btrfs-progs/kernel-shared/free-space-tree.h

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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.
*/
#ifndef __BTRFS_FREE_SPACE_TREE_H__
#define __BTRFS_FREE_SPACE_TREE_H__
#include "kerncompat.h"
#include "kernel-lib/bitops.h"
struct btrfs_block_group;
struct btrfs_fs_info;
struct btrfs_trans_handle;
/*
* The default size for new free space bitmap items. The last bitmap in a block
* group may be truncated, and none of the free space tree code assumes that
* existing bitmaps are this size.
*/
#define BTRFS_FREE_SPACE_BITMAP_SIZE 256
#define BTRFS_FREE_SPACE_BITMAP_BITS (BTRFS_FREE_SPACE_BITMAP_SIZE * BITS_PER_BYTE)
btrfs-progs: properly initialize block group thresholds [BUG] When creating btrfs with new v2 cache (the default behavior), mkfs.btrfs always create the free space tree using bitmap. It's fine for small fs, but will be a disaster if the device is large and the data profile is something like RAID0: $ mkfs.btrfs -f -m raid1 -d raid0 /dev/test/scratch[1234] btrfs-progs v5.17 [...] Block group profiles: Data: RAID0 4.00GiB Metadata: RAID1 256.00MiB System: RAID1 8.00MiB [..] $ btrfs ins dump-tree -t free-space /dev/test/scratch1 btrfs-progs v5.17 free space tree key (FREE_SPACE_TREE ROOT_ITEM 0) node 30441472 level 1 items 10 free space 483 generation 6 owner FREE_SPACE_TREE node 30441472 flags 0x1(WRITTEN) backref revision 1 fs uuid deddccae-afd0-4160-9a12-48fe7b526fb1 chunk uuid 68f6cf98-afe3-4f47-9797-37fd9c610219 key (1048576 FREE_SPACE_INFO 4194304) block 30457856 gen 6 key (475004928 FREE_SPACE_BITMAP 8388608) block 30703616 gen 5 key (953155584 FREE_SPACE_BITMAP 8388608) block 30720000 gen 5 key (1431306240 FREE_SPACE_BITMAP 8388608) block 30736384 gen 5 key (1909456896 FREE_SPACE_BITMAP 8388608) block 30752768 gen 5 key (2387607552 FREE_SPACE_BITMAP 8388608) block 30769152 gen 5 key (2865758208 FREE_SPACE_BITMAP 8388608) block 30785536 gen 5 key (3343908864 FREE_SPACE_BITMAP 8388608) block 30801920 gen 5 key (3822059520 FREE_SPACE_BITMAP 8388608) block 30818304 gen 5 key (4300210176 FREE_SPACE_BITMAP 8388608) block 30834688 gen 5 [...] ^^^ So many bitmaps that an empty fs will have two levels for free space tree already [CAUSE] Member btrfs_block_group::bitmap_high_thresh is never properly set to any value other than 0, thus in function update_free_space_extent_count(), the following check is always true: if (!(flags & BTRFS_FREE_SPACE_USING_BITMAPS) && extent_count > block_group->bitmap_high_thresh) { ret = convert_free_space_to_bitmaps(trans, block_group, path); Thus we always got converted to bitmaps. [FIX] Cross-port the function set_free_space_tree_thresholds() from kernel, and call that function in btrfs_make_block_group() and read_one_block_group() so that every block group has bitmap_high_thresh properly set. Now even for that 4GiB large data chunk, we still only have one free extent: btrfs-progs v5.17 free space tree key (FREE_SPACE_TREE ROOT_ITEM 0) leaf 30572544 items 15 free space 15860 generation 6 owner FREE_SPACE_TREE leaf 30572544 flags 0x1(WRITTEN) backref revision 1 fs uuid b24e52ea-6580-4a88-aa70-cb173090bfe3 chunk uuid d85f3905-fc61-4084-b335-2b6b97814b8e [...] item 13 key (298844160 FREE_SPACE_INFO 4294967296) itemoff 16235 itemsize 8 free space info extent count 1 flags 0 item 14 key (298844160 FREE_SPACE_EXTENT 4294967296) itemoff 16235 itemsize 0 free space extent Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-05-20 01:31:50 +00:00
void set_free_space_tree_thresholds(struct btrfs_fs_info *fs_info,
struct btrfs_block_group *cache);
int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info);
int load_free_space_tree(struct btrfs_fs_info *fs_info,
struct btrfs_block_group *block_group);
int populate_free_space_tree(struct btrfs_trans_handle *trans,
struct btrfs_block_group *block_group);
int remove_block_group_free_space(struct btrfs_trans_handle *trans,
struct btrfs_block_group *block_group);
int add_to_free_space_tree(struct btrfs_trans_handle *trans, u64 start,
u64 size);
int remove_from_free_space_tree(struct btrfs_trans_handle *trans, u64 start,
u64 size);
int btrfs_create_free_space_tree(struct btrfs_fs_info *info);
int add_block_group_free_space(struct btrfs_trans_handle *trans,
struct btrfs_block_group *block_group);
#endif