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>

2 files changed, 9 insertions, 59 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;
 }
 
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index 680bb3388919..d638c57e996e 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -353,41 +353,16 @@ struct fname {
  */
 static void free_rb_tree_fname(struct rb_root *root)
 {
-        struct rb_node  *n = root->rb_node;
-        struct rb_node  *parent;
-        struct fname    *fname;
-
-        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);
-                fname = rb_entry(n, struct fname, rb_hash);
+        struct fname *fname, *next;
+
+        rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
                 while (fname) {
                         struct fname *old = fname;
                         fname = fname->next;
                         kfree(old);
                 }
-                if (!parent)
-                        *root = RB_ROOT;
-                else if (parent->rb_left == n)
-                        parent->rb_left = NULL;
-                else if (parent->rb_right == n)
-                        parent->rb_right = NULL;
-                n = parent;
-        }
+
+        *root = RB_ROOT;
 }