Re: [PATCH] Btrfs-progs: add check-only option for balance

[Goffredo Baroncelli <kreijack@inwind.it>]

On 2016-06-14 20:16, Hugo Mills wrote:
[....]
>>
>> You are right. If the last item in the buffer is a EXTENT_ITEM, and the 
>> next item in the disk is a BLOCK_GROUP_ITEM with the same object id,
>> the latter would be skipped.
>>
>> I was find always terrible the BTRFS_IOC_TREE_SEARCH; if the min_*
>> fields was separate from the key, the use of this ioctl would
>> be a lot simpler. Moreover in most case (like this one), it would be 
>> reduced the context switches, because the ioctl would return
>> only valid data.
> 
>    There's an argument for implementing it. However, given the way the
> indexing works (concatenation of the key elements, resulting in
> lexical ordering of keys), you'd still have to do exactly the same
> work, only in the kernel instead. The only thing you really win is the
> number of context switches.
> 
>    It would really have to be a new ioctl, too. You can't change the
> behaviour of the existing one.
> 
>    Hugo.

It was 2010...

http://www.spinics.net/lists/linux-btrfs/msg07636.html


> 
>>>
>>> So, the important line here was: "...when the extent_item just
>>> manages to squeeze in as last result into the current result buffer
>>> from the ioctl..."
>>>
>>
>>
> 


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