btrfs-progs/free-space-tree.c

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/*
* Copyright (C) 2015 Facebook. 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 "ctree.h"
#include "disk-io.h"
#include "free-space-cache.h"
#include "free-space-tree.h"
static struct btrfs_free_space_info *
search_free_space_info(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path, int cow)
{
struct btrfs_root *root = fs_info->free_space_root;
struct btrfs_key key;
int ret;
key.objectid = block_group->key.objectid;
key.type = BTRFS_FREE_SPACE_INFO_KEY;
key.offset = block_group->key.offset;
ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
if (ret < 0)
return ERR_PTR(ret);
if (ret != 0)
return ERR_PTR(-ENOENT);
return btrfs_item_ptr(path->nodes[0], path->slots[0],
struct btrfs_free_space_info);
}
static int free_space_test_bit(struct btrfs_block_group_cache *block_group,
struct btrfs_path *path, u64 offset,
u64 sectorsize)
{
struct extent_buffer *leaf;
struct btrfs_key key;
u64 found_start, found_end;
unsigned long ptr, i;
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
found_start = key.objectid;
found_end = key.objectid + key.offset;
ASSERT(offset >= found_start && offset < found_end);
ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
i = (offset - found_start) / sectorsize;
return !!extent_buffer_test_bit(leaf, ptr, i);
}
static int load_free_space_bitmaps(struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path,
u32 expected_extent_count,
int *errors)
{
struct btrfs_root *root = fs_info->free_space_root;
struct btrfs_key key;
int prev_bit = 0, bit;
u64 extent_start = 0;
u64 start, end, offset;
u32 extent_count = 0;
int ret;
start = block_group->key.objectid;
end = block_group->key.objectid + block_group->key.offset;
while (1) {
ret = btrfs_next_item(root, path);
if (ret < 0)
goto out;
if (ret)
break;
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
break;
if (key.type != BTRFS_FREE_SPACE_BITMAP_KEY) {
fprintf(stderr, "unexpected key of type %u\n", key.type);
(*errors)++;
break;
}
if (key.objectid >= end) {
fprintf(stderr,
"free space bitmap starts at %llu, beyond end of block group %llu-%llu\n",
key.objectid, start, end);
(*errors)++;
break;
}
if (key.objectid + key.offset > end) {
fprintf(stderr,
"free space bitmap ends at %llu, beyond end of block group %llu-%llu\n",
key.objectid, start, end);
(*errors)++;
break;
}
offset = key.objectid;
while (offset < key.objectid + key.offset) {
bit = free_space_test_bit(block_group, path, offset,
root->sectorsize);
if (prev_bit == 0 && bit == 1) {
extent_start = offset;
} else if (prev_bit == 1 && bit == 0) {
add_new_free_space(block_group, fs_info, extent_start, offset);
extent_count++;
}
prev_bit = bit;
offset += root->sectorsize;
}
}
if (prev_bit == 1) {
add_new_free_space(block_group, fs_info, extent_start, end);
extent_count++;
}
if (extent_count != expected_extent_count) {
fprintf(stderr, "free space info recorded %u extents, counted %u\n",
expected_extent_count, extent_count);
(*errors)++;
}
ret = 0;
out:
return ret;
}
static int load_free_space_extents(struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path,
u32 expected_extent_count,
int *errors)
{
struct btrfs_root *root = fs_info->free_space_root;
struct btrfs_key key, prev_key;
int have_prev = 0;
u64 start, end;
u32 extent_count = 0;
int ret;
start = block_group->key.objectid;
end = block_group->key.objectid + block_group->key.offset;
while (1) {
ret = btrfs_next_item(root, path);
if (ret < 0)
goto out;
if (ret)
break;
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
break;
if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
fprintf(stderr, "unexpected key of type %u\n", key.type);
(*errors)++;
break;
}
if (key.objectid >= end) {
fprintf(stderr,
"free space extent starts at %llu, beyond end of block group %llu-%llu\n",
key.objectid, start, end);
(*errors)++;
break;
}
if (key.objectid + key.offset > end) {
fprintf(stderr,
"free space extent ends at %llu, beyond end of block group %llu-%llu\n",
key.objectid, start, end);
(*errors)++;
break;
}
if (have_prev) {
u64 cur_start = key.objectid;
u64 cur_end = cur_start + key.offset;
u64 prev_start = prev_key.objectid;
u64 prev_end = prev_start + prev_key.offset;
if (cur_start < prev_end) {
fprintf(stderr,
"free space extent %llu-%llu overlaps with previous %llu-%llu\n",
cur_start, cur_end,
prev_start, prev_end);
(*errors)++;
} else if (cur_start == prev_end) {
fprintf(stderr,
"free space extent %llu-%llu is unmerged with previous %llu-%llu\n",
cur_start, cur_end,
prev_start, prev_end);
(*errors)++;
}
}
add_new_free_space(block_group, fs_info, key.objectid, key.objectid + key.offset);
extent_count++;
prev_key = key;
have_prev = 1;
}
if (extent_count != expected_extent_count) {
fprintf(stderr, "free space info recorded %u extents, counted %u\n",
expected_extent_count, extent_count);
(*errors)++;
}
ret = 0;
out:
return ret;
}
int load_free_space_tree(struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group)
{
struct btrfs_free_space_info *info;
struct btrfs_path *path;
u32 extent_count, flags;
int errors = 0;
int ret;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
path->reada = 1;
info = search_free_space_info(NULL, fs_info, block_group, path, 0);
if (IS_ERR(info)) {
ret = PTR_ERR(info);
goto out;
}
extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
flags = btrfs_free_space_flags(path->nodes[0], info);
if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
ret = load_free_space_bitmaps(fs_info, block_group, path,
extent_count, &errors);
} else {
ret = load_free_space_extents(fs_info, block_group, path,
extent_count, &errors);
}
if (ret)
goto out;
ret = 0;
out:
btrfs_free_path(path);
return ret ? ret : errors;
}