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Date:   Tue, 9 Mar 2021 16:05:31 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Javier =?iso-8859-1?Q?Gonz=E1lez?= <javier@javigon.com>
Cc:     Christoph Hellwig <hch@lst.de>, linux-nvme@lists.infradead.org,
        linux-block@vger.kernel.org, kbusch@kernel.org, sagi@grimberg.me,
        minwoo.im.dev@gmail.com
Subject: Re: [PATCH V6 1/2] nvme: enable char device per namespace
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References: <20210301192452.16770-1-javier.gonz@samsung.com> <20210301192452.16770-2-javier.gonz@samsung.com> <20210303091022.GA12784@lst.de> <20210303100212.e43jgjvuomgybmy2@mpHalley.localdomain> <20210309113103.GA9233@lst.de> <20210309124104.uowad6bd4vlcthmw@mpHalley.local>
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On Tue, Mar 09, 2021 at 01:42:23PM +0100, Javier González wrote:
>> - nvme_cdev_fops implements file operations that directly on a nvme_ns,
>>   so they are path specific
>
> This is correct.
>
>> - we allow opening them even for a hidden controller
>
> This is also correct.
>
>> - there does not seem to be a char device node for ns_head at all.
>
> Also correct.
>
> We tried to keep it simple in the first iteration. Am I understanding
> that you see necessary to have per ns_head char devices?

That would be my understanding of "multipath support" for this character
device, yes.  Especially as hiding the individual char devices for the
hidden controllers once they are initially exposed would be an ABI break.