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 <getopt.h>
  26
  27 #include "kerncompat.h"
  28 #include "ctree.h"
  29 #include "disk-io.h"
  30 #include "print-tree.h"
  31 #include "transaction.h"
  32 #include "list.h"
  33 #include "volumes.h"
  34 #include "utils.h"
  35 #include "crc32c.h"
  36 #include "extent-cache.h"
  37 #include "find-root.h"
  38
  39 static void usage(void)
  40 {
  41         fprintf(stderr, "Usage: find-roots [-a] [-o search_objectid] "
  42                 "[ -g search_generation ] [ -l search_level ] <device>\n");
  43 }
  44
  45 /*
  46  * Get reliable generation and level for given root.
  47  *
  48  * We have two sources of gen/level: superblock and tree root.
  49  * superblock include the following level:
  50  *   Root, chunk, log
  51  * and the following generations:
  52  *   Root, chunk, uuid
  53  * Other gen/leven can only be read from its btrfs_tree_root if possible.
  54  *
  55  * Currently we only believe things from superblock.
  56  */
  57 static void get_root_gen_and_level(u64 objectid, struct btrfs_fs_info *fs_info,
  58                                    u64 *ret_gen, u8 *ret_level)
  59 {
  60         struct btrfs_super_block *super = fs_info->super_copy;
  61         u64 gen = (u64)-1;
  62         u8 level = (u8)-1;
  63
  64         switch (objectid) {
  65         case BTRFS_ROOT_TREE_OBJECTID:
  66                 level = btrfs_super_root_level(super);
  67                 gen = btrfs_super_generation(super);
  68                 break;
  69         case BTRFS_CHUNK_TREE_OBJECTID:
  70                 level = btrfs_super_chunk_root_level(super);
  71                 gen = btrfs_super_chunk_root_generation(super);
  72                 printf("Search for chunk root is not supported yet\n");
  73                 break;
  74         case BTRFS_TREE_LOG_OBJECTID:
  75                 level = btrfs_super_log_root_level(super);
  76                 gen = btrfs_super_log_root_transid(super);
  77                 break;
  78         case BTRFS_UUID_TREE_OBJECTID:
  79                 gen = btrfs_super_uuid_tree_generation(super);
  80                 break;
  81         }
  82         if (gen != (u64)-1) {
  83                 printf("Superblock thinks the generation is %llu\n", gen);
  84                 if (ret_gen)
  85                         *ret_gen = gen;
  86         } else {
  87                 printf("Superblock doesn't contain generation info for root %llu\n",
  88                        objectid);
  89         }
  90         if (level != (u8)-1) {
  91                 printf("Superblock thinks the level is %u\n", level);
  92                 if (ret_level)
  93                         *ret_level = level;
  94         } else {
  95                 printf("Superblock doesn't contain the level info for root %llu\n",
  96                        objectid);
  97         }
  98 }
  99
 100 static void print_one_result(struct cache_extent *tree_block,
 101                              u8 level, u64 generation,
 102                              struct btrfs_find_root_filter *filter)
 103 {
 104         int unsure = 0;
 105
 106         if (filter->match_gen == (u64)-1 || filter->match_level == (u8)-1)
 107                 unsure = 1;
 108         printf("Well block %llu(gen: %llu level: %u) seems good, ",
 109                tree_block->start, generation, level);
 110         if (unsure)
 111                 printf("but we are unsure about the correct generation/level\n");
 112         else if (level == filter->match_level &&
 113                  generation == filter->match_gen)
 114                 printf("and it matches superblock\n");
 115         else
 116                 printf("but generation/level doesn't match, want gen: %llu level: %u\n",
 117                        filter->match_gen, filter->match_level);
 118 }
 119
 120 static void print_find_root_result(struct cache_tree *result,
 121                                    struct btrfs_find_root_filter *filter)
 122 {
 123         struct btrfs_find_root_gen_cache *gen_cache;
 124         struct cache_extent *cache;
 125         struct cache_extent *tree_block;
 126         u64 generation = 0;
 127         u8 level = 0;
 128
 129         for (cache = last_cache_extent(result);
 130              cache; cache = prev_cache_extent(cache)) {
 131                 gen_cache = container_of(cache,
 132                                 struct btrfs_find_root_gen_cache, cache);
 133                 level = gen_cache->highest_level;
 134                 generation = cache->start;
 135                 /* For exact found one, skip it as it's output before */
 136                 if (level == filter->match_level &&
 137                     generation == filter->match_gen &&
 138                     !filter->search_all)
 139                         continue;
 140                 for (tree_block = last_cache_extent(&gen_cache->eb_tree);
 141                      tree_block; tree_block = prev_cache_extent(tree_block))
 142                         print_one_result(tree_block, level, generation, filter);
 143         }
 144 }
 145
 146 int main(int argc, char **argv)
 147 {
 148         struct btrfs_root *root;
 149         struct btrfs_find_root_filter filter = {0};
 150         struct cache_tree result;
 151         struct cache_extent *found;
 152         int ret;
 153
 154         /* Default to search root tree */
 155         filter.objectid = BTRFS_ROOT_TREE_OBJECTID;
 156         filter.match_gen = (u64)-1;
 157         filter.match_level = (u8)-1;
 158         while (1) {
 159                 static const struct option long_options[] = {
 160                         { "help", no_argument, NULL, GETOPT_VAL_HELP},
 161                         { NULL, 0, NULL, 0 }
 162                 };
 163                 int c = getopt_long(argc, argv, "al:o:g:", long_options, NULL);
 164
 165                 if (c < 0)
 166                         break;
 167
 168                 switch (c) {
 169                 case 'a':
 170                         filter.search_all = 1;
 171                         break;
 172                 case 'o':
 173                         filter.objectid = arg_strtou64(optarg);
 174                         break;
 175                 case 'g':
 176                         filter.generation = arg_strtou64(optarg);
 177                         break;
 178                 case 'l':
 179                         filter.level = arg_strtou64(optarg);
 180                         break;
 181                 case GETOPT_VAL_HELP:
 182                 default:
 183                         usage();
 184                         exit(c != GETOPT_VAL_HELP);
 185                 }
 186         }
 187
 188         set_argv0(argv);
 189         argc = argc - optind;
 190         if (check_argc_min(argc, 1)) {
 191                 usage();
 192                 exit(1);
 193         }
 194
 195         root = open_ctree(argv[optind], 0, OPEN_CTREE_CHUNK_ROOT_ONLY);
 196         if (!root) {
 197                 fprintf(stderr, "Open ctree failed\n");
 198                 exit(1);
 199         }
 200         cache_tree_init(&result);
 201
 202         get_root_gen_and_level(filter.objectid, root->fs_info,
 203                                &filter.match_gen, &filter.match_level);
 204         ret = btrfs_find_root_search(root, &filter, &result, &found);
 205         if (ret < 0) {
 206                 fprintf(stderr, "Fail to search the tree root: %s\n",
 207                         strerror(-ret));
 208                 goto out;
 209         }
 210         if (ret > 0) {
 211                 printf("Found tree root at %llu gen %llu level %u\n",
 212                        found->start, filter.match_gen, filter.match_level);
 213                 ret = 0;
 214         }
 215         print_find_root_result(&result, &filter);
 216 out:
 217         btrfs_find_root_free(&result);
 218         close_ctree(root);
 219         btrfs_close_all_devices();
 220         return ret;
 221 }