btrfs-progs/btrfs-select-super.c

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/*
* 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.
*/
#include "kerncompat.h"
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <getopt.h>
#include <unistd.h>
#include "kernel-shared/ctree.h"
#include "kernel-shared/volumes.h"
#include "kernel-shared/disk-io.h"
#include "common/help.h"
#include "common/open-utils.h"
#include "common/messages.h"
#include "common/string-utils.h"
#include "cmds/commands.h"
static const char * const select_super_usage[] = {
"btrfs-select-super -s number dev",
"Overwrite primary superblock by selected copy",
""
OPTLINE("-s super", "copy of superblock to overwrite the primary one (values: 1, 2)"),
NULL
};
static const struct cmd_struct select_super_cmd = {
.usagestr = select_super_usage
};
int main(int argc, char **argv)
{
struct btrfs_root *root;
int ret;
u64 num = 0;
u64 bytenr = 0;
while(1) {
int c;
c = getopt(argc, argv, "s:");
if (c < 0)
break;
switch(c) {
case 's':
num = arg_strtou64(optarg);
if (num >= BTRFS_SUPER_MIRROR_MAX) {
error("super mirror should be less than: %d",
BTRFS_SUPER_MIRROR_MAX);
exit(1);
}
bytenr = btrfs_sb_offset(((int)num));
break;
default:
usage(&select_super_cmd, 1);
}
}
set_argv0(argv);
if (check_argc_exact(argc - optind, 1))
return 1;
if (bytenr == 0) {
error("please select the super copy with -s");
usage(&select_super_cmd, 1);
}
if((ret = check_mounted(argv[optind])) < 0) {
errno = -ret;
error("cannot check mount status: %m");
return ret;
} else if(ret) {
error("%s is currently mounted, aborting", argv[optind]);
return -EBUSY;
}
root = open_ctree(argv[optind], bytenr, 1);
if (!root) {
error("open ctree failed");
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->fs_info);
/* 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
*/
printf("using SB copy %llu, bytenr %llu\n", num, bytenr);
close_ctree(root);
btrfs_close_all_devices();
return ret;
}