Re: [PATCH v3] null_blk: add support for max open/active zone limit for zoned devices

[Niklas Cassel <Niklas.Cassel@wdc.com>]

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 == 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.
> 
> 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().
> 
>  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