Re: [PATCH 1/3] block: inherit the zoned characteristics in blk_stack_limits

[Damien Le Moal <Damien.LeMoal@wdc.com>]

On 2020/07/20 15:13, Christoph Hellwig wrote:
> Lift the code from device mapper into blk_stack_limits to inherity
> the stacking limitations.  This ensures we do the right thing for
> all stacked zoned block devices.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  block/blk-settings.c   |  1 +
>  drivers/md/dm-table.c  | 19 -------------------
>  include/linux/blkdev.h |  9 ++++++---
>  3 files changed, 7 insertions(+), 22 deletions(-)
> 
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index 9a2c23cd970073..9cddbd73647405 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -609,6 +609,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
>  		t->chunk_sectors = min_not_zero(t->chunk_sectors,
>  						b->chunk_sectors);
>  
> +	t->zoned = max(t->zoned, b->zoned);
>  	return ret;
>  }
>  EXPORT_SYMBOL(blk_stack_limits);
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 0ea5b7367179ff..ec5364133cef7f 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -467,9 +467,6 @@ static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
>  		       q->limits.logical_block_size,
>  		       q->limits.alignment_offset,
>  		       (unsigned long long) start << SECTOR_SHIFT);
> -
> -	limits->zoned = blk_queue_zoned_model(q);
> -
>  	return 0;
>  }
>  
> @@ -1528,22 +1525,6 @@ int dm_calculate_queue_limits(struct dm_table *table,
>  			       dm_device_name(table->md),
>  			       (unsigned long long) ti->begin,
>  			       (unsigned long long) ti->len);
> -
> -		/*
> -		 * FIXME: this should likely be moved to blk_stack_limits(), would
> -		 * also eliminate limits->zoned stacking hack in dm_set_device_limits()
> -		 */
> -		if (limits->zoned == BLK_ZONED_NONE && ti_limits.zoned != BLK_ZONED_NONE) {
> -			/*
> -			 * By default, the stacked limits zoned model is set to
> -			 * BLK_ZONED_NONE in blk_set_stacking_limits(). Update
> -			 * this model using the first target model reported
> -			 * that is not BLK_ZONED_NONE. This will be either the
> -			 * first target device zoned model or the model reported
> -			 * by the target .io_hints.
> -			 */
> -			limits->zoned = ti_limits.zoned;
> -		}
>  	}
>  
>  	/*
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 06995b96e94679..67b9ccc1da3560 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -306,11 +306,14 @@ enum blk_queue_state {
>  
>  /*
>   * Zoned block device models (zoned limit).
> + *
> + * Note: This needs to be ordered from the least to the most severe
> + * restrictions for the inheritance in blk_stack_limits() to work.
>   */
>  enum blk_zoned_model {
> -	BLK_ZONED_NONE,	/* Regular block device */
> -	BLK_ZONED_HA,	/* Host-aware zoned block device */
> -	BLK_ZONED_HM,	/* Host-managed zoned block device */
> +	BLK_ZONED_NONE = 0,	/* Regular block device */
> +	BLK_ZONED_HA,		/* Host-aware zoned block device */
> +	BLK_ZONED_HM,		/* Host-managed zoned block device */
>  };
>  
>  struct queue_limits {
> 

Looks good.

Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>


-- 
Damien Le Moal
Western Digital Research