[PATCH V9 4/9] nvmet: add ZBD over ZNS backend support

[Christoph Hellwig]

On Wed, Jan 13, 2021 at 04:57:15AM +0000, Chaitanya Kulkarni wrote:
> >>  	/* command sets supported: NVMe command set: */
> >>  	ctrl->cap = (1ULL << 37);
> >> +	if (IS_ENABLED(CONFIG_BLK_DEV_ZONED))
> >> +		ctrl->cap |= (1ULL << 43);
> >>  	/* CC.EN timeout in 500msec units: */
> >>  	ctrl->cap |= (15ULL << 24);
> >>  	/* maximum queue entries supported: */
> > This needs to go into a separate patch for multiple command set support.
> > We can probably merge the CAP and CC bits with the CSI support, though.
> Do you mean previous patch ?

Yes.

> but we don't add handlers non-default I/O
> command set until this patch..

No, bit 43 just means the TP to support multiple comman sets is supported.
That infrastructure can be used even by controllers only supporting the
NVM command set.

> > bdev_is_zoned should be probably stubbed out for !CONFIG_BLK_DEV_ZONED
> > these days.
> Are you saying something like following in the prep patch ?or should
> just remove
> theIS_ENABLED(CONFIG_BLK_DEV_ZONED)part in above if?
> 
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 028ccc9bdf8d..124086c1a0ba 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -1570,6 +1570,9 @@ static inline bool bdev_is_zoned(struct
> block_device *bdev)
>  {
>         struct request_queue *q = bdev_get_queue(bdev);
>  
> +       if (!IS_ENABLED(CONFIG_BLK_DEV_ZONED))
> +               return false;
> +
>         if (q)
>                 return blk_queue_is_zoned(q);

blk_queue_is_zoned calls blk_queue_zoned_model, which is stubbed out
already.  So no extra work should be required.

> 	/*
> 	 * For ZBC and ZAC devices, writes into sequential zones must be aligned
> 	 * to the device physical block size. So use this value as the *physical*
> 	 * block size to avoid errors.
> 	 */

See my reply to Damien.