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Mon, 1 Feb 2021 13:18:42 -0500 (EST) Received: from veeam.com (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; Mon, 1 Feb 2021 19:18:40 +0100 Date: Mon, 1 Feb 2021 21:18:35 +0300 From: Sergei Shtepa To: Bart Van Assche Message-ID: <20210201181835.GA2515@veeam.com> References: <1611853955-32167-1-git-send-email-sergei.shtepa@veeam.com> <5c6c936a-f213-eaa3-f4fb-3461a0b4dbe1@acm.org> MIME-Version: 1.0 In-Reply-To: <5c6c936a-f213-eaa3-f4fb-3461a0b4dbe1@acm.org> X-Originating-IP: [172.24.14.5] X-ClientProxiedBy: prgmbx01.amust.local (172.24.0.171) To prgmbx01.amust.local (172.24.0.171) X-EsetResult: clean, is OK X-EsetId: 37303A29C604D26566776A X-Veeam-MMEX: True X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-loop: dm-devel@redhat.com Cc: "snitzer@redhat.com" , Pavel Tide , "ming.lei@redhat.com" , "linux-block@vger.kernel.org" , "dm-devel@redhat.com" , "agk@redhat.com" Subject: Re: [dm-devel] [PATCH 0/2] block: blk_interposer v3 X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit The 02/01/2021 18:45, Bart Van Assche wrote: > On 1/28/21 9:12 AM, Sergei Shtepa wrote: > > I`m ready to suggest the blk_interposer again. > > blk_interposer allows to intercept bio requests, remap bio to > > another devices or add new bios. > > > > This version has support from device mapper. > > > > For the dm-linear device creation command, the `noexcl` parameter > > has been added, which allows to open block devices without > > FMODE_EXCL mode. It allows to create dm-linear device on a block > > device with an already mounted file system. > > The new ioctl DM_DEV_REMAP allows to enable and disable bio > > interception. > > > > Thus, it is possible to add the dm-device to the block layer stack > > without reconfiguring and rebooting. > > What functionality does this driver provide that is not yet available in > a RAID level 1 (mirroring) driver + a custom dm driver? My understanding > is that there are already two RAID level 1 drivers in the kernel tree > and that both driver support sending bio's to two different block devices. > > Thanks, > > Bart. Hi Bart. The proposed patch is not realy aimed at RAID1. Creating a new dm device in the non-FMODE_EXCL mode and then remaping bio requests from the regular block device to the new DM device using the blk_interposer will allow to use device mapper for regular devices. For dm-linear, there is not much benefit from using blk_interposer. This is a good and illustrative example. Later, using blk-interposer, it will be possible to connect the dm-cache "on the fly" without having to reboot and/or reconfigure. My intention is to let users use dm-snap to create snapshots of any device. blk-interposer will allow to add new features to Device Mapper. As per Daniel's advice I want to add a documentation, I'm working on it now. The documentation will also contain a description of new features that blk_interposer will add to Device Mapper Thanks. -- Sergei Shtepa Veeam Software developer. -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel From mboxrd@z Thu Jan 1 00:00:00 1970 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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 94B2AC433DB for ; Mon, 1 Feb 2021 18:20:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F5F364EBA for ; Mon, 1 Feb 2021 18:20:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232749AbhBASTw (ORCPT ); Mon, 1 Feb 2021 13:19:52 -0500 Received: from mx2.veeam.com ([64.129.123.6]:54274 "EHLO mx2.veeam.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232735AbhBASTe (ORCPT ); Mon, 1 Feb 2021 13:19:34 -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 49F224114C; Mon, 1 Feb 2021 13:18:42 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=veeam.com; s=mx2; t=1612203523; bh=7r/MqH9loKA33bLlpIYLMsNQAOZIhKTb3ZZT72/pbio=; h=Date:From:To:CC:Subject:References:In-Reply-To:From; b=SCPSxI8onESKQULwBs41MWCYQCvDLrQscXJXXes6K/SSYKsX8zKbQ/M77lfQhSpQw l+trIQi0nIMJ5ZQMqHEqfmh9tkwkIl4QjNi+yJf9V/JZU9hoR/vPFqqw7xg37pZ5Tw FwcAAonoYJ5FU6OFgGVDMjLkLQAHIsWzaEwK14Zg= Received: from veeam.com (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; Mon, 1 Feb 2021 19:18:40 +0100 Date: Mon, 1 Feb 2021 21:18:35 +0300 From: Sergei Shtepa To: Bart Van Assche CC: "hare@suse.de" , "ming.lei@redhat.com" , "agk@redhat.com" , "snitzer@redhat.com" , "dm-devel@redhat.com" , "linux-block@vger.kernel.org" , Pavel Tide Subject: Re: [dm-devel] [PATCH 0/2] block: blk_interposer v3 Message-ID: <20210201181835.GA2515@veeam.com> References: <1611853955-32167-1-git-send-email-sergei.shtepa@veeam.com> <5c6c936a-f213-eaa3-f4fb-3461a0b4dbe1@acm.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline In-Reply-To: <5c6c936a-f213-eaa3-f4fb-3461a0b4dbe1@acm.org> X-Originating-IP: [172.24.14.5] X-ClientProxiedBy: prgmbx01.amust.local (172.24.0.171) To prgmbx01.amust.local (172.24.0.171) X-EsetResult: clean, is OK X-EsetId: 37303A29C604D26566776A X-Veeam-MMEX: True Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org The 02/01/2021 18:45, Bart Van Assche wrote: > On 1/28/21 9:12 AM, Sergei Shtepa wrote: > > I`m ready to suggest the blk_interposer again. > > blk_interposer allows to intercept bio requests, remap bio to > > another devices or add new bios. > > > > This version has support from device mapper. > > > > For the dm-linear device creation command, the `noexcl` parameter > > has been added, which allows to open block devices without > > FMODE_EXCL mode. It allows to create dm-linear device on a block > > device with an already mounted file system. > > The new ioctl DM_DEV_REMAP allows to enable and disable bio > > interception. > > > > Thus, it is possible to add the dm-device to the block layer stack > > without reconfiguring and rebooting. > > What functionality does this driver provide that is not yet available in > a RAID level 1 (mirroring) driver + a custom dm driver? My understanding > is that there are already two RAID level 1 drivers in the kernel tree > and that both driver support sending bio's to two different block devices. > > Thanks, > > Bart. Hi Bart. The proposed patch is not realy aimed at RAID1. Creating a new dm device in the non-FMODE_EXCL mode and then remaping bio requests from the regular block device to the new DM device using the blk_interposer will allow to use device mapper for regular devices. For dm-linear, there is not much benefit from using blk_interposer. This is a good and illustrative example. Later, using blk-interposer, it will be possible to connect the dm-cache "on the fly" without having to reboot and/or reconfigure. My intention is to let users use dm-snap to create snapshots of any device. blk-interposer will allow to add new features to Device Mapper. As per Daniel's advice I want to add a documentation, I'm working on it now. The documentation will also contain a description of new features that blk_interposer will add to Device Mapper Thanks. -- Sergei Shtepa Veeam Software developer.