two questions related to tablespace in PG8.0.1

Here are two questions related to PG8.0.1:

1. durability of "create tablespace" - what happens if several checkpoints
done after "create tablespace" then system crashes - without redo, will the
PG_VERSION file and symlinks survive in win32? Seems checkpoint didn't sync
the content of PG_VERSION file.

2. possible race on "set_short_version(location)" while creating
tablespace - what if two processes reach this point at the same time? So
directory emptiness check will not fail and both will create their own
PG_VERSION file ...

Thanks,
Qingqing