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/libfs.c b/fs/libfs.c
index 18d08f5..65c126f 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -104,18 +104,18 @@
 
 			spin_lock(&dentry->d_lock);
 			/* d_lock not required for cursor */
-			list_del(&cursor->d_u.d_child);
+			list_del(&cursor->d_child);
 			p = dentry->d_subdirs.next;
 			while (n && p != &dentry->d_subdirs) {
 				struct dentry *next;
-				next = list_entry(p, struct dentry, d_u.d_child);
+				next = list_entry(p, struct dentry, d_child);
 				spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
 				if (simple_positive(next))
 					n--;
 				spin_unlock(&next->d_lock);
 				p = p->next;
 			}
-			list_add_tail(&cursor->d_u.d_child, p);
+			list_add_tail(&cursor->d_child, p);
 			spin_unlock(&dentry->d_lock);
 		}
 	}
@@ -139,7 +139,7 @@
 {
 	struct dentry *dentry = filp->f_path.dentry;
 	struct dentry *cursor = filp->private_data;
-	struct list_head *p, *q = &cursor->d_u.d_child;
+	struct list_head *p, *q = &cursor->d_child;
 	ino_t ino;
 	int i = filp->f_pos;
 
@@ -165,7 +165,7 @@
 
 			for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
 				struct dentry *next;
-				next = list_entry(p, struct dentry, d_u.d_child);
+				next = list_entry(p, struct dentry, d_child);
 				spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
 				if (!simple_positive(next)) {
 					spin_unlock(&next->d_lock);
@@ -289,7 +289,7 @@
 	int ret = 0;
 
 	spin_lock(&dentry->d_lock);
-	list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) {
+	list_for_each_entry(child, &dentry->d_subdirs, d_child) {
 		spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
 		if (simple_positive(child)) {
 			spin_unlock(&child->d_lock);