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From:   Nitesh Shetty <nj.shetty@samsung.com>
To:     Jens Axboe <axboe@kernel.dk>, Jonathan Corbet <corbet@lwn.net>,
        Alasdair Kergon <agk@redhat.com>,
        Mike Snitzer <snitzer@kernel.org>, dm-devel@redhat.com,
        Keith Busch <kbusch@kernel.org>,
        Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>,
        Chaitanya Kulkarni <kch@nvidia.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>
Cc:     martin.petersen@oracle.com, mcgrof@kernel.org, dlemoal@kernel.org,
        gost.dev@samsung.com, Nitesh Shetty <nj.shetty@samsung.com>,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-nvme@lists.infradead.org,
        linux-fsdevel@vger.kernel.org
Subject: [PATCH v14 00/11] Implement copy offload support
Date:   Fri, 11 Aug 2023 16:22:43 +0530
Message-Id: <20230811105300.15889-1-nj.shetty@samsung.com>
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Precedence: bulk

The patch series covers the points discussed in past and most recently
in LSFMM'23[0].
We have covered the initial agreed requirements in this patch set and
further additional features suggested by community.

This is next iteration of our previous patch set v13[1].
We achieve copy offload by sending 2 bio's with source and destination
info and merge them to form a request. This request is sent to driver.
So this design works only for request based storage drivers.

Overall series supports:
========================
	1. Driver
		- NVMe Copy command (single NS, TP 4065), including support
		in nvme-target (for block and file back end).

	2. Block layer
		- Block-generic copy (REQ_OP_COPY_DST/SRC), operation with
                  interface accommodating two block-devs
                - Merging copy requests in request layer
		- Emulation, for in-kernel user when offload is natively 
                absent
		- dm-linear support (for cases not requiring split)

	3. User-interface
		- copy_file_range

Testing
=======
	Copy offload can be tested on:
	a. QEMU: NVME simple copy (TP 4065). By setting nvme-ns
		parameters mssrl,mcl, msrc. For more info [2].
	b. Null block device
        c. NVMe Fabrics loopback.
	d. blktests[3]

	Emulation can be tested on any device.

	fio[4].

Infra and plumbing:
===================
        We populate copy_file_range callback in def_blk_fops. 
        For devices that support copy-offload, use blkdev_copy_offload to
        achieve in-device copy.
        However for cases, where device doesn't support offload,
        fallback to generic_copy_file_range.
        For in-kernel users (like NVMe fabrics), use blkdev_copy_offload
        if device is copy offload capable or else fallback to emulation 
        using blkdev_copy_emulation.
        Modify checks in generic_copy_file_range to support block-device.

Blktests[3]
======================
	tests/block/035-040: Runs copy offload and emulation on null
                              block device.
	tests/block/050,055: Runs copy offload and emulation on test
                              nvme block device.
        tests/nvme/056-067: Create a loop backed fabrics device and
                              run copy offload and emulation.

Future Work
===========
	- loopback device copy offload support
	- upstream fio to use copy offload
	- upstream blktest to test copy offload
        - update man pages for copy_file_range
        - expand in-kernel users of copy offload

	These are to be taken up after this minimal series is agreed upon.

Additional links:
=================
	[0] https://lore.kernel.org/linux-nvme/CA+1E3rJ7BZ7LjQXXTdX+-0Edz=zT14mmPGMiVCzUgB33C60tbQ@mail.gmail.com/
            https://lore.kernel.org/linux-nvme/f0e19ae4-b37a-e9a3-2be7-a5afb334a5c3@nvidia.com/
            https://lore.kernel.org/linux-nvme/20230113094648.15614-1-nj.shetty@samsung.com/
	[1] https://lore.kernel.org/linux-nvme/20230627183629.26571-1-nj.shetty@samsung.com/
	[2] https://qemu-project.gitlab.io/qemu/system/devices/nvme.html#simple-copy
	[3] https://github.com/nitesh-shetty/blktests/tree/feat/copy_offload/v14
	[4] https://github.com/OpenMPDK/fio/tree/copyoffload-3.35-v14

Changes since v13:
=================
        - block:
            1. Simplified copy offload and emulation helpers, now
                  caller needs to decide between offload/emulation fallback
            2. src,dst bio order change (Christoph Hellwig)
            3. refcount changes similar to dio (Christoph Hellwig)
            4. Single outstanding IO for copy emulation (Christoph Hellwig)
            5. use copy_max_sectors to identify copy offload
                  capability and other reviews (Damien, Christoph)
            6. Return status in endio handler (Christoph Hellwig)
        - nvme-fabrics: fallback to emulation in case of partial
          offload completion
        - in kernel user addition (Ming lei)
        - indentation, documentation, minor fixes, misc changes (Damien,
          Christoph)
        - blktests changes to test kernel changes

Changes since v12:
=================
        - block,nvme: Replaced token based approach with request based
          single namespace capable approach (Christoph Hellwig)

Changes since v11:
=================
        - Documentation: Improved documentation (Damien Le Moal)
        - block,nvme: ssize_t return values (Darrick J. Wong)
        - block: token is allocated to SECTOR_SIZE (Matthew Wilcox)
        - block: mem leak fix (Maurizio Lombardi)

Changes since v10:
=================
        - NVMeOF: optimization in NVMe fabrics (Chaitanya Kulkarni)
        - NVMeOF: sparse warnings (kernel test robot)

Changes since v9:
=================
        - null_blk, improved documentation, minor fixes(Chaitanya Kulkarni)
        - fio, expanded testing and minor fixes (Vincent Fu)

Changes since v8:
=================
        - null_blk, copy_max_bytes_hw is made config fs parameter
          (Damien Le Moal)
        - Negative error handling in copy_file_range (Christian Brauner)
        - minor fixes, better documentation (Damien Le Moal)
        - fio upgraded to 3.34 (Vincent Fu)

Changes since v7:
=================
        - null block copy offload support for testing (Damien Le Moal)
        - adding direct flag check for copy offload to block device,
	  as we are using generic_copy_file_range for cached cases.
        - Minor fixes

Changes since v6:
=================
        - copy_file_range instead of ioctl for direct block device
        - Remove support for multi range (vectored) copy
        - Remove ioctl interface for copy.
        - Remove offload support in dm kcopyd.

Changes since v5:
=================
	- Addition of blktests (Chaitanya Kulkarni)
        - Minor fix for fabrics file backed path
        - Remove buggy zonefs copy file range implementation.

Changes since v4:
=================
	- make the offload and emulation design asynchronous (Hannes
	  Reinecke)
	- fabrics loopback support
	- sysfs naming improvements (Damien Le Moal)
	- use kfree() instead of kvfree() in cio_await_completion
	  (Damien Le Moal)
	- use ranges instead of rlist to represent range_entry (Damien
	  Le Moal)
	- change argument ordering in blk_copy_offload suggested (Damien
	  Le Moal)
	- removed multiple copy limit and merged into only one limit
	  (Damien Le Moal)
	- wrap overly long lines (Damien Le Moal)
	- other naming improvements and cleanups (Damien Le Moal)
	- correctly format the code example in description (Damien Le
	  Moal)
	- mark blk_copy_offload as static (kernel test robot)
	
Changes since v3:
=================
	- added copy_file_range support for zonefs
	- added documentation about new sysfs entries
	- incorporated review comments on v3
	- minor fixes

Changes since v2:
=================
	- fixed possible race condition reported by Damien Le Moal
	- new sysfs controls as suggested by Damien Le Moal
	- fixed possible memory leak reported by Dan Carpenter, lkp
	- minor fixes

Changes since v1:
=================
	- sysfs documentation (Greg KH)
        - 2 bios for copy operation (Bart Van Assche, Mikulas Patocka,
          Martin K. Petersen, Douglas Gilbert)
        - better payload design (Darrick J. Wong)

Anuj Gupta (1):
  fs/read_write: Enable copy_file_range for block device.

Nitesh Shetty (10):
  block: Introduce queue limits and sysfs for copy-offload support
  Add infrastructure for copy offload in block and request layer.
  block: add copy offload support
  block: add emulation for copy
  fs, block: copy_file_range for def_blk_ops for direct block device
  nvme: add copy offload support
  nvmet: add copy command support for bdev and file ns
  dm: Add support for copy offload
  dm: Enable copy offload for dm-linear target
  null_blk: add support for copy offload

 Documentation/ABI/stable/sysfs-block |  23 ++
 Documentation/block/null_blk.rst     |   5 +
 block/blk-core.c                     |   7 +
 block/blk-lib.c                      | 419 +++++++++++++++++++++++++++
 block/blk-merge.c                    |  41 +++
 block/blk-settings.c                 |  24 ++
 block/blk-sysfs.c                    |  36 +++
 block/blk.h                          |  16 +
 block/elevator.h                     |   1 +
 block/fops.c                         |  25 ++
 drivers/block/null_blk/main.c        |  99 ++++++-
 drivers/block/null_blk/null_blk.h    |   1 +
 drivers/block/null_blk/trace.h       |  23 ++
 drivers/md/dm-linear.c               |   1 +
 drivers/md/dm-table.c                |  37 +++
 drivers/md/dm.c                      |   7 +
 drivers/nvme/host/constants.c        |   1 +
 drivers/nvme/host/core.c             |  79 +++++
 drivers/nvme/host/trace.c            |  19 ++
 drivers/nvme/target/admin-cmd.c      |   9 +-
 drivers/nvme/target/io-cmd-bdev.c    |  97 +++++++
 drivers/nvme/target/io-cmd-file.c    |  50 ++++
 drivers/nvme/target/nvmet.h          |   4 +
 drivers/nvme/target/trace.c          |  19 ++
 fs/read_write.c                      |   8 +-
 include/linux/bio.h                  |   6 +-
 include/linux/blk_types.h            |  10 +
 include/linux/blkdev.h               |  22 ++
 include/linux/device-mapper.h        |   3 +
 include/linux/nvme.h                 |  43 ++-
 30 files changed, 1119 insertions(+), 16 deletions(-)


base-commit: f7dc24b3413851109c4047b22997bd0d95ed52a2
-- 
2.35.1.500.gb896f729e2