support for multi-range discard requests V3

[Jens Axboe]

On 02/08/2017 06:46 AM, Christoph Hellwig wrote:
> Hi all,
> 
> this series adds support for merging discontiguous discard bios into a
> single request if the driver supports it.  This reduces the number of
> discards sent to the device by about a factor of 5-6 for typical
> workloads on NVMe, and for slower devices that use I/O scheduling
> the number will probably be even bigger but I've not implemented
> that support yet.

This looks good to me. It's running testing now, but provided that
the tests are successful, we should get this queued up for 4.11.


-- 
Jens Axboe