret = btrfs_fdatawrite_range(inode, 0, (u64)-1);
1336        if (ret)
1337                goto out;
1338
1339        return 0;
1340
1341out:
1342        io_ctl->inode = NULL;
1343        io_ctl_free(io_ctl);
1344        if (ret) {
1345                invalidate_inode_pages2(inode->i_mapping);
1346                BTRFS_I(inode)->generation = 0;
1347        }
1348        btrfs_update_inode(trans, root, inode);
1349        if (must_iput)
1350                iput(inode);
1351        return ret;
1352
1353out_nospc_locked:
1354        cleanup_bitmap_list(&bitmap_list);
1355        spin_unlock(&ctl->tree_lock);
1356        mutex_unlock(&ctl->cache_writeout_mutex);
1357
1358out_nospc:
1359        cleanup_write_cache_enospc(inode, io_ctl, &cached_state);
1360
1361        if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA))
1362                up_write(&block_group->data_rwsem);
1363
1364        goto out;
1365}
1366
1367int btrfs_write_out_cache(struct btrfs_fs_info *fs_info,
1368                          struct btrfs_trans_handle *trans,
1369                          struct btrfs_block_group_cache *block_group,
1370                          struct btrfs_path *path)
1371{
1372        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
1373        struct inode *inode;
1374        int ret = 0;
1375
1376        spin_lock(&block_group->lock);
1377        if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
1378                spin_unlock(&block_group->lock);
1379                return 0;
1380        }
1381        spin_unlock(&block_group->lock);
1382
1383        inode = lookup_free_space_inode(fs_info, block_group, path);
1384        if (IS_ERR(inode))
1385                return 0;
1386
1387        ret = __btrfs_write_out_cache(fs_info->tree_root, inode, ctl,
1388                                block_group, &block_group->io_ctl, trans);
1389        if (ret) {
1390#ifdef DEBUG
1391                btrfs_err(fs_info,
1392                          "failed to write free space cache for block group %llu",
1393                          block_group->key.objectid);
1394#endif
1395                spin_lock(&block_group->lock);
1396                block_group->disk_cache_state = BTRFS_DC_ERROR;
1397                spin_unlock(&block_group->lock);
1398
1399                block_group->io_ctl.inode = NULL;
1400                iput(inode);
1401        }
1402
1403        /*
1404         * if ret == 0 the caller is expected to call btrfs_wait_cache_io
1405         * to wait for IO and put the inode
1406         */
1407
1408        return ret;
1409}
1410
1411static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
1412                                          u64 offset)
1413{
1414        ASSERT(offset >= bitmap_start);
1415        offset -= bitmap_start;
1416        return (unsigned long)(div_u64(offset, unit));
1417}
1418
1419static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
1420{
1421        return (unsigned long)(div_u64(bytes, unit));
1422}
1423
1424static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
1425                                   u64 offset)
1426{
1427        u64 bitmap_start;
1428        u64 bytes_per_bitmap;
1429
1430        bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
1431        bitmap_start = offset - ctl->start;
1432        bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
1433        bitmap_start *= bytes_per_bitmap;
1434        bitmap_start += ctl->start;
1435
1436        return bitmap_start;
1437}
1438
1439static int tree_insert_offset(struct rb_root *root, u64 offset,
1440                              struct rb_node *node, int bitmap)
1441{
1442        struct rb_node **p = &root->rb_node;
1443        struct rb_node *parent = NULL;
1444        struct btrfs_free_space *info;
1445
1446        while (*p) {
1447                parent = *p;
1448                info = rb_entry(parent, struct btrfs_free_space, offset_index);
1449
1450                if (offset < info->offset) {
1451                        p = &(*p)->rb_left;
1452                } else if (offset > info->offset) {
1453                        p = &(*p)->rb_right;
1454                } else {
1455                        /*
1456                         * we could have a bitmap entry and an extent entry
1457                         * share the same offset.  If this is the case, we want
1458                         * the extent entry to always be found first if we do a
1459                         * linear search through the tree, since we want to have
1460                         * the quickest allocation time, and allocating from an
1461                         * extent is faster than allocating from a bitmap.  So
1462                         * if we're inserting a bitmap and we find an entry at
1463                         * this offset, we want to go right, or after this entry
1464                         * logically.  If we are inserting an extent and we've
1465                         * found a bitmap, we want to go left, or before
1466                         * logically.
1467                         */
1468                        if (bitmap) {
1469                                if (info->bitmap) {
1470                                        WARN_ON_ONCE(1);
1471                                        return -EEXIST;
1472                                }
1473                                p = &(*p)->rb_right;
1474                        } else {
1475                                if (!info->bitmap) {
1476                                        WARN_ON_ONCE(1);
1477                                        return -EEXIST;
1478                                }
1479                                p = &(*p)->rb_left;
1480                        }
1481                }
1482        }
1483
1484        rb_link_node(node, parent, p);
1485        rb_insert_color(node, root);
1486
1487        return 0;
1488}
1489
1490/*
1491 * searches the tree for the given offset.
1492 *
1493 * fuzzy - If this is set, then we are trying to make an allocation, and we just
1494 * want a section that has at least bytes size and comes at or after the given
1495 * offset.
1496 */
1497static struct btrfs_free_space *
1498tree_search_offset(struct btrfs_free_space_ctl *ctl,
1499                   u64 offset, int bitmap_only, int fuzzy)
1500{
1501        struct rb_node *n = ctl->free_space_offset.rb_node;
1502        struct btrfs_free_space *entry, *prev = NULL;
1503
1504        /* find entry that is closest to the 'offset' */
1505        while (1) {
1506                if (!n) {
1507                        entry = NULL;
1508                        break;
1509                }
1510
1511                entry = rb_entry(n, struct btrfs_free_space, offset_index);
1512                prev = entry;
1513
1514                if (offset < entry->offset)
1515                        n = n->rb_left;
1516                else if (offset > entry->offset)
1517                        n = n->rb_right;
1518                else
1519                        break;
1520        }
1521
1522        if (bitmap_only) {
1523                if (!entry)
1524                        return NULL;
1525                if (entry->bitmap)
1526                        return entry;
1527
1528                /*
1529                 * bitmap entry and extent entry may share same offset,
1530                 * in that case, bitmap entry comes after extent entry.
1531                 */
1532                n = rb_next(n);
1533                if (!n)
1534                        return NULL;
1535                entry = rb_entry(n, struct btrfs_free_space, offset_index);
1536                if (entry->offset != offset)
1537                        return NULL;
1538
1539                WARN_ON(!entry->bitmap);
1540                return entry;
1541        } else if (entry) {
1542                if (entry->bitmap) {
1543                        /*
1544                         * if previous extent entry covers the offset,
1545                         * we should return it instead of the bitmap entry
1546                         */
1547                        n = rb_prev(&entry->offset_index);
1548                        if (n) {
1549                                prev = rb_entry(n, struct btrfs_free_space,
1550                                                offset_index);
1551                                if (!prev->bitmap &&
1552                                    prev->offset + prev->bytes > offset)
1553                                        entry = prev;
1554                        }
1555                }
1556                return entry;
1557        }
1558
1559        if (!prev)
1560                return NULL;
1561
1562        /* find last entry before the 'offset' */
1563        entry = prev;
1564        if (entry->offset > offset) {
1565                n = rb_prev(&entry->offset_index);
1566                if (n) {
1567                        entry = rb_entry(n, struct btrfs_free_space,
1568                                        offset_index);
1569                        ASSERT(entry->offset <= offset);
1570                } else {
1571                        if (fuzzy)
1572                                return entry;
1573                        else
1574                                return NULL;
1575                }
1576        }
1577
1578        if (entry->bitmap) {
1579                n = rb_prev(&entry->offset_index);
1580                if (n) {
1581                        prev = rb_entry(n, struct btrfs_free_space,
1582                                        offset_index);
1583                        if (!prev->bitmap &&
1584                            prev->offset + prev->bytes > offset)
1585                                return prev;
1586                }
1587                if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
1588                        return entry;
1589        } else if (entry->offset + entry->bytes > offset)
1590                return entry;
1591
1592        if (!fuzzy)
1593                return NULL;
1594
1595        while (1) {
1596                if (entry->bitmap) {
1597                        if (entry->offset + BITS_PER_BITMAP *
1598                            ctl->unit > offset)
1599                                break;
1600                } else {
1601                        if (entry->offset + entry->bytes > offset)
1602                                break;
1603                }
1604
1605                n = rb_next(&entry->offset_index);
1606                if (!n)
1607                        return NULL;
1608                entry = rb_entry(n, struct btrfs_free_space, offset_index);
1609        }
1610        return entry;
1611}
1612
1613static inline void
1614__unlink_free_space(struct btrfs_free_space_ctl *ctl,
1615                    struct btrfs_free_space *info)
1616{
1617        rb_erase(&info->offset_index, &ctl->free_space_offset);
1618        ctl->free_extents--;
1619}
1620
1621static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
1622                              struct btrfs_free_space *info)
1623{
1624        __unlink_free_space(ctl, info);
1625        ctl->free_space -= info->bytes;
1626}
1627
1628static int link_free_space(struct btrfs_free_space_ctl *ctl,
1629                           struct btrfs_free_space *info)
1630{
1631        int ret = 0;
1632
1633        ASSERT(info->bytes || info->bitmap);
1634        ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
1635                                 &info->offset_index, (info->bitmap != NULL));
1636        if (ret)
1637                return ret;
1638
1639        ctl->free_space += info->bytes;
1640        ctl->free_extents++;
1641        return ret;
1642}
1643
1644static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
1645{
1646        struct btrfs_block_group_cache *block_group = ctl->private;
1647        u64 max_bytes;
1648        u64 bitmap_bytes;
1649        u64 extent_bytes;
1650        u64 size = block_group->key.offset;
1651        u64 bytes_per_bg = BITS_PER_BITMAP * ctl->unit;
1652        u64 max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
1653
1654        max_bitmaps = max_t(u64, max_bitmaps, 1);
1655
1656        ASSERT(ctl->total_bitmaps <= max_bitmaps);
1657
1658        /*
1659         * The goal is to keep the total amount of memory used per 1gb of space
1660         * at or below 32k, so we need to adjust how much memory we allow to be
1661         * used by extent based free space tracking
1662         */
1663        if (size < SZ_1G)
1664                max_bytes = MAX_CACHE_BYTES_PER_GIG;
1665        else
1666                max_bytes = MAX_CACHE_BYTES_PER_GIG * div_u64(size, SZ_1G);
1667
1668        /*
1669         * we want to account for 1 more bitmap than what we have so we can make
1670         * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
1671         * we add more bitmaps.
1672         */
1673        bitmap_bytes = (ctl->total_bitmaps + 1) * ctl->unit;
1674
1675        if (bitmap_bytes >= max_bytes) {
1676                ctl->extents_thresh = 0;
1677                return;
1678        }
1679
1680        /*
1681         * we want the extent entry threshold to always be at most 1/2 the max
1682         * bytes we can have, or whatever is less than that.
1683         */
1684        extent_bytes = max_bytes - bitmap_bytes;
1685        extent_bytes = min_t(u64, extent_bytes, max_bytes >> 1);
1686
1687        ctl->extents_thresh =
1688                div_u64(extent_bytes, sizeof(struct btrfs_free_space));
1689}
1690
1691static inline void __bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1692                                       struct btrfs_free_space *info,
1693                                       u64 offset, u64 bytes)
1694{
1695        unsigned long start, count;
1696
1697        start = offset_to_bit(info->offset, ctl->unit, offset);
1698        count = bytes_to_bits(bytes, ctl->unit);
1699        ASSERT(start + count <= BITS_PER_BITMAP);
1700
1701        bitmap_clear(info->bitmap, start, count);
1702
1703        info->bytes -= bytes;
1704}
1705
1706static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
1707                              struct btrfs_free_space *info, u64 offset,
1708                              u64 bytes)
1709{
1710        __bitmap_clear_bits(ctl, info, offset, bytes);
1711        ctl->free_space -= bytes;
1712}
1713
1714static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
1715                            struct btrfs_free_space *info, u64 offset,
1716                            u64 bytes)
1717{
1718        unsigned long start, count;
1719
1720        start = offset_to_bit(info->offset, ctl->unit, offset);
1721        count = bytes_to_bits(bytes, ctl->unit);
1722        ASSERT(start + count <= BITS_PER_BITMAP);
1723
1724        bitmap_set(info->bitmap, start, count);
1725
1726        info->bytes += bytes;
1727        ctl->free_space += bytes;
1728}
1729
1730/*
1731 * If we can not find suitable extent, we will use bytes to record
1732 * the size of the max extent.
1733 */
1734static int search_bitmap(struct btrfs_free_space_ctl *ctl,
1735                         struct btrfs_free_space *bitmap_info, u64 *offset,
1736                         u64 *bytes, bool for_alloc)
1737{
1738        unsigned long found_bits = 0;
1739        unsigned long max_bits = 0;
1740        unsigned long bits, i;
1741        unsigned long next_zero;
1742        unsigned long extent_bits;
1743
1744        /*
1745         * Skip searching the bitmap if we don't have a contiguous section that
1746         * is large enough for this allocation.
1747         */
1748        if (for_alloc &&
1749            bitmap_info->max_extent_size &&
1750            bitmap_info->max_extent_size < *bytes) {
1751                *bytes = bitmap_info->max_extent_size;
1752                return -1;
1753        }
1754
1755        i = offset_to_bit(bitmap_info->offset, ctl->unit,
1756                          max_t(u64, *offset, bitmap_info->offset));
1757        bits = bytes_to_bits(*bytes, ctl->unit);
1758
1759        for_each_set_bit_from(i, bitmap_info->bitmap, BITS_PER_BITMAP) {
1760                if (for_alloc && bits == 1) {
1761                        found_bits = 1;
1762                        break;
1763                }
1764                next_zero = find_next_zero_bit(bitmap_info->bitmap,
1765                                               BITS_PER_BITMAP, i);
1766                extent_bits = next_zero - i;
1767                if (extent_bits >= bits) {
1768                        found_bits = extent_bits;
1769                        break;
1770                } else if (extent_bits > max_bits) {
1771                        max_bits = extent_bits;
1772                }
1773                i = next_zero;
1774        }
1775
1776        if (found_bits) {
1777                *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
1778                *bytes = (u64)(found_bits) * ctl->unit;
1779                return 0;
1780        }
1781
1782        *bytes = (u64)(max_bits) * ctl->unit;
1783        bitmap_info->max_extent_size = *bytes;
1784        return -1;
1785}
1786
1787/* Cache the size of the max extent in bytes */
1788static struct btrfs_free_space *
1789find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes,
1790                unsigned long align, u64 *max_extent_size)
1791{
1792        struct btrfs_free_space *entry;
1793        struct rb_node *node;
1794        u64 tmp;
1795        u64 align_off;
1796        int ret;
1797
1798        if (!ctl->free_space_offset.rb_node)
1799                goto out;
1800
1801        entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
1802        if (!entry)
1803                goto out;
1804
1805        for (node = &entry->offset_index; node; node = rb_next(node)) {
1806                entry = rb_entry(node, struct btrfs_free_space, offset_index);
1807                if (entry->bytes < *bytes) {
1808                        if (entry->bytes > *max_extent_size)
1809                                *max_extent_size = entry->bytes;
1810                        continue;
1811                }
1812
1813                /* make sure the space returned is big enough
1814                 * to match our requested alignment
1815                 */
1816                if (*bytes >= align) {
1817                        tmp = entry->offset - ctl->start + align - 1;
1818                        tmp = div64_u64(tmp, align);
1819                        tmp = tmp * align + ctl->start;
1820                        align_off = tmp - entry->offset;
1821                } else {
1822                        align_off = 0;
1823                        tmp = entry->offset;
1824                }
1825
1826                if (entry->bytes < *bytes + align_off) {
1827                        if (entry->bytes > *max_extent_size)
1828                                *max_extent_size = entry->bytes;
1829                        continue;
1830                }
1831
1832                if (entry->bitmap) {
1833                        u64 size = *bytes;
1834
1835                        ret = search_bitmap(ctl, entry, &tmp, &size, true);
1836                        if (!ret) {
1837                                *offset = tmp;
1838                                *bytes = size;
1839                                return entry;
1840                        } else if (size > *max_extent_size) {
1841                                *max_extent_size = size;
1842                        }
1843                        continue;
1844                }
1845
1846                *offset = tmp;
1847                *bytes = entry->bytes - align_off;
1848                return entry;
1849        }
1850out:
1851        return NULL;
1852}
1853
1854static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
1855                           struct btrfs_free_space *info, u64 offset)
1856{
1857        info->offset = offset_to_bitmap(ctl, offset);
1858        info->bytes = 0;
1859        INIT_LIST_HEAD(&info->list);
1860        link_free_space(ctl, info);
1861        ctl->total_bitmaps++;
1862
1863        ctl->op->recalc_thresholds(ctl);
1864}
1865
1866static void free_bitmap(struct btrfs_free_space_ctl *ctl,
1867                        struct btrfs_free_space *bitmap_info)
1868{
1869        unlink_free_space(ctl, bitmap_info);
1870        kfree(bitmap_info->bitmap);
1871        kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
1872        ctl->total_bitmaps--;
1873        ctl->op->recalc_thresholds(ctl);
1874}
1875
1876static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
1877                              struct btrfs_free_space *bitmap_info,
1878                              u64 *offset, u64 *bytes)
1879{
1880        u64 end;
1881        u64 search_start, search_bytes;
1882        int ret;
1883
1884again:
1885        end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
1886
1887        /*
1888         * We need to search for bits in this bitmap.  We could only cover some
1889         * of the extent in this bitmap thanks to how we add space, so we need
1890         * to search for as much as it as we can and clear that amount, and then
1891         * go searching for the next bit.
1892         */
1893        search_start = *offset;
1894        search_bytes = ctl->unit;
1895        search_bytes = min(search_bytes, end - search_start + 1);
1896        ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes,
1897                            false);
1898        if (ret < 0 || search_start != *offset)
1899                return -EINVAL;
1900
1901        /* We may have found more bits than what we need */
1902        search_bytes = min(search_bytes, *bytes);
1903
1904        /* Cannot clear past the end of the bitmap */
1905        search_bytes = min(search_bytes, end - search_start + 1);
1906
1907        bitmap_clear_bits(ctl, bitmap_info, search_start, search_bytes);
1908        *offset += search_bytes;
1909        *bytes -= search_bytes;
1910
1911        if (*bytes) {
1912                struct rb_node *next = rb_next(&bitmap_info->offset_index);
1913                if (!bitmap_info->bytes)
1914                        free_bitmap(ctl, bitmap_info);
1915
1916                /*
1917                 * no entry after this bitmap, but we still have bytes to
1918                 * remove, so something has gone wrong.
1919                 */
1920                if (!next)
1921                        return -EINVAL;
1922
1923                bitmap_info = rb_entry(next, struct btrfs_free_space,
1924                                       offset_index);
1925
1926                /*
1927                 * if the next entry isn't a bitmap we need to return to let the
1928                 * extent stuff do its work.
1929                 */
1930                if (!bitmap_info->bitmap)
1931                        return -EAGAIN;
1932
1933                /*
1934                 * Ok the next item is a bitmap, but it may not actually hold
1935                 * the information for the rest of this free space stuff, so
1936                 * look for it, and if we don't find it return so we can try
1937                 * everything over again.
1938                 */
1939                search_start = *offset;
1940                search_bytes = ctl->unit;
1941                ret = search_bitmap(ctl, bitmap_info, &search_start,
1942                                    &search_bytes, false);
1943                if (ret < 0 || search_start != *offset)
1944                        return -EAGAIN;
1945
1946                goto again;
1947        } else if (!bitmap_info->bytes)
1948                free_bitmap(ctl, bitmap_info);
1949
1950        return 0;
1951}
1952
1953static u64 add_bytes_to_bitmap(struct btrfs_free_space_ctl *ctl,
1954                               struct btrfs_free_space *info, u64 offset,
1955                               u64 bytes)
1956{
1957        u64 bytes_to_set = 0;
1958        u64 end;
1959
1960        end = info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
1961
1962        bytes_to_set = min(end - offset, bytes);
1963
1964        bitmap_set_bits(ctl, info, offset, bytes_to_set);
1965
1966        /*
1967         * We set some bytes, we have no idea what the max extent size is
1968         * anymore.
1969         */
1970        info->max_extent_size = 0;
1971
1972        return bytes_to_set;
1973
1974}
1975
1976static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
1977                      struct btrfs_free_space *info)
1978{
1979        struct btrfs_block_group_cache *block_group = ctl->private;
1980        struct btrfs_fs_info *fs_info = block_group->fs_info;
1981        bool forced = false;
1982
1983#ifdef CONFIG_BTRFS_DEBUG
1984        if (btrfs_should_fragment_free_space(block_group))
1985                forced = true;
1986#endif
1987
1988        /*
1989         * If we are below the extents threshold then we can add this as an
1990         * extent, and don't have to deal with the bitmap
1991         */
1992        if (!forced && ctl->free_extents < ctl->extents_thresh) {
1993                /*
1994                 * If this block group has some small extents we don't want to
1995                 * use up all of our free slots in the cache with them, we want
1996                 * to reserve them to larger extents, however if we have plenty
1997                 * of cache left then go ahead an dadd them, no sense in adding
1998                 * the overhead of a bitmap if we don't have to.
1999                 */
2000                if (info->bytes <= fs_info->sectorsize * 4) {
2001                        if (ctl->free_extents * 2 <= ctl->extents_thresh)
2002                                return false;
2003                } else {
2004                        return false;
2005                }
2006        }
2007
2008        /*
2009         * The original block groups from mkfs can be really small, like 8
2010         * megabytes, so don't bother with a bitmap for those entries.  However
2011         * some block groups can be smaller than what a bitmap would cover but
2012         * are still large enough that they could overflow the 32k memory limit,
2013         * so allow those block groups to still be allowed to have a bitmap
2014         * entry.
2015         */
2016        if (((BITS_PER_BITMAP * ctl->unit) >> 1) > block_group->key.offset)
2017                return false;
2018
2019        return true;
2020}
2021
2022static const struct btrfs_free_space_op free_space_op = {
2023        .recalc_thresholds      = recalculate_thresholds,
2024        .use_bitmap             = use_bitmap,
2025};
2026
2027static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
2028                              struct btrfs_free_space *info)
2029{
2030        struct btrfs_free_space *bitmap_info;
2031        struct btrfs_block_group_cache *block_group = NULL;
2032        int added = 0;
2033        u64 bytes, offset, bytes_added;
2034        int ret;
2035
2036        bytes = info->bytes;
2037        offset = info->offset;
2038
2039        if (!ctl->op->use_bitmap(ctl, info))
2040                return 0;
2041
2042        if (ctl->op == &free_space_op)
2043                block_group = ctl->private;
2044again:
2045        /*
2046         * Since we link bitmaps right into the cluster we need to see if we
2047         * have a cluster here, and if so and it has our bitmap we need to add
2048         * the free space to that bitmap.
2049         */
2050        if (block_group && !list_empty(&block_group->cluster_list)) {
2051                struct btrfs_free_cluster *cluster;
2052                struct rb_node *node;
2053                struct btrfs_free_space *entry;
2054
2055                cluster = list_entry(block_group->cluster_list.next,
2056                                     struct btrfs_free_cluster,
2057                                     block_group_list);
2058                spin_lock(&cluster->lock);
2059                node = rb_first(&cluster->root);
2060                if (!node) {
2061                        spin_unlock(&cluster->lock);
2062                        goto no_cluster_bitmap;
2063                }
2064
2065                entry = rb_entry(node, struct btrfs_free_space, offset_index);
2066                if (!entry->bitmap) {
2067                        spin_unlock(&cluster->lock);
2068                        goto no_cluster_bitmap;
2069                }
2070
2071                if (entry->offset == offset_to_bitmap(ctl, offset)) {
2072                        bytes_added = add_bytes_to_bitmap(ctl, entry,
2073                                                          offset, bytes);
2074                        bytes -= bytes_added;
2075                        offset += bytes_added;
2076                }
2077                spin_unlock(&cluster->lock);
2078                if (!bytes) {
2079                        ret = 1;
2080                        goto out;
2081                }
2082        }
2083
2084no_cluster_bitmap:
2085        bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
2086                                         1, 0);
2087        if (!bitmap_info) {
2088                ASSERT(added == 0);
2089                goto new_bitmap;
2090        }
2091
2092        bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
2093        bytes -= bytes_added;
2094        offset += bytes_added;
2095        added = 0;
2096
2097        if (!bytes) {
2098                ret = 1;
2099                goto out;
2100        } else
2101                goto again;
2102
2103new_bitmap:
2104        if (info && info->bitmap) {
2105                add_new_bitmap(ctl, info, offset);
2106                added = 1;
2107                info = NULL;
2108                goto again;
2109        } else {
2110                spin_unlock(&ctl->tree_lock);
2111
2112                /* no pre-allocated info, allocate a new one */
2113                if (!info) {
2114                        info = kmem_cache_zalloc(btrfs_free_space_cachep,
2115                                                 GFP_NOFS);
2116                        if (!info) {
2117                                spin_lock(&ctl->tree_lock);
2118                                ret = -ENOMEM;
2119                                goto out;
2120                        }
2121                }
2122
2123                /* allocate the bitmap */
2124                info->bitmap = kzalloc(PAGE_SIZE, GFP_NOFS);
2125                spin_lock(&ctl->tree_lock);
2126                if (!info->bitmap) {
2127                        ret = -ENOMEM;
2128                        goto out;
2129                }
2130                goto again;
2131        }
2132
2133out:
2134        if (info) {
2135                if (info->bitmap)
2136                        kfree(info->bitmap);
2137                kmem_cache_free(btrfs_free_space_cachep, info);
2138        }
2139
2140        return ret;
2141}
2142
2143static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
2144                          struct btrfs_free_space *info, bool update_stat)
2145{
2146        struct btrfs_free_space *left_info;
2147        struct btrfs_free_space *right_info;
2148        bool merged = false;
2149        u64 offset = info->offset;
2150        u64 bytes = info->bytes;
2151
2152        /*
2153         * first we want to see if there is free space adjacent to the range we
2154         * are adding, if there is remove that struct and add a new one to
2155         * cover the entire range
2156         */
2157        right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
2158        if (right_info && rb_prev(&right_info->offset_index))
2159                left_info = rb_entry(rb_prev(&right_info->offset_index),
2160                                     struct btrfs_free_space, offset_index);
2161        else
2162                left_info = tree_search_offset(ctl, offset - 1, 0, 0);
2163
2164        if (right_info && !right_info->bitmap) {
2165                if (update_stat)
2166                        unlink_free_space(ctl, right_info);
2167                else
2168                        __unlink_free_space(ctl, right_info);
2169                info->bytes += right_info->bytes;
2170                kmem_cache_free(btrfs_free_space_cachep, right_info);
2171                merged = true;
2172        }
2173
2174        if (left_info && !left_info->bitmap &&
2175            left_info->offset + left_info->bytes == offset) {
2176                if (update_stat)
2177                        unlink_free_space(ctl, left_info);
2178                else
2179                        __unlink_free_space(ctl, left_info);
2180                info->offset = left_info->offset;
2181                info->bytes += left_info->bytes;
2182                kmem_cache_free(btrfs_free_space_cachep, left_info);
2183                merged = true;
2184        }
2185
2186        return merged;
2187}
2188
2189static bool steal_from_bitmap_to_end(struct btrfs_free_space_ctl *ctl,
2190                                     struct btrfs_free_space *info,
2191                                     bool update_stat)
2192{
2193        struct btrfs_free_space *bitmap;
2194        unsigned long i;
2195        unsigned long j;
2196        const u64 end = info->offset + info->bytes;
2197        const u64 bitmap_offset = offset_to_bitmap(ctl, end);
2198        u64 bytes;
2199
2200        bitmap = tree_search_offset(ctl, bitmap_offset, 1, 0);
2201        if (!bitmap)
2202                return false;
2203
2204        i = offset_to_bit(bitmap->offset, ctl->unit, end);
2205        j = find_next_zero_bit(bitmap->bitmap, BITS_PER_BITMAP, i);
2206        if (j == i)
2207                return false;
2208        bytes = (j - i) * ctl->unit;
2209        info->bytes += bytes;
2210
2211        if (update_stat)
2212                bitmap_clear_bits(ctl, bitmap, end, bytes);
2213        else
2214                __bitmap_clear_bits(ctl, bitmap, end, bytes);
2215
2216        if (!bitmap->bytes)
2217                free_bitmap(ctl, bitmap);
2218
2219        return true;
2220}
2221
2222static bool steal_from_bitmap_to_front(struct btrfs_free_space_ctl *ctl,
2223                                       struct btrfs_free_space *info,
2224                                       bool update_stat)
2225{
2226        struct btrfs_free_space *bitmap;
2227        u64 bitmap_offset;
2228        unsigned long i;
2229        unsigned long j;
2230        unsigned long prev_j;
2231        u64 bytes;
2232
2233        bitmap_offset = offset_to_bitmap(ctl, info->offset);
2234        /* If we're on a boundary, try the previous logical bitmap. */
2235        if (bitmap_offset == info->offset) {
2236                if (info->offset == 0)
2237                        return false;
2238                bitmap_offset = offset_to_bitmap(ctl, info->offset - 1);
2239        }
2240
2241        bitmap = tree_search_offset(ctl, bitmap_offset, 1, 0);
2242        if (!bitmap)
2243                return false;
2244
2245        i = offset_to_bit(bitmap->offset, ctl->unit, info->offset) - 1;
2246        j = 0;
2247        prev_j = (unsigned long)-1;
2248        for_each_clear_bit_from(j, bitmap->bitmap, BITS_PER_BITMAP) {
2249                if (j > i)
2250                        break;
2251                prev_j = j;
2252        }
2253        if (prev_j == i)
2254                return false;
2255
2256        if (prev_j == (unsigned long)-1)
2257                bytes = (i + 1) * ctl->unit;
2258        else
2259                bytes = (i - prev_j) * ctl->unit;
2260
2261        info->offset -= bytes;
2262        info->bytes += bytes;
2263
2264        if (update_stat)
2265                bitmap_clear_bits(ctl, bitmap, info->offset, bytes);
2266        else
2267                __bitmap_clear_bits(ctl, bitmap, info->offset, bytes);
2268
2269        if (!bitmap->bytes)
2270                free_bitmap(ctl, bitmap);
2271
2272        return true;
2273}
2274
2275/*
2276 * We prefer always to allocate from extent entries, both for clustered and
2277 * non-clustered allocation requests. So when attempting to add a new extent
2278 * entry, try to see if there's adjacent free space in bitmap entries, and if
2279 * there is, migrate that space from the bitmaps to the extent.
2280 * Like this we get better chances of satisfying space allocation requests
2281 * because we attempt to satisfy them based on a single cache entry, and never
2282 * on 2 or more entries - even if the entries represent a contiguous free space
2283 * region (e.g. 1 extent entry + 1 bitmap entry starting where the extent entry
2284 * ends).
2285 */
2286static void steal_from_bitmap(struct btrfs_free_space_ctl *ctl,
2287                              struct btrfs_free_space *info,
2288                              bool update_stat)
2289{
2290        /*
2291         * Only work with disconnected entries, as we can change their offset,
2292         * and must be extent entries.
2293         */
2294        ASSERT(!info->bitmap);
2295        ASSERT(RB_EMPTY_NODE(&info->offset_index));
2296
2297        if (ctl->total_bitmaps > 0) {
2298                bool stole_end;
2299                bool stole_front = false;
2300
2301                stole_end = steal_from_bitmap_to_end(ctl, info, update_stat);
2302                if (ctl->total_bitmaps > 0)
2303                        stole_front = steal_from_bitmap_to_front(ctl, info,
2304                                                                 update_stat);
2305
2306                if (stole_end || stole_front)
2307                        try_merge_free_space(ctl, info, update_stat);
2308        }
2309}
2310
2311int __btrfs_add_free_space(struct btrfs_fs_info *fs_info,
2312                           struct btrfs_free_space_ctl *ctl,
2313                           u64 offset, u64 bytes)
2314{
2315        struct btrfs_free_space *info;
2316        int ret = 0;
2317
2318        info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
2319        if (!info)
2320                return -ENOMEM;
2321
2322        info->offset = offset;
2323        info->bytes = bytes;
2324        RB_CLEAR_NODE(&info->offset_index);
2325
2326        spin_lock(&ctl->tree_lock);
2327
2328        if (try_merge_free_space(ctl, info, true))
2329                goto link;
2330
2331        /*
2332         * There was no extent directly to the left or right of this new
2333         * extent then we know we're going to have to allocate a new extent, so
2334         * before we do that see if we need to drop this into a bitmap
2335         */
2336        ret = insert_into_bitmap(ctl, info);
2337        if (ret < 0) {
2338                goto out;
2339        } else if (ret) {
2340                ret = 0;
2341                goto out;
2342        }
2343link:
2344        /*
2345         * Only steal free space from adjacent bitmaps if we're sure we're not
2346         * going to add the new free space to existing bitmap entries - because
2347         * that would mean unnecessary work that would be reverted. Therefore
2348         * attempt to steal space from bitmaps if we're adding an extent entry.
2349         */
2350        steal_from_bitmap(ctl, info, true);
2351
2352        ret = link_free_space(ctl, info);
2353        if (ret)
2354                kmem_cache_free(btrfs_free_space_cachep, info);
2355out:
2356        spin_unlock(&ctl->tree_lock);
2357
2358        if (ret) {
2359                btrfs_crit(fs_info, "unable to add free space :%d", ret);
2360                ASSERT(ret != -EEXIST);
2361        }
2362
2363        return ret;
2364}
2365
2366int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
2367                            u64 offset, u64 bytes)
2368{
2369        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2370        struct btrfs_free_space *info;
2371        int ret;
2372        bool re_search = false;
2373
2374        spin_lock(&ctl->tree_lock);
2375
2376again:
2377        ret = 0;
2378        if (!bytes)
2379                goto out_lock;
2380
2381        info = tree_search_offset(ctl, offset, 0, 0);
2382        if (!info) {
2383                /*
2384                 * oops didn't find an extent that matched the space we wanted
2385                 * to remove, look for a bitmap instead
2386                 */
2387                info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
2388                                          1, 0);
2389                if (!info) {
2390                        /*
2391                         * If we found a partial bit of our free space in a
2392                         * bitmap but then couldn't find the other part this may
2393                         * be a problem, so WARN about it.
2394                         */
2395                        WARN_ON(re_search);
2396                        goto out_lock;
2397                }
2398        }
2399
2400        re_search = false;
2401        if (!info->bitmap) {
2402                unlink_free_space(ctl, info);
2403                if (offset == info->offset) {
2404                        u64 to_free = min(bytes, info->bytes);
2405
2406                        info->bytes -= to_free;
2407                        info->offset += to_free;
2408                        if (info->bytes) {
2409                                ret = link_free_space(ctl, info);
2410                                WARN_ON(ret);
2411                        } else {
2412                                kmem_cache_free(btrfs_free_space_cachep, info);
2413                        }
2414
2415                        offset += to_free;
2416                        bytes -= to_free;
2417                        goto again;
2418                } else {
2419                        u64 old_end = info->bytes + info->offset;
2420
2421                        info->bytes = offset - info->offset;
2422                        ret = link_free_space(ctl, info);
2423                        WARN_ON(ret);
2424                        if (ret)
2425                                goto out_lock;
2426
2427                        /* Not enough bytes in this entry to satisfy us */
2428                        if (old_end < offset + bytes) {
2429                                bytes -= old_end - offset;
2430                                offset = old_end;
2431                                goto again;
2432                        } else if (old_end == offset + bytes) {
2433                                /* all done */
2434                                goto out_lock;
2435                        }
2436                        spin_unlock(&ctl->tree_lock);
2437
2438                        ret = btrfs_add_free_space(block_group, offset + bytes,
2439                                                   old_end - (offset + bytes));
2440                        WARN_ON(ret);
2441                        goto out;
2442                }
2443        }
2444
2445        ret = remove_from_bitmap(ctl, info, &offset, &bytes);
2446        if (ret == -EAGAIN) {
2447                re_search = true;
2448                goto again;
2449        }
2450out_lock:
2451        spin_unlock(&ctl->tree_lock);
2452out:
2453        return ret;
2454}
2455
2456void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
2457                           u64 bytes)
2458{
2459        struct btrfs_fs_info *fs_info = block_group->fs_info;
2460        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2461        struct btrfs_free_space *info;
2462        struct rb_node *n;
2463        int count = 0;
2464
2465        for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
2466                info = rb_entry(n, struct btrfs_free_space, offset_index);
2467                if (info->bytes >= bytes && !block_group->ro)
2468                        count++;
2469                btrfs_crit(fs_info, "entry offset %llu, bytes %llu, bitmap %s",
2470                           info->offset, info->bytes,
2471                       (info->bitmap) ? "yes" : "no");
2472        }
2473        btrfs_info(fs_info, "block group has cluster?: %s",
2474               list_empty(&block_group->cluster_list) ? "no" : "yes");
2475        btrfs_info(fs_info,
2476                   "%d blocks of free space at or bigger than bytes is", count);
2477}
2478
2479void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
2480{
2481        struct btrfs_fs_info *fs_info = block_group->fs_info;
2482        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2483
2484        spin_lock_init(&ctl->tree_lock);
2485        ctl->unit = fs_info->sectorsize;
2486        ctl->start = block_group->key.objectid;
2487        ctl->private = block_group;
2488        ctl->op = &free_space_op;
2489        INIT_LIST_HEAD(&ctl->trimming_ranges);
2490        mutex_init(&ctl->cache_writeout_mutex);
2491
2492        /*
2493         * we only want to have 32k of ram per block group for keeping
2494         * track of free space, and if we pass 1/2 of that we want to
2495         * start converting things over to using bitmaps
2496         */
2497        ctl->extents_thresh = (SZ_32K / 2) / sizeof(struct btrfs_free_space);
2498}
2499
2500/*
2501 * for a given cluster, put all of its extents back into the free
2502 * space cache.  If the block group passed doesn't match the block group
2503 * pointed to by the cluster, someone else raced in and freed the
2504 * cluster already.  In that case, we just return without changing anything
2505 */
2506static int
2507__btrfs_return_cluster_to_free_space(
2508                             struct btrfs_block_group_cache *block_group,
2509                             struct btrfs_free_cluster *cluster)
2510{
2511        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2512        struct btrfs_free_space *entry;
2513        struct rb_node *node;
2514
2515        spin_lock(&cluster->lock);
2516        if (cluster->block_group != block_group)
2517                goto out;
2518
2519        cluster->block_group = NULL;
2520        cluster->window_start = 0;
2521        list_del_init(&cluster->block_group_list);
2522
2523        node = rb_first(&cluster->root);
2524        while (node) {
2525                bool bitmap;
2526
2527                entry = rb_entry(node, struct btrfs_free_space, offset_index);
2528                node = rb_next(&entry->offset_index);
2529                rb_erase(&entry->offset_index, &cluster->root);
2530                RB_CLEAR_NODE(&entry->offset_index);
2531
2532                bitmap = (entry->bitmap != NULL);
2533                if (!bitmap) {
2534                        try_merge_free_space(ctl, entry, false);
2535                        steal_from_bitmap(ctl, entry, false);
2536                }
2537                tree_insert_offset(&ctl->free_space_offset,
2538                                   entry->offset, &entry->offset_index, bitmap);
2539        }
2540        cluster->root = RB_ROOT;
2541
2542out:
2543        spin_unlock(&cluster->lock);
2544        btrfs_put_block_group(block_group);
2545        return 0;
2546}
2547
2548static void __btrfs_remove_free_space_cache_locked(
2549                                struct btrfs_free_space_ctl *ctl)
2550{
2551        struct btrfs_free_space *info;
2552        struct rb_node *node;
2553
2554        while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
2555                info = rb_entry(node, struct btrfs_free_space, offset_index);
2556                if (!info->bitmap) {
2557                        unlink_free_space(ctl, info);
2558                        kmem_cache_free(btrfs_free_space_cachep, info);
2559                } else {
2560                        free_bitmap(ctl, info);
2561                }
2562
2563                cond_resched_lock(&ctl->tree_lock);
2564        }
2565}
2566
2567void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
2568{
2569        spin_lock(&ctl->tree_lock);
2570        __btrfs_remove_free_space_cache_locked(ctl);
2571        spin_unlock(&ctl->tree_lock);
2572}
2573
2574void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
2575{
2576        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2577        struct btrfs_free_cluster *cluster;
2578        struct list_head *head;
2579
2580        spin_lock(&ctl->tree_lock);
2581        while ((head = block_group->cluster_list.next) !=
2582               &block_group->cluster_list) {
2583                cluster = list_entry(head, struct btrfs_free_cluster,
2584                                     block_group_list);
2585
2586                WARN_ON(cluster->block_group != block_group);
2587                __btrfs_return_cluster_to_free_space(block_group, cluster);
2588
2589                cond_resched_lock(&ctl->tree_lock);
2590        }
2591        __btrfs_remove_free_space_cache_locked(ctl);
2592        spin_unlock(&ctl->tree_lock);
2593
2594}
2595
2596u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
2597                               u64 offset, u64 bytes, u64 empty_size,
2598                               u64 *max_extent_size)
2599{
2600        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2601        struct btrfs_free_space *entry = NULL;
2602        u64 bytes_search = bytes + empty_size;
2603        u64 ret = 0;
2604        u64 align_gap = 0;
2605        u64 align_gap_len = 0;
2606
2607        spin_lock(&ctl->tree_lock);
2608        entry = find_free_space(ctl, &offset, &bytes_search,
2609                                block_group->full_stripe_len, max_extent_size);
2610        if (!entry)
2611                goto out;
2612
2613        ret = offset;
2614        if (entry->bitmap) {
2615                bitmap_clear_bits(ctl, entry, offset, bytes);
2616                if (!entry->bytes)
2617                        free_bitmap(ctl, entry);
2618        } else {
2619                unlink_free_space(ctl, entry);
2620                align_gap_len = offset - entry->offset;
2621                align_gap = entry->offset;
2622
2623                entry->offset = offset + bytes;
2624                WARN_ON(entry->bytes < bytes + align_gap_len);
2625
2626                entry->bytes -= bytes + align_gap_len;
2627                if (!entry->bytes)
2628                        kmem_cache_free(btrfs_free_space_cachep, entry);
2629                else
2630                        link_free_space(ctl, entry);
2631        }
2632out:
2633        spin_unlock(&ctl->tree_lock);
2634
2635        if (align_gap_len)
2636                __btrfs_add_free_space(block_group->fs_info, ctl,
2637                                       align_gap, align_gap_len);
2638        return ret;
2639}
2640
2641/*
2642 * given a cluster, put all of its extents back into the free space
2643 * cache.  If a block group is passed, this function will only free
2644 * a cluster that belongs to the passed block group.
2645 *
2646 * Otherwise, it'll get a reference on the block group pointed to by the
2647 * cluster and remove the cluster from it.
2648 */
2649int btrfs_return_cluster_to_free_space(
2650                               struct btrfs_block_group_cache *block_group,
2651                               struct btrfs_free_cluster *cluster)
2652{
2653        struct btrfs_free_space_ctl *ctl;
2654        int ret;
2655
2656        /* first, get a safe pointer to the block group */
2657        spin_lock(&cluster->lock);
2658        if (!block_group) {
2659                block_group = cluster->block_group;
2660                if (!block_group) {
2661                        spin_unlock(&cluster->lock);
2662                        return 0;
2663                }
2664        } else if (cluster->block_group != block_group) {
2665                /* someone else has already freed it don't redo their work */
2666                spin_unlock(&cluster->lock);
2667                return 0;
2668        }
2669        atomic_inc(&block_group->count);
2670        spin_unlock(&cluster->lock);
2671
2672        ctl = block_group->free_space_ctl;
2673
2674        /* now return any extents the cluster had on it */
2675        spin_lock(&ctl->tree_lock);
2676        ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
2677        spin_unlock(&ctl->tree_lock);
2678
2679        /* finally drop our ref */
2680        btrfs_put_block_group(block_group);
2681        return ret;
2682}
2683
2684static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
2685                                   struct btrfs_free_cluster *cluster,
2686                                   struct btrfs_free_space *entry,
2687                                   u64 bytes, u64 min_start,
2688                                   u64 *max_extent_size)
2689{
2690        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2691        int err;
2692        u64 search_start = cluster->window_start;
2693        u64 search_bytes = bytes;
2694        u64 ret = 0;
2695
2696        search_start = min_start;
2697        search_bytes = bytes;
2698
2699        err = search_bitmap(ctl, entry, &search_start, &search_bytes, true);
2700        if (err) {
2701                if (search_bytes > *max_extent_size)
2702                        *max_extent_size = search_bytes;
2703                return 0;
2704        }
2705
2706        ret = search_start;
2707        __bitmap_clear_bits(ctl, entry, ret, bytes);
2708
2709        return ret;
2710}
2711
2712/*
2713 * given a cluster, try to allocate 'bytes' from it, returns 0
2714 * if it couldn't find anything suitably large, or a logical disk offset
2715 * if things worked out
2716 */
2717u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
2718                             struct btrfs_free_cluster *cluster, u64 bytes,
2719                             u64 min_start, u64 *max_extent_size)
2720{
2721        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2722        struct btrfs_free_space *entry = NULL;
2723        struct rb_node *node;
2724        u64 ret = 0;
2725
2726        spin_lock(&cluster->lock);
2727        if (bytes > cluster->max_size)
2728                goto out;
2729
2730        if (cluster->block_group != block_group)
2731                goto out;
2732
2733        node = rb_first(&cluster->root);
2734        if (!node)
2735                goto out;
2736
2737        entry = rb_entry(node, struct btrfs_free_space, offset_index);
2738        while (1) {
2739                if (entry->bytes < bytes && entry->bytes > *max_extent_size)
2740                        *max_extent_size = entry->bytes;
2741
2742                if (entry->bytes < bytes ||
2743                    (!entry->bitmap && entry->offset < min_start)) {
2744                        node = rb_next(&entry->offset_index);
2745                        if (!node)
2746                                break;
2747                        entry = rb_entry(node, struct btrfs_free_space,
2748                                         offset_index);
2749                        continue;
2750                }
2751
2752                if (entry->bitmap) {
2753                        ret = btrfs_alloc_from_bitmap(block_group,
2754                                                      cluster, entry, bytes,
2755                                                      cluster->window_start,
2756                                                      max_extent_size);
2757                        if (ret == 0) {
2758                                node = rb_next(&entry->offset_index);
2759                                if (!node)
2760                                        break;
2761                                entry = rb_entry(node, struct btrfs_free_space,
2762                                                 offset_index);
2763                                continue;
2764                        }
2765                        cluster->window_start += bytes;
2766                } else {
2767                        ret = entry->offset;
2768
2769                        entry->offset += bytes;
2770                        entry->bytes -= bytes;
2771                }
2772
2773                if (entry->bytes == 0)
2774                        rb_erase(&entry->offset_index, &cluster->root);
2775                break;
2776        }
2777out:
2778        spin_unlock(&cluster->lock);
2779
2780        if (!ret)
2781                return 0;
2782
2783        spin_lock(&ctl->tree_lock);
2784
2785        ctl->free_space -= bytes;
2786        if (entry->bytes == 0) {
2787                ctl->free_extents--;
2788                if (entry->bitmap) {
2789                        kfree(entry->bitmap);
2790                        ctl->total_bitmaps--;
2791                        ctl->op->recalc_thresholds(ctl);
2792                }
2793                kmem_cache_free(btrfs_free_space_cachep, entry);
2794        }
2795
2796        spin_unlock(&ctl->tree_lock);
2797
2798        return ret;
2799}
2800
2801static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
2802                                struct btrfs_free_space *entry,
2803                                struct btrfs_free_cluster *cluster,
2804                                u64 offset, u64 bytes,
2805                                u64 cont1_bytes, u64 min_bytes)
2806{
2807        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2808        unsigned long next_zero;
2809        unsigned long i;
2810        unsigned long want_bits;
2811        unsigned long min_bits;
2812        unsigned long found_bits;
2813        unsigned long max_bits = 0;
2814        unsigned long start = 0;
2815        unsigned long total_found = 0;
2816        int ret;
2817
2818        i = offset_to_bit(entry->offset, ctl->unit,
2819                          max_t(u64, offset, entry->offset));
2820        want_bits = bytes_to_bits(bytes, ctl->unit);
2821        min_bits = bytes_to_bits(min_bytes, ctl->unit);
2822
2823        /*
2824         * Don't bother looking for a cluster in this bitmap if it's heavily
2825         * fragmented.
2826         */
2827        if (entry->max_extent_size &&
2828            entry->max_extent_size < cont1_bytes)
2829                return -ENOSPC;
2830again:
2831        found_bits = 0;
2832        for_each_set_bit_from(i, entry->bitmap, BITS_PER_BITMAP) {
2833                next_zero = find_next_zero_bit(entry->bitmap,
2834                                               BITS_PER_BITMAP, i);
2835                if (next_zero - i >= min_bits) {
2836                        found_bits = next_zero - i;
2837                        if (found_bits > max_bits)
2838                                max_bits = found_bits;
2839                        break;
2840                }
2841                if (next_zero - i > max_bits)
2842                        max_bits = next_zero - i;
2843                i = next_zero;
2844        }
2845
2846        if (!found_bits) {
2847                entry->max_extent_size = (u64)max_bits * ctl->unit;
2848                return -ENOSPC;
2849        }
2850
2851        if (!total_found) {
2852                start = i;
2853                cluster->max_size = 0;
2854        }
2855
2856        total_found += found_bits;
2857
2858        if (cluster->max_size < found_bits * ctl->unit)
2859                cluster->max_size = found_bits * ctl->unit;
2860
2861        if (total_found < want_bits || cluster->max_size < cont1_bytes) {
2862                i = next_zero + 1;
2863                goto again;
2864        }
2865
2866        cluster->window_start = start * ctl->unit + entry->offset;
2867        rb_erase(&entry->offset_index, &ctl->free_space_offset);
2868        ret = tree_insert_offset(&cluster->root, entry->offset,
2869                                 &entry->offset_index, 1);
2870        ASSERT(!ret); /* -EEXIST; Logic error */
2871
2872        trace_btrfs_setup_cluster(block_group, cluster,
2873                                  total_found * ctl->unit, 1);
2874        return 0;
2875}
2876
2877/*
2878 * This searches the block group for just extents to fill the cluster with.
2879 * Try to find a cluster with at least bytes total bytes, at least one
2880 * extent of cont1_bytes, and other clusters of at least min_bytes.
2881 */
2882static noinline int
2883setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
2884                        struct btrfs_free_cluster *cluster,
2885                        struct list_head *bitmaps, u64 offset, u64 bytes,
2886                        u64 cont1_bytes, u64 min_bytes)
2887{
2888        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2889        struct btrfs_free_space *first = NULL;
2890        struct btrfs_free_space *entry = NULL;
2891        struct btrfs_free_space *last;
2892        struct rb_node *node;
2893        u64 window_free;
2894        u64 max_extent;
2895        u64 total_size = 0;
2896
2897        entry = tree_search_offset(ctl, offset, 0, 1);
2898        if (!entry)
2899                return -ENOSPC;
2900
2901        /*
2902         * We don't want bitmaps, so just move along until we find a normal
2903         * extent entry.
2904         */
2905        while (entry->bitmap || entry->bytes < min_bytes) {
2906                if (entry->bitmap && list_empty(&entry->list))
2907                        list_add_tail(&entry->list, bitmaps);
2908                node = rb_next(&entry->offset_index);
2909                if (!node)
2910                        return -ENOSPC;
2911                entry = rb_entry(node, struct btrfs_free_space, offset_index);
2912        }
2913
2914        window_free = entry->bytes;
2915        max_extent = entry->bytes;
2916        first = entry;
2917        last = entry;
2918
2919        for (node = rb_next(&entry->offset_index); node;
2920             node = rb_next(&entry->offset_index)) {
2921                entry = rb_entry(node, struct btrfs_free_space, offset_index);
2922
2923                if (entry->bitmap) {
2924                        if (list_empty(&entry->list))
2925                                list_add_tail(&entry->list, bitmaps);
2926                        continue;
2927                }
2928
2929                if (entry->bytes < min_bytes)
2930                        continue;
2931
2932                last = entry;
2933                window_free += entry->bytes;
2934                if (entry->bytes > max_extent)
2935                        max_extent = entry->bytes;
2936        }
2937
2938        if (window_free < bytes || max_extent < cont1_bytes)
2939                return -ENOSPC;
2940
2941        cluster->window_start = first->offset;
2942
2943        node = &first->offset_index;
2944
2945        /*
2946         * now we've found our entries, pull them out of the free space
2947         * cache and put them into the cluster rbtree
2948         */
2949        do {
2950                int ret;
2951
2952                entry = rb_entry(node, struct btrfs_free_space, offset_index);
2953                node = rb_next(&entry->offset_index);
2954                if (entry->bitmap || entry->bytes < min_bytes)
2955                        continue;
2956
2957                rb_erase(&entry->offset_index, &ctl->free_space_offset);
2958                ret = tree_insert_offset(&cluster->root, entry->offset,
2959                                         &entry->offset_index, 0);
2960                total_size += entry->bytes;
2961                ASSERT(!ret); /* -EEXIST; Logic error */
2962        } while (node && entry != last);
2963
2964        cluster->max_size = max_extent;
2965        trace_btrfs_setup_cluster(block_group, cluster, total_size, 0);
2966        return 0;
2967}
2968
2969/*
2970 * This specifically looks for bitmaps that may work in the cluster, we assume
2971 * that we have already failed to find extents that will work.
2972 */
2973static noinline int
2974setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
2975                     struct btrfs_free_cluster *cluster,
2976                     struct list_head *bitmaps, u64 offset, u64 bytes,
2977                     u64 cont1_bytes, u64 min_bytes)
2978{
2979        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
2980        struct btrfs_free_space *entry = NULL;
2981        int ret = -ENOSPC;
2982        u64 bitmap_offset = offset_to_bitmap(ctl, offset);
2983
2984        if (ctl->total_bitmaps == 0)
2985                return -ENOSPC;
2986
2987        /*
2988         * The bitmap that covers offset won't be in the list unless offset
2989         * is just its start offset.
2990         */
2991        if (!list_empty(bitmaps))
2992                entry = list_first_entry(bitmaps, struct btrfs_free_space, list);
2993
2994        if (!entry || entry->offset != bitmap_offset) {
2995                entry = tree_search_offset(ctl, bitmap_offset, 1, 0);
2996                if (entry && list_empty(&entry->list))
2997                        list_add(&entry->list, bitmaps);
2998        }
2999
3000        list_for_each_entry(entry, bitmaps, list) {
3001                if (entry->bytes < bytes)
3002                        continue;
3003                ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
3004                                           bytes, cont1_bytes, min_bytes);
3005                if (!ret)
3006                        return 0;
3007        }
3008
3009        /*
3010         * The bitmaps list has all the bitmaps that record free space
3011         * starting after offset, so no more search is required.
3012         */
3013        return -ENOSPC;
3014}
3015
3016/*
3017 * here we try to find a cluster of blocks in a block group.  The goal
3018 * is to find at least bytes+empty_size.
3019 * We might not find them all in one contiguous area.
3020 *
3021 * returns zero and sets up cluster if things worked out, otherwise
3022 * it returns -enospc
3023 */
3024int btrfs_find_space_cluster(struct btrfs_fs_info *fs_info,
3025                             struct btrfs_block_group_cache *block_group,
3026                             struct btrfs_free_cluster *cluster,
3027                             u64 offset, u64 bytes, u64 empty_size)
3028{
3029        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
3030        struct btrfs_free_space *entry, *tmp;
3031        LIST_HEAD(bitmaps);
3032        u64 min_bytes;
3033        u64 cont1_bytes;
3034        int ret;
3035
3036        /*
3037         * Choose the minimum extent size we'll require for this
3038         * cluster.  For SSD_SPREAD, don't allow any fragmentation.
3039         * For metadata, allow allocates with smaller extents.  For
3040         * data, keep it dense.
3041         */
3042        if (btrfs_test_opt(fs_info, SSD_SPREAD)) {
3043                cont1_bytes = min_bytes = bytes + empty_size;
3044        } else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
3045                cont1_bytes = bytes;
3046                min_bytes = fs_info->sectorsize;
3047        } else {
3048                cont1_bytes = max(bytes, (bytes + empty_size) >> 2);
3049                min_bytes = fs_info->sectorsize;
3050        }
3051
3052        spin_lock(&ctl->tree_lock);
3053
3054        /*
3055         * If we know we don't have enough space to make a cluster don't even
3056         * bother doing all the work to try and find one.
3057         */
3058        if (ctl->free_space < bytes) {
3059                spin_unlock(&ctl->tree_lock);
3060                return -ENOSPC;
3061        }
3062
3063        spin_lock(&cluster->lock);
3064
3065        /* someone already found a cluster, hooray */
3066        if (cluster->block_group) {
3067                ret = 0;
3068                goto out;
3069        }
3070
3071        trace_btrfs_find_cluster(block_group, offset, bytes, empty_size,
3072                                 min_bytes);
3073
3074        ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
3075                                      bytes + empty_size,
3076                                      cont1_bytes, min_bytes);
3077        if (ret)
3078                ret = setup_cluster_bitmap(block_group, cluster, &bitmaps,
3079                                           offset, bytes + empty_size,
3080                                           cont1_bytes, min_bytes);
3081
3082        /* Clear our temporary list */
3083        list_for_each_entry_safe(entry, tmp, &bitmaps, list)
3084                list_del_init(&entry->list);
3085
3086        if (!ret) {
3087                atomic_inc(&block_group->count);
3088                list_add_tail(&cluster->block_group_list,
3089                              &block_group->cluster_list);
3090                cluster->block_group = block_group;
3091        } else {
3092                trace_btrfs_failed_cluster_setup(block_group);
3093        }
3094out:
3095        spin_unlock(&cluster->lock);
3096        spin_unlock(&ctl->tree_lock);
3097
3098        return ret;
3099}
3100
3101/*
3102 * simple code to zero out a cluster
3103 */
3104void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
3105{
3106        spin_lock_init(&cluster->lock);
3107        spin_lock_init(&cluster->refill_lock);
3108        cluster->root = RB_ROOT;
3109        cluster->max_size = 0;
3110        cluster->fragmented = false;
3111        INIT_LIST_HEAD(&cluster->block_group_list);
3112        cluster->block_group = NULL;
3113}
3114
3115static int do_trimming(struct btrfs_block_group_cache *block_group,
3116                       u64 *total_trimmed, u64 start, u64 bytes,
3117                       u64 reserved_start, u64 reserved_bytes,
3118                       struct btrfs_trim_range *trim_entry)
3119{
3120        struct btrfs_space_info *space_info = block_group->space_info;
3121        struct btrfs_fs_info *fs_info = block_group->fs_info;
3122        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
3123        int ret;
3124        int update = 0;
3125        u64 trimmed = 0;
3126
3127        spin_lock(&space_info->lock);
3128        spin_lock(&block_group->lock);
3129        if (!block_group->ro) {
3130                block_group->reserved += reserved_bytes;
3131                space_info->bytes_reserved += reserved_bytes;
3132                update = 1;
3133        }
3134        spin_unlock(&block_group->lock);
3135        spin_unlock(&space_info->lock);
3136
3137        ret = btrfs_discard_extent(fs_info, start, bytes, &trimmed);
3138        if (!ret)
3139                *total_trimmed += trimmed;
3140
3141        mutex_lock(&ctl->cache_writeout_mutex);
3142        btrfs_add_free_space(block_group, reserved_start, reserved_bytes);
3143        list_del(&trim_entry->list);
3144        mutex_unlock(&ctl->cache_writeout_mutex);
3145
3146        if (update) {
3147                spin_lock(&space_info->lock);
3148                spin_lock(&block_group->lock);
3149                if (block_group->ro)
3150                        space_info->bytes_readonly += reserved_bytes;
3151                block_group->reserved -= reserved_bytes;
3152                space_info->bytes_reserved -= reserved_bytes;
3153                spin_unlock(&space_info->lock);
3154                spin_unlock(&block_group->lock);
3155        }
3156
3157        return ret;
3158}
3159
3160static int trim_no_bitmap(struct btrfs_block_group_cache *block_group,
3161                          u64 *total_trimmed, u64 start, u64 end, u64 minlen)
3162{
3163        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
3164        struct btrfs_free_space *entry;
3165        struct rb_node *node;
3166        int ret = 0;
3167        u64 extent_start;
3168        u64 extent_bytes;
3169        u64 bytes;
3170
3171        while (start < end) {
3172                struct btrfs_trim_range trim_entry;
3173
3174                mutex_lock(&ctl->cache_writeout_mutex);
3175                spin_lock(&ctl->tree_lock);
3176
3177                if (ctl->free_space < minlen) {
3178                        spin_unlock(&ctl->tree_lock);
3179                        mutex_unlock(&ctl->cache_writeout_mutex);
3180                        break;
3181                }
3182
3183                entry = tree_search_offset(ctl, start, 0, 1);
3184                if (!entry) {
3185                        spin_unlock(&ctl->tree_lock);
3186                        mutex_unlock(&ctl->cache_writeout_mutex);
3187                        break;
3188                }
3189
3190                /* skip bitmaps */
3191                while (entry->bitmap) {
3192                        node = rb_next(&entry->offset_index);
3193                        if (!node) {
3194                                spin_unlock(&ctl->tree_lock);
3195                                mutex_unlock(&ctl->cache_writeout_mutex);
3196                                goto out;
3197                        }
3198                        entry = rb_entry(node, struct btrfs_free_space,
3199                                         offset_index);
3200                }
3201
3202                if (entry->offset >= end) {
3203                        spin_unlock(&ctl->tree_lock);
3204                        mutex_unlock(&ctl->cache_writeout_mutex);
3205                        break;
3206                }
3207
3208                extent_start = entry->offset;
3209                extent_bytes = entry->bytes;
3210                start = max(start, extent_start);
3211                bytes = min(extent_start + extent_bytes, end) - start;
3212                if (bytes < minlen) {
3213                        spin_unlock(&ctl->tree_lock);
3214                        mutex_unlock(&ctl->cache_writeout_mutex);
3215                        goto next;
3216                }
3217
3218                unlink_free_space(ctl, entry);
3219                kmem_cache_free(btrfs_free_space_cachep, entry);
3220
3221                spin_unlock(&ctl->tree_lock);
3222                trim_entry.start = extent_start;
3223                trim_entry.bytes = extent_bytes;
3224                list_add_tail(&trim_entry.list, &ctl->trimming_ranges);
3225                mutex_unlock(&ctl->cache_writeout_mutex);
3226
3227                ret = do_trimming(block_group, total_trimmed, start, bytes,
3228                                  extent_start, extent_bytes, &trim_entry);
3229                if (ret)
3230                        break;
3231next:
3232                start += bytes;
3233
3234                if (fatal_signal_pending(current)) {
3235                        ret = -ERESTARTSYS;
3236                        break;
3237                }
3238
3239                cond_resched();
3240        }
3241out:
3242        return ret;
3243}
3244
3245static int trim_bitmaps(struct btrfs_block_group_cache *block_group,
3246                        u64 *total_trimmed, u64 start, u64 end, u64 minlen)
3247{
3248        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
3249        struct btrfs_free_space *entry;
3250        int ret = 0;
3251        int ret2;
3252        u64 bytes;
3253        u64 offset = offset_to_bitmap(ctl, start);
3254
3255        while (offset < end) {
3256                bool next_bitmap = false;
3257                struct btrfs_trim_range trim_entry;
3258
3259                mutex_lock(&ctl->cache_writeout_mutex);
3260                spin_lock(&ctl->tree_lock);
3261
3262                if (ctl->free_space < minlen) {
3263                        spin_unlock(&ctl->tree_lock);
3264                        mutex_unlock(&ctl->cache_writeout_mutex);
3265                        break;
3266                }
3267
3268                entry = tree_search_offset(ctl, offset, 1, 0);
3269                if (!entry) {
3270                        spin_unlock(&ctl->tree_lock);
3271                        mutex_unlock(&ctl->cache_writeout_mutex);
3272                        next_bitmap = true;
3273                        goto next;
3274                }
3275
3276                bytes = minlen;
3277                ret2 = search_bitmap(ctl, entry, &start, &bytes, false);
3278                if (ret2 || start >= end) {
3279                        spin_unlock(&ctl->tree_lock);
3280                        mutex_unlock(&ctl->cache_writeout_mutex);
3281                        next_bitmap = true;
3282                        goto next;
3283                }
3284
3285                bytes = min(bytes, end - start);
3286                if (bytes < minlen) {
3287                        spin_unlock(&ctl->tree_lock);
3288                        mutex_unlock(&ctl->cache_writeout_mutex);
3289                        goto next;
3290                }
3291
3292                bitmap_clear_bits(ctl, entry, start, bytes);
3293                if (entry->bytes == 0)
3294                        free_bitmap(ctl, entry);
3295
3296                spin_unlock(&ctl->tree_lock);
3297                trim_entry.start = start;
3298                trim_entry.bytes = bytes;
3299                list_add_tail(&trim_entry.list, &ctl->trimming_ranges);
3300                mutex_unlock(&ctl->cache_writeout_mutex);
3301
3302                ret = do_trimming(block_group, total_trimmed, start, bytes,
3303                                  start, bytes, &trim_entry);
3304                if (ret)
3305                        break;
3306next:
3307                if (next_bitmap) {
3308                        offset += BITS_PER_BITMAP * ctl->unit;
3309                } else {
3310                        start += bytes;
3311                        if (start >= offset + BITS_PER_BITMAP * ctl->unit)
3312                                offset += BITS_PER_BITMAP * ctl->unit;
3313                }
3314
3315                if (fatal_signal_pending(current)) {
3316                        ret = -ERESTARTSYS;
3317                        break;
3318                }
3319
3320                cond_resched();
3321        }
3322
3323        return ret;
3324}
3325
3326void btrfs_get_block_group_trimming(struct btrfs_block_group_cache *cache)
3327{
3328        atomic_inc(&cache->trimming);
3329}
3330
3331void btrfs_put_block_group_trimming(struct btrfs_block_group_cache *block_group)
3332{
3333        struct btrfs_fs_info *fs_info = block_group->fs_info;
3334        struct extent_map_tree *em_tree;
3335        struct extent_map *em;
3336        bool cleanup;
3337
3338        spin_lock(&block_group->lock);
3339        cleanup = (atomic_dec_and_test(&block_group->trimming) &&
3340                   block_group->removed);
3341        spin_unlock(&block_group->lock);
3342
3343        if (cleanup) {
3344                mutex_lock(&fs_info->chunk_mutex);
3345                em_tree = &fs_info->mapping_tree.map_tree;
3346                write_lock(&em_tree->lock);
3347                em = lookup_extent_mapping(em_tree, block_group->key.objectid,
3348                                           1);
3349                BUG_ON(!em); /* logic error, can't happen */
3350                /*
3351                 * remove_extent_mapping() will delete us from the pinned_chunks
3352                 * list, which is protected by the chunk mutex.
3353                 */
3354                remove_extent_mapping(em_tree, em);
3355                write_unlock(&em_tree->lock);
3356                mutex_unlock(&fs_info->chunk_mutex);
3357
3358                /* once for us and once for the tree */
3359                free_extent_map(em);
3360                free_extent_map(em);
3361
3362                /*
3363                 * We've left one free space entry and other tasks trimming
3364                 * this block group have left 1 entry each one. Free them.
3365                 */
3366                __btrfs_remove_free_space_cache(block_group->free_space_ctl);
3367        }
3368}
3369
3370int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
3371                           u64 *trimmed, u64 start, u64 end, u64 minlen)
3372{
3373        int ret;
3374
3375        *trimmed = 0;
3376
3377        spin_lock(&block_group->lock);
3378        if (block_group->removed) {
3379                spin_unlock(&block_group->lock);
3380                return 0;
3381        }
3382        btrfs_get_block_group_trimming(block_group);
3383        spin_unlock(&block_group->lock);
3384
3385        ret = trim_no_bitmap(block_group, trimmed, start, end, minlen);
3386        if (ret)
3387                goto out;
3388
3389        ret = trim_bitmaps(block_group, trimmed, start, end, minlen);
3390out:
3391        btrfs_put_block_group_trimming(block_group);
3392        return ret;
3393}
3394
3395/*
3396 * Find the left-most item in the cache tree, and then return the
3397 * smallest inode number in the item.
3398 *
3399 * Note: the returned inode number may not be the smallest one in
3400 * the tree, if the left-most item is a bitmap.
3401 */
3402u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root)
3403{
3404        struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl;
3405        struct btrfs_free_space *entry = NULL;
3406        u64 ino = 0;
3407
3408        spin_lock(&ctl->tree_lock);
3409
3410        if (RB_EMPTY_ROOT(&ctl->free_space_offset))
3411                goto out;
3412
3413        entry = rb_entry(rb_first(&ctl->free_space_offset),
3414                         struct btrfs_free_space, offset_index);
3415
3416        if (!entry->bitmap) {
3417                ino = entry->offset;
3418
3419                unlink_free_space(ctl, entry);
3420                entry->offset++;
3421                entry->bytes--;
3422                if (!entry->bytes)
3423                        kmem_cache_free(btrfs_free_space_cachep, entry);
3424                else
3425                        link_free_space(ctl, entry);
3426        } else {
3427                u64 offset = 0;
3428                u64 count = 1;
3429                int ret;
3430
3431                ret = search_bitmap(ctl, entry, &offset, &count, true);
3432                /* Logic error; Should be empty if it can't find anything */
3433                ASSERT(!ret);
3434
3435                ino = offset;
3436                bitmap_clear_bits(ctl, entry, offset, 1);
3437                if (entry->bytes == 0)
3438                        free_bitmap(ctl, entry);
3439        }
3440out:
3441        spin_unlock(&ctl->tree_lock);
3442
3443        return ino;
3444}
3445
3446struct inode *lookup_free_ino_inode(struct btrfs_root *root,
3447                                    struct btrfs_path *path)
3448{
3449        struct inode *inode = NULL;
3450
3451        spin_lock(&root->ino_cache_lock);
3452        if (root->ino_cache_inode)
3453                inode = igrab(root->ino_cache_inode);
3454        spin_unlock(&root->ino_cache_lock);
3455        if (inode)
3456                return inode;
3457
3458        inode = __lookup_free_space_inode(root, path, 0);
3459        if (IS_ERR(inode))
3460                return inode;
3461
3462        spin_lock(&root->ino_cache_lock);
3463        if (!btrfs_fs_closing(root->fs_info))
3464                root->ino_cache_inode = igrab(inode);
3465        spin_unlock(&root->ino_cache_lock);
3466
3467        return inode;
3468}
3469
3470int create_free_ino_inode(struct btrfs_root *root,
3471                          struct btrfs_trans_handle *trans,
3472                          struct btrfs_path *path)
3473{
3474        return __create_free_space_inode(root, trans, path,
3475                                         BTRFS_FREE_INO_OBJECTID, 0);
3476}
3477
3478int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
3479{
3480        struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
3481        struct btrfs_path *path;
3482        struct inode *inode;
3483        int ret = 0;
3484        u64 root_gen = btrfs_root_generation(&root->root_item);
3485
3486        if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
3487                return 0;
3488
3489        /*
3490         * If we're unmounting then just return, since this does a search on the
3491         * normal root and not the commit root and we could deadlock.
3492         */
3493        if (btrfs_fs_closing(fs_info))
3494                return 0;
3495
3496        path = btrfs_alloc_path();
3497        if (!path)
3498                return 0;
3499
3500        inode = lookup_free_ino_inode(root, path);
3501        if (IS_ERR(inode))
3502                goto out;
3503
3504        if (root_gen != BTRFS_I(inode)->generation)
3505                goto out_put;
3506
3507        ret = __load_free_space_cache(root, inode, ctl, path, 0);
3508
3509        if (ret < 0)
3510                btrfs_err(fs_info,
3511                        "failed to load free ino cache for root %llu",
3512                        root->root_key.objectid);
3513out_put:
3514        iput(inode);
3515out:
3516        btrfs_free_path(path);
3517        return ret;
3518}
3519
3520int btrfs_write_out_ino_cache(struct btrfs_root *root,
3521                              struct btrfs_trans_handle *trans,
3522                              struct btrfs_path *path,
3523                              struct inode *inode)
3524{
3525        struct btrfs_fs_info *fs_info = root->fs_info;
3526        struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
3527        int ret;
3528        struct btrfs_io_ctl io_ctl;
3529        bool release_metadata = true;
3530
3531        if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
3532                return 0;
3533
3534        memset(&io_ctl, 0, sizeof(io_ctl));
3535        ret = __btrfs_write_out_cache(root, inode, ctl, NULL, &io_ctl, trans);
3536        if (!ret) {
3537                /*
3538                 * At this point writepages() didn't error out, so our metadata
3539                 * reservation is released when the writeback finishes, at
3540                 * inode.c:btrfs_finish_ordered_io(), regardless of it finishing
3541                 * with or without an error.
3542                 */
3543                release_metadata = false;
3544                ret = btrfs_wait_cache_io_root(root, trans, &io_ctl, path);
3545        }
3546
3547        if (ret) {
3548                if (release_metadata)
3549                        btrfs_delalloc_release_metadata(BTRFS_I(inode),
3550                                        inode->i_size);
3551#ifdef DEBUG
3552                btrfs_err(fs_info,
3553                          "failed to write free ino cache for root %llu",
3554                          root->root_key.objectid);
3555#endif
3556        }
3557
3558        return ret;
3559}
3560
3561#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
3562/*
3563 * Use this if you need to make a bitmap or extent entry specifically, it
3564 * doesn't do any of the merging that add_free_space does, this acts a lot like
3565 * how the free space cache loading stuff works, so you can get really weird
3566 * configurations.
3567 */
3568int test_add_free_space_entry(struct btrfs_block_group_cache *cache,
3569                              u64 offset, u64 bytes, bool bitmap)
3570{
3571        struct btrfs_free_space_ctl *ctl = cache->free_space_ctl;
3572        struct btrfs_free_space *info = NULL, *bitmap_info;
3573        void *map = NULL;
3574        u64 bytes_added;
3575        int ret;
3576
3577again:
3578        if (!info) {
3579                info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
3580                if (!info)
3581                        return -ENOMEM;
3582        }
3583
3584        if (!bitmap) {
3585                spin_lock(&ctl->tree_lock);
3586                info->offset = offset;
3587                info->bytes = bytes;
3588                info->max_extent_size = 0;
3589                ret = link_free_space(ctl, info);
3590                spin_unlock(&ctl->tree_lock);
3591                if (ret)
3592                        kmem_cache_free(btrfs_free_space_cachep, info);
3593                return ret;
3594        }
3595
3596        if (!map) {
3597                map = kzalloc(PAGE_SIZE, GFP_NOFS);
3598                if (!map) {
3599                        kmem_cache_free(btrfs_free_space_cachep, info);
3600                        return -ENOMEM;
3601                }
3602        }
3603
3604        spin_lock(&ctl->tree_lock);
3605        bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
3606                                         1, 0);
3607        if (!bitmap_info) {
3608                info->bitmap = map;
3609                map = NULL;
3610                add_new_bitmap(ctl, info, offset);
3611                bitmap_info = info;
3612                info = NULL;
3613        }
3614
3615        bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
3616
3617        bytes -= bytes_added;
3618        offset += bytes_added;
3619        spin_unlock(&ctl->tree_lock);
3620
3621        if (bytes)
3622                goto again;
3623
3624        if (info)
3625                kmem_cache_free(btrfs_free_space_cachep, info);
3626        if (map)
3627                kfree(map);
3628        return 0;
3629}
3630
3631/*
3632 * Checks to see if the given range is in the free space cache.  This is really
3633 * just used to check the absence of space, so if there is free space in the
3634 * range at all we will return 1.
3635 */
3636int test_check_exists(struct btrfs_block_group_cache *cache,
3637                      u64 offset, u64 bytes)
3638{
3639        struct btrfs_free_space_ctl *ctl = cache->free_space_ctl;
3640        struct btrfs_free_space *info;
3641        int ret = 0;
3642
3643        spin_lock(&ctl->tree_lock);
3644        info = tree_search_offset(ctl, offset, 0, 0);
3645        if (!info) {
3646                info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
3647                                          1, 0);
3648                if (!info)
3649                        goto out;
3650        }
3651
3652have_info:
3653        if (info->bitmap) {
3654                u64 bit_off, bit_bytes;
3655                struct rb_node *n;
3656                struct btrfs_free_space *tmp;
3657
3658                bit_off = offset;
3659                bit_bytes = ctl->unit;
3660                ret = search_bitmap(ctl, info, &bit_off, &bit_bytes, false);
3661                if (!ret) {
3662                        if (bit_off == offset) {
3663                                ret = 1;
3664                                goto out;
3665                        } else if (bit_off > offset &&
3666                                   offset + bytes > bit_off) {
3667                                ret = 1;
3668                                goto out;
3669                        }
3670                }
3671
3672                n = rb_prev(&info->offset_index);
3673                while (n) {
3674                        tmp = rb_entry(n, struct btrfs_free_space,
3675                                       offset_index);
3676                        if (tmp->offset + tmp->bytes < offset)
3677                                break;
3678                        if (offset + bytes < tmp->offset) {
3679                                n = rb_prev(&tmp->offset_index);
3680                                continue;
3681                        }
3682                        info = tmp;
3683                        goto have_info;
3684                }
3685
3686                n = rb_next(&info->offset_index);
3687                while (n) {
3688                        tmp = rb_entry(n, struct btrfs_free_space,
3689                                       offset_index);
3690                        if (offset + bytes < tmp->offset)
3691                                break;
3692                        if (tmp->offset + tmp->bytes < offset) {
3693                                n = rb_next(&tmp->offset_index);
3694                                continue;
3695                        }
3696                        info = tmp;
3697                        goto have_info;
3698                }
3699
3700                ret = 0;
3701                goto out;
3702        }
3703
3704        if (info->offset == offset) {
3705                ret = 1;
3706                goto out;
3707        }
3708
3709        if (offset > info->offset && offset < info->offset + info->bytes)
3710                ret = 1;
3711out:
3712        spin_unlock(&ctl->tree_lock);
3713        return ret;
3714}
3715#endif /* CONFIG_BTRFS_FS_RUN_SANITY_TESTS */
3716