Change in vdsm[master]: Add additional vgcheck to fix vgextend workflow on HSMs.

Pavel Zhukov has posted comments on this change.

Change subject: Add additional vgcheck to fix vgextend workflow on HSMs.
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Patch Set 9:
> > I don't understand how this fixes the related bug. If the issue was a missing pv, how running vgchk again fixes the missing pv?

The issue is stale filters
> > If the issue is stale filters, why not invalidate the filters in _reloadvgs, when we find that a vg has missing pv? Why wait until selftest()?

Because _reloadvgs uses vgs (not vgck). VGs returns zero even if PV is missed (see commit message) and We know nothing about missed PVs on this step. I thought about rebuilding filters before vgs command, but do we really want to do it each time for each vg?