path: root/fs/btrfs/free-space-tree.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2015 Facebook.  All rights reserved.
 */

#include <linux/kernel.h>
#include <linux/sched/mm.h>
#include "messages.h"
#include "ctree.h"
#include "disk-io.h"
#include "locking.h"
#include "free-space-tree.h"
#include "transaction.h"
#include "block-group.h"
#include "fs.h"
#include "accessors.h"
#include "extent-tree.h"
#include "root-tree.h"

static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
					struct btrfs_block_group *block_group,
					struct btrfs_path *path);

static struct btrfs_root *btrfs_free_space_root(
				struct btrfs_block_group *block_group)
{
	struct btrfs_key key = {
		.objectid = BTRFS_FREE_SPACE_TREE_OBJECTID,
		.type = BTRFS_ROOT_ITEM_KEY,
		.offset = 0,
	};

	if (btrfs_fs_incompat(block_group->fs_info, EXTENT_TREE_V2))
		key.offset = block_group->global_root_id;
	return btrfs_global_root(block_group->fs_info, &key);
}

void set_free_space_tree_thresholds(struct btrfs_block_group *cache)
{
	u32 bitmap_range;
	size_t bitmap_size;
	u64 num_bitmaps, total_bitmap_size;

	if (WARN_ON(cache->length == 0))
		btrfs_warn(cache->fs_info, "block group %llu length is zero",
			   cache->start);

	/*
	 * We convert to bitmaps when the disk space required for using extents
	 * exceeds that required for using bitmaps.
	 */
	bitmap_range = cache->fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
	num_bitmaps = div_u64(cache->length + bitmap_range - 1, bitmap_range);
	bitmap_size = sizeof(struct btrfs_item) + BTRFS_FREE_SPACE_BITMAP_SIZE;
	total_bitmap_size = num_bitmaps * bitmap_size;
	cache->bitmap_high_thresh = div_u64(total_bitmap_size,
					    sizeof(struct btrfs_item));

	/*
	 * We allow for a small buffer between the high threshold and low
	 * threshold to avoid thrashing back and forth between the two formats.
	 */
	if (cache->bitmap_high_thresh > 100)
		cache->bitmap_low_thresh = cache->bitmap_high_thresh - 100;
	else
		cache->bitmap_low_thresh = 0;
}

static int add_new_free_space_info(struct btrfs_trans_handle *trans,
				   struc