lvmlockd: update method for changing clustered VG

The previous method for forcibly changing a clustered VG
to a local VG involved using -cn and locking_type 0.
Since those options are deprecated, replace it with
the same command used for other forced lock type changes:
vgchange --locktype none --lockopt force.

lib/commands/toolcontext.h

@@ -153,6 +153,7 @@ struct cmd_context {
 	unsigned include_shared_vgs:1;		/* report/display cmds can reveal lockd VGs */
 	unsigned include_active_foreign_vgs:1;	/* cmd should process foreign VGs with active LVs */
 	unsigned vg_read_print_access_error:1;	/* print access errors from vg_read */
+	unsigned force_access_clustered:1;
 	unsigned lockd_gl_disable:1;
 	unsigned lockd_vg_disable:1;
 	unsigned lockd_lv_disable:1;

lib/metadata/metadata.c

@@ -4689,6 +4689,15 @@ int vg_flag_write_locked(struct volume_group *vg)
 static int _access_vg_clustered(struct cmd_context *cmd, const struct volume_group *vg)
 {
 	if (vg_is_clustered(vg)) {
+		/*
+		 * force_access_clustered is only set when forcibly
+		 * converting a clustered vg to lock type none.
+		 */
+		if (cmd->force_access_clustered) {
+			log_debug("Allowing forced access to clustered vg %s", vg->name);
+			return 1;
+		}
+
 		if (!cmd->ignore_clustered_vgs)
 			log_error("Skipping clustered volume group %s", vg->name);
 		else

man/lvmlockd.8_main

@@ -814,8 +814,8 @@ dlm), first change it to a local VG, then to the new type.
 
 All LVs must be inactive to change the lock type.
 
-First change the clvm VG to a local VG.  Within a running clvm cluster,
-change a clvm VG to a local VG with the command:
+First change the clvm/clustered VG to a local VG.  Within a running clvm
+cluster, change a clustered VG to a local VG with the command:
 
 vgchange -cn <vgname>
 
@@ -823,10 +823,7 @@ If the clvm cluster is no longer running on any nodes, then extra options
 can be used to forcibly make the VG local.  Caution: this is only safe if
 all nodes have stopped using the VG:
 
-vgchange --config 'global/locking_type=0 global/use_lvmlockd=0'
-.RS
--cn <vgname>
-.RE
+vgchange  --lock-type none --lock-opt force <vgname>
 
 After the VG is local, follow the steps described in "changing a local VG
 to a lockd VG".

tools/vgchange.c

@@ -1039,6 +1039,7 @@ int vgchange_locktype_cmd(struct cmd_context *cmd, int argc, char **argv)
 		cmd->lockd_vg_disable = 1;
 		cmd->lockd_lv_disable = 1;
 		cmd->handles_missing_pvs = 1;
+		cmd->force_access_clustered = 1;
 		goto process;
 	}