cg: Add ability to dump specified controllers only

For example in containers case there might be a number
of controllers mounted on the node which we should not
carry inside image when container is migrated. So
add ability to dump predefined controllers only
specified via command line --cgroup-dump-controller
option.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/cgroup-props.c

@@ -477,12 +477,41 @@ err:
 	return ret;
 }
 
+static char **dump_controllers;
+static size_t nr_dump_controllers;
+
+bool cgp_add_dump_controller(const char *name)
+{
+	if (xrealloc_safe(&dump_controllers, (nr_dump_controllers + 1) * sizeof(char *))) {
+		pr_err("Can't add controller \"%s\" to mark\n", name);
+		return false;
+	}
+
+	dump_controllers[nr_dump_controllers] = xstrdup(name);
+	if (!dump_controllers[nr_dump_controllers])
+		return false;
+
+	pr_debug("Mark controller \"%s\" to dump\n", name);
+	nr_dump_controllers++;
+	return true;
+}
+
 bool cgp_should_skip_controller(const char *name)
 {
+	size_t i;
+
 	/*
-	 * FIXME Implement!
+	 * Dump all by default.
 	 */
-	return false;
+	if (!nr_dump_controllers)
+		return false;
+
+	for (i = 0; i < nr_dump_controllers; i++) {
+		if (!strcmp(name, dump_controllers[i]))
+			return false;
+	}
+
+	return true;
 }
 
 const cgp_t *cgp_get_props(const char *name)
@@ -500,8 +529,14 @@ const cgp_t *cgp_get_props(const char *name)
 void cgp_fini(void)
 {
 	cgp_list_entry_t *p, *t;
+	size_t i;
 
 	list_for_each_entry_safe(p, t, &cgp_list, list)
 		cgp_free(p);
 	INIT_LIST_HEAD(&cgp_list);
+
+	for (i = 0; i < nr_dump_controllers; i++)
+		xfree(dump_controllers[i]);
+	xfree(dump_controllers);
+	nr_dump_controllers = 0;
 }

criu/crtools.c

@@ -278,6 +278,7 @@ int main(int argc, char *argv[], char *envp[])
 		{ "all",			no_argument,		0, 1079	},
 		{ "cgroup-props",		required_argument,	0, 1080	},
 		{ "cgroup-props-file",		required_argument,	0, 1081	},
+		{ "cgroup-dump-controller",	required_argument,	0, 1082	},
 		{ },
 	};
 
@@ -578,6 +579,10 @@ int main(int argc, char *argv[], char *envp[])
 		case 1081:
 			opts.cgroup_props_file = optarg;
 			break;
+		case 1082:
+			if (!cgp_add_dump_controller(optarg))
+				return 1;
+			break;
 		case 'V':
 			pr_msg("Version: %s\n", CRIU_VERSION);
 			if (strcmp(CRIU_GITID, "0"))
@@ -822,6 +827,9 @@ usage:
 "  --cgroup-props-file FILE\n"
 "                        same as --cgroup-props but taking descrition\n"
 "                        from the path specified.\n"
+"  --cgroup-dump-controller NAME\n"
+"                        define cgroup controller to be dumped\n"
+"                        and skip anything else present in system.\n"
 "  --skip-mnt PATH       ignore this mountpoint when dumping the mount namespace.\n"
 "  --enable-fs FSNAMES   a comma separated list of filesystem names or \"all\".\n"
 "                        force criu to (try to) dump/restore these filesystem's\n"

criu/include/cgroup-props.h

@@ -12,6 +12,7 @@ typedef struct {
 extern cgp_t cgp_global;
 extern const cgp_t *cgp_get_props(const char *name);
 extern bool cgp_should_skip_controller(const char *name);
+extern bool cgp_add_dump_controller(const char *name);
 
 extern int cgp_init(char *stream, size_t len, char *path);
 extern void cgp_fini(void);