mount: parse devpts options

The newinstance options isn't shown in mountinfo. Currently it is
detected in devpts_dump. It is added only for root mounts and it
isn't added for bind-mounts. So mounts_equal(a, b, true) returns false
for such mounts and criu doesn't understand that they should be
bind-mounted.
Reported-by: Tycho Andersen <tycho.andersen@canonical.com>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

mount.c

@@ -672,7 +672,7 @@ static int attach_option(struct mount_info *pm, char *opt)
 }
 
 /* Is it mounted w or w/o the newinstance option */
-static int devpts_dump(struct mount_info *pm)
+static int devpts_parse(struct mount_info *pm)
 {
 	struct stat *host_st;
 
@@ -839,7 +839,7 @@ static struct fstype fstypes[] = {
 		.restore = tmpfs_restore,
 	}, {
 		.name = "devpts",
-		.dump = devpts_dump,
+		.parse = devpts_parse,
 		.code = FSTYPE__DEVPTS,
 	}, {
 		.name = "simfs",

test/zdtm/lib/ns.c

@@ -81,6 +81,10 @@ static int prepare_mntns()
 			fprintf(stderr, "mount(/dev/pts) failed: %m\n");
 			return -1;
 		}
+		if (mount("/dev/pts/ptmx", "/dev/ptmx", NULL, MS_BIND, NULL)) {
+			fprintf(stderr, "mount(/dev/pts) failed: %m\n");
+			return -1;
+		}
 		if (fchdir(dfd)) {
 			fprintf(stderr, "fchdir() failed: %m\n");
 			return -1;