ocfs2: Break out stackglue into modules.

We define the ocfs2_stack_plugin structure to represent a stack driver.
The o2cb stack code is split into stack_o2cb.c.  This becomes the
ocfs2_stack_o2cb.ko module.

The stackglue generic functions are similarly split into the
ocfs2_stackglue.ko module.  This module now provides an interface to
register drivers.  The ocfs2_stack_o2cb driver registers itself.  As
part of this interface, ocfs2_stackglue can load drivers on demand.
This is accomplished in ocfs2_cluster_connect().

ocfs2_cluster_disconnect() is now notified when a _hangup() is pending.
If a hangup is pending, it will not release the driver module and will
let _hangup() do that.

Signed-off-by: Joel Becker <joel.becker@oracle.com>

fs/ocfs2/Makefile

@@ -2,7 +2,7 @@ EXTRA_CFLAGS += -Ifs/ocfs2
 
 EXTRA_CFLAGS += -DCATCH_BH_JBD_RACES
 
-obj-$(CONFIG_OCFS2_FS) += ocfs2.o
+obj-$(CONFIG_OCFS2_FS) += ocfs2.o ocfs2_stackglue.o ocfs2_stack_o2cb.o
 
 ocfs2-objs := \
 	alloc.o 		\
@@ -24,14 +24,15 @@ ocfs2-objs := \
 	namei.o 		\
 	resize.o		\
 	slot_map.o 		\
-	stackglue.o		\
-	stack_o2cb.o		\
 	suballoc.o 		\
 	super.o 		\
 	symlink.o 		\
 	sysfile.o 		\
 	uptodate.o		\
 	ver.o
 
+ocfs2_stackglue-objs := stackglue.o
+ocfs2_stack_o2cb-objs := stack_o2cb.o
+
 obj-$(CONFIG_OCFS2_FS) += cluster/
 obj-$(CONFIG_OCFS2_FS) += dlm/

fs/ocfs2/dlmglue.c

@@ -2641,7 +2641,7 @@ int ocfs2_dlm_init(struct ocfs2_super *osb)
 		mlog_errno(status);
 		mlog(ML_ERROR,
 		     "could not find this host's node number\n");
-		ocfs2_cluster_disconnect(conn);
+		ocfs2_cluster_disconnect(conn, 0);
 		goto bail;
 	}
 
@@ -2663,7 +2663,8 @@ int ocfs2_dlm_init(struct ocfs2_super *osb)
 	return status;
 }
 
-void ocfs2_dlm_shutdown(struct ocfs2_super *osb)
+void ocfs2_dlm_shutdown(struct ocfs2_super *osb,
+			int hangup_pending)
 {
 	mlog_entry_void();
 
@@ -2683,7 +2684,7 @@ void ocfs2_dlm_shutdown(struct ocfs2_super *osb)
 	ocfs2_lock_res_free(&osb->osb_super_lockres);
 	ocfs2_lock_res_free(&osb->osb_rename_lockres);
 
-	ocfs2_cluster_disconnect(osb->cconn);
+	ocfs2_cluster_disconnect(osb->cconn, hangup_pending);
 	osb->cconn = NULL;
 
 	ocfs2_dlm_shutdown_debug(osb);

fs/ocfs2/dlmglue.h

@@ -58,7 +58,7 @@ struct ocfs2_meta_lvb {
 #define OCFS2_LOCK_NONBLOCK		(0x04)
 
 int ocfs2_dlm_init(struct ocfs2_super *osb);
-void ocfs2_dlm_shutdown(struct ocfs2_super *osb);
+void ocfs2_dlm_shutdown(struct ocfs2_super *osb, int hangup_pending);
 void ocfs2_lock_res_init_once(struct ocfs2_lock_res *res);
 void ocfs2_inode_lock_res_init(struct ocfs2_lock_res *res,
 			       enum ocfs2_lock_type type,

fs/ocfs2/stack_o2cb.c

@@ -18,7 +18,7 @@
  */
 
 #include <linux/crc32.h>
-#include <linux/kmod.h>
+#include <linux/module.h>
 
 /* Needed for AOP_TRUNCATED_PAGE in mlog_errno() */
 #include <linux/fs.h>
@@ -33,6 +33,8 @@ struct o2dlm_private {
 	struct dlm_eviction_cb op_eviction_cb;
 };
 
+static struct ocfs2_stack_plugin o2cb_stack;
+
 /* These should be identical */
 #if (DLM_LOCK_IV != LKM_IVMODE)
 # error Lock modes do not match
@@ -158,23 +160,23 @@ static int dlm_status_to_errno(enum dlm_status status)
 
 static void o2dlm_lock_ast_wrapper(void *astarg)
 {
-	BUG_ON(stack_glue_lproto == NULL);
+	BUG_ON(o2cb_stack.sp_proto == NULL);
 
-	stack_glue_lproto->lp_lock_ast(astarg);
+	o2cb_stack.sp_proto->lp_lock_ast(astarg);
 }
 
 static void o2dlm_blocking_ast_wrapper(void *astarg, int level)
 {
-	BUG_ON(stack_glue_lproto == NULL);
+	BUG_ON(o2cb_stack.sp_proto == NULL);
 
-	stack_glue_lproto->lp_blocking_ast(astarg, level);
+	o2cb_stack.sp_proto->lp_blocking_ast(astarg, level);
 }
 
 static void o2dlm_unlock_ast_wrapper(void *astarg, enum dlm_status status)
 {
 	int error = dlm_status_to_errno(status);
 
-	BUG_ON(stack_glue_lproto == NULL);
+	BUG_ON(o2cb_stack.sp_proto == NULL);
 
 	/*
 	 * In o2dlm, you can get both the lock_ast() for the lock being
@@ -190,7 +192,7 @@ static void o2dlm_unlock_ast_wrapper(void *astarg, enum dlm_status status)
 	if (status == DLM_CANCELGRANT)
 		return;
 
-	stack_glue_lproto->lp_unlock_ast(astarg, error);
+	o2cb_stack.sp_proto->lp_unlock_ast(astarg, error);
 }
 
 static int o2cb_dlm_lock(struct ocfs2_cluster_connection *conn,
@@ -267,6 +269,7 @@ static int o2cb_cluster_connect(struct ocfs2_cluster_connection *conn)
 	struct dlm_protocol_version dlm_version;
 
 	BUG_ON(conn == NULL);
+	BUG_ON(o2cb_stack.sp_proto == NULL);
 
 	/* for now we only have one cluster/node, make sure we see it
 	 * in the heartbeat universe */
@@ -314,7 +317,8 @@ static int o2cb_cluster_connect(struct ocfs2_cluster_connection *conn)
 	return rc;
 }
 
-static int o2cb_cluster_disconnect(struct ocfs2_cluster_connection *conn)
+static int o2cb_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+				   int hangup_pending)
 {
 	struct dlm_ctxt *dlm = conn->cc_lockspace;
 	struct o2dlm_private *priv = conn->cc_private;
@@ -393,3 +397,24 @@ struct ocfs2_stack_operations o2cb_stack_ops = {
 	.dump_lksb	= o2cb_dump_lksb,
 };
 
+static struct ocfs2_stack_plugin o2cb_stack = {
+	.sp_name	= "o2cb",
+	.sp_ops		= &o2cb_stack_ops,
+	.sp_owner	= THIS_MODULE,
+};
+
+static int __init o2cb_stack_init(void)
+{
+	return ocfs2_stack_glue_register(&o2cb_stack);
+}
+
+static void __exit o2cb_stack_exit(void)
+{
+	ocfs2_stack_glue_unregister(&o2cb_stack);
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_DESCRIPTION("ocfs2 driver for the classic o2cb stack");
+MODULE_LICENSE("GPL");
+module_init(o2cb_stack_init);
+module_exit(o2cb_stack_exit);