linux-kernel - Re: [PATCH v8 04/11] nvmet: Allow ZNS target to support non-power_of

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Message-ID: <137b8772-a2cc-f195-1c0d-476214fabd52@opensource.wdc.com>
Date:   Thu, 28 Jul 2022 12:09:36 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Pankaj Raghav <p.raghav@...sung.com>, hch@....de, axboe@...nel.dk,
        snitzer@...nel.org, Johannes.Thumshirn@....com
Cc:     matias.bjorling@....com, gost.dev@...sung.com,
        linux-kernel@...r.kernel.org, hare@...e.de,
        linux-block@...r.kernel.org, pankydev8@...il.com,
        bvanassche@....org, jaegeuk@...nel.org, dm-devel@...hat.com,
        linux-nvme@...ts.infradead.org,
        Luis Chamberlain <mcgrof@...nel.org>
Subject: Re: [PATCH v8 04/11] nvmet: Allow ZNS target to support
 non-power_of_2 zone sizes

On 7/28/22 01:22, Pankaj Raghav wrote:
> A generic bdev_zone_no() helper is added to calculate zone number for a
> given sector in a block device. This helper internally uses disk_zone_no()
> to find the zone number.
> 
> Use the helper bdev_zone_no() to calculate nr of zones. This let's us
> make modifications to the math if needed in one place and adds now
> support for npo2 zone devices.
> 
> Reviewed by: Adam Manzanares <a.manzanares@...sung.com>
> Reviewed-by: Bart Van Assche <bvanassche@....org>
> Reviewed-by: Hannes Reinecke <hare@...e.de>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@....com>
> Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
> Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
> ---
>  drivers/nvme/target/zns.c | 3 +--
>  include/linux/blkdev.h    | 5 +++++
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/nvme/target/zns.c b/drivers/nvme/target/zns.c
> index c7ef69f29fe4..662f1a92f39b 100644
> --- a/drivers/nvme/target/zns.c
> +++ b/drivers/nvme/target/zns.c
> @@ -241,8 +241,7 @@ static unsigned long nvmet_req_nr_zones_from_slba(struct nvmet_req *req)
>  {
>  	unsigned int sect = nvmet_lba_to_sect(req->ns, req->cmd->zmr.slba);
>  
> -	return bdev_nr_zones(req->ns->bdev) -
> -		(sect >> ilog2(bdev_zone_sectors(req->ns->bdev)));
> +	return bdev_nr_zones(req->ns->bdev) - bdev_zone_no(req->ns->bdev, sect);
>  }

This change should go into patch 3. Otherwise, adding patch 3 only will
break the nvme target zone code.

>  
>  static unsigned long get_nr_zones_from_buf(struct nvmet_req *req, u32 bufsize)
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 1be805223026..d1ef9b9552ed 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -1350,6 +1350,11 @@ static inline enum blk_zoned_model bdev_zoned_model(struct block_device *bdev)
>  	return BLK_ZONED_NONE;
>  }
>  
> +static inline unsigned int bdev_zone_no(struct block_device *bdev, sector_t sec)
> +{
> +	return disk_zone_no(bdev->bd_disk, sec);
> +}
> +

This should go into a prep patch before patch 3.

>  static inline int queue_dma_alignment(const struct request_queue *q)
>  {
>  	return q ? q->dma_alignment : 511;


-- 
Damien Le Moal
Western Digital Research