btrfs-progs/btrfs-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.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <zlib.h>
#include <getopt.h>
#include "kerncompat.h"
#include "kernel-shared/ctree.h"
#include "kernel-shared/disk-io.h"
#include "kernel-shared/print-tree.h"
#include "kernel-shared/transaction.h"
#include "kernel-lib/list.h"
#include "kernel-shared/volumes.h"
#include "common/utils.h"
#include "crypto/crc32c.h"
#include "common/extent-cache.h"
#include "common/help.h"
#include "cmds/commands.h"
/*
* Find-root will restore the search result in a 2-level trees.
* Search result is a cache_tree consisted of generation_cache.
* Each generation cache records the highest level of this generation
* and all the tree blocks with this generation.
*
* <result>
* cache_tree ----> generation_cache: gen:1 level: 2 eb_tree ----> eb1
* | |-> eb2
* | ......
* |-> generation_cache: gen:2 level: 3 eb_tree ---> eb3
*
* In the above example, generation 1's highest level is 2, but have multiple
* eb with same generation, so the root of generation 1 must be missing,
* possibly has already been overwritten.
* On the other hand, generation 2's highest level is 3 and we find only one
* eb for it, so it may be the root of generation 2.
*/
struct btrfs_find_root_gen_cache {
struct cache_extent cache; /* cache->start is generation */
u64 highest_level;
struct cache_tree eb_tree;
};
struct btrfs_find_root_filter {
u64 objectid; /* Only search tree with this objectid */
u64 generation; /* Only record tree block with higher or
equal generation */
u8 level; /* Only record tree block with higher or
equal level */
u8 match_level;
u64 match_gen;
int search_all;
/*
* If set search_all, even the tree block matches match_gen
* and match_level and objectid, still continue searching
* This *WILL* take *TONS* of extra time.
*/
};
int btrfs_find_root_search(struct btrfs_fs_info *fs_info,
struct btrfs_find_root_filter *filter,
struct cache_tree *result,
struct cache_extent **match);
static void btrfs_find_root_free(struct cache_tree *result)
{
struct btrfs_find_root_gen_cache *gen_cache;
struct cache_extent *cache;
cache = first_cache_extent(result);
while (cache) {
gen_cache = container_of(cache,
struct btrfs_find_root_gen_cache, cache);
free_extent_cache_tree(&gen_cache->eb_tree);
remove_cache_extent(result, cache);
free(gen_cache);
cache = first_cache_extent(result);
}
}
/* Return value is the same as btrfs_find_root_search(). */
static int add_eb_to_result(struct extent_buffer *eb,
struct cache_tree *result,
u32 nodesize,
struct btrfs_find_root_filter *filter,
struct cache_extent **match)
{
u64 generation = btrfs_header_generation(eb);
u64 level = btrfs_header_level(eb);
u64 owner = btrfs_header_owner(eb);
u64 start = eb->start;
struct cache_extent *cache;
struct btrfs_find_root_gen_cache *gen_cache = NULL;
int ret = 0;
if (owner != filter->objectid || level < filter->level ||
generation < filter->generation)
return ret;
/*
* Get the generation cache or create one
*
* NOTE: search_cache_extent() may return cache that doesn't cover
* the range. So we need an extra check to make sure it's the right one.
*/
cache = search_cache_extent(result, generation);
if (!cache || cache->start != generation) {
gen_cache = malloc(sizeof(*gen_cache));
BUG_ON(!gen_cache);
cache = &gen_cache->cache;
cache->start = generation;
cache->size = 1;
cache->objectid = 0;
gen_cache->highest_level = 0;
cache_tree_init(&gen_cache->eb_tree);
ret = insert_cache_extent(result, cache);
if (ret < 0)
return ret;
}
gen_cache = container_of(cache, struct btrfs_find_root_gen_cache,
cache);
/* Higher level, clean tree and insert the new one */
if (level > gen_cache->highest_level) {
free_extent_cache_tree(&gen_cache->eb_tree);
gen_cache->highest_level = level;
/* Fall into the insert routine */
}
/* Same level, insert it into the eb_tree */
if (level == gen_cache->highest_level) {
ret = add_cache_extent(&gen_cache->eb_tree,
start, nodesize);
if (ret < 0 && ret != -EEXIST)
return ret;
ret = 0;
}
if (generation == filter->match_gen &&
level == filter->match_level &&
!filter->search_all) {
ret = 1;
if (match)
*match = search_cache_extent(&gen_cache->eb_tree,
start);
}
return ret;
}
/*
* Return 0 if iterating all the metadata extents.
* Return 1 if found root with given gen/level and set *match to it.
* Return <0 if error happens
*/
int btrfs_find_root_search(struct btrfs_fs_info *fs_info,
struct btrfs_find_root_filter *filter,
struct cache_tree *result,
struct cache_extent **match)
{
struct extent_buffer *eb;
u64 chunk_offset = 0;
u64 chunk_size = 0;
u64 offset = 0;
u32 nodesize = btrfs_super_nodesize(fs_info->super_copy);
int suppress_errors = 0;
int ret = 0;
suppress_errors = fs_info->suppress_check_block_errors;
fs_info->suppress_check_block_errors = 1;
while (1) {
if (filter->objectid != BTRFS_CHUNK_TREE_OBJECTID)
ret = btrfs_next_bg_metadata(fs_info,
&chunk_offset,
&chunk_size);
else
ret = btrfs_next_bg_system(fs_info,
&chunk_offset,
&chunk_size);
if (ret) {
if (ret == -ENOENT)
ret = 0;
break;
}
for (offset = chunk_offset;
offset < chunk_offset + chunk_size;
offset += nodesize) {
eb = read_tree_block(fs_info, offset, 0);
if (!eb || IS_ERR(eb))
continue;
ret = add_eb_to_result(eb, result, nodesize, filter,
match);
free_extent_buffer(eb);
if (ret)
goto out;
}
}
out:
fs_info->suppress_check_block_errors = suppress_errors;
return ret;
}
/*
* Get reliable generation and level for given root.
*
* We have two sources of gen/level: superblock and tree root.
* superblock include the following level:
* Root, chunk, log
* and the following generations:
* Root, chunk, uuid
* Other gen/leven can only be read from its btrfs_tree_root if possible.
*
* Currently we only believe things from superblock.
*/
static void get_root_gen_and_level(u64 objectid, struct btrfs_fs_info *fs_info,
u64 *ret_gen, u8 *ret_level)
{
struct btrfs_super_block *super = fs_info->super_copy;
u64 gen = (u64)-1;
u8 level = (u8)-1;
switch (objectid) {
case BTRFS_ROOT_TREE_OBJECTID:
level = btrfs_super_root_level(super);
gen = btrfs_super_generation(super);
break;
case BTRFS_CHUNK_TREE_OBJECTID:
level = btrfs_super_chunk_root_level(super);
gen = btrfs_super_chunk_root_generation(super);
break;
case BTRFS_TREE_LOG_OBJECTID:
level = btrfs_super_log_root_level(super);
gen = btrfs_super_log_root_transid(super);
break;
case BTRFS_UUID_TREE_OBJECTID:
gen = btrfs_super_uuid_tree_generation(super);
break;
}
if (gen != (u64)-1) {
printf("Superblock thinks the generation is %llu\n", gen);
if (ret_gen)
*ret_gen = gen;
} else {
printf("Superblock doesn't contain generation info for root %llu\n",
objectid);
}
if (level != (u8)-1) {
printf("Superblock thinks the level is %u\n", level);
if (ret_level)
*ret_level = level;
} else {
printf("Superblock doesn't contain the level info for root %llu\n",
objectid);
}
}
static void print_one_result(struct cache_extent *tree_block,
u8 level, u64 generation,
struct btrfs_find_root_filter *filter)
{
int unsure = 0;
if (filter->match_gen == (u64)-1 || filter->match_level == (u8)-1)
unsure = 1;
printf("Well block %llu(gen: %llu level: %u) seems good, ",
tree_block->start, generation, level);
if (unsure)
printf("but we are unsure about the correct generation/level\n");
else if (level == filter->match_level &&
generation == filter->match_gen)
printf("and it matches superblock\n");
else
printf("but generation/level doesn't match, want gen: %llu level: %u\n",
filter->match_gen, filter->match_level);
}
static void print_find_root_result(struct cache_tree *result,
struct btrfs_find_root_filter *filter)
{
struct btrfs_find_root_gen_cache *gen_cache;
struct cache_extent *cache;
struct cache_extent *tree_block;
u64 generation = 0;
u8 level = 0;
for (cache = last_cache_extent(result);
cache; cache = prev_cache_extent(cache)) {
gen_cache = container_of(cache,
struct btrfs_find_root_gen_cache, cache);
level = gen_cache->highest_level;
generation = cache->start;
/* For exact found one, skip it as it's output before */
if (level == filter->match_level &&
generation == filter->match_gen &&
!filter->search_all)
continue;
for (tree_block = last_cache_extent(&gen_cache->eb_tree);
tree_block; tree_block = prev_cache_extent(tree_block))
print_one_result(tree_block, level, generation, filter);
}
}
static const char * btrfs_find_root_usage[] = {
"btrfs-find-usage [options] <device>",
"Attempt to find tree roots on the device",
"",
" -a search through all metadata even if the root has been found",
" -o OBJECTID filter by the tree's object id",
" -l LEVEL filter by tree level, (default: 0)",
" -g GENERATION filter by tree generation",
};
static const struct cmd_struct btrfs_find_root_cmd = {
"btrfs-find-root", NULL, btrfs_find_root_usage, NULL, 0,
};
int main(int argc, char **argv)
{
struct btrfs_fs_info *fs_info;
struct btrfs_find_root_filter filter = {0};
struct cache_tree result;
struct cache_extent *found;
int ret;
/* Default to search root tree */
filter.objectid = BTRFS_ROOT_TREE_OBJECTID;
filter.match_gen = (u64)-1;
filter.match_level = (u8)-1;
opterr = 0;
while (1) {
static const struct option long_options[] = {
{ "help", no_argument, NULL, GETOPT_VAL_HELP},
{ NULL, 0, NULL, 0 }
};
int c = getopt_long(argc, argv, "al:o:g:", long_options, NULL);
if (c < 0)
break;
switch (c) {
case 'a':
filter.search_all = 1;
break;
case 'o':
filter.objectid = arg_strtou64(optarg);
break;
case 'g':
filter.generation = arg_strtou64(optarg);
break;
case 'l':
filter.level = arg_strtou64(optarg);
break;
case GETOPT_VAL_HELP:
usage_command(&btrfs_find_root_cmd, 0, 0);
return 0;
default:
usage_unknown_option(&btrfs_find_root_cmd, argv);
}
}
set_argv0(argv);
if (check_argc_min(argc - optind, 1))
return 1;
fs_info = open_ctree_fs_info(argv[optind], 0, 0, 0,
OPEN_CTREE_CHUNK_ROOT_ONLY |
OPEN_CTREE_IGNORE_CHUNK_TREE_ERROR);
if (!fs_info) {
error("open ctree failed");
return 1;
}
cache_tree_init(&result);
get_root_gen_and_level(filter.objectid, fs_info,
&filter.match_gen, &filter.match_level);
ret = btrfs_find_root_search(fs_info, &filter, &result, &found);
if (ret < 0) {
errno = -ret;
fprintf(stderr, "Fail to search the tree root: %m\n");
goto out;
}
if (ret > 0) {
printf("Found tree root at %llu gen %llu level %u\n",
found->start, filter.match_gen, filter.match_level);
ret = 0;
}
print_find_root_result(&result, &filter);
out:
btrfs_find_root_free(&result);
close_ctree_fs_info(fs_info);
btrfs_close_all_devices();
return ret;
}