btrfs-find-root.c

   1 /*
   2  * Copyright (C) 2011 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 <stdio.h>
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22 #include <fcntl.h>
  23 #include <sys/stat.h>
  24 #include <zlib.h>
  25 #include "kerncompat.h"
  26 #include "ctree.h"
  27 #include "disk-io.h"
  28 #include "print-tree.h"
  29 #include "transaction.h"
  30 #include "list.h"
  31 #include "volumes.h"
  32 #include "utils.h"
  33 #include "crc32c.h"
  34 #include "extent-cache.h"
  35 #include "find-root.h"
  36
  37 static void usage(void)
  38 {
  39         fprintf(stderr, "Usage: find-roots [-a] [-o search_objectid] "
  40                 "[ -g search_generation ] [ -l search_level ] <device>\n");
  41 }
  42
  43 /*
  44  * Get reliable generation and level for given root.
  45  *
  46  * We have two sources of gen/level: superblock and tree root.
  47  * superblock include the following level:
  48  *   Root, chunk, log
  49  * and the following generations:
  50  *   Root, chunk, uuid
  51  * Other gen/leven can only be read from its btrfs_tree_root if possible.
  52  *
  53  * Currently we only believe things from superblock.
  54  */
  55 static void get_root_gen_and_level(u64 objectid, struct btrfs_fs_info *fs_info,
  56                                    u64 *ret_gen, u8 *ret_level)
  57 {
  58         struct btrfs_super_block *super = fs_info->super_copy;
  59         u64 gen = (u64)-1;
  60         u8 level = (u8)-1;
  61
  62         switch (objectid) {
  63         case BTRFS_ROOT_TREE_OBJECTID:
  64                 level = btrfs_super_root_level(super);
  65                 gen = btrfs_super_generation(super);
  66                 break;
  67         case BTRFS_CHUNK_TREE_OBJECTID:
  68                 level = btrfs_super_chunk_root_level(super);
  69                 gen = btrfs_super_chunk_root_generation(super);
  70                 printf("Search for chunk root is not supported yet\n");
  71                 break;
  72         case BTRFS_TREE_LOG_OBJECTID:
  73                 level = btrfs_super_log_root_level(super);
  74                 gen = btrfs_super_log_root_transid(super);
  75                 break;
  76         case BTRFS_UUID_TREE_OBJECTID:
  77                 gen = btrfs_super_uuid_tree_generation(super);
  78                 break;
  79         }
  80         if (gen != (u64)-1) {
  81                 printf("Superblock thinks the generation is %llu\n", gen);
  82                 if (ret_gen)
  83                         *ret_gen = gen;
  84         } else {
  85                 printf("Superblock doesn't contain generation info for root %llu\n",
  86                        objectid);
  87         }
  88         if (level != (u8)-1) {
  89                 printf("Superblock thinks the level is %u\n", level);
  90                 if (ret_level)
  91                         *ret_level = level;
  92         } else {
  93                 printf("Superblock doesn't contain the level info for root %llu\n",
  94                        objectid);
  95         }
  96 }
  97
  98 static void print_one_result(struct cache_extent *tree_block,
  99                              u8 level, u64 generation,
 100                              struct btrfs_find_root_filter *filter)
 101 {
 102         int unsure = 0;
 103
 104         if (filter->match_gen == (u64)-1 || filter->match_level == (u8)-1)
 105                 unsure = 1;
 106         printf("Well block %llu(gen: %llu level: %u) seems good, ",
 107                tree_block->start, generation, level);
 108         if (unsure)
 109                 printf("but we are unsure about the correct generation/level\n");
 110         else
 111                 printf("but generation/level doesn't match, want gen: %llu level: %u\n",
 112                        filter->match_gen, filter->match_level);
 113 }
 114
 115 static void print_find_root_result(struct cache_tree *result,
 116                                    struct btrfs_find_root_filter *filter)
 117 {
 118         struct btrfs_find_root_gen_cache *gen_cache;
 119         struct cache_extent *cache;
 120         struct cache_extent *tree_block;
 121         u64 generation = 0;
 122         u8 level = 0;
 123
 124         for (cache = last_cache_extent(result);
 125              cache; cache = prev_cache_extent(cache)) {
 126                 gen_cache = container_of(cache,
 127                                 struct btrfs_find_root_gen_cache, cache);
 128                 level = gen_cache->highest_level;
 129                 generation = cache->start;
 130                 if (level == filter->match_level &&
 131                     generation == filter->match_gen)
 132                         continue;
 133                 for (tree_block = last_cache_extent(&gen_cache->eb_tree);
 134                      tree_block; tree_block = prev_cache_extent(tree_block))
 135                         print_one_result(tree_block, level, generation, filter);
 136         }
 137 }
 138
 139 int main(int argc, char **argv)
 140 {
 141         struct btrfs_root *root;
 142         struct btrfs_find_root_filter filter = {0};
 143         struct cache_tree result;
 144         struct cache_extent *found;
 145         int opt;
 146         int ret;
 147
 148         /* Default to search root tree */
 149         filter.objectid = BTRFS_ROOT_TREE_OBJECTID;
 150         filter.match_gen = (u64)-1;
 151         filter.match_level = (u8)-1;
 152         while ((opt = getopt(argc, argv, "al:o:g:")) != -1) {
 153                 switch(opt) {
 154                 case 'a':
 155                         filter.search_all = 1;
 156                         break;
 157                 case 'o':
 158                         filter.objectid = arg_strtou64(optarg);
 159                         break;
 160                 case 'g':
 161                         filter.generation = arg_strtou64(optarg);
 162                         break;
 163                 case 'l':
 164                         filter.level = arg_strtou64(optarg);
 165                         break;
 166                 default:
 167                         usage();
 168                         exit(1);
 169                 }
 170         }
 171
 172         set_argv0(argv);
 173         argc = argc - optind;
 174         if (check_argc_min(argc, 1)) {
 175                 usage();
 176                 exit(1);
 177         }
 178
 179         root = open_ctree(argv[optind], 0, OPEN_CTREE_CHUNK_ROOT_ONLY);
 180         if (!root) {
 181                 fprintf(stderr, "Open ctree failed\n");
 182                 exit(1);
 183         }
 184         cache_tree_init(&result);
 185
 186         get_root_gen_and_level(filter.objectid, root->fs_info,
 187                                &filter.match_gen, &filter.match_level);
 188         ret = btrfs_find_root_search(root, &filter, &result, &found);
 189         if (ret < 0) {
 190                 fprintf(stderr, "Fail to search the tree root: %s\n",
 191                         strerror(-ret));
 192                 goto out;
 193         }
 194         if (ret > 0) {
 195                 printf("Found tree root at %llu gen %llu level %u\n",
 196                        found->start, filter.match_gen, filter.match_level);
 197                 ret = 0;
 198         }
 199         print_find_root_result(&result, &filter);
 200 out:
 201         btrfs_find_root_free(&result);
 202         close_ctree(root);
 203         return ret;
 204 }