Merge "fs_mgr: Skip zram setup on swapon_all if mmd zram management is enabled" into main

    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) {

        }

        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 << "'";

            }

  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.