inventory: save uptime to know when dump had happened

We want to use a simple fact: If we have an alive process in a pstree we
want to dump, and a starttime of that process is less than pre-dump's
timestamp (taken while all processes were freezed), then these exact
process existed (100% sure) at the time of these pre-dump and the
process' memory was dumped in images.

So save inventory image on pre-dump and put there an uptime.

https://jira.sw.ru/browse/PSBM-67502

v9: improve comment, put uptime to ivnentory image as 1) where is no
stats in parent images directory if --work-dir option is set to
something different then images directory, 2) stats-dump is not an image
and it is a bad practice to put there data required for restoring.
v10:s/u_int64_t/uint64_t/
Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/cr-dump.c

@@ -1472,6 +1472,7 @@ static int setup_alarm_handler()
 
 static int cr_pre_dump_finish(int ret)
 {
+	InventoryEntry he = INVENTORY_ENTRY__INIT;
 	struct pstree_item *item;
 
 	/*
@@ -1480,6 +1481,8 @@ static int cr_pre_dump_finish(int ret)
 	 */
 	if (arch_set_thread_regs(root_item, false) < 0)
 		goto err;
+
+	prepare_inventory_pre_dump(&he);
 	pstree_switch_state(root_item, TASK_ALIVE);
 
 	timing_stop(TIME_FROZEN);
@@ -1527,6 +1530,9 @@ err:
 	if (bfd_flush_images())
 		ret = -1;
 
+	if (write_img_inventory(&he))
+		ret = -1;
+
 	if (ret)
 		pr_err("Pre-dumping FAILED.\n");
 	else {

criu/image.c

@@ -16,6 +16,7 @@
 #include "xmalloc.h"
 #include "images/inventory.pb-c.h"
 #include "images/pagemap.pb-c.h"
+#include "proc_parse.h"
 
 bool ns_per_id = false;
 bool img_common_magic = true;
@@ -105,6 +106,16 @@ int write_img_inventory(InventoryEntry *he)
 	return 0;
 }
 
+void prepare_inventory_pre_dump(InventoryEntry *he)
+{
+	pr_info("Perparing image inventory for pre-dump (version %u)\n", CRTOOLS_IMAGES_V1);
+
+	he->img_version = CRTOOLS_IMAGES_V1_1;
+
+	if (!parse_uptime(&he->dump_uptime))
+		he->has_dump_uptime = true;
+}
+
 int prepare_inventory(InventoryEntry *he)
 {
 	struct pid pid;

criu/include/crtools.h

@@ -12,6 +12,7 @@
 
 extern int check_img_inventory(void);
 extern int write_img_inventory(InventoryEntry *he);
+extern void prepare_inventory_pre_dump(InventoryEntry *he);
 extern int prepare_inventory(InventoryEntry *he);
 struct pprep_head {
 	int (*actor)(struct pprep_head *);

criu/proc_parse.c

@@ -2632,7 +2632,7 @@ err:
 
 #define CSEC_PER_SEC 100
 
-__maybe_unused int parse_uptime(uint64_t *upt)
+int parse_uptime(uint64_t *upt)
 {
 	unsigned long sec, csec;
 	FILE *f;

images/inventory.proto

@@ -15,4 +15,5 @@ message inventory_entry {
 	optional bool			ns_per_id	= 4;
 	optional uint32			root_cg_set	= 5;
 	optional lsmtype		lsmtype		= 6;
+	optional uint64			dump_uptime	= 8;
 }