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From: "hch@lst.de" <hch@lst.de>
To: Javier Gonzalez <javier@javigon.com>
Cc: "hch@lst.de" <hch@lst.de>, Keith Busch <kbusch@kernel.org>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"sagi@grimberg.me" <sagi@grimberg.me>,
	"axboe@kernel.dk" <axboe@kernel.dk>,
	"joshi.k@samsung.com" <joshi.k@samsung.com>,
	"Klaus B. Jensen" <k.jensen@samsung.com>,
	"Niklas.Cassel@wdc.com" <Niklas.Cassel@wdc.com>
Subject: Re: nvme: report capacity 0 for non supported ZNS SSDs
Date: Tue, 3 Nov 2020 10:06:28 +0100	[thread overview]
Message-ID: <20201103090628.GA15656@lst.de> (raw)
In-Reply-To: <20201102212405.j43m47ewg65v4k5k@MacBook-Pro.localdomain>

On Mon, Nov 02, 2020 at 10:24:05PM +0100, Javier Gonzalez wrote:
> If I understand correctly, the model would be that a namespace will
> always have (i) a character device associated where I/O is always allowed
> through user formed commands, and if the namespace has full support in
> the kernel (ii) a block device where I/O is as it is today. In case of
> (ii) both interfaces can be used for I/O.

Yes.

> While we work on iterations for c), do you believe it is reasonable to
> merge a version of the current path that follows the PI convention for
> unsupported command sets and features? I would assume that we will have
> to convert PI to this model too when it is available.

I'm rather torn.  I think the model of the zero capacity block device
is a really, really bad one and we should haver never added it.  That
being said, for a ZNS namespace that does not support Zone Append I
can think of a model that actually makes sense:  expose it as a read-only
block device, as we can actually read from it perfectly fine, and that
would also allow ioctl access.

WARNING: multiple messages have this Message-ID (diff)
From: "hch@lst.de" <hch@lst.de>
To: Javier Gonzalez <javier@javigon.com>
Cc: "axboe@kernel.dk" <axboe@kernel.dk>,
	"Niklas.Cassel@wdc.com" <Niklas.Cassel@wdc.com>,
	"sagi@grimberg.me" <sagi@grimberg.me>,
	"joshi.k@samsung.com" <joshi.k@samsung.com>,
	"Klaus B. Jensen" <k.jensen@samsung.com>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	Keith Busch <kbusch@kernel.org>, "hch@lst.de" <hch@lst.de>
Subject: Re: nvme: report capacity 0 for non supported ZNS SSDs
Date: Tue, 3 Nov 2020 10:06:28 +0100	[thread overview]
Message-ID: <20201103090628.GA15656@lst.de> (raw)
In-Reply-To: <20201102212405.j43m47ewg65v4k5k@MacBook-Pro.localdomain>

On Mon, Nov 02, 2020 at 10:24:05PM +0100, Javier Gonzalez wrote:
> If I understand correctly, the model would be that a namespace will
> always have (i) a character device associated where I/O is always allowed
> through user formed commands, and if the namespace has full support in
> the kernel (ii) a block device where I/O is as it is today. In case of
> (ii) both interfaces can be used for I/O.

Yes.

> While we work on iterations for c), do you believe it is reasonable to
> merge a version of the current path that follows the PI convention for
> unsupported command sets and features? I would assume that we will have
> to convert PI to this model too when it is available.

I'm rather torn.  I think the model of the zero capacity block device
is a really, really bad one and we should haver never added it.  That
being said, for a ZNS namespace that does not support Zone Append I
can think of a model that actually makes sense:  expose it as a read-only
block device, as we can actually read from it perfectly fine, and that
would also allow ioctl access.

_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

  reply	other threads:[~2020-11-03  9:06 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20201102161505eucas1p19415e34eb0b14c7eca5a2c648569cf1e@eucas1p1.samsung.com>
     [not found] ` <0916865d50c640e3aa95dc542f3986b9@CAMSVWEXC01.scsc.local>
2020-11-02 16:30   ` [PATCH V2] nvme: report capacity 0 for non supported ZNS SSDs Niklas Cassel
2020-11-02 16:30     ` Niklas Cassel
2020-11-02 21:25     ` Javier Gonzalez
2020-11-02 21:25       ` Javier Gonzalez
2020-11-02 18:08   ` [PATCH V2] " hch
2020-11-02 18:08     ` hch
2020-11-02 18:33     ` Keith Busch
2020-11-02 18:33       ` Keith Busch
2020-11-02 18:58       ` hch
2020-11-02 18:58         ` hch
2020-11-02 21:24         ` Javier Gonzalez
2020-11-02 21:24           ` Javier Gonzalez
2020-11-03  9:06           ` hch [this message]
2020-11-03  9:06             ` hch
2020-11-03 14:10             ` Javier Gonzalez
2020-11-03 14:10               ` Javier Gonzalez
2020-11-03 15:26               ` hch
2020-11-03 15:26                 ` hch
2020-11-03 15:54                 ` Javier Gonzalez
2020-11-03 15:54                   ` Javier Gonzalez
2020-11-04 14:26         ` [PATCH V2] " Hannes Reinecke
2020-11-04 14:26           ` Hannes Reinecke
2020-11-04 14:29           ` hch
2020-11-04 14:29             ` hch
2020-11-04 14:46             ` Hannes Reinecke
2020-11-04 14:46               ` Hannes Reinecke
2020-11-05  7:37               ` hch
2020-11-05  7:37                 ` hch
2020-11-05  7:42                 ` Hannes Reinecke
2020-11-05  7:42                   ` Hannes Reinecke

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