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Subject: Re: [PATCH v3] null_blk: add support for max open/active zone limit
 for zoned devices
To:     Niklas Cassel <niklas.cassel@wdc.com>
Cc:     damien.lemoal@wdc.com, johannes.thumshirn@wdc.com,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20200828105400.80893-1-niklas.cassel@wdc.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <ea94a097-c5c1-1996-3398-a08d64503941@kernel.dk>
Date:   Tue, 29 Sep 2020 08:13:02 -0600
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On 8/28/20 4:54 AM, Niklas Cassel wrote:
> Add support for user space to set a max open zone and a max active zone
> limit via configfs. By default, the default values are 0 == no limit.
> 
> Call the block layer API functions used for exposing the configured
> limits to sysfs.
> 
> Add accounting in null_blk_zoned so that these new limits are respected.
> Performing an operation that would exceed these limits results in a
> standard I/O error.
> 
> A max open zone limit exists in the ZBC standard.
> While null_blk_zoned is used to test the Zoned Block Device model in
> Linux, when it comes to differences between ZBC and ZNS, null_blk_zoned
> mostly follows ZBC.
> 
> Therefore, implement the manage open zone resources function from ZBC,
> but additionally add support for max active zones.
> This enables user space not only to test against a device with an open
> zone limit, but also to test against a device with an active zone limit.

Applied, thanks.

-- 
Jens Axboe