move d_rcu from overlapping d_child to overlapping d_alias

move d_rcu from overlapping d_child to overlapping d_alias

commit 946e51f2bf37f1656916eb75bd0742ba33983c28 upstream.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ben Hutchings <ben@decadent.org.uk>
[hujianyang: Backported to 3.10 refer to the work of Ben Hutchings in 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: hujianyang <hujianyang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[sw0312.kim: cherry-pick from linux-3.10.y to fix CVE-2014-8559]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: If4e2a5cdcf9b0759f54cc1c1adca4f73b32cca07