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Date:   Mon, 24 May 2021 09:37:03 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Sagi Grimberg <sagi@grimberg.me>
Cc:     Keith Busch <kbusch@kernel.org>, Daniel Wagner <dwagner@suse.de>,
        linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
        Jens Axboe <axboe@fb.com>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] nvme: Use NN for max_namespaces if MNAN is zero
Message-ID: <20210524073703.GA24372@lst.de>
References: <20210521144734.90044-1-dwagner@suse.de> <20210521145306.ld7jc6alchimyzny@beryllium.lan> <20210521152702.GB29013@redsun51.ssa.fujisawa.hgst.com> <f89bf79e-937c-96ba-4622-4a29fce00b0e@grimberg.me>
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On Fri, May 21, 2021 at 01:19:26PM -0700, Sagi Grimberg wrote:
>
>>> Forgot to mention: During testing dynamically adding namespaces it was
>>> possible to trigger the WARNINGs in the nvme_parse_ana_log(). Initially
>>> the subsystem started with 8 namespaces and during runtime another 8
>>> namespaces was added.
>>
>> The controller is required to have a non-zero MNAN value if it supports
>> ANA:
>>
>>    If the controller supports Asymmetric Namespace Access Reporting, then
>>    this field shall be set to a non-zero value that is less than or equal
>>    to the NN value.
>
> That was my thought exactly

I think we should add a sanity check for that and reject the broken
controller if that is not the case rather than working around it.