[OpenAFS-devel] Proposed change for handling backup volumes

[Kris Van Hees]

I've implemented a change that makes it possible to request (under control of
a kernel module variable (on Linux under control of /proc/sys/afs/bkVolPref))
EvalMountPoint to give preference to a backup volume (if one exists) rather
than the RO volume (if that exists), if you are crossing a mountpoint from a
backup volume.  The end result is that when this is enabled, normal volume
mountpoints will be treated in a way where once you enter a backup volume, you
remain within a tree of backup volumes as long as they are available for all
the mountpoints you pass.

Now, since this is something that can be enabled at runtime, I either need to
add code to force re-evaluation of all mountpoints (since the result from the
evaluation would be cached), or people who use this would need to issue any
'fs flushv' commands to accomplish the same on request of the user.

Any opinions on which ought to be considered best?  Should flipping the switch
on this backup volume preference change the world all around you (such that e.g.
cd .. might drop you off somewhere other than where you came from), or should
it be left upon the user to flush the cache where needed?

	Kris
-- 
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