first_stage_mount: Bind mount /system after switch root

This ensures /system to be a mountpoint, which allows adb-remount to
change the subtree propagation type of /system and MS_MOVE submounts
under /system.

Test: Add submount under /system and adb remount
Change-Id: Ib281be41eaf86bc3e6b7dfac893e5e27b8374da8

parent 827389c9

init/first_stage_mount.cpp

+6 −0

Original line number	Diff line number	Diff line
		@@ -518,6 +518,12 @@ bool FirstStageMount::TrySwitchSystemAsRoot() {
		return false;
		}

		// Make /system a mountpoint so that adb-remount can move submounts under /system.
		if (access("/system", F_OK) == 0 &&
		mount("/system", "/system", nullptr, MS_BIND, nullptr) != 0) {
		PLOG(WARNING) << "Failed to bind mount /system for overlayfs";
		}

		return true;
		}