[mandatory]
__fd_install() & fd_install() can now sleep. Callers should not
hold a spinlock or other resources that do not allow a schedule.
+--
+[mandatory]
+ any symlink that might use page_follow_link_light/page_put_link() must
+ have inode_nohighmem(inode) called before anything might start playing with
+ its pagecache.
+--
+[mandatory]
+ ->follow_link() is replaced with ->get_link(); same API, except that
+ * ->get_link() gets inode as a separate argument
+ * ->get_link() may be called in RCU mode - in that case NULL
+ dentry is passed
+--
+[mandatory]
+ ->get_link() gets struct delayed_call *done now, and should do
+ set_delayed_call() where it used to set *cookie.
+ ->put_link() is gone - just give the destructor to set_delayed_call()
+ in ->get_link().