+/*
+ * Each cluster stack implements the stack operations structure. Not used
+ * in the ocfs2 code, the stackglue code translates generic cluster calls
+ * into stack operations.
+ */
+struct ocfs2_stack_operations {
+ /*
+ * The fs code calls ocfs2_cluster_connect() to attach a new
+ * filesystem to the cluster stack. The ->connect() op is passed
+ * an ocfs2_cluster_connection with the name and recovery field
+ * filled in.
+ *
+ * The stack must set up any notification mechanisms and create
+ * the filesystem lockspace in the DLM. The lockspace should be
+ * stored on cc_lockspace. Any other information can be stored on
+ * cc_private.
+ *
+ * ->connect() must not return until it is guaranteed that
+ *
+ * - Node down notifications for the filesystem will be recieved
+ * and passed to conn->cc_recovery_handler().
+ * - Locking requests for the filesystem will be processed.
+ */
+ int (*connect)(struct ocfs2_cluster_connection *conn);
+
+ /*
+ * The fs code calls ocfs2_cluster_disconnect() when a filesystem
+ * no longer needs cluster services. All DLM locks have been
+ * dropped, and recovery notification is being ignored by the
+ * fs code. The stack must disengage from the DLM and discontinue
+ * recovery notification.
+ *
+ * Once ->disconnect() has returned, the connection structure will
+ * be freed. Thus, a stack must not return from ->disconnect()
+ * until it will no longer reference the conn pointer.
+ *
+ * If hangup_pending is zero, ocfs2_cluster_disconnect() will also
+ * be dropping the reference on the module.
+ */
+ int (*disconnect)(struct ocfs2_cluster_connection *conn,
+ int hangup_pending);
+
+ /*
+ * ocfs2_cluster_hangup() exists for compatibility with older
+ * ocfs2 tools. Only the classic stack really needs it. As such
+ * ->hangup() is not required of all stacks. See the comment by
+ * ocfs2_cluster_hangup() for more details.
+ *
+ * Note that ocfs2_cluster_hangup() can only be called if
+ * hangup_pending was passed to ocfs2_cluster_disconnect().
+ */
+ void (*hangup)(const char *group, int grouplen);
+
+ /*
+ * ->this_node() returns the cluster's unique identifier for the
+ * local node.
+ */
+ int (*this_node)(unsigned int *node);
+
+ /*
+ * Call the underlying dlm lock function. The ->dlm_lock()
+ * callback should convert the flags and mode as appropriate.
+ *
+ * ast and bast functions are not part of the call because the
+ * stack will likely want to wrap ast and bast calls before passing
+ * them to stack->sp_proto.
+ */
+ int (*dlm_lock)(struct ocfs2_cluster_connection *conn,
+ int mode,
+ union ocfs2_dlm_lksb *lksb,
+ u32 flags,
+ void *name,
+ unsigned int namelen,
+ void *astarg);
+
+ /*
+ * Call the underlying dlm unlock function. The ->dlm_unlock()
+ * function should convert the flags as appropriate.
+ *
+ * The unlock ast is not passed, as the stack will want to wrap
+ * it before calling stack->sp_proto->lp_unlock_ast().
+ */
+ int (*dlm_unlock)(struct ocfs2_cluster_connection *conn,
+ union ocfs2_dlm_lksb *lksb,
+ u32 flags,
+ void *astarg);
+
+ /*
+ * Return the status of the current lock status block. The fs
+ * code should never dereference the union. The ->lock_status()
+ * callback pulls out the stack-specific lksb, converts the status
+ * to a proper errno, and returns it.
+ */
+ int (*lock_status)(union ocfs2_dlm_lksb *lksb);
+
+ /*
+ * Pull the lvb pointer off of the stack-specific lksb.
+ */
+ void *(*lock_lvb)(union ocfs2_dlm_lksb *lksb);
+
+ /*
+ * This is an optoinal debugging hook. If provided, the
+ * stack can dump debugging information about this lock.
+ */
+ void (*dump_lksb)(union ocfs2_dlm_lksb *lksb);
+};
+
+/*
+ * Each stack plugin must describe itself by registering a
+ * ocfs2_stack_plugin structure. This is only seen by stackglue and the
+ * stack driver.
+ */
+struct ocfs2_stack_plugin {
+ char *sp_name;
+ struct ocfs2_stack_operations *sp_ops;
+ struct module *sp_owner;
+
+ /* These are managed by the stackglue code. */
+ struct list_head sp_list;
+ unsigned int sp_count;
+ struct ocfs2_locking_protocol *sp_proto;
+};
+
+
+/* Used by the filesystem */
+int ocfs2_cluster_connect(const char *stack_name,
+ const char *group,