Merge "overlayfs: use overlayfs for f2fs readonly mode"

    return (info.feat_ro_compat & EXT4_FEATURE_RO_COMPAT_SHARED_BLOCKS) != 0;

}

#define F2FS_SUPER_OFFSET 1024

#define F2FS_FEATURE_OFFSET 2180

#define F2FS_FEATURE_RO 0x4000

bool fs_mgr_is_read_only_f2fs(const std::string& dev) {

    if (!fs_mgr_is_f2fs(dev)) return false;

    android::base::unique_fd fd(open(dev.c_str(), O_RDONLY | O_CLOEXEC));

    if (fd < 0) return false;

    __le32 feat;

    if ((TEMP_FAILURE_RETRY(lseek64(fd, F2FS_SUPER_OFFSET + F2FS_FEATURE_OFFSET, SEEK_SET)) < 0) ||

        (TEMP_FAILURE_RETRY(read(fd, &feat, sizeof(feat))) < 0)) {

        return false;

    }

    return (feat & cpu_to_le32(F2FS_FEATURE_RO)) != 0;

}

bool fs_mgr_overlayfs_enabled(FstabEntry* entry) {

    // readonly filesystem, can not be mount -o remount,rw

    // for squashfs, erofs or if free space is (near) zero making such a remount

        return true;

    }

    // f2fs read-only mode doesn't support remount,rw

    if (fs_mgr_is_read_only_f2fs(entry->blk_device)) {

        return true;

    }

    // check if ext4 de-dupe

    auto has_shared_blocks = fs_mgr_has_shared_blocks(entry->mount_point, entry->blk_device);

    if (!has_shared_blocks && (entry->mount_point == "/system")) {