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 <redacted>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Ming Lei <redacted>

-- 
Ming