[lustre-discuss] Question about permissions on directory with sticky bit set with 2.16.1 client, 2.12.6 server Lewis

[Benjamin Smith]

Hi,

Given that you've got different behaviour with non-lustre filesystems,
this probably isn't the issue, but have you checked the
fs.protected_regular sysctl? The sequence you tried below works with
that at 0 for me, but not at 2.

-Ben.

On 21/01/2025 18:54, Lewis Hyatt wrote:
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> Hello-
>
> I have a lustre server running 2.12.6. I am planning to upgrade the
> clients (not the server) from Ubuntu 18 to Ubuntu 24, and I am testing
> this configuration using lustre 2.16.1 on the client side. So far, it
> builds and performs just fine like this, but I have come across one
> obscure issue. If a file resides in a world-writable directory with
> the sticky bit set, then I am not able to append to files in that
> directory as the root user. As an example:
>
> $ uname -r
> 6.8.0-51-generic
> $ lfs --version
> lfs 2.16.1
> $ mkdir tmp
> $ chmod 1777 tmp
> $ cd tmp
> $ touch f
> $ chmod 644 f
> $ sudo chown nobody f  #any user other than the current user goes here
> $ sudo su
> # echo >> f
> bash: f: Permission denied
>
> strace sees:
>
> openat(AT_FDCWD, "f", O_WRONLY|O_CREAT|O_APPEND, 0666) = -1 EACCES
> (Permission denied)
>
> The above sequence works as expected for non-lustre filesystems on the
> same client, and it works for lustre with the same lustre server on
> the Ubuntu 18 clients running lustre client 2.12.9_11_g60c2827.
>
> I am wondering if this change is expected or if there's something I
> can configure to preserve the previous behavior... thanks very much in
> advance for any help!
>
> -Lewis
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Benjamin Smith <bsmith5 at ed.ac.uk>

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