df -h reports resource unavailable for CIFS mounts

[JB2Cool]

Description: Ubuntu 20.04.6 LTS
Release: 20.04

I have some CIFS mounts on a server wth 5.15.0-1056 installed, these were all working working fine and reporting correctly. Once i updated the server to be using 5.15.0-1058 these all started reporting 'resource unavailable'. I could always list, touch and remove files the whole time even on the 5.15.0-1058 kernel when this was 'broken'.

This seems to be similar to some issues reported between 5.15.0-101 and 5.15.0-102 and these were resolved in 5.12.0-105

https://forums.linuxmint.com/viewtopic.php?t=417371
https://answers.launchpad.net/ubuntu/+source/linux/+question/809137
https://askubuntu.com/questions/1509987/cifs-on-22-04-lts-has-something-changed-between-kernel-5-15-0-101-generic-and
https://bugs.launchpad.net/ubuntu/+source/cifs-utils/+bug/2060797

[Matthew Ruffell (mruffell)]

Hi JB2Cool,

Yes, you are correct. You are seeing the exact same as bug 2060780, that was introduced between 5.15.0-101 and 5.15.0-102 and fixed in 5.15.0-105.

For AWS, the fix is in:

$ git log --grep "smb3: Replace smb2pdu 1-element arrays with flex-arrays" Ubuntu-aws-5.15.0-1*
commit 9f1d43ea8e5f7e49485eb2e3288524af2fb5a5d5
Author: Kees Cook <email address hidden>
Date: Fri Feb 17 16:24:40 2023 -0800

    smb3: Replace smb2pdu 1-element arrays with flex-arrays
...
$ git describe --contains 9f1d43ea8e5f7e49485eb2e3288524af2fb5a5d5
Ubuntu-aws-5.15.0-1060.66~247

Please upgrade to 5.15.0-1060-aws or later.

Thanks,
Matthew

[JB2Cool (jb2cool)]

Thanks Matthew
Tested on 5.15.0-1061-aws that my users problems were resolved. Have replied on the linked bug #2060780 thread too.

Hopefully this can be pushed into main for AWS users so they don't have to perform any manual workarounds.