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Wed, 3 Mar 2021 15:30:33 +0300 (MSK) 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 Mar 2021 13:30:31 +0100 From: Sergei Shtepa To: , , , , , , , , , Date: Wed, 3 Mar 2021 15:30:14 +0300 Message-ID: <1614774618-22410-1-git-send-email-sergei.shtepa@veeam.com> MIME-Version: 1.0 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: 37303A29C604D265637363 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 2.78 on 10.11.54.3 X-loop: dm-devel@redhat.com Cc: pavel.tide@veeam.com, sergei.shtepa@veeam.com Subject: [dm-devel] [PATCH v6 0/4] block-layer interposer 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 10.5.11.23 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 Hi all. I'm joyful to suggest the block-layer interposer (blk_interposer) v6. blk_interposer allows to intercept bio requests, remap bio to another devices or add new bios. This series of patches adds the ability to use blk_interposer for any dm-target using the DM_INTERPOSED_FLAG flag. The first patch adds the function blk_mq_is_queue_frozen(). It allows to assert a queue state. The second patch is dedicated to blk_interposer itself, which provides the ability to intercept bio. The third one adds support for blk_interposer from the device mapper. The fourth patch 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 blk_interposer. Changes: v6 - current patch set * 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 (4): block: add blk_mq_is_queue_frozen() block: add blk_interposer dm: introduce dm-interposer dm: add DM_INTERPOSED_FLAG block/bio.c | 2 + block/blk-core.c | 36 +++++ block/blk-mq.c | 12 ++ block/genhd.c | 93 ++++++++++++ drivers/md/Makefile | 2 +- drivers/md/dm-core.h | 6 + drivers/md/dm-interposer.c | 258 ++++++++++++++++++++++++++++++++++ drivers/md/dm-interposer.h | 40 ++++++ drivers/md/dm-ioctl.c | 9 ++ drivers/md/dm-table.c | 115 +++++++++++++-- drivers/md/dm.c | 38 +++-- include/linux/blk-mq.h | 1 + include/linux/blk_types.h | 4 + include/linux/blkdev.h | 17 +++ include/linux/device-mapper.h | 1 + include/uapi/linux/dm-ioctl.h | 6 + 16 files changed, 618 insertions(+), 22 deletions(-) create mode 100644 drivers/md/dm-interposer.c create mode 100644 drivers/md/dm-interposer.h