On Tue, Aug 21, 2018 at 4:10 PM Austin S. Hemmelgarn
[off-list ref] wrote:

Also, once you've got the space cache set up by mounting once writable
with the appropriate flag and then waiting for it to initialize, you
should not ever need to specify the `space_cache` option again.

True.
I am not sure why I thought I have to keep cache-v2 in the rootflag
list. I guess I forgot it was meant to be removed after a reboot. Or
may be some old kernels misbehaved (always cleared the space-tree for
some reason and re-initialized a space-cache instead unless the flag
was there). But I removed it now and everything works as intended.
Thanks.