From: Damien Le Moal <Damien.LeMoal@wdc.com>
To: "hch@lst.de" <hch@lst.de>
Cc: "Javier González" <javier@javigon.com>,
"Matias Bjørling" <mb@lightnvm.io>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"kbusch@kernel.org" <kbusch@kernel.org>,
"sagi@grimberg.me" <sagi@grimberg.me>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"SelvaKumar S" <selvakuma.s1@samsung.com>,
"Kanchan Joshi" <joshi.k@samsung.com>,
"Nitesh Shetty" <nj.shetty@samsung.com>
Subject: Re: [PATCH 3/6] block: add support for zone offline transition
Date: Fri, 26 Jun 2020 09:15:14 +0000 [thread overview]
Message-ID: <CY4PR04MB3751E3DF3A1BD1FC77E6C101E7930@CY4PR04MB3751.namprd04.prod.outlook.com> (raw)
In-Reply-To: 20200626091113.GB26616@lst.de
On 2020/06/26 18:11, hch@lst.de wrote:
> On Fri, Jun 26, 2020 at 01:14:30AM +0000, Damien Le Moal wrote:
>> As long as you keep ZNS namespace report itself as being "host-managed" like
>> ZBC/ZAC disks, we need the consistency and common interface. If you break that,
>> the meaning of the zoned model queue attribute disappears and an application or
>> in-kernel user cannot rely on this model anymore to know how the drive will behave.
>
> We just need a way to expose to applications that new feature are
> supported. Just like we did with zone capacity support. That is why
> we added the feature flags to uapi zone structure.
>
>> Think of a file system, or any other in-kernel user. If they have to change
>> their code based on the device type (NVMe vs SCSI), then the zoned block device
>> interface is broken. Right now, that is not the case, everything works equally
>> well on ZNS and SCSI, modulo the need by a user for conventional zones that ZNS
>> do not define. But that is still consistent with the host-managed model since
>> conventional zones are optional.
>
> That is why we have the feature flag. That user should not know the
> underlying transport or spec. But it can reliably discover "this thing
> support zone capacity" or "this thing supports offline zones" or even
> nasty thing like "this zone can time out when open" which are much
> harder to deal with.
>
>> For this particular patch, there is currently no in-kernel user, and it is not
>> clear how this will be useful to applications. At least please clarify this. And
>
> The main user is the ioctl. And if you think about how offline zones are
> (suppose to) be used driving this from management tools in userspace
> actually totally make sense. Unlike for example open/close all which
> just don't make sense as primitives to start with.
OK. Adding a new BLKZONEOFFLINE ioctl is easy though and fits into the current
zone management plumbing well, I think. So the patch can be significantly
simplified (no need for the new zone management op function with flags).
>
--
Damien Le Moal
Western Digital Research
next prev parent reply other threads:[~2020-06-26 9:15 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-25 12:21 [PATCH 0/6] ZNS: Extra features for current patches Javier González
2020-06-25 12:21 ` [PATCH 1/6] block: introduce IOCTL for zone mgmt Javier González
2020-06-26 1:17 ` Damien Le Moal
2020-06-26 6:01 ` Javier González
2020-06-26 6:37 ` Damien Le Moal
2020-06-26 6:51 ` Javier González
2020-06-26 7:03 ` Damien Le Moal
2020-06-26 7:08 ` Javier González
2020-06-25 12:21 ` [PATCH 2/6] block: add support for selecting all zones Javier González
2020-06-26 1:27 ` Damien Le Moal
2020-06-26 5:58 ` Javier González
2020-06-26 6:35 ` Damien Le Moal
2020-06-26 6:52 ` Javier González
2020-06-26 7:06 ` Damien Le Moal
2020-06-25 12:21 ` [PATCH 3/6] block: add support for zone offline transition Javier González
2020-06-25 14:12 ` Matias Bjørling
2020-06-25 19:48 ` Javier González
2020-06-26 1:14 ` Damien Le Moal
2020-06-26 6:18 ` Javier González
2020-06-26 9:11 ` hch
2020-06-26 9:15 ` Damien Le Moal [this message]
2020-06-26 9:17 ` hch
2020-06-26 10:02 ` Javier González
2020-06-26 9:07 ` Christoph Hellwig
2020-06-26 1:34 ` Damien Le Moal
2020-06-26 6:08 ` Javier González
2020-06-26 6:42 ` Damien Le Moal
2020-06-26 6:58 ` Javier González
2020-06-26 7:17 ` Damien Le Moal
2020-06-26 7:26 ` Javier González
2020-06-25 12:21 ` [PATCH 4/6] block: introduce IOCTL to report dev properties Javier González
2020-06-25 13:10 ` Matias Bjørling
2020-06-25 19:42 ` Javier González
2020-06-25 19:58 ` Matias Bjørling
2020-06-26 6:24 ` Javier González
2020-06-25 20:25 ` Keith Busch
2020-06-26 6:28 ` Javier González
2020-06-26 15:52 ` Keith Busch
2020-06-26 16:25 ` Javier González
2020-06-26 0:57 ` Damien Le Moal
2020-06-26 6:27 ` Javier González
2020-06-26 1:38 ` Damien Le Moal
2020-06-26 6:22 ` Javier González
2020-06-25 12:21 ` [PATCH 5/6] block: add zone attr. to zone mgmt IOCTL struct Javier González
2020-06-25 15:13 ` Matias Bjørling
2020-06-25 19:51 ` Javier González
2020-06-26 1:45 ` Damien Le Moal
2020-06-26 6:03 ` Javier González
2020-06-26 6:38 ` Damien Le Moal
2020-06-26 6:49 ` Javier González
2020-06-26 9:14 ` Christoph Hellwig
2020-06-26 10:01 ` Javier González
2020-06-25 12:21 ` [PATCH 6/6] nvme: Add consistency check for zone count Javier González
2020-06-25 13:16 ` Matias Bjørling
2020-06-25 19:45 ` Javier González
2020-06-25 21:49 ` Keith Busch
2020-06-26 0:04 ` Damien Le Moal
2020-06-26 6:13 ` Javier González
2020-06-26 6:49 ` Damien Le Moal
2020-06-26 6:55 ` Javier González
2020-06-26 7:09 ` Damien Le Moal
2020-06-26 7:29 ` Javier González
2020-06-26 7:42 ` Damien Le Moal
2020-06-26 9:16 ` Christoph Hellwig
2020-06-26 10:03 ` Javier González
2020-06-25 13:04 ` [PATCH 0/6] ZNS: Extra features for current patches Matias Bjørling
2020-06-25 14:48 ` Matias Bjørling
2020-06-25 19:39 ` Javier González
2020-06-25 19:53 ` Matias Bjørling
2020-06-26 6:26 ` Javier González
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