free-space-tree.c

   1 /*
   2  * Copyright (C) 2015 Facebook.  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 "ctree.h"
  20 #include "disk-io.h"
  21 #include "free-space-cache.h"
  22 #include "free-space-tree.h"
  23
  24 static struct btrfs_free_space_info *
  25 search_free_space_info(struct btrfs_trans_handle *trans,
  26                        struct btrfs_fs_info *fs_info,
  27                        struct btrfs_block_group_cache *block_group,
  28                        struct btrfs_path *path, int cow)
  29 {
  30         struct btrfs_root *root = fs_info->free_space_root;
  31         struct btrfs_key key;
  32         int ret;
  33
  34         key.objectid = block_group->key.objectid;
  35         key.type = BTRFS_FREE_SPACE_INFO_KEY;
  36         key.offset = block_group->key.offset;
  37
  38         ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
  39         if (ret < 0)
  40                 return ERR_PTR(ret);
  41         if (ret != 0)
  42                 return ERR_PTR(-ENOENT);
  43
  44         return btrfs_item_ptr(path->nodes[0], path->slots[0],
  45                               struct btrfs_free_space_info);
  46 }
  47
  48 static int free_space_test_bit(struct btrfs_block_group_cache *block_group,
  49                                struct btrfs_path *path, u64 offset,
  50                                u64 sectorsize)
  51 {
  52         struct extent_buffer *leaf;
  53         struct btrfs_key key;
  54         u64 found_start, found_end;
  55         unsigned long ptr, i;
  56
  57         leaf = path->nodes[0];
  58         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
  59         ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
  60
  61         found_start = key.objectid;
  62         found_end = key.objectid + key.offset;
  63         ASSERT(offset >= found_start && offset < found_end);
  64
  65         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
  66         i = (offset - found_start) / sectorsize;
  67         return !!extent_buffer_test_bit(leaf, ptr, i);
  68 }
  69
  70 static int load_free_space_bitmaps(struct btrfs_fs_info *fs_info,
  71                                    struct btrfs_block_group_cache *block_group,
  72                                    struct btrfs_path *path,
  73                                    u32 expected_extent_count,
  74                                    int *errors)
  75 {
  76         struct btrfs_root *root = fs_info->free_space_root;
  77         struct btrfs_key key;
  78         int prev_bit = 0, bit;
  79         u64 extent_start = 0;
  80         u64 start, end, offset;
  81         u32 extent_count = 0;
  82         int ret;
  83
  84         start = block_group->key.objectid;
  85         end = block_group->key.objectid + block_group->key.offset;
  86
  87         while (1) {
  88                 ret = btrfs_next_item(root, path);
  89                 if (ret < 0)
  90                         goto out;
  91                 if (ret)
  92                         break;
  93
  94                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
  95
  96                 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
  97                         break;
  98
  99                 if (key.type != BTRFS_FREE_SPACE_BITMAP_KEY) {
 100                         fprintf(stderr, "unexpected key of type %u\n", key.type);
 101                         (*errors)++;
 102                         break;
 103                 }
 104                 if (key.objectid >= end) {
 105                         fprintf(stderr,
 106         "free space bitmap starts at %llu, beyond end of block group %llu-%llu\n",
 107                                 key.objectid, start, end);
 108                         (*errors)++;
 109                         break;
 110                 }
 111                 if (key.objectid + key.offset > end) {
 112                         fprintf(stderr,
 113         "free space bitmap ends at %llu, beyond end of block group %llu-%llu\n",
 114                                 key.objectid, start, end);
 115                         (*errors)++;
 116                         break;
 117                 }
 118
 119                 offset = key.objectid;
 120                 while (offset < key.objectid + key.offset) {
 121                         bit = free_space_test_bit(block_group, path, offset,
 122                                                   root->sectorsize);
 123                         if (prev_bit == 0 && bit == 1) {
 124                                 extent_start = offset;
 125                         } else if (prev_bit == 1 && bit == 0) {
 126                                 add_new_free_space(block_group, fs_info, extent_start, offset);
 127                                 extent_count++;
 128                         }
 129                         prev_bit = bit;
 130                         offset += root->sectorsize;
 131                 }
 132         }
 133
 134         if (prev_bit == 1) {
 135                 add_new_free_space(block_group, fs_info, extent_start, end);
 136                 extent_count++;
 137         }
 138
 139         if (extent_count != expected_extent_count) {
 140                 fprintf(stderr, "free space info recorded %u extents, counted %u\n",
 141                         expected_extent_count, extent_count);
 142                 (*errors)++;
 143         }
 144
 145         ret = 0;
 146 out:
 147         return ret;
 148 }
 149
 150 static int load_free_space_extents(struct btrfs_fs_info *fs_info,
 151                                    struct btrfs_block_group_cache *block_group,
 152                                    struct btrfs_path *path,
 153                                    u32 expected_extent_count,
 154                                    int *errors)
 155 {
 156         struct btrfs_root *root = fs_info->free_space_root;
 157         struct btrfs_key key, prev_key;
 158         int have_prev = 0;
 159         u64 start, end;
 160         u32 extent_count = 0;
 161         int ret;
 162
 163         start = block_group->key.objectid;
 164         end = block_group->key.objectid + block_group->key.offset;
 165
 166         while (1) {
 167                 ret = btrfs_next_item(root, path);
 168                 if (ret < 0)
 169                         goto out;
 170                 if (ret)
 171                         break;
 172
 173                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 174
 175                 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
 176                         break;
 177
 178                 if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
 179                         fprintf(stderr, "unexpected key of type %u\n", key.type);
 180                         (*errors)++;
 181                         break;
 182                 }
 183                 if (key.objectid >= end) {
 184                         fprintf(stderr,
 185         "free space extent starts at %llu, beyond end of block group %llu-%llu\n",
 186                                 key.objectid, start, end);
 187                         (*errors)++;
 188                         break;
 189                 }
 190                 if (key.objectid + key.offset > end) {
 191                         fprintf(stderr,
 192         "free space extent ends at %llu, beyond end of block group %llu-%llu\n",
 193                                 key.objectid, start, end);
 194                         (*errors)++;
 195                         break;
 196                 }
 197
 198                 if (have_prev) {
 199                         u64 cur_start = key.objectid;
 200                         u64 cur_end = cur_start + key.offset;
 201                         u64 prev_start = prev_key.objectid;
 202                         u64 prev_end = prev_start + prev_key.offset;
 203
 204                         if (cur_start < prev_end) {
 205                                 fprintf(stderr,
 206         "free space extent %llu-%llu overlaps with previous %llu-%llu\n",
 207                                         cur_start, cur_end,
 208                                         prev_start, prev_end);
 209                                 (*errors)++;
 210                         } else if (cur_start == prev_end) {
 211                                 fprintf(stderr,
 212         "free space extent %llu-%llu is unmerged with previous %llu-%llu\n",
 213                                         cur_start, cur_end,
 214                                         prev_start, prev_end);
 215                                 (*errors)++;
 216                         }
 217                 }
 218
 219                 add_new_free_space(block_group, fs_info, key.objectid, key.objectid + key.offset);
 220                 extent_count++;
 221
 222                 prev_key = key;
 223                 have_prev = 1;
 224         }
 225
 226         if (extent_count != expected_extent_count) {
 227                 fprintf(stderr, "free space info recorded %u extents, counted %u\n",
 228                         expected_extent_count, extent_count);
 229                 (*errors)++;
 230         }
 231
 232         ret = 0;
 233 out:
 234         return ret;
 235 }
 236
 237 int load_free_space_tree(struct btrfs_fs_info *fs_info,
 238                          struct btrfs_block_group_cache *block_group)
 239 {
 240         struct btrfs_free_space_info *info;
 241         struct btrfs_path *path;
 242         u32 extent_count, flags;
 243         int errors = 0;
 244         int ret;
 245
 246         path = btrfs_alloc_path();
 247         if (!path)
 248                 return -ENOMEM;
 249         path->reada = 1;
 250
 251         info = search_free_space_info(NULL, fs_info, block_group, path, 0);
 252         if (IS_ERR(info)) {
 253                 ret = PTR_ERR(info);
 254                 goto out;
 255         }
 256         extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
 257         flags = btrfs_free_space_flags(path->nodes[0], info);
 258
 259         if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
 260                 ret = load_free_space_bitmaps(fs_info, block_group, path,
 261                                               extent_count, &errors);
 262         } else {
 263                 ret = load_free_space_extents(fs_info, block_group, path,
 264                                               extent_count, &errors);
 265         }
 266         if (ret)
 267                 goto out;
 268
 269         ret = 0;
 270 out:
 271         btrfs_free_path(path);
 272         return ret ? ret : errors;
 273 }