From patchwork Wed Feb 3 15:53:58 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergei Shtepa X-Patchwork-Id: 12064679 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8F22C433DB for ; Wed, 3 Feb 2021 15:57:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9E01364F65 for ; Wed, 3 Feb 2021 15:57:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234682AbhBCP5O (ORCPT ); Wed, 3 Feb 2021 10:57:14 -0500 Received: from mx2.veeam.com ([64.129.123.6]:56874 "EHLO mx2.veeam.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234693AbhBCP4w (ORCPT ); Wed, 3 Feb 2021 10:56:52 -0500 Received: from mail.veeam.com (prgmbx01.amust.local [172.24.0.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx2.veeam.com (Postfix) with ESMTPS id 3009441585; Wed, 3 Feb 2021 10:54:53 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=veeam.com; s=mx2; t=1612367693; bh=iOyxKFHPVnSJiNEqoIQLb5N7mlhEeMv/ecD8/bTsSt0=; h=From:To:CC:Subject:Date:In-Reply-To:References:From; b=Cu+rQypwSrNR/OGjg5GfLNWUQxA3We0G2OVdCd5KnehT/KVVe/iAsaSCXZaZWlJDY Ao/VQEAVEVBRBDGOohsmH9IZAENV1Bg/+OyxZooN0W7OF7zPCVhYm9G/E/YuJnqi5c 2hxC7FAnYrQ6lUC4JS29BTXdkwzuB8z0BrVPoJXI= Received: from prgdevlinuxpatch01.amust.local (172.24.14.5) by prgmbx01.amust.local (172.24.0.171) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.721.2; Wed, 3 Feb 2021 16:54:28 +0100 From: Sergei Shtepa To: , , , , , , , , , , , , , , , CC: , Subject: [PATCH v4 6/6] docs: device-mapper: 'noexcl' option for dm-linear Date: Wed, 3 Feb 2021 18:53:58 +0300 Message-ID: <1612367638-3794-7-git-send-email-sergei.shtepa@veeam.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1612367638-3794-1-git-send-email-sergei.shtepa@veeam.com> References: <1612367638-3794-1-git-send-email-sergei.shtepa@veeam.com> MIME-Version: 1.0 X-Originating-IP: [172.24.14.5] X-ClientProxiedBy: prgmbx02.amust.local (172.24.0.172) To prgmbx01.amust.local (172.24.0.171) X-EsetResult: clean, is OK X-EsetId: 37303A29C604D265667062 X-Veeam-MMEX: True Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org New 'noexcl' option allow to open underlying block-device without FMODE_EXCL flag. Signed-off-by: Sergei Shtepa --- .../admin-guide/device-mapper/linear.rst | 26 ++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/Documentation/admin-guide/device-mapper/linear.rst b/Documentation/admin-guide/device-mapper/linear.rst index 9d17fc6e64a9..f035cd7ad78c 100644 --- a/Documentation/admin-guide/device-mapper/linear.rst +++ b/Documentation/admin-guide/device-mapper/linear.rst @@ -6,12 +6,22 @@ Device-Mapper's "linear" target maps a linear range of the Device-Mapper device onto a linear range of another device. This is the basic building block of logical volume managers. -Parameters: +Parameters: [] : - Full pathname to the underlying block-device, or a + Full pathname to the underlying block-device, or a "major:minor" device-number. : - Starting sector within the device. + Starting sector within the device. + : + Options allow to set the exclusivity mode. The exclusivity mode + can be 'excl' and 'noexcl'. By default, then options is not set, + the 'excl' mode is used. 'noexcl' mode allow to open device + without FMODE_EXCL flag. This allow to create liner device with + underlying block-device that are already used by the system. For + example, the file system on this device is already mounted. + The 'noexcl' option should be used when creating dm devices that + will be used as acceptor when connecting the device mapper to an + existing block device with the 'dmsetup remap' command. Example scripts @@ -61,3 +71,13 @@ Example scripts } `echo \"$table\" | dmsetup create $name`; + +:: + + #!/bin/sh + # Create linear device and remap all requests from the original device + # to new linear. + DEV=$1 + + echo "0 `blockdev --getsz $DEV` linear $DEV 0 noexcl" | dmsetup create dm-noexcl + dmsetup remap start dm-noexcl $DEV