If you are using the ext4 journaled file system (or
potentially any other filesystem/device using JBD2), this option
allows you to enable debugging output while the system is running,
in order to help track down any problems you are having.
By default, the debugging output will be turned off.
If you select Y here, then you will be able to turn on debugging
with "echo N > /sys/kernel/debug/jbd2/jbd2-debug", where N is a
number between 1 and 5. The higher the number, the more debugging
output is generated. To turn debugging off again, do
"echo 0 > /sys/kernel/debug/jbd2/jbd2-debug".