fs/ubifs: use rbtree postorder iteration helper instead of opencoding

Use rbtree_postorder_for_each_entry_safe() to destroy the rbtree instead
of opencoding an alternate postorder iteration that modifies the tree

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Artem Bityutskiy <dedekind1@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index cc1febd..5157b86 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -2118,26 +2118,10 @@
  */
 static void free_inodes(struct fsck_data *fsckd)
 {
-	struct rb_node *this = fsckd->inodes.rb_node;
-	struct fsck_inode *fscki;
+	struct fsck_inode *fscki, *n;
 
-	while (this) {
-		if (this->rb_left)
-			this = this->rb_left;
-		else if (this->rb_right)
-			this = this->rb_right;
-		else {
-			fscki = rb_entry(this, struct fsck_inode, rb);
-			this = rb_parent(this);
-			if (this) {
-				if (this->rb_left == &fscki->rb)
-					this->rb_left = NULL;
-				else
-					this->rb_right = NULL;
-			}
-			kfree(fscki);
-		}
-	}
+	rbtree_postorder_for_each_entry_safe(fscki, n, &fsckd->inodes, rb)
+		kfree(fscki);
 }
 
 /**