commit 6de5d06e657acdbcf9637dac37916a4a5309e0f4 upstream.

In preparation for not holding a lock over the execution of nd_ioctl(),
update the implementation to allow multiple threads to be attempting
ioctls at the same time. The bus lock still prevents multiple in-flight
->ndctl() invocations from corrupting each other's state, but static
global staging buffers are moved to the heap.
Reported-by: NVishal Verma <vishal.l.verma@intel.com>
Reviewed-by: NVishal Verma <vishal.l.verma@intel.com>
Tested-by: NVishal Verma <vishal.l.verma@intel.com>
Link: https://lore.kernel.org/r/156341208947.292348.10560140326807607481.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>