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

[Jeff Mahoney]

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@xxxxxxxxx]
>>> Sent: Sunday, September 04, 2016 7:54 PM
>>> To: dsterba@xxxxxxxx
>>> Cc: clm@xxxxxx; anand.jain@xxxxxxxxxx; fdmanana@xxxxxxxx;
>>> zhaolei@xxxxxxxxxxxxxx; linux-btrfs@xxxxxxxxxxxxxxx;
>>> linux-kernel@xxxxxxxxxxxxxxx; Sean Fu <fxinrong@xxxxxxxxx>
>>> 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".
>>> âroot->fs_info = fs_infoâ 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.

-Jeff


> Thanks,
> Qu
> 
>>
>> Thanks
>> Zhaolei
>>
>>> Signed-off-by: Sean Fu <fxinrong@xxxxxxxxx>
>>> ---
>>>  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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