LU-13759 dom: lock cancel to drop pages

LU-13759 dom: lock cancel to drop pages

Prevent stale pages after lock cancel by creating
cl_page connection for read-on-open pages.

Since VM pages are connected to cl_object they can be
found and discarded by CLIO properly.

Lustre-change: https://review.whamcloud.com/39401
Lustre-commit: e95eca236471cf23083ef281ef204a5920e4db9b

Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Change-Id: Iba8c87c934c442b4c0b45d7d3821ceede1a6e68f
Reviewed-on: https://review.whamcloud.com/40302
Tested-by: Maloo <maloo@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>