Re: [PATCH 03/10] btrfs-progs: port block group cache tree insertion and lookup functions

[Su Yue <Damenly_Su@gmx.com>]

On 2019/12/5 3:29 PM, Qu Wenruo wrote:
>
>
> On 2019/12/5 下午12:29, damenly.su@gmail.com wrote:
>> From: Su Yue <Damenly_Su@gmx.com>
>>
>> Simple copy and paste codes, remove useless lock operantions in progs.
>> Th new coming lookup functions are named with suffix _kernel in
>> temporary.
>>
>> Signed-off-by: Su Yue <Damenly_Su@gmx.com>
>
> Reviewed-by: Qu Wenruo <wqu@suse.com>
>
> Just an extra hint, it would be much better if we backport this
> functions to block-group.c.
>
Considered it, then porting functions moved will not require
any suffixes to avoid conflictions. It will be more clean while doing
reform work. But I wonder if it's a proper timing to create
block-group.c in progs.

Thanks
> Thanks,
> Qu
>> ---
>>   extent-tree.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 86 insertions(+)
>>
>> diff --git a/extent-tree.c b/extent-tree.c
>> index 4a3db029e811..ab576f8732a2 100644
>> --- a/extent-tree.c
>> +++ b/extent-tree.c
>> @@ -164,6 +164,92 @@ err:
>>   	return 0;
>>   }
>>
>> +/*
>> + * This adds the block group to the fs_info rb tree for the block group cache
>> + */
>> +static int btrfs_add_block_group_cache(struct btrfs_fs_info *info,
>> +				struct btrfs_block_group_cache *block_group)
>> +{
>> +	struct rb_node **p;
>> +	struct rb_node *parent = NULL;
>> +	struct btrfs_block_group_cache *cache;
>> +
>> +	p = &info->block_group_cache_tree.rb_node;
>> +
>> +	while (*p) {
>> +		parent = *p;
>> +		cache = rb_entry(parent, struct btrfs_block_group_cache,
>> +				 cache_node);
>> +		if (block_group->key.objectid < cache->key.objectid)
>> +			p = &(*p)->rb_left;
>> +		else if (block_group->key.objectid > cache->key.objectid)
>> +			p = &(*p)->rb_right;
>> +		else
>> +			return -EEXIST;
>> +	}
>> +
>> +	rb_link_node(&block_group->cache_node, parent, p);
>> +	rb_insert_color(&block_group->cache_node,
>> +			&info->block_group_cache_tree);
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>> + * This will return the block group at or after bytenr if contains is 0, else
>> + * it will return the block group that contains the bytenr
>> + */
>> +static struct btrfs_block_group_cache *block_group_cache_tree_search(
>> +		struct btrfs_fs_info *info, u64 bytenr, int contains)
>> +{
>> +	struct btrfs_block_group_cache *cache, *ret = NULL;
>> +	struct rb_node *n;
>> +	u64 end, start;
>> +
>> +	n = info->block_group_cache_tree.rb_node;
>> +
>> +	while (n) {
>> +		cache = rb_entry(n, struct btrfs_block_group_cache,
>> +				 cache_node);
>> +		end = cache->key.objectid + cache->key.offset - 1;
>> +		start = cache->key.objectid;
>> +
>> +		if (bytenr < start) {
>> +			if (!contains && (!ret || start < ret->key.objectid))
>> +				ret = cache;
>> +			n = n->rb_left;
>> +		} else if (bytenr > start) {
>> +			if (contains && bytenr <= end) {
>> +				ret = cache;
>> +				break;
>> +			}
>> +			n = n->rb_right;
>> +		} else {
>> +			ret = cache;
>> +			break;
>> +		}
>> +	}
>> +	return ret;
>> +}
>> +
>> +/*
>> + * Return the block group that starts at or after bytenr
>> + */
>> +struct btrfs_block_group_cache *btrfs_lookup_first_block_group_kernel(
>> +		struct btrfs_fs_info *info, u64 bytenr)
>> +{
>> +	return block_group_cache_tree_search(info, bytenr, 0);
>> +}
>> +
>> +/*
>> + * Return the block group that contains the given bytenr
>> + */
>> +struct btrfs_block_group_cache *btrfs_lookup_block_group_kernel(
>> +		struct btrfs_fs_info *info, u64 bytenr)
>> +{
>> +	return block_group_cache_tree_search(info, bytenr, 1);
>> +}
>> +
>>   /*
>>    * Return the block group that contains @bytenr, otherwise return the next one
>>    * that starts after @bytenr
>>
>