Merge remote-tracking branch 'kwolf/for-anthony' into staging
* kwolf/for-anthony:
ATA: Allow WIN_SECURITY_FREEZE_LOCK as nop
rbd: add discard support
qcow2: fix the return value -ENOENT -> -EEXIST
qcow2: Don't hold cache references across yield
qcow2: Remove unused parameter in do_alloc_cluster_offset
qemu-iotests: Many parallel allocating I/O requests
docs: fix one issue in qcow2 specs
block/qcow2: Add missing GCC_FMT_ATTR to function report_unsupported()
qemu-iotests: ignore fragmentation information for qed