cg: Add ability to dump custom cgroup properties

We have some common predefined properties such as "cpuset.cpus" and etc gathered
in @cgp_predefined set, but there might be situation when only predefined ones
are not enough, so add ability to specify properties via --cgroup-props
and/or --cgroup-props-file options.

For example one may pass file with content

"cpu":
 - "strategy": "merge"
 - "properties": ["cpu.shares", "cpu.cfs_period_us"]

to dump custom properties for cpu controller.

The description is implemented in almost valid yaml, probably we will
need to support the various forms, but oneline is enough for now.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/Makefile.crtools

@@ -5,6 +5,7 @@ obj-y			+= aio.o
 obj-y			+= bfd.o
 obj-y			+= bitmap.o
 obj-y			+= cgroup.o
+obj-y			+= cgroup-props.o
 obj-y			+= cr-check.o
 obj-y			+= cr-dedup.o
 obj-y			+= cr-dump.o

criu/cgroup.c

@@ -10,6 +10,7 @@
 #include "list.h"
 #include "xmalloc.h"
 #include "cgroup.h"
+#include "cgroup-props.h"
 #include "cr_options.h"
 #include "pstree.h"
 #include "proc_parse.h"
@@ -24,73 +25,6 @@
 #include "images/core.pb-c.h"
 #include "images/cgroup.pb-c.h"
 
-/*
- * These string arrays have the names of all the properties that will be
- * restored. To add a property for a cgroup type, add it to the
- * corresponding char array above the NULL terminator. If you are adding
- * a new cgroup family all together, you must also edit get_known_properties()
- * Currently the code only supports properties with 1 value
- */
-
-static const char *cpu_props[] = {
-	"cpu.shares",
-	"cpu.cfs_period_us",
-	"cpu.cfs_quota_us",
-	"cpu.rt_period_us",
-	"cpu.rt_runtime_us",
-	"notify_on_release",
-	NULL
-};
-
-static const char *memory_props[] = {
-	/* limit_in_bytes and memsw.limit_in_bytes must be set in this order */
-	"memory.limit_in_bytes",
-	"memory.memsw.limit_in_bytes",
-	"memory.use_hierarchy",
-	"notify_on_release",
-	NULL
-};
-
-static const char *cpuset_props[] = {
-	/*
-	 * cpuset.cpus and cpuset.mems must be set before the process moves
-	 * into its cgroup; they are "initialized" below to whatever the root
-	 * values are in copy_special_cg_props so as not to cause ENOSPC when
-	 * values are restored via this code.
-	 */
-	"cpuset.cpus",
-	"cpuset.mems",
-	"cpuset.memory_migrate",
-	"cpuset.cpu_exclusive",
-	"cpuset.mem_exclusive",
-	"cpuset.mem_hardwall",
-	"cpuset.memory_spread_page",
-	"cpuset.memory_spread_slab",
-	"cpuset.sched_load_balance",
-	"cpuset.sched_relax_domain_level",
-	"notify_on_release",
-	NULL
-};
-
-static const char *blkio_props[] = {
-	"blkio.weight",
-	"notify_on_release",
-	NULL
-};
-
-static const char *freezer_props[] = {
-	"notify_on_release",
-	NULL
-};
-
-static const char *global_props[] = {
-	"cgroup.clone_children",
-	"notify_on_release",
-	"cgroup.procs",
-	"tasks",
-	NULL
-};
-
 /*
  * This structure describes set of controller groups
  * a task lives in. The cg_ctl entries are stored in
@@ -421,33 +355,14 @@ static void free_all_cgroup_props(struct cgroup_dir *ncd)
 	ncd->n_properties = 0;
 }
 
-static const char **get_known_properties(char *controller)
-{
-	const char **prop_arr = NULL;
-
-	if (!strcmp(controller, "cpu"))
-		prop_arr = cpu_props;
-	else if (!strcmp(controller, "memory"))
-		prop_arr = memory_props;
-	else if (!strcmp(controller, "cpuset"))
-		prop_arr = cpuset_props;
-	else if (!strcmp(controller, "blkio"))
-		prop_arr = blkio_props;
-	else if (!strcmp(controller, "freezer"))
-		prop_arr = freezer_props;
-
-	return prop_arr;
-}
-
-static int dump_cg_props_array(const char *fpath, struct cgroup_dir *ncd,
-			       const char **prop_arr)
+static int dump_cg_props_array(const char *fpath, struct cgroup_dir *ncd, const cgp_t *cgp)
 {
 	int j;
 	char buf[PATH_MAX];
 	struct cgroup_prop *prop;
 
-	for (j = 0; prop_arr != NULL && prop_arr[j] != NULL; ++j) {
-		if (snprintf(buf, PATH_MAX, "%s/%s", fpath, prop_arr[j]) >= PATH_MAX) {
+	for (j = 0; cgp && j < cgp->nr_props; j++) {
+		if (snprintf(buf, PATH_MAX, "%s/%s", fpath, cgp->props[j]) >= PATH_MAX) {
 			pr_err("snprintf output was truncated\n");
 			return -1;
 		}
@@ -457,7 +372,7 @@ static int dump_cg_props_array(const char *fpath, struct cgroup_dir *ncd,
 			continue;
 		}
 
-		prop = create_cgroup_prop(prop_arr[j]);
+		prop = create_cgroup_prop(cgp->props[j]);
 		if (!prop) {
 			free_all_cgroup_props(ncd);
 			return -1;
@@ -483,15 +398,14 @@ static int add_cgroup_properties(const char *fpath, struct cgroup_dir *ncd,
 	int i;
 
 	for (i = 0; i < controller->n_controllers; ++i) {
+		const cgp_t *cgp = cgp_get_props(controller->controllers[i]);
 
-		const char **prop_arr = get_known_properties(controller->controllers[i]);
-
-		if (dump_cg_props_array(fpath, ncd, prop_arr) < 0) {
+		if (dump_cg_props_array(fpath, ncd, cgp) < 0) {
 			pr_err("dumping known properties failed");
 			return -1;
 		}
 
-		if (dump_cg_props_array(fpath, ncd, global_props) < 0) {
+		if (dump_cg_props_array(fpath, ncd, &cgp_global) < 0) {
 			pr_err("dumping global properties failed");
 			return -1;
 		}

criu/cr-dump.c

@@ -61,6 +61,7 @@
 #include "cpu.h"
 #include "elf.h"
 #include "cgroup.h"
+#include "cgroup-props.h"
 #include "file-lock.h"
 #include "page-xfer.h"
 #include "kerndat.h"
@@ -1538,6 +1539,7 @@ static int cr_dump_finish(int ret)
 		ret = -1;
 
 	cr_plugin_fini(CR_PLUGIN_STAGE__DUMP, ret);
+	cgp_fini();
 
 	if (!ret) {
 		/*
@@ -1637,6 +1639,12 @@ int cr_dump_tasks(pid_t pid)
 	if (vdso_init())
 		goto err;
 
+	if (cgp_init(opts.cgroup_props,
+		     opts.cgroup_props ?
+		     strlen(opts.cgroup_props) : 0,
+		     opts.cgroup_props_file))
+		goto err;
+
 	if (parse_cg_info())
 		goto err;
 

criu/crtools.c

@@ -38,6 +38,7 @@
 #include "mount.h"
 #include "namespaces.h"
 #include "cgroup.h"
+#include "cgroup-props.h"
 #include "cpu.h"
 #include "action-scripts.h"
 #include "irmap.h"
@@ -275,6 +276,8 @@ int main(int argc, char *argv[], char *envp[])
 		{ "extra",			no_argument,		0, 1077	},
 		{ "experimental",		no_argument,		0, 1078	},
 		{ "all",			no_argument,		0, 1079	},
+		{ "cgroup-props",		required_argument,	0, 1080	},
+		{ "cgroup-props-file",		required_argument,	0, 1081	},
 		{ },
 	};
 
@@ -569,6 +572,12 @@ int main(int argc, char *argv[], char *envp[])
 			opts.check_extra_features = true;
 			opts.check_experimental_features = true;
 			break;
+		case 1080:
+			opts.cgroup_props = optarg;
+			break;
+		case 1081:
+			opts.cgroup_props_file = optarg;
+			break;
 		case 'V':
 			pr_msg("Version: %s\n", CRIU_VERSION);
 			if (strcmp(CRIU_GITID, "0"))
@@ -806,6 +815,13 @@ usage:
 "                        change the root cgroup the controller will be\n"
 "                        installed into. No controller means that root is the\n"
 "                        default for all controllers not specified.\n"
+"  --cgroup-props STRING\n"
+"                        define cgroup controllers and properties\n"
+"                        to be checkpointed, which are described\n"
+"                        via STRING using simplified YAML format.\n"
+"  --cgroup-props-file FILE\n"
+"                        same as --cgroup-props but taking descrition\n"
+"                        from the path specified.\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

+#ifndef __CR_CGROUP_PROPS_H__
+#define __CR_CGROUP_PROPS_H__
+
+#include <stdbool.h>
+
+typedef struct {
+	const char	*name;
+	size_t		nr_props;
+	const char	**props;
+} cgp_t;
+
+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 int cgp_init(char *stream, size_t len, char *path);
+extern void cgp_fini(void);
+
+#endif /* __CR_CGROUP_PROPS_H__ */

criu/include/cr_options.h

@@ -95,6 +95,8 @@ struct cr_options {
 	char			**exec_cmd;
 	unsigned int		manage_cgroups;
 	char			*new_global_cg_root;
+	char			*cgroup_props;
+	char			*cgroup_props_file;
 	struct list_head	new_cgroup_roots;
 	bool			autodetect_ext_mounts;
 	bool			enable_external_sharing;

criu/proc_parse.c

@@ -33,6 +33,7 @@
 #include "namespaces.h"
 #include "files-reg.h"
 #include "cgroup.h"
+#include "cgroup-props.h"
 
 #include "protobuf.h"
 #include "images/fdinfo.pb-c.h"
@@ -2232,6 +2233,18 @@ int parse_cgroup_file(FILE *f, struct list_head *retl, unsigned int *n)
 		if (e)
 			*e = '\0';
 
+		/*
+		 * Controllers and their props might be
+		 * configured the way some of them are
+		 * not taken into the image for migration
+		 * sake or container specifics.
+		 */
+		if (cgp_should_skip_controller(name)) {
+			pr_debug("cg-prop: Skipping controller %s\n", name);
+			xfree(ncc);
+			continue;
+		}
+
 		ncc->name = xstrdup(name);
 		ncc->path = xstrdup(path);
 		ncc->cgns_prefix = 0;