+/**
+ * Implementation of ldlm_valblock_ops::lvbo_update for OFD.
+ *
+ * When a client generates a glimpse enqueue, it wants to get the current
+ * file size and updated attributes for a stat() type operation, but these
+ * attributes may be writeback cached on another client. The client with
+ * the DLM extent lock at the highest offset is asked for its current
+ * attributes via a glimpse callback on its extent lock, on the assumption
+ * that it has the highest file size and the newest timestamps. The timestamps
+ * are guaranteed to be correct if there is only a single writer on the file,
+ * but may be slightly inaccurate if there are multiple concurrent writers on
+ * the same object. In order to avoid race conditions between the glimpse AST
+ * and the client cancelling the lock, ofd_lvbo_update() also updates
+ * the attributes from the local object. If the last client hasn't done any
+ * writes yet, or has already written its data and cancelled its lock before
+ * it processed the glimpse, then the local inode will have more uptodate
+ * information.