btrfs-progs/find-root.c

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/*
* Copyright (C) 2011 Red Hat. 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 <zlib.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 "volumes.h"
#include "utils.h"
#include "crc32c.h"
static int verbose = 0;
static u16 csum_size = 0;
static u64 search_objectid = BTRFS_ROOT_TREE_OBJECTID;
static void usage()
{
fprintf(stderr, "Usage: find-roots [-v] <device>\n");
}
int csum_block(void *buf, u32 len)
{
char *result;
u32 crc = ~(u32)0;
int ret = 0;
result = malloc(csum_size * sizeof(char));
if (!result) {
fprintf(stderr, "No memory\n");
return 1;
}
len -= BTRFS_CSUM_SIZE;
crc = crc32c(crc, buf + BTRFS_CSUM_SIZE, len);
btrfs_csum_final(crc, result);
if (memcmp(buf, result, csum_size))
ret = 1;
free(result);
return ret;
}
static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
u32 stripesize, struct btrfs_root *root,
struct btrfs_fs_info *fs_info, u64 objectid)
{
root->node = NULL;
root->commit_root = NULL;
root->sectorsize = sectorsize;
root->nodesize = nodesize;
root->leafsize = leafsize;
root->stripesize = stripesize;
root->ref_cows = 0;
root->track_dirty = 0;
root->fs_info = fs_info;
root->objectid = objectid;
root->last_trans = 0;
root->highest_inode = 0;
root->last_inode_alloc = 0;
INIT_LIST_HEAD(&root->dirty_list);
memset(&root->root_key, 0, sizeof(root->root_key));
memset(&root->root_item, 0, sizeof(root->root_item));
root->root_key.objectid = objectid;
return 0;
}
static int close_all_devices(struct btrfs_fs_info *fs_info)
{
struct list_head *list;
struct list_head *next;
struct btrfs_device *device;
return 0;
list = &fs_info->fs_devices->devices;
list_for_each(next, list) {
device = list_entry(next, struct btrfs_device, dev_list);
close(device->fd);
}
return 0;
}
static struct btrfs_root *open_ctree_broken(int fd, const char *device)
{
u32 sectorsize;
u32 nodesize;
u32 leafsize;
u32 blocksize;
u32 stripesize;
u64 generation;
struct btrfs_root *tree_root = malloc(sizeof(struct btrfs_root));
struct btrfs_root *extent_root = malloc(sizeof(struct btrfs_root));
struct btrfs_root *chunk_root = malloc(sizeof(struct btrfs_root));
struct btrfs_root *dev_root = malloc(sizeof(struct btrfs_root));
struct btrfs_root *csum_root = malloc(sizeof(struct btrfs_root));
struct btrfs_fs_info *fs_info = malloc(sizeof(*fs_info));
int ret;
struct btrfs_super_block *disk_super;
struct btrfs_fs_devices *fs_devices = NULL;
u64 total_devs;
u64 features;
ret = btrfs_scan_one_device(fd, device, &fs_devices,
&total_devs, BTRFS_SUPER_INFO_OFFSET);
if (ret) {
fprintf(stderr, "No valid Btrfs found on %s\n", device);
goto out;
}
if (total_devs != 1) {
ret = btrfs_scan_for_fsid(fs_devices, total_devs, 1);
if (ret)
goto out;
}
memset(fs_info, 0, sizeof(*fs_info));
fs_info->tree_root = tree_root;
fs_info->extent_root = extent_root;
fs_info->chunk_root = chunk_root;
fs_info->dev_root = dev_root;
fs_info->csum_root = csum_root;
fs_info->readonly = 1;
extent_io_tree_init(&fs_info->extent_cache);
extent_io_tree_init(&fs_info->free_space_cache);
extent_io_tree_init(&fs_info->block_group_cache);
extent_io_tree_init(&fs_info->pinned_extents);
extent_io_tree_init(&fs_info->pending_del);
extent_io_tree_init(&fs_info->extent_ins);
cache_tree_init(&fs_info->fs_root_cache);
cache_tree_init(&fs_info->mapping_tree.cache_tree);
mutex_init(&fs_info->fs_mutex);
fs_info->fs_devices = fs_devices;
INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
INIT_LIST_HEAD(&fs_info->space_info);
__setup_root(4096, 4096, 4096, 4096, tree_root,
fs_info, BTRFS_ROOT_TREE_OBJECTID);
ret = btrfs_open_devices(fs_devices, O_RDONLY);
if (ret)
goto out_cleanup;
fs_info->super_bytenr = BTRFS_SUPER_INFO_OFFSET;
disk_super = &fs_info->super_copy;
ret = btrfs_read_dev_super(fs_devices->latest_bdev,
disk_super, BTRFS_SUPER_INFO_OFFSET);
if (ret) {
printk("No valid btrfs found\n");
goto out_devices;
}
memcpy(fs_info->fsid, &disk_super->fsid, BTRFS_FSID_SIZE);
features = btrfs_super_incompat_flags(disk_super) &
~BTRFS_FEATURE_INCOMPAT_SUPP;
if (features) {
printk("couldn't open because of unsupported "
"option features (%Lx).\n", features);
goto out_devices;
}
features = btrfs_super_incompat_flags(disk_super);
if (!(features & BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF)) {
features |= BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF;
btrfs_set_super_incompat_flags(disk_super, features);
}
nodesize = btrfs_super_nodesize(disk_super);
leafsize = btrfs_super_leafsize(disk_super);
sectorsize = btrfs_super_sectorsize(disk_super);
stripesize = btrfs_super_stripesize(disk_super);
tree_root->nodesize = nodesize;
tree_root->leafsize = leafsize;
tree_root->sectorsize = sectorsize;
tree_root->stripesize = stripesize;
ret = btrfs_read_sys_array(tree_root);
if (ret)
goto out_devices;
blocksize = btrfs_level_size(tree_root,
btrfs_super_chunk_root_level(disk_super));
generation = btrfs_super_chunk_root_generation(disk_super);
__setup_root(nodesize, leafsize, sectorsize, stripesize,
chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
chunk_root->node = read_tree_block(chunk_root,
btrfs_super_chunk_root(disk_super),
blocksize, generation);
if (!chunk_root->node) {
printk("Couldn't read chunk root\n");
goto out_devices;
}
read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
(unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
BTRFS_UUID_SIZE);
if (!(btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)) {
ret = btrfs_read_chunk_tree(chunk_root);
if (ret)
goto out_chunk;
}
return fs_info->chunk_root;
out_chunk:
free_extent_buffer(fs_info->chunk_root->node);
out_devices:
close_all_devices(fs_info);
out_cleanup:
extent_io_tree_cleanup(&fs_info->extent_cache);
extent_io_tree_cleanup(&fs_info->free_space_cache);
extent_io_tree_cleanup(&fs_info->block_group_cache);
extent_io_tree_cleanup(&fs_info->pinned_extents);
extent_io_tree_cleanup(&fs_info->pending_del);
extent_io_tree_cleanup(&fs_info->extent_ins);
out:
free(tree_root);
free(extent_root);
free(chunk_root);
free(dev_root);
free(csum_root);
free(fs_info);
return NULL;
}
static int search_iobuf(struct btrfs_root *root, void *iobuf,
size_t iobuf_size, off_t offset)
{
u64 gen = btrfs_super_generation(&root->fs_info->super_copy);
u64 objectid = search_objectid;
u32 size = btrfs_super_nodesize(&root->fs_info->super_copy);
u8 level = root->fs_info->super_copy.root_level;
size_t block_off = 0;
while (block_off < iobuf_size) {
void *block = iobuf + block_off;
struct btrfs_header *header = block;
u64 h_byte, h_level, h_gen, h_owner;
// printf("searching %Lu\n", offset + block_off);
h_byte = le64_to_cpu(header->bytenr);
h_owner = le64_to_cpu(header->owner);
h_level = header->level;
h_gen = le64_to_cpu(header->generation);
if (h_owner != objectid)
goto next;
if (h_byte != (offset + block_off))
goto next;
if (h_level != level)
goto next;
if (csum_block(block, size)) {
fprintf(stderr, "Well block %Lu seems good, "
"but the csum doesn't match\n",
h_byte);
goto next;
}
if (h_gen != gen) {
fprintf(stderr, "Well block %Lu seems great, "
"but generation doesn't match, "
"have=%Lu, want=%Lu\n", h_byte, h_gen,
gen);
goto next;
}
printf("Found tree root at %Lu\n", h_byte);
return 0;
next:
block_off += size;
}
return 1;
}
static int read_physical(struct btrfs_root *root, int fd, u64 offset,
u64 bytenr, u64 len)
{
char *iobuf = malloc(len);
ssize_t done;
size_t total_read = 0;
int ret = 1;
if (!iobuf) {
fprintf(stderr, "No memory\n");
return -1;
}
while (total_read < len) {
done = pread64(fd, iobuf + total_read, len - total_read,
bytenr + total_read);
if (done < 0) {
fprintf(stderr, "Failed to read: %s\n",
strerror(errno));
ret = -1;
goto out;
}
total_read += done;
}
ret = search_iobuf(root, iobuf, total_read, offset);
out:
free(iobuf);
return ret;
}
static int find_root(struct btrfs_root *root)
{
struct btrfs_multi_bio *multi = NULL;
struct btrfs_device *device;
u64 metadata_offset = 0, metadata_size = 0;
off_t offset = 0;
off_t bytenr;
int fd;
int err;
int ret = 1;
printf("Super think's the tree root is at %Lu, chunk root %Lu\n",
btrfs_super_root(&root->fs_info->super_copy),
btrfs_super_chunk_root(&root->fs_info->super_copy));
err = btrfs_next_metadata(&root->fs_info->mapping_tree,
&metadata_offset, &metadata_size);
if (err)
return ret;
offset = metadata_offset;
while (1) {
u64 map_length = 4096;
u64 type;
if (offset >
btrfs_super_total_bytes(&root->fs_info->super_copy)) {
printf("Went past the fs size, exiting");
break;
}
if (offset >= (metadata_offset + metadata_size)) {
err = btrfs_next_metadata(&root->fs_info->mapping_tree,
&metadata_offset,
&metadata_size);
if (err) {
printf("No more metdata to scan, exiting\n");
break;
}
offset = metadata_offset;
}
err = __btrfs_map_block(&root->fs_info->mapping_tree, READ,
offset, &map_length, &type, &multi, 0);
if (err) {
offset += map_length;
continue;
}
if (!(type & BTRFS_BLOCK_GROUP_METADATA)) {
offset += map_length;
continue;
}
device = multi->stripes[0].dev;
fd = device->fd;
bytenr = multi->stripes[0].physical;
kfree(multi);
err = read_physical(root, fd, offset, bytenr, map_length);
if (!err) {
ret = 0;
break;
} else if (err < 0) {
ret = err;
break;
}
offset += map_length;
}
return ret;
}
int main(int argc, char **argv)
{
struct btrfs_root *root;
int dev_fd;
int opt;
int ret;
while ((opt = getopt(argc, argv, "vo:")) != -1) {
switch(opt) {
case 'v':
verbose++;
break;
case 'o':
errno = 0;
search_objectid = (u64)strtoll(optarg, NULL,
10);
if (errno) {
fprintf(stderr, "Error parsing "
"objectid\n");
exit(1);
}
break;
default:
usage();
exit(1);
}
}
if (optind >= argc) {
usage();
exit(1);
}
dev_fd = open(argv[optind], O_RDONLY);
if (dev_fd < 0) {
fprintf(stderr, "Failed to open device %s\n", argv[optind]);
exit(1);
}
root = open_ctree_broken(dev_fd, argv[optind]);
close(dev_fd);
if (!root) {
fprintf(stderr, "Open ctree failed\n");
exit(1);
}
csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
ret = find_root(root);
close_ctree(root);
return ret;
}