[Bug 2059197] Re: mount.nfs: Fix minor version parsing when '-t nfs4' and '-o vers=4.x' are used together

Wed Apr 3 02:55:54 UTC 2024

Hi Jeff,

Again, I apologise for introducing this regression, but we are on our
way to getting this fixed.

The fixes are:

commit 1e3ca7fe199531a372bb8e1c1033d8973097be50
Author: NeilBrown <neilb at suse.com>
Date:   Wed Jul 26 13:47:42 2017 -0400
Subject: mount: move handling of "-t nfs4" into nfs_nfs_version()
Link: https://git.linux-nfs.org/?p=steved/nfs-utils.git;a=commitdiff;h=1e3ca7fe199531a372bb8e1c1033d8973097be50

commit 050153ef6a86ff5ab06ef65be36336824a323779
Author: NeilBrown <neilb at suse.com>
Date:   Wed Jul 26 13:51:51 2017 -0400
Subject: mount: Fix problems with parsing minorversion=
Link: https://git.linux-nfs.org/?p=steved/nfs-utils.git;a=commitdiff;h=050153ef6a86ff5ab06ef65be36336824a323779

commit 71b807e1a69940beb31fdeb481c2e54509e8bd32
Author: Steve Dickson <steved at redhat.com>
Date:   Thu Mar 1 13:52:47 2018 -0500
Subject: mount.nfs: minorversion setting is being ignored with the -t flag
Link: https://git.linux-nfs.org/?p=steved/nfs-utils.git;a=commitdiff;h=71b807e1a69940beb31fdeb481c2e54509e8bd32

I have built these into a test package, if you are interested in taking
a look.

Please note this package is NOT SUPPORTED by Canonical, and is for TESTING
PURPOSES ONLY. ONLY Install in a dedicated test environment.

Instructions to install (On a Focal system):
1) sudo add-apt-repository ppa:mruffell/lp2059197-test
2) sudo apt update
3) sudo apt install nfs-common
4) sudo apt-cache policy nfs-common | grep Installed
Installed: 1:1.3.4-2.5ubuntu3.6+lp2059197v20240403b1

If you try mount your share with the version specified, it should work.

I'll write back once we have a package in -proposed with the fix.

Thanks,
Matthew

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Title:
  mount.nfs: Fix minor version parsing when '-t nfs4' and '-o vers=4.x'
  are used together

Status in nfs-utils package in Ubuntu:
  Fix Released
Status in nfs-utils source package in Focal:
  In Progress

Bug description:
  [Impact]

  When specifying both '-t nfs4' and '-o vers=4.x' on the mount command
  line, mount.nfs ignores any specific version set with '-o vers=4.x' or
  '-o vers=4,minorversion=x', and simply attempts version negotiation,
  which due to my recent changes in bug 2049262, would land on the
  highest supported nfs version, likely 4.2.

  Users who specify what version they want should get the version they
  ask for, and thus, this is a regression introduced in
  1:1.3.4-2.5ubuntu3.6.

  A workaround is to drop '-t nfs4' and to use mount.nfs directly
  instead, i.e.:

  $ sudo mount.nfs -o vers=4.1 -vvv jammy-nfs-server:/ /mnt

  [Testcase]

  Create two VMs, one jammy and one focal.

  The jammy VM will be the server.

  Server VM:
  $ sudo hostnamectl set-hostname jammy-nfs-server
  $ sudo apt update && sudo apt upgrade -y
  $ sudo apt install nfs-kernel-server
  $ sudo mkdir /export
  $ sudo mkdir /export/users
  $ sudo mkdir /home/users
  $ sudo vi /etc/fstab # add the following line:
  /home/users /export/users none bind 0 0
  $ sudo mount -a
  $ sudo vi /etc/exports # add the following lines:
  /export 192.168.122.0/24(rw,fsid=0,no_subtree_check,sync)
  /export/users 192.168.122.0/24(rw,nohide,insecure,no_subtree_check,sync)
  $ sudo systemctl restart nfs-server.service

  Focal VM:
  $ sudo hostnamectl set-hostname focal-nfs-client
  $ sudo apt update && sudo apt upgrade -y
  $ sudo apt install nfs-common

  And then try mounting with both '-t nfs4' and '-o vers=4.1':

  $ sudo mount -t nfs4 -o vers=4.1 -vvv jammy-nfs-server:/ /mnt
  mount.nfs4: timeout set for Wed Apr  3 00:51:23 2024
  mount.nfs4: trying text-based options 'vers=4.2,addr=192.168.122.217,clientaddr=192.168.122.9'

  and then try with both '-t nfs4' and '-o vers=4,minorversion=1':

  $ sudo mount -t nfs4 -o vers=4,minorversion=1 -vvv jammy-nfs-server:/ /mnt
  mount.nfs4: timeout set for Wed Apr  3 02:19:03 2024
  mount.nfs4: trying text-based options 'minorversion=1,vers=4.2,addr=192.168.122.217,clientaddr=192.168.122.9'

  In each of those mounts, it incorrectly uses protocol version 4.2,
  instead of requested 4.1.

  If you install the test packages in the following ppa:

  https://launchpad.net/~mruffell/+archive/ubuntu/lp2059197-test

  then vers should always be 4.1, instead of 4.2.

  [Where problems can occur]

  It is quite clear now that changing version negotiation and parsing is
  quite problematic, after the number of regressions the previous
  1:1.3.4-2.5ubuntu3.6 caused the community, and the sheer number of
  commits upstream took to resolve lingering issues.

  We need to be careful, to make sure we don't introduce any further
  regressions.

  This time, we are only changing how mount.nfs parses and processes
  command line arguments for version specification, and not changing
  version negotiation itself. This could impact NFS clients, when they
  go to mount NFS filesystems.

  If a regression were to occur, then users might have to manually mount
  their NFS filesystems or look into autofs. There should be no breaking
  changes to any behaviour when mounting NFS filesystems.

  There are no changes to nfs server.

  [Other Info]

  This was fixed multiple times, across the following three commits:

  commit 1e3ca7fe199531a372bb8e1c1033d8973097be50
  Author: NeilBrown <neilb at suse.com>
  Date:   Wed Jul 26 13:47:42 2017 -0400
  Subject: mount: move handling of "-t nfs4" into nfs_nfs_version()
  Link: https://git.linux-nfs.org/?p=steved/nfs-utils.git;a=commitdiff;h=1e3ca7fe199531a372bb8e1c1033d8973097be50

  commit 050153ef6a86ff5ab06ef65be36336824a323779
  Author: NeilBrown <neilb at suse.com>
  Date:   Wed Jul 26 13:51:51 2017 -0400
  Subject: mount: Fix problems with parsing minorversion=
  Link: https://git.linux-nfs.org/?p=steved/nfs-utils.git;a=commitdiff;h=050153ef6a86ff5ab06ef65be36336824a323779

  commit 71b807e1a69940beb31fdeb481c2e54509e8bd32
  Author: Steve Dickson <steved at redhat.com>
  Date:   Thu Mar 1 13:52:47 2018 -0500
  Subject: mount.nfs: minorversion setting is being ignored with the -t flag
  Link: https://git.linux-nfs.org/?p=steved/nfs-utils.git;a=commitdiff;h=71b807e1a69940beb31fdeb481c2e54509e8bd32

  Jammy has all of these, and does not need any fixes.

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