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You have been subscribed to a public bug by Rodrigo Barbieri (rodrigo-barbieri2010):

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]

** Affects: nfs-utils (Ubuntu)
     Importance: Undecided
     Assignee: Rodrigo Barbieri (rodrigo-barbieri2010)
         Status: Fix Committed

** Affects: nfs-utils (Ubuntu Bionic)
     Importance: Undecided
         Status: New

** Affects: nfs-utils (Ubuntu Eoan)
     Importance: Undecided
         Status: New

** Affects: nfs-utils (Ubuntu Focal)
     Importance: Undecided
         Status: In Progress


** Tags: sts
-- 
[SRU] nfsd doesn't start if exports depend on mount
https://bugs.launchpad.net/bugs/1871214
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