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From:   Niklas Cassel <Niklas.Cassel@wdc.com>
To:     Jens Axboe <axboe@kernel.dk>
CC:     Damien Le Moal <Damien.LeMoal@wdc.com>,
        Johannes Thumshirn <Johannes.Thumshirn@wdc.com>,
        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3] null_blk: add support for max open/active zone limit
 for zoned devices
Thread-Topic: [PATCH v3] null_blk: add support for max open/active zone limit
 for zoned devices
Thread-Index: AQHWfSmaLTmCYxbnp0e4nXLEl3R9Fqlc5JUA
Date:   Mon, 7 Sep 2020 08:18:26 +0000
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On Fri, Aug 28, 2020 at 12:54:00PM +0200, 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 =3D=3D no limit.
>=20
> Call the block layer API functions used for exposing the configured
> limits to sysfs.
>=20
> 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.
>=20
> 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.
>=20
> 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.
>=20
> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
> ---
> Changes since v2:
> -Picked up Damien's Reviewed-by tag.
> -Fixed a typo in the commit message.
> -Renamed null_manage_zone_resources() to null_has_zone_resources().
>=20
>  drivers/block/null_blk.h       |   5 +
>  drivers/block/null_blk_main.c  |  16 +-
>  drivers/block/null_blk_zoned.c | 319 +++++++++++++++++++++++++++------
>  3 files changed, 282 insertions(+), 58 deletions(-)

Hello Jens,

A gentle ping on this.

As far as I can tell, there are no outstanding review comments.


Kind regards,
Niklas=