opts: Allo to specify the maximum size of ghost files

For example we hit a case where systemd carries journal
file with 4M in size.

https://jira.sw.ru/browse/PSBM-38571

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Documentation/criu.txt

@@ -176,6 +176,12 @@ In other words, do not use it until really needed.
 *--link-remap*::
     Allow one to link unlinked files back when possible (modifies FS till *restore*).
 
+*--ghost-limit* 'size'::
+    Allow one to specify maximum allowed size of deleted file to be carried
+    inside image files. By default up to 1M file is allowed. It is done in
+    a sake to not carry big files inside images. 'size' may be postfixed
+    with 'K', 'M' or 'G' (which stands for kilo, mega and gigabytes accordingly).
+
 *-j*, *--shell-job*::
     Allow one to dump shell jobs. This implies the restored task will inherit session and
     process group ID from the criu itself. Also this option allows one to migrate a

crtools.c

@@ -60,6 +60,7 @@ void init_opts(void)
 	opts.cpu_cap = CPU_CAP_DEFAULT;
 	opts.manage_cgroups = CG_MODE_DEFAULT;
 	opts.ps_socket = -1;
+	opts.ghost_limit = DEFAULT_GHOST_LIMIT;
 }
 
 static int parse_ns_string(const char *ptr)
@@ -175,6 +176,17 @@ Esyntax:
 	return -1;
 }
 
+static size_t parse_size(char *optarg)
+{
+	if (index(optarg, 'K'))
+		return (size_t)KILO(atol(optarg));
+	else if (index(optarg, 'M'))
+		return (size_t)MEGA(atol(optarg));
+	else if (index(optarg, 'G'))
+		return (size_t)GIGA(atol(optarg));
+	return (size_t)atol(optarg);
+}
+
 int main(int argc, char *argv[], char *envp[])
 {
 	pid_t pid = 0, tree_id = 0;
@@ -236,6 +248,7 @@ int main(int argc, char *argv[], char *envp[])
 		{ "enable-external-sharing", 	no_argument, 		0, 1066 },
 		{ "enable-external-masters", 	no_argument, 		0, 1067 },
 		{ "freeze-cgroup",		required_argument,	0, 1068 },
+		{ "ghost-limit",		required_argument,	0, 1069 },
 		{ },
 	};
 
@@ -469,6 +482,9 @@ int main(int argc, char *argv[], char *envp[])
 		case 1068:
 			opts.freeze_cgroup = optarg;
 			break;
+		case 1069:
+			opts.ghost_limit = parse_size(optarg);
+			break;
 		case 'M':
 			{
 				char *aux;
@@ -693,6 +709,7 @@ usage:
 "                        can optionally append @<bridge-name> to OUT for moving\n"
 "                        the outside veth to the named bridge\n"
 "  --link-remap          allow one to link unlinked files back when possible\n"
+"  --ghost-limit size    specify maximum size of deleted file contents to be carried inside an image file\n"
 "  --action-script FILE  add an external action script\n"
 "  -j|--" OPT_SHELL_JOB "        allow one to dump and restore shell jobs\n"
 "  -l|--" OPT_FILE_LOCKS "       handle file locks, for safety, only used for container\n"

files-reg.c

@@ -66,12 +66,6 @@ struct link_remap_rlb {
 };
 static LIST_HEAD(link_remaps);
 
-/*
- * This constant is selected without any calculations. Just do not
- * want to pick up too big files with us in the image.
- */
-#define MAX_GHOST_FILE_SIZE	(1 * 1024 * 1024)
-
 static int create_ghost(struct ghost_file *gf, GhostFileEntry *gfe, char *root, struct cr_img *img)
 {
 	int gfd, ghost_flags, ret = -1;
@@ -423,8 +417,8 @@ static int dump_ghost_remap(char *path, const struct stat *st,
 
 	pr_info("Dumping ghost file for fd %d id %#x\n", lfd, id);
 
-	if (st->st_size > MAX_GHOST_FILE_SIZE) {
+	if (st->st_size > opts.ghost_limit) {
-		pr_err("Can't dump ghost file %s of %"PRIu64" size\n",
+		pr_err("Can't dump ghost file %s of %"PRIu64" size, increase limit\n",
 				path, st->st_size);
 		return -1;
 	}

include/cr_options.h

@@ -33,6 +33,11 @@ struct cg_root_opt {
 
 #define CG_MODE_DEFAULT		(CG_MODE_SOFT)
 
+/*
+ * Ghost file size we allow to carry by default.
+ */
+#define DEFAULT_GHOST_LIMIT	(1 << 20)
+
 struct cr_options {
 	int			final_state;
 	char			*show_dump_file;
@@ -81,6 +86,7 @@ struct cr_options {
 	bool			enable_external_masters;
 	bool			aufs;		/* auto-deteced, not via cli */
 	bool			overlayfs;
+	size_t			ghost_limit;
 };
 
 extern struct cr_options opts;