This test case tests if we are able to disable quotas on a filesystem
while a quota rescan is running. Up to now (4.3) this would result
in a kernel NULL pointer dereference.
Fixed by patch (btrfs: qgroup: fix quota disable during rescan).
Signed-off-by: Justin Maggard <jmaggard@netgear.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Dave Chinner <david@fromorbit.com>