'from' is the input buffer, it should be prefetched with prefetch, not
prefetchw.
Tested-by: NMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: NMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>