btrfs-progs/btrfs-select-super.c
Chris Mason b4382217f1 Btrfs-progs: add a btrfs-select-super command to overwrite the super
Btrfs stores multiple copies of the superblock, and for common power-failure
crashes where barriers were not in use, one of the super copies is often
valid while the first copy is not.

This adds a btrfs-select-super -s N /dev/xxx command, which can
overwrite all the super blocks with a copy that you have already
determined is valid with btrfsck -s

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-10-25 09:18:31 -04:00

100 lines
2.4 KiB
C

/*
* Copyright (C) 2007 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#define _XOPEN_SOURCE 500
#define _GNU_SOURCE 1
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include "kerncompat.h"
#include "ctree.h"
#include "disk-io.h"
#include "print-tree.h"
#include "transaction.h"
#include "list.h"
#include "version.h"
#include "utils.h"
static void print_usage(void)
{
fprintf(stderr, "usage: btrfs-select-super -s number dev\n");
fprintf(stderr, "%s\n", BTRFS_BUILD_VERSION);
exit(1);
}
int main(int ac, char **av)
{
struct btrfs_root *root;
int ret;
int num;
u64 bytenr = 0;
while(1) {
int c;
c = getopt(ac, av, "s:");
if (c < 0)
break;
switch(c) {
case 's':
num = atol(optarg);
bytenr = btrfs_sb_offset(num);
printf("using SB copy %d, bytenr %llu\n", num,
(unsigned long long)bytenr);
break;
default:
print_usage();
}
}
ac = ac - optind;
if (ac != 1)
print_usage();
if (bytenr == 0) {
fprintf(stderr, "Please select the super copy with -s\n");
print_usage();
}
radix_tree_init();
if((ret = check_mounted(av[optind])) < 0) {
fprintf(stderr, "Could not check mount status: %s\n", strerror(ret));
return ret;
} else if(ret) {
fprintf(stderr, "%s is currently mounted. Aborting.\n", av[optind]);
return -EBUSY;
}
root = open_ctree(av[optind], bytenr, 1);
if (root == NULL)
return 1;
/* make the super writing code think we've read the first super */
root->fs_info->super_bytenr = BTRFS_SUPER_INFO_OFFSET;
ret = write_all_supers(root);
/* we don't close the ctree or anything, because we don't want a real
* transaction commit. We just want the super copy we pulled off the
* disk to overwrite all the other copies
*/
return ret;
}