From patchwork Tue Oct 1 17:10:26 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paulo Alcantara X-Patchwork-Id: 1170081 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-cifs-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=cjr.nz Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; secure) header.d=cjr.nz header.i=@cjr.nz header.b="dFbX3/St"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 46jQlV2NNgz9s4Y for ; Wed, 2 Oct 2019 03:11:02 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726314AbfJARLB (ORCPT ); Tue, 1 Oct 2019 13:11:01 -0400 Received: from mx.cjr.nz ([51.158.111.142]:51096 "EHLO mx.cjr.nz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726053AbfJARLB (ORCPT ); Tue, 1 Oct 2019 13:11:01 -0400 Received: from authenticated-user (mx.cjr.nz [51.158.111.142]) (Authenticated sender: pc) by mx.cjr.nz (Postfix) with ESMTPSA id CD95F80A7A; Tue, 1 Oct 2019 17:10:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cjr.nz; s=dkim; t=1569949858; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=A8qzreD3Aoux2woi5Fj9Leo7MHUln5di2PJf76EqfBk=; b=dFbX3/Sttcc+w4N56hh9JsQQan/u+sklnnafSgX3HnMYorBA4/Tp4wJ4wYSIVCFrpQ+EWQ gABpNigKj86CLsd6ndZE0+fy9vsYgyBZK3Q13dBFzfvmuFB5VhaU1ZqeZJIce/5wWIM9qS qlq5vL+D7KBq5RTaKgMQvH60pq45hP8NTU97MqTbcuXhWWpktEfZEyjANTXrDJuBM20GLY QtaxMOigBL8naSmx17XTh96QHyyUBsWAj3kfTItGcr/10o+5GG3EAFssuwKsjwHXKqUSvD /x4fFmxkhtiJBbdEzQzh8fPj0AqkMz7P9FiS5fDUq9hSr4GU+B2dp4uVlSkEDw== From: "Paulo Alcantara (SUSE)" To: netdev@vger.kernel.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, davem@davemloft.net, smfrench@gmail.com Cc: "Paulo Alcantara (SUSE)" Subject: [PATCH net-next 0/2] Experimental SMB rootfs support Date: Tue, 1 Oct 2019 14:10:26 -0300 Message-Id: <20191001171028.23356-1-pc@cjr.nz> MIME-Version: 1.0 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=cjr.nz; s=dkim; t=1569949858; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:references; bh=A8qzreD3Aoux2woi5Fj9Leo7MHUln5di2PJf76EqfBk=; b=0jWn1vZPGuBwKQF7WiKqAsuPRIRJ3N6ed2Qygf2UT7EaH83ROI4bgdtmvNtdwFm5QIWd69 6oIxrcsUUN9NTmYc7xXdVJD/42pwxWlXMKHtb+bZPCRMJ/Rh5lew+zNhQNijaW+OrVYlgC pYvdAfPGzkkLvKlvaZwuSR0It/e+cvTXxLIHPCpP02G8unGv7bFnk+LnAxYrl9nvRQpH6d k/9JFf7i9XiC/cnvwfHLcd+jj5F8PPm8gIPosMSb9zyJ/Pzl+hRfTkJi9WD7z8qUSpS1bH pyBAE0yCqVl9Rf4EEiQSVeBeEqM4NVWzAjQ5E1u1+KKmrSZUymN8oUG1a/qJEA== ARC-Seal: i=1; s=dkim; d=cjr.nz; t=1569949858; a=rsa-sha256; cv=none; b=RvTtBqrBobfZxGGV9MX69/AOI8AfPqYC6jwIGMZOCdUSCiMFSIx5tqXan459VeTtwcCU0E ZhzfDPo7gg/CkHSuAQ/IYeNhrEtqqO4GHtwGRcRumnT/qdvF746rxTRiaHhR10RwCSKvZW T1E69VRt90LtHJ8PU5toi49jS54iQc9r5sfdDkXHChsLCkg4HcNcaaunbKha1NwwnbwuN+ faPMN+xmPch+3YJGBkIThUH+qXD0ndoa57Qpkn/F/Hg+T8xEk96ofIaZSmgaQLqhW51A8Z UBahCDJ0M+xbdCT+Vwvh8BnzSUVVWvTYhASC7tsOa0Cw0Y15p+3KWXDFxIwIUQ== ARC-Authentication-Results: i=1; mx.cjr.nz; auth=pass smtp.auth=pc smtp.mailfrom=pc@cjr.nz Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org Hi, This patch series enables Linux to mount root file systems over the network by utilizing SMB protocol. Upstream commit 8eecd1c2e5bc ("cifs: Add support for root file systems") introduced a new CONFIG_CIFS_ROOT option, a virtual device (Root_CIFS) and a kernel cmdline parameter "cifsroot=" which tells the kernel to actually mount the root filesystem over a SMB share. The feature relies on ipconfig to set up the network prior to mounting the rootfs, so when it is set along with "cifsroot=" parameter: (1) cifs_root_setup() parses all necessary data out of "cifsroot=" parameter for the init process know how to mount the SMB rootfs (e.g. SMB server address, mount options). (2) If DHCP failed for some reason in ipconfig, we keep retrying forever as we have nowhere to go for NFS or SMB root filesystems (see PATCH 2/2). Otherwise go to (3). (3) mount_cifs_root() is then called by mount_root() (ROOT_DEV == Root_CIFS), retrieves early parsed data from (1), then attempt to mount SMB rootfs by CIFSROOT_RETRY_MAX times at most (see PATCH 1/2). (4) If all attempts failed, fall back to floppy drive, otherwise continue the boot process with rootfs mounted over a SMB share. My idea was to keep the same behavior of nfsroot - as it seems to work for most users so far. For more information on how this feature works, see Documentation/filesystems/cifs/cifsroot.txt. Paulo Alcantara (SUSE) (2): init: Support mounting root file systems over SMB ipconfig: Handle CONFIG_CIFS_ROOT option init/do_mounts.c | 49 +++++++++++++++++++++++++++++++++++++++++++++ net/ipv4/ipconfig.c | 10 +++++++-- 2 files changed, 57 insertions(+), 2 deletions(-)