[dm-devel] Re: [PATCH 1/3] block: Add blk_queue_copy_limits()

[Mike Snitzer <snitzer redhat com>]

On Fri, Sep 18 2009 at  3:28pm -0400,
Martin K. Petersen <martin petersen oracle com> wrote:

> >>>>> "Jun'ichi" == Jun'ichi Nomura <j-nomura ce jp nec com> writes:
> 
> +	if (q->limits.max_sectors == 0 || q->limits.max_hw_sectors == 0)
> +		blk_queue_max_sectors(q, SAFE_MAX_SECTORS);
> 
> I'm really not keen on perpetuating SAFE_MAX_SECTORS for something that
> was written in this millennium.
> 
> I'd much rather we just do this, then:
> 
> block: Set max_sectors correctly for stacking devices
> 
> The topology changes unintentionally caused SAFE_MAX_SECTORS to be set
> for stacking devices.  Set the default limit to BLK_DEF_MAX_SECTORS and
> provide SAFE_MAX_SECTORS in blk_queue_make_request() for legacy hw
> drivers that depend on the old behavior.
> 
> Signed-off-by: Martin K. Petersen <martin petersen oracle com>

Nice.  Avoids the need for a safe queue_limits copy and associated naunce.

Acked-by: Mike Snitzer <snitzer redhat com>