RFC: changing the default NFSv4 minor version?

Rick Macklem rmacklem at uoguelph.ca
Thu May 13 23:02:38 UTC 2021


I believe that NFSv4.1 and NFSv4.2 are now mature in freebsd-current/main.
I also believe that NFSv4.1/4.2 is a better protocol than NFSv4.0.
(In particular, the sessions mechanism for "exactly once RPC semantics"
 is a significant improvement over the duplicate request cache for NFSv4.0,
 plus other improvements.)

Right now, the FreeBSD NFSv4 client will use NFSv4.0 unless the
"minorversion" mount option is used to set the minor version to 1 or 2.

The Linux client uses the highest minor version supported by both
client and server by default.
I'd like to propose that the default behaviour of the FreeBSD client
be changed to do the same, so that NFSv4.1/4.2 will be used when possible.
--> The "minorversion" mount option could still be used to override the
      above default.

I have hesitated doing this change because it could be considered a POLA
violation, but I think the change from 4.0->4.1/4.2 will normally be a
neutral to positive experience. (To be honest, I suspect most won't notice
the change.)

How do others feel about this change?


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