Introduce md_cluster_operations to handle cluster functions

This allows dynamic registering of cluster hooks.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

drivers/md/md-cluster.c

@@ -13,6 +13,7 @@
 #include <linux/dlm.h>
 #include <linux/sched.h>
 #include "md.h"
+#include "md-cluster.h"
 
 #define LVB_SIZE	64
 
@@ -113,15 +114,32 @@ static void lockres_free(struct dlm_lock_resource *res)
 	kfree(res);
 }
 
+static int join(struct mddev *mddev, int nodes)
+{
+	return 0;
+}
+
+static int leave(struct mddev *mddev)
+{
+	return 0;
+}
+
+static struct md_cluster_operations cluster_ops = {
+	.join   = join,
+	.leave  = leave,
+};
+
 static int __init cluster_init(void)
 {
 	pr_warn("md-cluster: EXPERIMENTAL. Use with caution\n");
 	pr_info("Registering Cluster MD functions\n");
+	register_md_cluster_operations(&cluster_ops, THIS_MODULE);
 	return 0;
 }
 
 static void cluster_exit(void)
 {
+	unregister_md_cluster_operations();
 }
 
 module_init(cluster_init);

drivers/md/md-cluster.h

@@ -0,0 +1,15 @@
+
+
+#ifndef _MD_CLUSTER_H
+#define _MD_CLUSTER_H
+
+#include "md.h"
+
+struct mddev;
+
+struct md_cluster_operations {
+	int (*join)(struct mddev *mddev);
+	int (*leave)(struct mddev *mddev);
+};
+
+#endif /* _MD_CLUSTER_H */

drivers/md/md.c

@@ -53,6 +53,7 @@
 #include <linux/slab.h>
 #include "md.h"
 #include "bitmap.h"
+#include "md-cluster.h"
 
 #ifndef MODULE
 static void autostart_arrays(int part);
@@ -66,6 +67,10 @@ static void autostart_arrays(int part);
 static LIST_HEAD(pers_list);
 static DEFINE_SPINLOCK(pers_lock);
 
+struct md_cluster_operations *md_cluster_ops;
+struct module *md_cluster_mod;
+EXPORT_SYMBOL(md_cluster_mod);
+
 static DECLARE_WAIT_QUEUE_HEAD(resync_wait);
 static struct workqueue_struct *md_wq;
 static struct workqueue_struct *md_misc_wq;
@@ -7231,6 +7236,53 @@ int unregister_md_personality(struct md_personality *p)
 }
 EXPORT_SYMBOL(unregister_md_personality);
 
+int register_md_cluster_operations(struct md_cluster_operations *ops, struct module *module)
+{
+	if (md_cluster_ops != NULL)
+		return -EALREADY;
+	spin_lock(&pers_lock);
+	md_cluster_ops = ops;
+	md_cluster_mod = module;
+	spin_unlock(&pers_lock);
+	return 0;
+}
+EXPORT_SYMBOL(register_md_cluster_operations);
+
+int unregister_md_cluster_operations(void)
+{
+	spin_lock(&pers_lock);
+	md_cluster_ops = NULL;
+	spin_unlock(&pers_lock);
+	return 0;
+}
+EXPORT_SYMBOL(unregister_md_cluster_operations);
+
+int md_setup_cluster(struct mddev *mddev, int nodes)
+{
+	int err;
+
+	err = request_module("md-cluster");
+	if (err) {
+		pr_err("md-cluster module not found.\n");
+		return err;
+	}
+
+	spin_lock(&pers_lock);
+	if (!md_cluster_ops || !try_module_get(md_cluster_mod)) {
+		spin_unlock(&pers_lock);
+		return -ENOENT;
+	}
+	spin_unlock(&pers_lock);
+
+	return md_cluster_ops->join(mddev);
+}
+
+void md_cluster_stop(struct mddev *mddev)
+{
+	md_cluster_ops->leave(mddev);
+	module_put(md_cluster_mod);
+}
+
 static int is_mddev_idle(struct mddev *mddev, int init)
 {
 	struct md_rdev *rdev;

drivers/md/md.h

@@ -23,6 +23,7 @@
 #include <linux/timer.h>
 #include <linux/wait.h>
 #include <linux/workqueue.h>
+#include "md-cluster.h"
 
 #define MaxSector (~(sector_t)0)
 
@@ -608,6 +609,11 @@ static inline void safe_put_page(struct page *p)
 
 extern int register_md_personality(struct md_personality *p);
 extern int unregister_md_personality(struct md_personality *p);
+extern int register_md_cluster_operations(struct md_cluster_operations *ops,
+		struct module *module);
+extern int unregister_md_cluster_operations(void);
+extern int md_setup_cluster(struct mddev *mddev, int nodes);
+extern void md_cluster_stop(struct mddev *mddev);
 extern struct md_thread *md_register_thread(
 	void (*run)(struct md_thread *thread),
 	struct mddev *mddev,
@@ -669,4 +675,5 @@ static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
 	}
 }
 
+extern struct md_cluster_operations *md_cluster_ops;
 #endif /* _MD_MD_H */