+ * storage. Locking/refcounting rules:
+ * - To access or modify any data fields, the lock must be held. This
+ * includes file blocks.
+ * - One reference is held by the BlueSkyFS inode hash table. If that is the
+ * only reference (and the inode is unlocked), the inode is subject to
+ * dropping from the cache.
+ * - Any pending operations should hold extra references to the inode as
+ * appropriate to keep it available until the operation completes.
+ * */