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Message-ID: <024d16ac-d685-0fcf-1ad3-e99946852b03@acm.org>
Date:   Wed, 27 Jul 2022 19:58:00 -0700
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Subject: Re: [PATCH v8 00/11] support non power of 2 zoned device
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To:     Damien Le Moal <damien.lemoal@opensource.wdc.com>,
        Pankaj Raghav <p.raghav@samsung.com>, hch@lst.de,
        axboe@kernel.dk, snitzer@kernel.org, Johannes.Thumshirn@wdc.com
Cc:     matias.bjorling@wdc.com, gost.dev@samsung.com,
        linux-kernel@vger.kernel.org, hare@suse.de,
        linux-block@vger.kernel.org, pankydev8@gmail.com,
        jaegeuk@kernel.org, dm-devel@redhat.com,
        linux-nvme@lists.infradead.org
References: <CGME20220727162246eucas1p1a758799f13d36ba99d30bf92cc5e2754@eucas1p1.samsung.com>
 <20220727162245.209794-1-p.raghav@samsung.com>
 <51255650-ddc2-4f3d-52e5-14007b9ff538@acm.org>
 <f2f29f97-5994-37f9-c922-31158c1c1b9a@opensource.wdc.com>
From:   Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <f2f29f97-5994-37f9-c922-31158c1c1b9a@opensource.wdc.com>
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On 7/27/22 18:52, Damien Le Moal wrote:
> On 7/28/22 08:19, Bart Van Assche wrote:
>> On 7/27/22 09:22, Pankaj Raghav wrote:
>>> This series adds support to npo2 zoned devices in the block and nvme
>>> layer and a new **dm target** is added: dm-po2z-target. This new
>>> target will be initially used for filesystems such as btrfs and
>>> f2fs that does not have native npo2 zone support.
>>
>> Should any SCSI changes be included in this patch series? From sd_zbc.c:
>>
>> 	if (!is_power_of_2(zone_blocks)) {
>> 		sd_printk(KERN_ERR, sdkp,
>> 			  "Zone size %llu is not a power of two.\n",
>> 			  zone_blocks);
>> 		return -EINVAL;
>> 	}
> 
> There are no non-power of 2 SMR drives on the market and no plans to have
> any as far as I know. Users want power of 2 zone size. So I think it is
> better to leave sd_zbc & scsi_debug as is for now.

Zoned UFS devices will support ZBC and may have a zone size that is not 
a power of two.

Thanks,

Bart.