From patchwork Fri Mar 12 15:44:52 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sergei Shtepa X-Patchwork-Id: 12135031 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=-14.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 F2B25C43381 for ; Fri, 12 Mar 2021 15:46:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D267F65033 for ; Fri, 12 Mar 2021 15:46:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232559AbhCLPpk (ORCPT ); Fri, 12 Mar 2021 10:45:40 -0500 Received: from mx4.veeam.com ([104.41.138.86]:49884 "EHLO mx4.veeam.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231789AbhCLPpT (ORCPT ); Fri, 12 Mar 2021 10:45:19 -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 mx4.veeam.com (Postfix) with ESMTPS id BB4E1114A84; Fri, 12 Mar 2021 18:45:13 +0300 (MSK) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=veeam.com; s=mx4; t=1615563913; bh=ay5rQDiZzTT+utrO+8oIcBlw6h3n728bJRSViccZ2nw=; h=From:To:CC:Subject:Date:From; b=miu7nl73pYbNAwOnTFVd1AAqr9VBxGeSW9ETKlmzb6i0Dxgpi5B/t7J/tTJ9vFzfc zPZmDoWbfnyfYnjeKj+RDcRLWoF5DW1K6w23phFtpke15oFbZVHPCxe89CbdGqYM4/ b+NvT21p4tk40WgRS8jprPUICz+ebalgOQytu6+U= 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; Fri, 12 Mar 2021 16:45:12 +0100 From: Sergei Shtepa To: Christoph Hellwig , Mike Snitzer , Alasdair Kergon , Hannes Reinecke , Jens Axboe , , , , CC: , Subject: [PATCH v7 0/3] block device interposer Date: Fri, 12 Mar 2021 18:44:52 +0300 Message-ID: <1615563895-28565-1-git-send-email-sergei.shtepa@veeam.com> X-Mailer: git-send-email 1.8.3.1 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: 37303A29D2A50B58627366 X-Veeam-MMEX: True Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hi all. I'm joyful to suggest the block device interposer (bdev_interposer) v7. bdev_interposer allows to redirect bio requests to other block devices. In this series of patches I suggest a different implementation of the bio interception mechanism. Now the interposer is a different block device. Instead of an additional hook, the function fops->submit_bio() of the interposer device is used. This implementation greatly simplifies the application of this bdev_interposer in device-mapper. But there is one limitation - the size of the interposer device must be greater than or equal to the size of the original device. The first patch adds the function blk_mq_is_queue_frozen(). It allows to check a queue state. The second patch is dedicated to bdev_interposer itself, which provides the ability to redirect bio to the interposer device. The third one adds the DM_INTERPOSED_FLAG flag. When this flag is applied with the ioctl DM_TABLE_LOAD_CMD, the underlying devices are opened without the FMODE_EXCL flag and connected via bdev_interposer. Changes in this patchset v7: * the request interception mechanism. Now the interposer is a block device that receives requests instead of the original device; * code design fixes. History: v6 - https://patchwork.kernel.org/project/linux-block/cover/1614774618-22410-1-git-send-email-sergei.shtepa@veeam.com/ * designed for 5.12; * thanks to the new design of the bio structure in v5.12, it is possible to perform interception not for the entire disk, but for each block device; * instead of the new ioctl DM_DEV_REMAP_CMD and the 'noexcl' option, the DM_INTERPOSED_FLAG flag for the ioctl DM_TABLE_LOAD_CMD is applied. v5 - https://patchwork.kernel.org/project/linux-block/cover/1612881028-7878-1-git-send-email-sergei.shtepa@veeam.com/ * rebase for v5.11-rc7; * patch set organization; * fix defects in documentation; * add some comments; * change mutex names for better code readability; * remove calling bd_unlink_disk_holder() for targets with non-exclusive flag; * change type for struct dm_remap_param from uint8_t to __u8. v4 - https://patchwork.kernel.org/project/linux-block/cover/1612367638-3794-1-git-send-email-sergei.shtepa@veeam.com/ Mostly changes were made, due to Damien's comments: * on the design of the code; * by the patch set organization; * bug with passing a wrong parameter to dm_get_device(); * description of the 'noexcl' parameter in the linear.rst. Also added remap_and_filter.rst. v3 - https://patchwork.kernel.org/project/linux-block/cover/1611853955-32167-1-git-send-email-sergei.shtepa@veeam.com/ In this version, I already suggested blk_interposer to apply to dm-linear. Problems were solved: * Interception of bio requests from a specific device on the disk, not from the entire disk. To do this, we added the dm_interposed_dev structure and an interval tree to store these structures. * Implemented ioctl DM_DEV_REMAP_CMD. A patch with changes in the lvm2 project was sent to the team lvm-devel@redhat.com. * Added the 'noexcl' option for dm-linear, which allows you to open the underlying block-device without FMODE_EXCL mode. v2 - https://patchwork.kernel.org/project/linux-block/cover/1607518911-30692-1-git-send-email-sergei.shtepa@veeam.com/ I tried to suggest blk_interposer without using it in device mapper, but with the addition of a sample of its use. It was then that I learned about the maintainers' attitudes towards the samples directory :). v1 - https://lwn.net/ml/linux-block/20201119164924.74401-1-hare@suse.de/ This Hannes's patch can be considered as a starting point, since this is where the interception mechanism and the term blk_interposer itself appeared. It became clear that blk_interposer can be useful for device mapper. before v1 - https://patchwork.kernel.org/project/linux-block/cover/1603271049-20681-1-git-send-email-sergei.shtepa@veeam.com/ I tried to offer a rather cumbersome blk-filter and a monster-like blk-snap module for creating snapshots. Thank you to everyone who was able to take the time to review the previous versions. I hope that this time I achieved the required quality. Thanks, Sergei. Sergei Shtepa (3): block: add blk_mq_is_queue_frozen() block: add bdev_interposer dm: add DM_INTERPOSED_FLAG block/bio.c | 2 ++ block/blk-core.c | 57 ++++++++++++++++++++++++++++++++ block/blk-mq.c | 13 ++++++++ block/genhd.c | 54 +++++++++++++++++++++++++++++++ drivers/md/dm-core.h | 3 ++ drivers/md/dm-ioctl.c | 13 ++++++++ drivers/md/dm-table.c | 61 +++++++++++++++++++++++++++++------ drivers/md/dm.c | 38 +++++++++++++++------- include/linux/blk-mq.h | 1 + include/linux/blk_types.h | 3 ++ include/linux/blkdev.h | 9 ++++++ include/linux/device-mapper.h | 1 + include/uapi/linux/dm-ioctl.h | 6 ++++ 13 files changed, 240 insertions(+), 21 deletions(-)