Re: [PATCH] NFSv4/flexfiles: add a soft dependency on nfsv3

["Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de>]

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Frankly, I think this is my change that has introduced the trouble:

a68c6fbb638a ("nfs41: drop dependency between flexfiles layout driver and NFSv3 modules")

The intent was to be able to build a kernel with flexfiles support even if NFSv3 is disabled.
No objections if you want to revert it.

Best regards,
   Tigran.


----- Original Message -----
> From: "Benjamin Coddington" <ben.coddington@hammerspace.com>
> To: "Roberto Bergantinos Corpas" <rbergant@redhat.com>, "Mike Snitzer" <snitzer@kernel.org>
> Cc: "Antonio Alvarez Feijoo" <antonio.feijoo@suse.com>, "linux-nfs" <linux-nfs@vger.kernel.org>, "Mike Snitzer"
> <snitzer@kernel.org>, "Anna Schumaker" <anna.schumaker@hammerspace.com>, "Trond Myklebust"
> <trond.myklebust@hammerspace.com>
> Sent: Friday, 23 October, 2026 16:16:32
> Subject: Re: [PATCH] NFSv4/flexfiles: add a soft dependency on nfsv3

> On 23 Oct 2026, at 8:30, Roberto Bergantinos Corpas wrote:
> 
>> There is another problematic case for this problem : if an
>> unprivileged container attempts pNFS I/O, SELinux may block the
>> request_module() call, leading to a writeback hang instead of a boot hang.
>>
>> Having the module pre-loaded at mount time avoids that scenario too.
> 
> I think this is a stronger case than the nfs-root, which already requires a
> sysadmin to have knowledge and desire to configure the client a certain way,
> and can certainly apply the work-around.
> 
> Roberto's case would look functional to the admin, and the failure would
> happen later and be difficult to diagnose.
> 
> I think Fixes: 7a375cafc14e (7.2.y) is the accurate tag, though - because
> before that the -EPROTONOSUPPORT would fall back to the MDS - it gives the
> WARN, but doesn't hang the system.
> 
> I also think 7a375cafc14e also needs a follow-on fix (Cc: Mike) - because it
> now causes permanent failure cases to retry forever- we should probably just
> fail the IO.
> 
> The last thing here is that the MODULE_SOFTDEP is just informative, it only
> advises modprobe and initramfs builders.  It not going to fix
> CONFIG_NFS_V4=y with CONFIG_NFS_V3=n or m.  So - I think we should just make
> flexfiles publish a hard dependency on a v3 symbol, which fixes the module
> dependency directly, and also fixup Kconfig so that there aren't unexpected
> build failures as a result.
> 
> My 2 cents,
> 
> Ben

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