mnt: Read mount images early

Mappings from mount id to namespace will be required to
remove ghosts on restore failure.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

include/mount.h

@@ -118,6 +118,7 @@ extern int depopulate_roots_yard(void);
 extern int rst_get_mnt_root(int mnt_id, char *path, int plen);
 extern int ext_mount_add(char *key, char *val);
 extern int mntns_maybe_create_roots(void);
+extern int read_mnt_ns_img(void);
 extern void cleanup_mnt_ns(void);
 
 #endif /* __CR_MOUNT_H__ */

mount.c

@@ -2509,7 +2509,7 @@ err:
 	return -1;
 }
 
-static int read_mnt_ns_img(void)
+int read_mnt_ns_img(void)
 {
 	struct mount_info *pms = NULL;
 	struct ns_id *nsid;
@@ -2673,9 +2673,6 @@ static int populate_mnt_ns(void)
 	struct mount_info *pms;
 	struct ns_id *nsid;
 
-	if (read_mnt_ns_img())
-		return -1;
-
 	pms = mnt_build_tree(mntinfo);
 	if (!pms)
 		return -1;

namespaces.c

@@ -1324,8 +1324,13 @@ int prepare_namespace_before_tasks(void)
 	if (mntns_maybe_create_roots())
 		goto err_mnt;
 
+	if (read_mnt_ns_img())
+		goto err_img;
+
 	return 0;
 
+err_img:
+	cleanup_mnt_ns();
 err_mnt:
 	/*
 	 * Nothing, netns' descriptor will be closed