Support DISCARD command is meaningful when eMMC usage is high or
there are lots of remove operations. For example, when Guest
Android is running, there will be lots of files being created and
removed. However, virtio-blk BE does not support DISCARD command,
data remove operation in UOS will not trigger erase in eMMC. After
period of time, the eMMC will be consumed out, and erase must be
done by eMMC firmware before writing any new data. This causes the
eMMC performance decrease in the whole system (SOS and UOS).
To solve the problem, DISCARD should be supported in virtio-blk BE.
Tracked-On: #2547
Signed-off-by: Conghui Chen <conghui.chen@intel.com>
Reviewed-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
b595abcc23