Commit 379be50f authored Jul 20, 2022 by Yi-Yo Chiang Committed by Yi-yo Chiang Jul 21, 2022

fs_mgr_overlayfs: Try "/system" and "/" when setting "/system" shared type

b/239574953 uncovers an obscure test device configuration that breaks
with aosp/2146960.

Without aosp/2146960, "/system" is not a mountpoint, because after
switch_root, the "/system" mount entry becomes "/", thus changing the
subtree propagation type of "/system" would fail.
With aosp/2146960, "/system" is bind-mounted to itself after
switch_root, ensuring "/system" being a mountpoint, thus changing the
subtree propagation type of "/system" is allowed.

Before we can re-land aosp/2146960, just try both "/system" and "/"
when changing the subtree shared propagation type of "/system", so
both scenarios are handled.

Test: Add submount under /system and adb remount
Change-Id: I4006a5c1b1987d5f6452efa069ec5c7d2ac7c8ec

parent c20b6b58

fs_mgr/fs_mgr_overlayfs.cpp

+4 −0

Original line number	Original line	Diff line number	Diff line
	@@ -642,6 +642,10 @@ bool fs_mgr_overlayfs_set_shared_mount(const std::string& mount_point, bool shar
	if (ret) {		if (ret) {
	PERROR << "__mount(target=" << mount_point		PERROR << "__mount(target=" << mount_point
	<< ",flag=" << (shared_flag ? "MS_SHARED" : "MS_PRIVATE") << ")=" << ret;		<< ",flag=" << (shared_flag ? "MS_SHARED" : "MS_PRIVATE") << ")=" << ret;
			// If "/system" doesn't look like a mountpoint, retry with "/".
			if (errno == EINVAL && mount_point == "/system") {
			return fs_mgr_overlayfs_set_shared_mount("/", shared_flag);
			}
	return false;		return false;
	}		}
	return true;		return true;