move d_rcu from overlapping d_child to overlapping d_alias

commit 946e51f2bf37f1656916eb75bd0742ba33983c28 upstream.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[bwh: Backported to 3.2:
 - Apply name changes in all the different places we use d_alias and d_child
 - Move the WARN_ON() in __d_free() to d_free() as we don't have dentry_free()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
[lizf: Backported to 3.4:
 - adjust context
 - need one more name change in debugfs]
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 9dc6e76..47d64e9 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -539,7 +539,7 @@
 	parent = dentry;
  down:
 	mutex_lock(&parent->d_inode->i_mutex);
-	list_for_each_entry_safe(child, next, &parent->d_subdirs, d_u.d_child) {
+	list_for_each_entry_safe(child, next, &parent->d_subdirs, d_child) {
 		if (!debugfs_positive(child))
 			continue;
 
@@ -560,8 +560,8 @@
 	mutex_lock(&parent->d_inode->i_mutex);
 
 	if (child != dentry) {
-		next = list_entry(child->d_u.d_child.next, struct dentry,
-					d_u.d_child);
+		next = list_entry(child->d_child.next, struct dentry,
+					d_child);
 		goto up;
 	}