Freed root index page should be skipped

[lichang98]

Description

Some root index page are freed ones during bulk load, and they should not be considered as a real index root.

How to repeat

Firstly, prepare data with sysbench.

./sysbench --mysql-host=<host> --mysql-port=<port> --mysql-db=<db> --mysql-user=<user> --rand-type=gaussian --threads=4 --table-size=640000 --tables=1 oltp_read_write prepare

Then run innodb_space.

innodb_space -f ./sbtest1.ibd  space-indexes 

How to fix it

--- a/lib/innodb/space.rb
+++ b/lib/innodb/space.rb
@@ -327,7 +327,10 @@ module Innodb
         # for IBD files, if they haven't added indexes online.
+        xdes = xdes_for_page(3)
         (3...@pages).each do |page_number|
           page = page(page_number)
-          yield page_number if page.type == :INDEX && page.root?
+          xdes = xdes_for_page(page_number)
+                                                if (page_number % pages_per_extent).zero?
+          xdes_status = xdes.page_status(page_number)
+          yield page_number if !xdes_status[:free] && page.type == :INDEX &&
+                               page.root?
         end
       end