[CRIU] [PATCH 1/3] devmap: Introduce --device-map argument

[Cyrill Gorcunov]

We will need it when migration causes device numbers
being changed and we need to proceed on new hardware.

At the moment this is needed for block devices.

https://jira.sw.ru/PSBM-41357

Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 Documentation/criu.txt |  4 ++++
 crtools.c              | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/cr_options.h   |  2 ++
 3 files changed, 54 insertions(+)

diff --git a/Documentation/criu.txt b/Documentation/criu.txt
index 652706ee1aaa..c5dd4e56746e 100644
--- a/Documentation/criu.txt
+++ b/Documentation/criu.txt
@@ -272,6 +272,10 @@ The '<mode>' may be one of below.
     These flags enable external shared or slave mounts to be resolved
     automatically when '*--ext-mount-map auto*' is passed.
 
+*--device-map* '<A>'*:*'<B>'[,'<C>'*:*'<D>']::
+    Specify device mappings when migrating from one environment
+    to another. Currently used for block devices.
+
 *--auto-dedup*::
     As soon as a page is restored it get punched out from image.
 
diff --git a/crtools.c b/crtools.c
index d3812a18f4f0..8a51d205d4d5 100644
--- a/crtools.c
+++ b/crtools.c
@@ -190,6 +190,48 @@ static size_t parse_size(char *optarg)
 	return (size_t)atol(optarg);
 }
 
+static int parse_device_map(struct cr_options *opts, char *optarg)
+{
+	size_t nr_alloc = 0, nr_devmap = 0;
+	unsigned int *devmap = NULL;
+	char *p = optarg;
+	int ret = -1;
+
+	if (!optarg)
+		return -EINVAL;
+
+	while (p) {
+		unsigned int s, d;
+		char *at;
+
+		if (sscanf(p, "%u:%u", &s, &d) != 2)
+			goto out;
+
+		if (nr_alloc <= nr_devmap) {
+			nr_alloc += 8;
+			if (xrealloc_safe(&devmap, sizeof(*devmap) * nr_alloc))
+				goto out;
+		}
+
+		devmap[nr_devmap + 0] = s;
+		devmap[nr_devmap + 1] = d;
+
+		nr_devmap += 2;
+
+		at = strchr(p, ',');
+		p = at ? at + 1 : NULL;
+	}
+
+	opts->devmap = devmap;
+	opts->nr_devmap = nr_devmap;
+
+	devmap = NULL;
+	ret = 0;
+out:
+	xfree(devmap);
+	return ret;
+}
+
 int main(int argc, char *argv[], char *envp[])
 {
 	pid_t pid = 0, tree_id = 0;
@@ -253,6 +295,7 @@ int main(int argc, char *argv[], char *envp[])
 		{ "freeze-cgroup",		required_argument,	0, 1068 },
 		{ "ghost-limit",		required_argument,	0, 1069 },
 		{ "irmap-scan-path",		required_argument,	0, 1070 },
+		{ "device-map",			required_argument,	0, 1071 },
 		{ },
 	};
 
@@ -498,6 +541,10 @@ int main(int argc, char *argv[], char *envp[])
 			if (irmap_scan_path_add(optarg))
 				return -1;
 			break;
+		case 1071:
+			if (parse_device_map(&opts, optarg))
+				goto bad_arg;
+			break;
 		case 'M':
 			{
 				char *aux;
@@ -747,6 +794,7 @@ usage:
 "  --enable-fs FSNAMES   a comma separated list of filesystem names or \"all\".\n"
 "                        force criu to (try to) dump/restore these filesystem's\n"
 "                        mountpoints even if fs is not supported.\n"
+"  --device-map a:b[,..] a comma separated colon splitted device mapping pairs.\n"
 "\n"
 "* Logging:\n"
 "  -o|--log-file FILE    log file name\n"
diff --git a/include/cr_options.h b/include/cr_options.h
index eac7283a4821..1451b386cce1 100644
--- a/include/cr_options.h
+++ b/include/cr_options.h
@@ -95,6 +95,8 @@ struct cr_options {
 	bool			overlayfs;
 	size_t			ghost_limit;
 	struct list_head	irmap_scan_paths;
+	unsigned int		*devmap;
+	size_t			nr_devmap;
 };
 
 extern struct cr_options opts;
-- 
2.5.0