On Thu, Sep 24 2020 at  2:51am -0400,
Christoph Hellwig [off-list ref] wrote:

Drivers shouldn't really mess with the readahead size, as that is a VM
concept.  Instead set it based on the optimal I/O size by lifting the
algorithm from the md driver when registering the disk.  Also set
bdi->io_pages there as well by applying the same scheme based on
max_sectors.  To ensure the limits work well for stacking drivers a
new helper is added to update the readahead limits from the block
limits, which is also called from disk_stack_limits.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Coly Li <redacted>
Reviewed-by: Johannes Thumshirn <redacted>

Thanks for adding blk_queue_update_readahead()

Reviewed-by: Mike Snitzer <redacted>