The btrfs_insert_empty_item() function doesn't modify its
key argument.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Reviewed-by: Zach Brown <zab@redhat.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>