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From: Christoph Hellwig <hch@infradead.org>
To: Nitesh Shetty <nj.shetty@samsung.com>
Cc: "Christoph Hellwig" <hch@infradead.org>,
	"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>,
	"James Smart" <james.smart@broadcom.com>,
	"Chaitanya Kulkarni" <kch@nvidia.com>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	"Christian Brauner" <brauner@kernel.org>,
	martin.petersen@oracle.com, linux-scsi@vger.kernel.org,
	willy@infradead.org, hare@suse.de, djwong@kernel.org,
	bvanassche@acm.org, ming.lei@redhat.com, dlemoal@kernel.org,
	nitheshshetty@gmail.com, gost.dev@samsung.com,
	"Kanchan Joshi" <joshi.k@samsung.com>,
	"Javier González" <javier.gonz@samsung.com>,
	"Anuj Gupta" <anuj20.g@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: Re: [PATCH v12 5/9] nvme: add copy offload support
Date: Wed, 7 Jun 2023 00:12:46 -0700	[thread overview]
Message-ID: <ZIAt7vL+/isPJEl5@infradead.org> (raw)
In-Reply-To: <20230606113535.rjbhe6eqlyqk4pqq@green245>

On Tue, Jun 06, 2023 at 05:05:35PM +0530, Nitesh Shetty wrote:
> Downside will be duplicating checks which are present for read, write in
> block layer, device-mapper and zoned devices.
> But we can do this, shouldn't be an issue.

Yes.  Please never overload operations, this is just causing problems
everywhere, and that why I split the operations from the flag a few
years ago.

> The idea behind subsys is to prevent copy across different subsystem.
> For example, copy across nvme subsystem and the scsi subsystem. [1]
> At present, we don't support inter-namespace(copy across NVMe namespace),
> but after community feedback for previous series we left scope for it.

Never leave scope for something that isn't actually added.  That just
creates a giant maintainance nightmare.  Cross-device copies are giant
nightmare in general, and in the case of NVMe completely unusable
as currently done in the working group.  Messing up something that
is entirely reasonable (local copy) for something like that is a sure
way to never get this series in.

  reply	other threads:[~2023-06-07  7:13 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20230605122104epcas5p4ef1775cd4a218faa7b2459d58f63c275@epcas5p4.samsung.com>
2023-06-05 12:17 ` [PATCH v12 0/9] Implement copy offload support Nitesh Shetty
     [not found]   ` <CGME20230605122122epcas5p27d70bd972c1063ecb543ea4489870fd7@epcas5p2.samsung.com>
2023-06-05 12:17     ` [PATCH v12 1/9] block: Introduce queue limits for copy-offload support Nitesh Shetty
     [not found]   ` <CGME20230605122141epcas5p256df105da840c937758de63e67516f32@epcas5p2.samsung.com>
2023-06-05 12:17     ` [PATCH v12 2/9] block: Add copy offload support infrastructure Nitesh Shetty
     [not found]   ` <CGME20230605122208epcas5p297068ea23b0aff43e40751219574ff9f@epcas5p2.samsung.com>
2023-06-05 12:17     ` [PATCH v12 3/9] block: add emulation for copy Nitesh Shetty
     [not found]   ` <CGME20230605122239epcas5p236a716d16fa1d1a2dfff856158deb5af@epcas5p2.samsung.com>
2023-06-05 12:17     ` [PATCH v12 4/9] fs, block: copy_file_range for def_blk_ops for direct block device Nitesh Shetty
     [not found]   ` <CGME20230605122310epcas5p4aaebfc26fe5377613a36fe50423cf494@epcas5p4.samsung.com>
2023-06-05 12:17     ` [PATCH v12 5/9] nvme: add copy offload support Nitesh Shetty
2023-06-05 13:43       ` Christoph Hellwig
2023-06-06 11:35         ` Nitesh Shetty
2023-06-07  7:12           ` Christoph Hellwig [this message]
2023-06-08 12:08             ` Nitesh Shetty
2023-06-09  4:24               ` Christoph Hellwig
2023-07-10  6:14                 ` Nitesh Shetty
2023-06-08  1:36         ` Martin K. Petersen
     [not found]   ` <CGME20230605122330epcas5p18a452356d5bc39b852b85304bac5b0cc@epcas5p1.samsung.com>
2023-06-05 12:17     ` [PATCH v12 6/9] nvmet: add copy command support for bdev and file ns Nitesh Shetty
     [not found]   ` <CGME20230605122349epcas5p2de6c758bc38194ebfb1fd8c700e45608@epcas5p2.samsung.com>
2023-06-05 12:17     ` [PATCH v12 7/9] dm: Add support for copy offload Nitesh Shetty
     [not found]   ` <CGME20230605122402epcas5p2d2fc7493b04aaa70363324429411e689@epcas5p2.samsung.com>
2023-06-05 12:17     ` [PATCH v12 8/9] dm: Enable copy offload for dm-linear target Nitesh Shetty
     [not found]   ` <CGME20230605122416epcas5p3b37c08a7bf7ad57361b22be0f30d3bf7@epcas5p3.samsung.com>
2023-06-05 12:17     ` [PATCH v12 9/9] null_blk: add support for copy offload Nitesh Shetty

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