From patchwork Thu Feb 27 21:33:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 11410255 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6FA5E17E0 for ; Thu, 27 Feb 2020 21:33:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5070D246A4 for ; Thu, 27 Feb 2020 21:33:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="vJ5jiJr4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729893AbgB0Vdj (ORCPT ); Thu, 27 Feb 2020 16:33:39 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:43378 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726460AbgB0Vdj (ORCPT ); Thu, 27 Feb 2020 16:33:39 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 01RLMmiZ030019; Thu, 27 Feb 2020 21:33:37 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : from : to : cc : date : message-id : mime-version : content-type : content-transfer-encoding; s=corp-2020-01-29; bh=26vP5yqSHUgG0Uo9ubIi3AuFzWFw+pcCN2GIKW+ya98=; b=vJ5jiJr4gw5mgi8EBHIfXBIvvScf2HTA7sucQRgyk30vUw5mHKrxrqcSO0iPwU8nVCIx UaRzwnaTeTR64PZBsSUMKOi8PIQ3tPIvZQy/x805fp+NRW0U15Lj/7kEmRJAm7M77KuX YmOH3oAIS5eisCl/aTxDeHgL5lrKvqZvC4lU+6vEU8TXr2U8tfbCJz+d32ZY3h226N5K t1kZ4m9UEMgKw4SrejQvDoqM0I8r4IK6twEwjR1BJTytjLu3KZh6fM6AdjW/81TMCWCt 95U7fcLZbAYI1CqohTdP9XKRUTeKA43sWgSA9w5PbzXLxM2DExNYDueWR15walx6+zNy bQ== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2120.oracle.com with ESMTP id 2ydct3ds4b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 27 Feb 2020 21:33:37 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 01RLIEDZ167823; Thu, 27 Feb 2020 21:33:37 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userp3020.oracle.com with ESMTP id 2ydj4nnqvs-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 27 Feb 2020 21:33:37 +0000 Received: from abhmp0007.oracle.com (abhmp0007.oracle.com [141.146.116.13]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 01RLXaGL010885; Thu, 27 Feb 2020 21:33:36 GMT Received: from localhost (/10.145.179.117) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 27 Feb 2020 13:33:36 -0800 Subject: [PATCH RFC 0/3] fs: online filesystem uuid operations From: "Darrick J. Wong" To: darrick.wong@oracle.com Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org Date: Thu, 27 Feb 2020 13:33:35 -0800 Message-ID: <158283921562.904118.13877489081184026686.stgit@magnolia> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9544 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 phishscore=0 suspectscore=1 spamscore=0 adultscore=0 malwarescore=0 mlxlogscore=999 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002270142 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9544 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 spamscore=0 priorityscore=1501 malwarescore=0 adultscore=0 phishscore=0 mlxlogscore=999 mlxscore=0 suspectscore=1 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002270142 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hi all, This patch series creates a couple of new ioctls to query and set the filesystem uuid of mounted filesystems. This is apparently desirous for some cloud providers who wish to be able to deploy pre-baked rootfs images to a machine, boot it, and have the client machine be able to change the label and uuid to reflect that it's now derivative of the original image. For ext4 this is pretty easy to do as all the pieces are already in place. For XFS this is a little more difficult because we need to get our house in order w.r.t. dependencies between the log uuid and filesystem superblock uuid, which means that this is really new ext4 functionality that I'd like to share with the other filesystems. I'm particularly curious to hear what people think about the FORCE_INCOMPAT flag. There are some circumstances (namely when the entire fs metadata is keyed to a certain uuid) where we can only change the uuid by turning on an incompat feature flag. The currently running kernel should be able to handle that just fine, but older kernels won't be able to mount the fs after that. We (XFS) normally don't do things like that, which is why I require positive affirmation from userspace that doing so is ok. This is an extraordinary way to destroy everything. Enjoy! Comments and questions are, as always, welcome. --D