[PATCHv4] blk: Replace SG_GAPGS with new queue limits mask

[Christoph Hellwig]

On Tue, Aug 04, 2015 at 01:32:13PM -0600, Keith Busch wrote:
> The SG_GAPS queue flag caused checks for bio vector alignment against
> PAGE_SIZE, but the device may have different constraints. This patch
> adds a queue limits so a driver with such constraints can set to allow
> requests that would have been unnecessarily split. The new gaps check
> takes the request_queue as a parameter to simplify the logic around
> invoking this function.
> 
> This new limit makes the queue flag redundant, so removing it and
> all usage. Device-mappers will inherit the correct settings through
> blk_stack_limits().
> 
> Signed-off-by: Keith Busch <keith.busch at intel.com>

Looks good,

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