Re: [PATCH 1/2] btrfs-progs: add comments of block group lookup functions

[Su Yue <Damenly_Su@gmx.com>]

On 2019/11/11 5:28 PM, Qu Wenruo wrote:
>
>
> On 2019/11/11 下午4:42, damenly.su@gmail.com wrote:
>> From: Su Yue <Damenly_Su@gmx.com>
>>
>> The progs side function btrfs_lookup_first_block_group() calls
>> find_first_extent_bit() to find block group which contains bytenr
>> or after the bytenr. This behavior differs from kernel code, so
>> add the comments.
>>
>> Add the coments of btrfs_lookup_block_group() too, this one works
>> like kernel side.
>>
>> Signed-off-by: Su Yue <Damenly_Su@gmx.com>
>> ---
>>   extent-tree.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/extent-tree.c b/extent-tree.c
>> index d67e4098351f..f690ae999f37 100644
>> --- a/extent-tree.c
>> +++ b/extent-tree.c
>> @@ -164,6 +164,9 @@ err:
>>   	return 0;
>>   }
>>
>> +/*
>> + * Return the block group that contains or after bytenr
>> + */
>
> What about "Return the block group thart starts at or after @bytenr" ?
>

That's what documented in kernel already.
The thing I try to express is "contains".
For such a block group marked as B[n, m).
btrfs_lookup_first_block_group(x) (x > n && x < m). Kernel code will
return the block group next to B. However, progs side will return the
block group B.

Thanks.
> Thanks,
> Qu
>
>>   struct btrfs_block_group_cache *btrfs_lookup_first_block_group(struct
>>   						       btrfs_fs_info *info,
>>   						       u64 bytenr)
>> @@ -193,6 +196,9 @@ struct btrfs_block_group_cache *btrfs_lookup_first_block_group(struct
>>   	return block_group;
>>   }
>>
>> +/*
>> + * Return the block group that contains the given bytenr
>> + */
>>   struct btrfs_block_group_cache *btrfs_lookup_block_group(struct
>>   							 btrfs_fs_info *info,
>>   							 u64 bytenr)
>>
>