fs/ext4: 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>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Michel Lespinasse <walken@google.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 29 deletions

diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index 3f11656bd72e..41eb9dcfac7e 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -180,37 +180,12 @@ int ext4_setup_system_zone(struct super_block *sb)
 /* Called when the filesystem is unmounted */
 void ext4_release_system_zone(struct super_block *sb)
 {
-	struct rb_node	*n = EXT4_SB(sb)->system_blks.rb_node;
-	struct rb_node	*parent;
-	struct ext4_system_zone	*entry;
+	struct ext4_system_zone	*entry, *n;
 
-	while (n) {
-		/* Do the node's children first */
-		if (n->rb_left) {
-			n = n->rb_left;
-			continue;
-		}
-		if (n->rb_right) {
-			n = n->rb_right;
-			continue;
-		}
-		/*
-		 * The node has no children; free it, and then zero
-		 * out parent's link to it.  Finally go to the
-		 * beginning of the loop and try to free the parent
-		 * node.
-		 */
-		parent = rb_parent(n);
-		entry = rb_entry(n, struct ext4_system_zone, node);
+	rbtree_postorder_for_each_entry_safe(entry, n,
+			&EXT4_SB(sb)->system_blks, node)
 		kmem_cache_free(ext4_system_zone_cachep, entry);
-		if (!parent)
-			EXT4_SB(sb)->system_blks = RB_ROOT;
-		else if (parent->rb_left == n)
-			parent->rb_left = NULL;
-		else if (parent->rb_right == n)
-			parent->rb_right = NULL;
-		n = parent;
-	}
+
 	EXT4_SB(sb)->system_blks = RB_ROOT;
 }