fs-ext3-use-rbtree-postorder-iteration-helper-instead-of-opencoding-fix

use do{}while - more efficient and it squishes a coccinelle warning

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>