Re: [PATCH V5 06/14] block: Add zoned block device information to request queue

[Ming Lei <ming.lei@redhat.com>]

On Mon, Sep 25, 2017 at 03:14:46PM +0900, Damien Le Moal wrote:
> Components relying only on the requeuest_queue structure for accessing
> block devices (e.g. I/O schedulers) have a limited knowledged of the
> device characteristics. In particular, the device capacity cannot be
> easily discovered, which for a zoned block device also result in the
> inability to easily know the number of zones of the device (the zone
> size is indicated by the chunk_sectors field of the queue limits).
> 
> Introduce the nr_zones field to the request_queue sturcture to simplify
> access to this information. Also, add the bitmap seq_zone_bitmap which
> indicates which zones of the device are sequential zones (write
> preferred or write required). These two fields are initialized by the
> low level block device driver (sd.c for ZBC/ZAC disks). They are not
> initialized by stacking drivers (device mappers) handling zoned block
> devices (e.g. dm-linear).
> 
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Ming Lei <ming.lei@redhat.com>

-- 
Ming