Re: [PATCH v2] null_blk: add support for max open/active zone limit for zoned devices

[Randy Dunlap]

On 8/27/20 6:50 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.

Hi,

How does a user find out about how to use/set these limits?


> 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 operating 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@xxxxxxx>
> ---
> Changes since v1:
> -Fixed review comments by Damien Le Moal.
> 
>  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(-)

thanks.
-- 
~Randy