Re: [PATCH] Btrfs: remove unnecessary code of chunk_root assignment in btrfs_read_chunk_tree.

[Jeff Mahoney <jeffm@suse.com>]

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On 9/5/16 11:05 PM, Jeff Mahoney wrote:
> On 9/5/16 3:56 AM, Qu Wenruo wrote:
>>
>>
>> At 09/05/2016 09:19 AM, Zhao Lei wrote:
>>> Hi, Sean Fu
>>>
>>>> From: Sean Fu [mailto:fxinrong@gmail.com]
>>>> Sent: Sunday, September 04, 2016 7:54 PM
>>>> To: dsterba@suse.com
>>>> Cc: clm@fb.com; anand.jain@oracle.com; fdmanana@suse.com;
>>>> zhaolei@cn.fujitsu.com; linux-btrfs@vger.kernel.org;
>>>> linux-kernel@vger.kernel.org; Sean Fu <fxinrong@gmail.com>
>>>> Subject: [PATCH] Btrfs: remove unnecessary code of chunk_root
>>>> assignment in
>>>> btrfs_read_chunk_tree.
>>>>
>>>> The input argument root is already set with "fs_info->chunk_root".
>>>> "chunk_root = fs_info->chunk_root = btrfs_alloc_root(fs_info)" in caller
>>>> "open_ctree".
>>>> “root->fs_info = fs_info” in "btrfs_alloc_root".
>>>>
>>> The root argument of this function means "any root".
>>> And the function is designed getting chunk root from
>>> "any root" in head.
>>>
>>> Since there is only one caller of this function,
>>> and the caller always send chunk_root as root argument in
>>> current code, we can remove above conversion,
>>> and I suggest renaming root to chunk_root to make it clear,
>>> something like:
>>>
>>> - btrfs_read_chunk_tree(struct btrfs_root *root)
>>> + btrfs_read_chunk_tree(struct btrfs_root *chunk_root)
>>
>> Since root is only used to get fs_info->chunk_root, why not use fs_info
>> directly?
> 
> Weird.  Exactly this was a part of my fs_info patchset.  I guess I need
> to go back and check what else is missing.

Actually, most of this didn't land.  Pretty much anything that's a root
->fs_info conversion is in there.

-Jeff

> -Jeff
> 
> 
>> Thanks,
>> Qu
>>
>>>
>>> Thanks
>>> Zhaolei
>>>
>>>> Signed-off-by: Sean Fu <fxinrong@gmail.com>
>>>> ---
>>>>  fs/btrfs/volumes.c | 2 --
>>>>  1 file changed, 2 deletions(-)
>>>>
>>>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>>>> index 366b335..384a6d2 100644
>>>> --- a/fs/btrfs/volumes.c
>>>> +++ b/fs/btrfs/volumes.c
>>>> @@ -6600,8 +6600,6 @@ int btrfs_read_chunk_tree(struct btrfs_root *root)
>>>>      int ret;
>>>>      int slot;
>>>>
>>>> -    root = root->fs_info->chunk_root;
>>>> -
>>>>      path = btrfs_alloc_path();
>>>>      if (!path)
>>>>          return -ENOMEM;
>>>> -- 
>>>> 2.6.2
>>>>
>>>
>>>
>>>
>>>
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>>
>>
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> 
> 


-- 
Jeff Mahoney
SUSE Labs


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