IronPort-SDR: pan+VCVTgmWCxRgjIpjj7OncvVKey13HMo0KmaL7yTJnwu4S6jLUiYEZtd6UkF10hGrwQ+vAej
 G0F9WiYCEYVeYVG6J470O9OyXHkxDIhMcchTrA6FHkOf9/316JPPDfBdaL4zwQgPCBDIGSz81J
 heJZlv3AUADFSUU7tO6iPCNrfDb53Jjw1nrXEgP6IEe2f3Uwh+oH11FeudBfZcOrV1BJMWIXbo
 OUKadQiny4Hz6nihWiu+gZ5P7NfyeHrUZJPAATF1RyWVUuA+WUXkCkBV21HqWu9alHYwid3c/l
 SGs=
IronPort-SDR: GfmfME/QGAxFTewS80NOHIE43EsY+xLvMU/x4de0lhPajT/XqRPqlT0fPPlgtEMy9OvgmjaqlH
 DMHDZ/DpC8g790y+PIu8ksf6XrazVcUtVIP2e9ljKRzMBmZ3kvl/AksiOsQwGiz/eBBz69jZ+z
 UATc5PWjVrKw9SN8vmPRoEbn1+ULUyG3+0VQrOpCJNCZjQv5ip45WzO1p3YVW8sduzB79DWVTu
 fC0BrstFTfP5Q7rHam5Jipda9LILDGMSd+Vl5K2Oa9hkvsCxD85vEyvx7ypdy/l0i5G6dXv10Q
 6Qo=
WDCIronportException: Internal
Message-ID: <0d0e5c63-a155-d2ad-1829-c016c61acad6@opensource.wdc.com>
Date:   Thu, 2 Mar 2023 17:19:20 +0900
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.8.0
Subject: Re: [PATCH v2] block: ublk: enable zoned storage support
Content-Language: en-US
To:     Andreas Hindborg <nmi@metaspace.dk>, Ming Lei <ming.lei@redhat.com>
Cc:     linux-block@vger.kernel.org, Hans Holmberg <Hans.Holmberg@wdc.com>,
        Matias Bjorling <Matias.Bjorling@wdc.com>,
        Niklas Cassel <Niklas.Cassel@wdc.com>,
        kernel test robot <lkp@intel.com>,
        Jens Axboe <axboe@kernel.dk>,
        open list <linux-kernel@vger.kernel.org>
References: <20230224200502.391570-1-nmi@metaspace.dk> <ZAAPBFfqP671N4ue@T590>
 <87o7pblhi1.fsf@metaspace.dk>
From:   Damien Le Moal <damien.lemoal@opensource.wdc.com>
Organization: Western Digital Research
In-Reply-To: <87o7pblhi1.fsf@metaspace.dk>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 3/2/23 16:31, Andreas Hindborg wrote:
>>> +struct ublk_param_zoned {
>>> +	__u64	max_open_zones;
>>> +	__u64	max_active_zones;
>>> +	__u64	max_append_size;
>>> +};
>>
>> Is the above zoned parameter enough for future extension?
>> Does ZNS need extra parameter? Or some zoned new(important) features?
> 
> @Damien, @Hans, @Matias, what do you think?

Yes, add some reserved fields. The struct is 24 B for now, you can make it 32 B.
But it is a little odd: why 64 bits for max open/active zones and max append ?
bio len is 32 bits and number of zones also 32 bits. You do not need 64 bits for
all these fields. Also, no zone model reported with this ? What about write
granularity (for SMR HDDs) too ?

So something like:

struct ublk_param_zoned {
	__u32	model;
	__u32	write_granularity;
	__u32	max_open_zones;
	__u32	max_active_zones;
	__u32	max_append_size;
	__u8	reserved[12];
};

looks better to me. Note sure about the need for model and write_granularity
here though. I did not follow zoned ublk patches.


-- 
Damien Le Moal
Western Digital Research