[PATCH 2/3] maple_tree: not possible to be a root node after loop

[Wei Yang]

On Tue, Nov 19, 2024 at 09:12:31AM -0500, Liam R. Howlett wrote:
>* Wei Yang <richard.weiyang at gmail.com> [241118 21:10]:
>> On Mon, Nov 18, 2024 at 03:49:55PM -0500, Liam R. Howlett wrote:
>> >* Wei Yang <richard.weiyang at gmail.com> [241115 20:48]:
>> >> Empty tree and single entry tree is handled else whether, so the maple
>> >> tree here must be a tree with nodes.
>> >> 
>> >> If the height is 1 and we found the gap, it will jump to *done* since it
>> >> is also a leaf.
>> >> If the height is more than one, and there may be an available range, we
>> >> will descend the tree, which is not root anymore.
>> >> 
>> >> If there is no available range, we will set error and return.
>> >
>> >Isn't this needed for the overflow case?  That is, if there is a range
>> >that ends at ULONG_MAX, then we will break from the loop on the offset
>> >limit, but not check for root, return false, and continue to loop.
>> >
>> 
>> I may not follow you correctly.
>> 
>> If there is an available range that ends at ULONG_MAX for a root node, we
>> break the loop with two conditions:
>> 
>>   * the root node is a leaf node, then we will set found to true
>>   * the root node has children, then descend to a non-root node
>> 
>> Not sure this is the case you mentioned.
>
>I am concerned of the case where there isn't a gap in the last slot of a
>leaf root node.  Examining it, I think we are okay.
>
>next_slot:
>                min = pivot + 1; <-----min = 0, overflow.

Oh, this overflow.

>                if (mas->last <= pivot) { <-- still okay.
>                        mas_set_err(mas, -EBUSY);
>                        return true;
>                }

Thanks.

So it looks good to you ?

-- 
Wei Yang
Help you, Help me