mount: don't dump content for external mounts

External mounts are provided by an user and CRIU doesn't
need to restore their content.

https://github.com/xemul/criu/issues/299

Reported-by: Stéphane Graber
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/mount.c

@@ -1263,13 +1263,14 @@ static int dump_one_mountpoint(struct mount_info *pm, struct cr_img *img)
 	if (me.fstype == FSTYPE__AUTO)
 		me.fsname = pm->fsname;
 
+	if (!pm->external) {
+		if (!pm->dumped && dump_one_fs(pm))
+			return -1;
 
-	if (!pm->dumped && dump_one_fs(pm))
-		return -1;
-
-	if (!fsroot_mounted(pm) &&
-	    pm->fstype->check_bindmount && pm->fstype->check_bindmount(pm))
-		return -1;
+		if (!fsroot_mounted(pm) &&
+		    pm->fstype->check_bindmount && pm->fstype->check_bindmount(pm))
+			return -1;
+	}
 
 	if (pm->mnt_id == CRTIME_MNT_ID) {
 		pr_info("Skip dumping cr-time mountpoint: %s\n", pm->mountpoint);