ocfs2: framework for version LVB

Use the native DLM locks for version control negotiation.  Most of the
framework is taken from gfs2/lock_dlm.c

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: Goldwyn Rodrigues

fs/ocfs2/stack_user.c

@@ -102,6 +102,7 @@
 #define OCFS2_TEXT_UUID_LEN			32
 #define OCFS2_CONTROL_MESSAGE_VERNUM_LEN	2
 #define OCFS2_CONTROL_MESSAGE_NODENUM_LEN	8
+#define VERSION_LOCK				"version_lock"
 
 enum ocfs2_connection_type {
 	WITH_CONTROLD,
@@ -118,6 +119,9 @@ struct ocfs2_live_connection {
 	enum ocfs2_connection_type	oc_type;
 	atomic_t                        oc_this_node;
 	int                             oc_our_slot;
+	struct dlm_lksb                 oc_version_lksb;
+	char                            oc_lvb[DLM_LVB_LEN];
+	struct completion               oc_sync_wait;
 };
 
 struct ocfs2_control_private {
@@ -796,6 +800,103 @@ static int fs_protocol_compare(struct ocfs2_protocol_version *existing,
 	return 0;
 }
 
+static void lvb_to_version(char *lvb, struct ocfs2_protocol_version *ver)
+{
+	struct ocfs2_protocol_version *pv =
+		(struct ocfs2_protocol_version *)lvb;
+	/*
+	 * ocfs2_protocol_version has two u8 variables, so we don't
+	 * need any endian conversion.
+	 */
+	ver->pv_major = pv->pv_major;
+	ver->pv_minor = pv->pv_minor;
+}
+
+static void version_to_lvb(struct ocfs2_protocol_version *ver, char *lvb)
+{
+	struct ocfs2_protocol_version *pv =
+		(struct ocfs2_protocol_version *)lvb;
+	/*
+	 * ocfs2_protocol_version has two u8 variables, so we don't
+	 * need any endian conversion.
+	 */
+	pv->pv_major = ver->pv_major;
+	pv->pv_minor = ver->pv_minor;
+}
+
+static void sync_wait_cb(void *arg)
+{
+	struct ocfs2_cluster_connection *conn = arg;
+	struct ocfs2_live_connection *lc = conn->cc_private;
+	complete(&lc->oc_sync_wait);
+}
+
+static int sync_unlock(struct ocfs2_cluster_connection *conn,
+		struct dlm_lksb *lksb, char *name)
+{
+	int error;
+	struct ocfs2_live_connection *lc = conn->cc_private;
+
+	error = dlm_unlock(conn->cc_lockspace, lksb->sb_lkid, 0, lksb, conn);
+	if (error) {
+		printk(KERN_ERR "%s lkid %x error %d\n",
+				name, lksb->sb_lkid, error);
+		return error;
+	}
+
+	wait_for_completion(&lc->oc_sync_wait);
+
+	if (lksb->sb_status != -DLM_EUNLOCK) {
+		printk(KERN_ERR "%s lkid %x status %d\n",
+				name, lksb->sb_lkid, lksb->sb_status);
+		return -1;
+	}
+	return 0;
+}
+
+static int sync_lock(struct ocfs2_cluster_connection *conn,
+		int mode, uint32_t flags,
+		struct dlm_lksb *lksb, char *name)
+{
+	int error, status;
+	struct ocfs2_live_connection *lc = conn->cc_private;
+
+	error = dlm_lock(conn->cc_lockspace, mode, lksb, flags,
+			name, strlen(name),
+			0, sync_wait_cb, conn, NULL);
+	if (error) {
+		printk(KERN_ERR "%s lkid %x flags %x mode %d error %d\n",
+				name, lksb->sb_lkid, flags, mode, error);
+		return error;
+	}
+
+	wait_for_completion(&lc->oc_sync_wait);
+
+	status = lksb->sb_status;
+
+	if (status && status != -EAGAIN) {
+		printk(KERN_ERR "%s lkid %x flags %x mode %d status %d\n",
+				name, lksb->sb_lkid, flags, mode, status);
+	}
+
+	return status;
+}
+
+
+static int version_lock(struct ocfs2_cluster_connection *conn, int mode,
+		int flags)
+{
+	struct ocfs2_live_connection *lc = conn->cc_private;
+	return sync_lock(conn, mode, flags,
+			&lc->oc_version_lksb, VERSION_LOCK);
+}
+
+static int version_unlock(struct ocfs2_cluster_connection *conn)
+{
+	struct ocfs2_live_connection *lc = conn->cc_private;
+	return sync_unlock(conn, &lc->oc_version_lksb, VERSION_LOCK);
+}
+
 static void user_recover_prep(void *arg)
 {
 }