[Bug 1973101] Re: After upgrade to 22.04 NFS exports for vers 2 and 3 no longer work

[Andreas Hasenack]

NFS UDP was disabled in the upstream kernel[1] in 2019, and the first
Ubuntu release with that change was 20.10 (groovy). I didn't find this
change in the 20.10 release notes, and added this bit to the 22.04
release notes[2] about a month before the release:

"""
UDP disabled for NFS mounts

Since Ubuntu 20.10 (“Groovy Gorilla”), the kernel option
CONFIG_NFS_DISABLE_UDP_SUPPORT=y is set and this disables using UDP as
the transport for NFS mounts, regardless of NFS version.

In practice, if you try to use udp, you will get this error:

$ sudo mount f1:/storage /mnt -o udp
mount.nfs: an incorrect mount option was specified
"""

If you can't get the older clients to use TCP, then I think the only way
is for you to stick to an older Ubuntu release that still has UDP NFS
support, like Focal (20.04).

1. https://patchwork.kernel.org/project/linux-nfs/patch/20191121160651.5317-1-olga.kornievskaia@gmail.com/
2. https://discourse.ubuntu.com/t/jammy-jellyfish-release-notes/24668

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https://bugs.launchpad.net/bugs/1973101

Title:
  After upgrade to 22.04 NFS exports for vers 2 and 3 no longer work

Status in nfs-utils package in Ubuntu:
  Incomplete

Bug description:
  I upgraded from 20.04 to 22.04 a server which has NFS clients that are
  version 2 (SunOS 4.1.4), version 3 (Redhat 6.2) and version 4.2 (other
  modern Linux systems).

  After upgrading the version 2 and version 3 clients no longer can
  mount the file systems.

  A check with rpcinfo -p showed version 2 no longer being advertised, I
  checked the conf and found the update had disabled it, I re-enabled
  it.

  Version 3 was still advertised, but the mount still fails, and after
  re-enabling version 2, the mount still fails.

  I am also not at all appreciative of the unauthorized changes that the
  upgrade made to my exports file.

  ProblemType: Bug
  DistroRelease: Ubuntu 22.04
  Package: nfs-kernel-server 1:2.6.1-1ubuntu1
  Uname: Linux 5.17.6 x86_64
  .etc.request-key.d.id_resolver.conf: create	id_resolver	*	*	/usr/sbin/nfsidmap -t 600 %k %d
  ApportVersion: 2.20.11-0ubuntu82
  Architecture: amd64
  CasperMD5CheckResult: unknown
  CurrentDesktop: MATE
  Date: Wed May 11 18:44:54 2022
  NFSMounts:
   
  NFSv4Mounts:
   /bu    204.122.16.128:/mail.bu nfs4   rw,relatime,vers=4.2,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=204.122.16.222,local_lock=none,addr=204.122.16.128
   /misc  204.122.16.12:/misc     nfs4   rw,nosuid,nodev,relatime,vers=4.2,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=204.122.16.222,local_lock=none,addr=204.122.16.12
   /home  204.122.16.12:/home     nfs4   rw,nosuid,nodev,relatime,vers=4.2,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=204.122.16.222,local_lock=none,addr=204.122.16.12
  RebootRequiredPkgs: Error: path contained symlinks.
  SourcePackage: nfs-utils
  UpgradeStatus: Upgraded to jammy on 2022-05-10 (1 days ago)

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