[dm-devel] DM MULTIPATH: Allow dm to send larger request if underlying device set to larger max_sectors value

[Mike Snitzer]

On Sun, Jul 08 2012 at  1:59pm -0400,
Chauhan, Vijay <Vijay.Chauhan at netapp.com> wrote:

> Even though underlying paths are set with larger value for max_sectors, dm 
> sets 1024(i.e 512KB) for max_sectors as default. max_sectors for dm 
> device can be reset through sysfs but any time map is updated, max_sectors
> is again set back to default. This patch gets the minimum of max_sectors from 
> physical paths and sets it to dm device.

There shouldn't be any need for additional DM overrides for max_sectors.

DM will stack the limits for all underlying devices each table reload
(via dm_calculate_queue_limits).  And max_sectors is properly stacked in
the block layer's bdev_stack_limits (called by dm_set_device_limits).

So is something resetting max_sectors with sysfs?  multipathd?

Mike