Re: Newbie questions on some of btrfs code...

[Alex Lyakas <alex.bolshoy.btrfs@gmail.com>]

Thank you Jan, Hugo & Lio,
for taking time answering my questions.

Alex.
P.S.: I have dug in some more, so probably more questions will arrive:)


On Tue, May 29, 2012 at 12:13 PM, Jan Schmidt <list.btrfs@jan-o-sch.net> wrote:
> On Mon, May 28, 2012 at 20:45 (+0200), Alex Lyakas wrote:
>> I have re-looked at btrfs_search_slot, and don't see how it would end
>> up in leaf B. The bin_search() function will clearly return the slot
>> *after* the slot of N that has key==5 (which is the parent slot of A).
>> So then the following code:
>>               if (level != 0) {
>>                       int dec = 0;
>>                       if (ret && slot > 0) {
>>                               dec = 1;
>>                               slot -= 1;
>>                       }
>> will bring us back into the slot of N with key=5. And we will go to
>> leaf A. While if key(N) of that slot was 10, we would never have ended
>> up in that slot, unless there is no lesser key in the tree.
>
> Yes, that's right. As already said in my previous mail (in the paragraph
> you didn't quote), the key in the leaf must be an exact match. The key
> in N pointing to A will be 10.
>
>> Actually, it looks like "no lesser key" is the only case when we can
>> get ret==1 and slot==0.
>
> Correct.
>
>> Except perhaps an empty leaf, which I am not sure can happen.
>
> It can't.
>
> -Jan