Merge "fs_mgr: Refactor fs_mgr_overlayfs_already_mounted() to be more readable" into main

bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point, bool overlay_only) {

    Fstab fstab;

    if (!ReadFstabFromFile("/proc/mounts", &fstab)) {

    if (!ReadFstabFromProcMounts(&fstab)) {

        return false;

    }

    const auto lowerdir = kLowerdirOption + mount_point;

    for (const auto& entry : fstab) {

        if (overlay_only && "overlay" != entry.fs_type && "overlayfs" != entry.fs_type) continue;

        if (mount_point != entry.mount_point) continue;

        if (!overlay_only) return true;

        const auto options = android::base::Split(entry.fs_options, ",");

    for (const auto& entry : GetEntriesForMountPoint(&fstab, mount_point)) {

        if (!overlay_only) {

            return true;

        }

        if (entry->fs_type != "overlay" && entry->fs_type != "overlayfs") {

            continue;

        }

        const auto options = android::base::Split(entry->fs_options, ",");

        for (const auto& opt : options) {

            if (opt == lowerdir) {

                return true;