btrfs-select-super.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  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 #define _XOPEN_SOURCE 500
  20 #define _GNU_SOURCE 1
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <unistd.h>
  24 #include <fcntl.h>
  25 #include <sys/stat.h>
  26 #include "kerncompat.h"
  27 #include "ctree.h"
  28 #include "disk-io.h"
  29 #include "print-tree.h"
  30 #include "transaction.h"
  31 #include "list.h"
  32 #include "version.h"
  33 #include "utils.h"
  34
  35 static void print_usage(void)
  36 {
  37         fprintf(stderr, "usage: btrfs-select-super -s number dev\n");
  38         fprintf(stderr, "%s\n", BTRFS_BUILD_VERSION);
  39         exit(1);
  40 }
  41
  42 int main(int ac, char **av)
  43 {
  44         struct btrfs_root *root;
  45         int ret;
  46         int num;
  47         u64 bytenr = 0;
  48
  49         while(1) {
  50                 int c;
  51                 c = getopt(ac, av, "s:");
  52                 if (c < 0)
  53                         break;
  54                 switch(c) {
  55                         case 's':
  56                                 num = atol(optarg);
  57                                 bytenr = btrfs_sb_offset(num);
  58                                 printf("using SB copy %d, bytenr %llu\n", num,
  59                                        (unsigned long long)bytenr);
  60                                 break;
  61                         default:
  62                                 print_usage();
  63                 }
  64         }
  65         ac = ac - optind;
  66
  67         if (ac != 1)
  68                 print_usage();
  69
  70         if (bytenr == 0) {
  71                 fprintf(stderr, "Please select the super copy with -s\n");
  72                 print_usage();
  73         }
  74
  75         radix_tree_init();
  76
  77         if((ret = check_mounted(av[optind])) < 0) {
  78                 fprintf(stderr, "Could not check mount status: %s\n", strerror(-ret));
  79                 return ret;
  80         } else if(ret) {
  81                 fprintf(stderr, "%s is currently mounted. Aborting.\n", av[optind]);
  82                 return -EBUSY;
  83         }
  84
  85         root = open_ctree(av[optind], bytenr, 1);
  86
  87         if (root == NULL)
  88                 return 1;
  89
  90         /* make the super writing code think we've read the first super */
  91         root->fs_info->super_bytenr = BTRFS_SUPER_INFO_OFFSET;
  92         ret = write_all_supers(root);
  93
  94         /* we don't close the ctree or anything, because we don't want a real
  95          * transaction commit.  We just want the super copy we pulled off the
  96          * disk to overwrite all the other copies
  97          */
  98         return ret;
  99 }