find-root.c

   1 /*
   2  * Copyright (C) 2015 Fujitsu.  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 "kerncompat.h"
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include "ctree.h"
  24 #include "utils.h"
  25 #include "find-root.h"
  26 #include "volumes.h"
  27 #include "disk-io.h"
  28 #include "extent-cache.h"
  29
  30 /* Return value is the same as btrfs_find_root_search(). */
  31 static int add_eb_to_result(struct extent_buffer *eb,
  32                             struct cache_tree *result,
  33                             u32 nodesize,
  34                             struct btrfs_find_root_filter *filter,
  35                             struct cache_extent **match)
  36 {
  37         u64 generation = btrfs_header_generation(eb);
  38         u64 level = btrfs_header_level(eb);
  39         u64 owner = btrfs_header_owner(eb);
  40         u64 start = eb->start;
  41         struct cache_extent *cache;
  42         struct btrfs_find_root_gen_cache *gen_cache = NULL;
  43         int ret = 0;
  44
  45         if (owner != filter->objectid || level < filter->level ||
  46             generation < filter->generation)
  47                 return ret;
  48
  49         /*
  50          * Get the generation cache or create one
  51          *
  52          * NOTE: search_cache_extent() may return cache that doesn't cover
  53          * the range. So we need an extra check to make sure it's the right one.
  54          */
  55         cache = search_cache_extent(result, generation);
  56         if (!cache || cache->start != generation) {
  57                 gen_cache = malloc(sizeof(*gen_cache));
  58                 BUG_ON(!gen_cache);
  59                 cache = &gen_cache->cache;
  60                 cache->start = generation;
  61                 cache->size = 1;
  62                 cache->objectid = 0;
  63                 gen_cache->highest_level = 0;
  64                 cache_tree_init(&gen_cache->eb_tree);
  65
  66                 ret = insert_cache_extent(result, cache);
  67                 if (ret < 0)
  68                         return ret;
  69         }
  70         gen_cache = container_of(cache, struct btrfs_find_root_gen_cache,
  71                                  cache);
  72
  73         /* Higher level, clean tree and insert the new one */
  74         if (level > gen_cache->highest_level) {
  75                 free_extent_cache_tree(&gen_cache->eb_tree);
  76                 gen_cache->highest_level = level;
  77                 /* Fall into the insert routine */
  78         }
  79
  80         /* Same level, insert it into the eb_tree */
  81         if (level == gen_cache->highest_level) {
  82                 ret = add_cache_extent(&gen_cache->eb_tree,
  83                                        start, nodesize);
  84                 if (ret < 0 && ret != -EEXIST)
  85                         return ret;
  86                 ret = 0;
  87         }
  88         if (generation == filter->match_gen &&
  89             level == filter->match_level &&
  90             !filter->search_all) {
  91                 ret = 1;
  92                 if (match)
  93                         *match = search_cache_extent(&gen_cache->eb_tree,
  94                                                      start);
  95         }
  96         return ret;
  97 }
  98
  99 /*
 100  * Return 0 if iterating all the metadata extents.
 101  * Return 1 if found root with given gen/level and set *match to it.
 102  * Return <0 if error happens
 103  */
 104 int btrfs_find_root_search(struct btrfs_fs_info *fs_info,
 105                            struct btrfs_find_root_filter *filter,
 106                            struct cache_tree *result,
 107                            struct cache_extent **match)
 108 {
 109         struct extent_buffer *eb;
 110         u64 chunk_offset = 0;
 111         u64 chunk_size = 0;
 112         u64 offset = 0;
 113         u32 nodesize = btrfs_super_nodesize(fs_info->super_copy);
 114         int suppress_errors = 0;
 115         int ret = 0;
 116
 117         suppress_errors = fs_info->suppress_check_block_errors;
 118         fs_info->suppress_check_block_errors = 1;
 119         while (1) {
 120                 if (filter->objectid != BTRFS_CHUNK_TREE_OBJECTID)
 121                         ret = btrfs_next_bg_metadata(fs_info,
 122                                                   &chunk_offset,
 123                                                   &chunk_size);
 124                 else
 125                         ret = btrfs_next_bg_system(fs_info,
 126                                                 &chunk_offset,
 127                                                 &chunk_size);
 128                 if (ret) {
 129                         if (ret == -ENOENT)
 130                                 ret = 0;
 131                         break;
 132                 }
 133                 for (offset = chunk_offset;
 134                      offset < chunk_offset + chunk_size;
 135                      offset += nodesize) {
 136                         eb = read_tree_block(fs_info, offset, 0);
 137                         if (!eb || IS_ERR(eb))
 138                                 continue;
 139                         ret = add_eb_to_result(eb, result, nodesize, filter,
 140                                                match);
 141                         free_extent_buffer(eb);
 142                         if (ret)
 143                                 goto out;
 144                 }
 145         }
 146 out:
 147         fs_info->suppress_check_block_errors = suppress_errors;
 148         return ret;
 149 }