[Bug 1871214] Re: [SRU] nfsd doesn't start if exports depend on mount

[Timo Aaltonen]

Hello Rodrigo, or anyone else affected,

Accepted nfs-utils into focal-proposed. The package will build now and
be available at https://launchpad.net/ubuntu/+source/nfs-
utils/1:1.3.4-2.5ubuntu3.1 in a few hours, and then in the -proposed
repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, what testing has been
performed on the package and change the tag from verification-needed-
focal to verification-done-focal. If it does not fix the bug for you,
please add a comment stating that, and change the tag to verification-
failed-focal. In either case, without details of your testing we will
not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: nfs-utils (Ubuntu Focal)
       Status: In Progress => Fix Committed

** Tags added: verification-needed verification-needed-focal

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https://bugs.launchpad.net/bugs/1871214

Title:
  [SRU] nfsd doesn't start if exports depend on mount

Status in nfs-utils package in Ubuntu:
  Fix Released
Status in nfs-utils source package in Bionic:
  In Progress
Status in nfs-utils source package in Eoan:
  In Progress
Status in nfs-utils source package in Focal:
  Fix Committed
Status in nfs-utils source package in Groovy:
  Fix Released

Bug description:
  Reproduced in Bionic and Focal, packages 1:1.3.4-2.1ubuntu5.2 and
  1:1.3.4-2.5ubuntu3 respectively.

  Steps to reproduce:

  1) Set up a ISCSI client to a 1GB+ volume, mount it in /data and set fstab to mount at boot
  2) Create a folder in /data like /data/dir1 and set up /etc/exports to export it
  3) Reboot
  4) Notice nfs-server does not start. Check journalctl and see it was because of "exportfs -r" returning -1 because /data/dir1 is not available.

  In Xenial (1:1.2.8-9ubuntu12.2), exportfs always returns 0, so this
  bug is not present there.

  This can be workaroundable in two ways:

  1) Editing nfs-server.service and adding "-" in
  "ExecStartPre=/usr/sbin/exportfs -r" to be
  "ExecStartPre=-/usr/sbin/exportfs -r". This will retain xenial
  behavior.

  2) Editing nfs-server.service and removing "Before=remote-fs-
  pre.target" and adding "RequiresMountsFor=/data". This will cause the
  systemd service load ordering to change, and nfs-server will wait for
  /data to be available.

  #2 is the upstream approach with commit [0] where this new comment
  identifies mount dependencies and automatically sets up
  RequiresMountFor.

  [0] http://git.linux-nfs.org/?p=steved/nfs-
  utils.git;a=commitdiff;h=4776bd0599420f9d073c9e2601ed438062dccd19

  =======================================================================

  [Impact]

  Users attempting to export folders from iSCSI or any remote mounted
  filesystem will experience their exports not being available at system
  start up, requiring workarounds or manual intervention.

  [Test case]

  1. Reproducing the bug:

  1a. Set up a ISCSI client to a 1GB+ volume
  1b. Format /dev/<device> using mkfs.xfs
  1c. Mount it in /data and set fstab as follows to mount at boot

  UUID="<uuid_from_blkid>" /data xfs defaults,auto,_netdev 0 0

  1d. Create a folder in /data like /data/dir1 and set permissions as
  follows

  chmod 777 /data/dir1
  chown nobody:nogroup /data/dir1

  1e. Set up /etc/exports as follows to export it

  data/dir1 *(rw,async,root_squash,subtree_check)

  1f. Reboot
  1g. Notice nfs-server does not start. Running "showmount -e" displays error.

  2. No cleanup necessary

  3. Install the updated package that contains the fix

  4. Confirming the fix:

  4a. Reboot
  4b. Notice nfs-server starts sucessfully, "showmount -e" displays the exports. 

  
  [Regression Potential]

  Regression potential is minimal. The dependency commit only moves code
  around and the actual fix only introduces an external systemd-
  generator without changing actual pre-existing code.

  I tested and confirmed that the fix introduced [0] also covers the fix
  removed [1], so there should not be any regression on this particular
  code change as well.

  [1] http://git.linux-nfs.org/?p=steved/nfs-
  utils.git;a=commitdiff;h=1e41488f428cd36b200b48b84d31446e38dfdc50

  
  [Other Info]

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