cachefiles: add tracepoints for on-demand read mode

Add tracepoints for on-demand read mode. Currently following tracepoints
are added:

	OPEN request / COPEN reply
	CLOSE request
	READ request / CREAD reply
	write through anonymous fd
	release of anonymous fd

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Acked-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20220425122143.56815-8-jefflexu@linux.alibaba.com


Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>