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Date:   Sat, 23 Jul 2022 13:29:17 -0400
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Subject: Re: Why keep var-lib-nfs-rpc_pipefs.mount around?
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To:     Benjamin Coddington <bcodding@redhat.com>,
        Andreas Hasenack <andreas@canonical.com>
Cc:     linux-nfs@vger.kernel.org
References: <CANYNYEFSdBua3Ay6jGk2cacossVJ8_CzDgDBnFCjXfk5XSoGEQ@mail.gmail.com>
 <EE39279C-4E40-48C8-ABC9-707EB1AD6D79@redhat.com>
From:   Steve Dickson <steved@redhat.com>
In-Reply-To: <EE39279C-4E40-48C8-ABC9-707EB1AD6D79@redhat.com>
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My apologies delayed response... extended PTO

On 7/11/22 9:13 AM, Benjamin Coddington wrote:
> On 8 Jul 2022, at 12:50, Andreas Hasenack wrote:
> 
>> Hi,
>>
>> I was tracking down a Debian/Ubuntu bug with nfs-utils 2.6.1 where in
>> one case, after installing the packages, you would end up with
>> rpc_pipefs mounted at the same time in two locations: /run/rpc_pipefs
>> and /var/lib/nfs/rpc_pipefs. The /run location is what debian/ubuntu
>> default to.
>>
>> After poking around a bit, I think I found out why that is
>> happening[1], but it led me to ask this question: why is
>> var-lib-nfs-rpc_pipefs.mount (and its corresponding rpc_pipefs.target
>> unit) still shipped, given that nfs-utils now has a generator?
> 
> Could just be an oversight, or perhaps a better reason exists.  The
> nfs-utils userspace has to handle a lot of different cases and legacy
> setups.
> 
> Steve D, do you know?
Its not clear to me, if the read from nfs.conf does not
happen how changing the rpc_pipefs directory could happen.

When the read from nfs.conf happens and the rpc_pipefs directory
is not defined, the compiled in default rpc_pipefs directory
will be used and the generator will exit and not
generating the systemd files (using the installed ones).

If the rpc_pipefs directory is defined in nfs.conf, the
generator will set up that directory as the
rpc_pipefs directory and systemd files will be
generated.

So by taking out the nfs.conf read, the only way to change
the default rpc_pipefs directory is to recompile nfs-utils.

steved.
> 
> Ben
> 
>> Shouldn't the generator be enough for all cases, where rpc_pipefs is
>> mounted in the default compile-time location, or changed via a config
>> change to nfs.conf? I know currently it checks[2] whether the config
>> points at the default location, but that check could just be skipped
>> and then the generator would always produce the correct mount and
>> target units.
>>
>>
>> 1. 
>> https://bugs.launchpad.net/ubuntu/+source/nfs-utils/+bug/1971935/comments/22 
>>
>> 2. 
>> https://salsa.debian.org/kernel-team/nfs-utils/-/blob/master/systemd/rpc-pipefs-generator.c#L138 
>>
>