From: Christoph Hellwig <hch@lst.de>
To: javier@javigon.com
Cc: linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
hch@lst.de, kbusch@kernel.org, sagi@grimberg.me,
minwoo.im.dev@gmail.com,
"Javier González" <javier.gonz@samsung.com>
Subject: Re: [PATCH V6 1/2] nvme: enable char device per namespace
Date: Wed, 3 Mar 2021 10:10:22 +0100 [thread overview]
Message-ID: <20210303091022.GA12784@lst.de> (raw)
In-Reply-To: <20210301192452.16770-2-javier.gonz@samsung.com>
On Mon, Mar 01, 2021 at 08:24:51PM +0100, javier@javigon.com wrote:
> From: Javier González <javier.gonz@samsung.com>
>
> Create a char device per NVMe namespace. This char device is always
> initialized, independently of whether the features implemented by the
> device are supported by the kernel. User-space can therefore always
> issue IOCTLs to the NVMe driver using the char device.
>
> The char device is presented as /dev/nvme-generic-XcYnZ. This naming
> scheme follows the convention of the hidden device (nvmeXcYnZ). Support
> for multipath will follow.
So I'm a little worried about the "support for multipath will follow" as
this has implications for the naming scheme, and our policy of how we
allow access to a namespace.
Ignoring some of the deprecated historic mistakes I think the policy
should be:
- admin commands that often are controller specific should usually
go to a controller-specific device, the existing /dev/nvmeX
devices
- I/O commands and admin command that do specific a nsid should go
through a per-namespace node that is multipath aware and not
controller specific
Which also makes me wonder about patch 2 in the series that seems
somewhat dangerous. Can we clearly state the policy implemented?
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next prev parent reply other threads:[~2021-03-03 21:25 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-01 19:24 [PATCH V6 0/2] nvme: enable char device per namespace javier
2021-03-01 19:24 ` [PATCH V6 1/2] " javier
2021-03-03 9:10 ` Christoph Hellwig [this message]
2021-03-03 10:02 ` Javier González
2021-03-09 11:31 ` Christoph Hellwig
2021-03-09 12:42 ` Javier González
2021-03-09 15:05 ` Christoph Hellwig
2021-03-09 21:18 ` Javier González
2021-03-24 12:29 ` Niklas Cassel
2021-03-25 2:09 ` Minwoo Im
2021-03-25 8:26 ` hch
2021-03-25 8:39 ` Niklas Cassel
2021-03-25 9:34 ` Minwoo Im
2021-03-25 12:25 ` Niklas Cassel
2021-03-25 12:33 ` Minwoo Im
2021-03-25 15:14 ` Keith Busch
2021-03-01 19:24 ` [PATCH V6 2/2] nvme: allow open for nvme-generic char device javier
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