Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [linux-next] rootfs: rootflags take effect when mount rootfs
To:     Greg KH <gregkh@linuxfoundation.org>
CC:     <viro@zeniv.linux.org.uk>, <keescook@chromium.org>,
        <linux-kernel@vger.kernel.org>
References: <20210626011655.351057-1-chenweilong@huawei.com>
 <YNhW/XQlZxfJR9Us@kroah.com>
From:   chenweilong <chenweilong@huawei.com>
Message-ID: <929b30c6-9d5e-0e57-c2a0-5c166b32dc10@huawei.com>
Date:   Mon, 28 Jun 2021 09:47:53 +0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101
 Thunderbird/68.9.0
MIME-Version: 1.0
In-Reply-To: <YNhW/XQlZxfJR9Us@kroah.com>
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit
Content-Language: en-US
Precedence: bulk

On 2021/6/27 18:46, Greg KH wrote:
> On Sat, Jun 26, 2021 at 09:16:55AM +0800, Weilong Chen wrote:
>> The kernel root filesystem may use the rootflags parameters
>> when mount, especially for tmpfs, to setup a variety of features.
>>
>> For example:
>> 1. Add 'rootflags=huge=always' to boot args.
>> 2. When the OS bootup:
>> rootfs on / type rootfs (..., huge=always)
>> Then we can get the hugepage performance improvement of tmpfs.
>>
>> Signed-off-by: Weilong Chen <chenweilong@huawei.com>
>> ---
>>  fs/namespace.c       | 5 +++--
>>  include/linux/init.h | 2 +-
>>  init/do_mounts.c     | 4 +++-
>>  3 files changed, 7 insertions(+), 4 deletions(-)
> No documentation update for this new user/kernel api you added?

There is already relevant documents (Documentation/admin-guide/kernel-parameters.txt)

description:

    rootflags=      [KNL] Set root filesystem mount option string

This patch make it work for tmpfs.

> .