1 files changed, 261 insertions, 0 deletions
diff --git a/fs/ocfs2/stackglue.h b/fs/ocfs2/stackglue.h
new file mode 100644
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+++ b/fs/ocfs2/stackglue.h
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+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * stackglue.h
+ *
+ * Glue to the underlying cluster stack.
+ *
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+
+#ifndef STACKGLUE_H
+#define STACKGLUE_H
+
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/dlmconstants.h>
+
+#include "dlm/dlmapi.h"
+#include <linux/dlm.h>
+
+/*
+ * dlmconstants.h does not have a LOCAL flag.  We hope to remove it
+ * some day, but right now we need it.  Let's fake it.  This value is larger
+ * than any flag in dlmconstants.h.
+ */
+#define DLM_LKF_LOCAL		0x00100000
+
+/*
+ * This shadows DLM_LOCKSPACE_LEN in fs/dlm/dlm_internal.h.  That probably
+ * wants to be in a public header.
+ */
+#define GROUP_NAME_MAX		64
+
+
+/*
+ * ocfs2_protocol_version changes when ocfs2 does something different in
+ * its inter-node behavior.  See dlmglue.c for more information.
+ */
+struct ocfs2_protocol_version {
+	u8 pv_major;
+	u8 pv_minor;
+};
+
+/*
+ * The ocfs2_locking_protocol defines the handlers called on ocfs2's behalf.
+ */
+struct ocfs2_locking_protocol {
+	struct ocfs2_protocol_version lp_max_version;
+	void (*lp_lock_ast)(void *astarg);
+	void (*lp_blocking_ast)(void *astarg, int level);
+	void (*lp_unlock_ast)(void *astarg, int error);
+};
+
+
+/*
+ * The dlm_lockstatus struct includes lvb space, but the dlm_lksb struct only
+ * has a pointer to separately allocated lvb space.  This struct exists only to
+ * include in the lksb union to make space for a combined dlm_lksb and lvb.
+ */
+struct fsdlm_lksb_plus_lvb {
+	struct dlm_lksb lksb;
+	char lvb[DLM_LVB_LEN];
+};
+
+/*
+ * A union of all lock status structures.  We define it here so that the
+ * size of the union is known.  Lock status structures are embedded in
+ * ocfs2 inodes.
+ */
+union ocfs2_dlm_lksb {
+	struct dlm_lockstatus lksb_o2dlm;
+	struct dlm_lksb lksb_fsdlm;
+	struct fsdlm_lksb_plus_lvb padding;
+};
+
+/*
+ * A cluster connection.  Mostly opaque to ocfs2, the connection holds
+ * state for the underlying stack.  ocfs2 does use cc_version to determine
+ * locking compatibility.
+ */
+struct ocfs2_cluster_connection {
+	char cc_name[GROUP_NAME_MAX];
+	int cc_namelen;
+	struct ocfs2_protocol_version cc_version;
+	void (*cc_recovery_handler)(int node_num, void *recovery_data);
+	void *cc_recovery_data;
+	void *cc_lockspace;
+	void *cc_private;
+};
+
+/*
+ * 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,
+			  int grouplen,
+			  void (*recovery_handler)(int node_num,
+						   void *recovery_data),
+			  void *recovery_data,
+			  struct ocfs2_cluster_connection **conn);
+int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+			     int hangup_pending);
+void ocfs2_cluster_hangup(const char *group, int grouplen);
+int ocfs2_cluster_this_node(unsigned int *node);
+
+struct ocfs2_lock_res;
+int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
+		   int mode,
+		   union ocfs2_dlm_lksb *lksb,
+		   u32 flags,
+		   void *name,
+		   unsigned int namelen,
+		   struct ocfs2_lock_res *astarg);
+int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
+		     union ocfs2_dlm_lksb *lksb,
+		     u32 flags,
+		     struct ocfs2_lock_res *astarg);
+
+int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb);
+void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb);
+void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb);
+
+void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto);
+
+
+/* Used by stack plugins */
+int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
+void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
+#endif  /* STACKGLUE_H */