Merge "fs_mgr: Skip zram setup on swapon_all if mmd zram management is... (8121fc90) · Commits · e / os / android_system_core

fs_mgr/fs_mgr.cpp

+82 −0

Original line number	Diff line number	Diff line
		@@ -2023,6 +2023,84 @@ static bool PrepareZramBackingDevice(off64_t size) {
		return InstallZramDevice(loop_device);
		}

		// Check whether it is in recovery mode or not.
		//
		// This is a copy from util.h in libinit.
		//
		// You need to check ALL relevant executables calling this function has access to
		// "/system/bin/recovery" (including SELinux permissions and UNIX permissions).
		static bool IsRecovery() {
		return access("/system/bin/recovery", F_OK) == 0;
		}

		// Decides whether swapon_all should skip setting up zram.
		//
		// swapon_all is deprecated to setup zram after mmd is launched. swapon_all command should skip
		// setting up zram if mmd is enabled by AConfig flag and mmd is configured to set up zram.
		static bool ShouldSkipZramSetup() {
		if (IsRecovery()) {
		// swapon_all continue to support zram setup in recovery mode after mmd launch.
		return false;
		}

		// Since AConfig does not support to load the status from init, we use the system property
		// "mmd.enabled_aconfig" copied from AConfig by `mmd --set-property` command to check whether
		// mmd is enabled or not.
		//
		// aconfig_prop can have either of:
		//
		// * "true": mmd is enabled by AConfig
		// * "false": mmd is disabled by AConfig
		// * "": swapon_all is executed before `mmd --set-property`
		//
		// During mmd being launched, we request OEMs, who decided to use mmd to set up zram, to execute
		// swapon_all after "mmd.enabled_aconfig" system property is initialized. Init can wait the
		// "mmd.enabled_aconfig" initialization by `property:mmd.enabled_aconfig=*` trigger.
		//
		// After mmd is launched, we deprecate swapon_all command for setting up zram but recommend to
		// use `mmd --setup-zram`. It means that the system should call swapon_all with fstab with no
		// zram entry or the system should never call swapon_all.
		//
		// As a transition, OEMs can use the deprecated swapon_all to set up zram for several versions
		// after mmd is launched. swapon_all command will show warning logs during the transition
		// period.
		const std::string aconfig_prop = android::base::GetProperty("mmd.enabled_aconfig", "");
		const bool is_zram_managed_by_mmd = android::base::GetBoolProperty("mmd.zram.enabled", false);
		if (aconfig_prop == "true" && is_zram_managed_by_mmd) {
		// Skip zram setup since zram is managed by mmd.
		//
		// We expect swapon_all is not called when mmd is enabled by AConfig flag.
		// TODO: b/394484720 - Make this log as warning after mmd is launched.
		LINFO << "Skip setting up zram because mmd sets up zram instead.";
		return true;
		}

		if (aconfig_prop == "false") {
		// It is expected to swapon_all command to set up zram before mmd is launched.
		LOG(DEBUG) << "mmd is not launched yet. swapon_all setup zram.";
		} else if (is_zram_managed_by_mmd) {
		// This branch is for aconfig_prop == ""

		// On the system which uses mmd to setup zram, swapon_all must be executed after
		// mmd.enabled_aconfig is initialized.
		LERROR << "swapon_all must be called after mmd.enabled_aconfig system "
		"property is initialized";
		// Since we don't know whether mmd is enabled on the system or not, we fall back to enable
		// zram from swapon_all conservatively. Both swapon_all and `mmd --setup-zram` command
		// trying to set up zram does not break the system but just either ends up failing.
		} else {
		// We show the warning log for swapon_all deprecation on both aconfig_prop is "true" and ""
		// cases.
		// If mmd is enabled, swapon_all is already deprecated.
		// If aconfig_prop is "", we don't know whether mmd is launched or not. But we show the
		// deprecation warning log conservatively.
		LWARNING << "mmd is recommended to set up zram over swapon_all command with "
		"fstab entry.";
		}

		return false;
		}

		bool fs_mgr_swapon_all(const Fstab& fstab) {
		bool ret = true;
		for (const auto& entry : fstab) {
		@@ -2032,6 +2110,10 @@ bool fs_mgr_swapon_all(const Fstab& fstab) {
		}

		if (entry.zram_size > 0) {
		if (ShouldSkipZramSetup()) {
		continue;
		}

		if (!PrepareZramBackingDevice(entry.zram_backingdev_size)) {
		LERROR << "Failure of zram backing device file for '" << entry.blk_device << "'";
		}

init/README.md

+10 −0

Original line number	Diff line number	Diff line
		@@ -785,6 +785,16 @@ provides the `aidl_lazy_test_1` interface.
		fstab.${ro.hardware} or fstab.${ro.hardware.platform} will be scanned for
		under /odm/etc, /vendor/etc, or / at runtime, in that order.

		> swapon_all is deprecated and will do nothing if `mmd_enabled` AConfig flag
		in `system_performance` namespace and `mmd.zram.enabled` sysprop are enabled.
		OEMs, who decided to use mmd to manage zram, must remove zram entry from fstab
		or remove swapon_all call from their init script.

		> swapon_all continues to support setting up non-zram swap devices.

		> swapon_all on recovery mode continues to support setting up zram because mmd
		does not support the recovery mode.

		`swapoff <path>`
		> Stops swapping to the file or block device specified by path.