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From:   "NeilBrown" <neilb@suse.de>
To:     "Benjamin Coddington" <bcodding@redhat.com>
Cc:     "Trond Myklebust" <trondmy@hammerspace.com>, steved@redhat.com,
        linux-nfs@vger.kernel.org
Subject: Re: [nfs-utils PATCH] nfs4id: a tool to create and persist nfs4
 client uniquifiers
In-reply-to: <6BAAA0D0-7212-480F-9C33-DA1F656FF09F@redhat.com>
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Date:   Fri, 11 Feb 2022 09:54:57 +1100
Message-id: <164453369792.27779.10668875903268728405@noble.neil.brown.name>
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On Thu, 10 Feb 2022, Benjamin Coddington wrote:
> 
> Yes, but even better than having the tool do the writing is to have udev do
> it, because udev makes the problem of when and who will execute this tool go
> away, and the entire process is configurable for anyone that needs to change
> any part of it or use their own methods of generating/storing ids.

I really don't understand the focus on udev.

Something, somewhere, deliberately creates the new network namespace.
It then deliberately configures that namespace - creating a virtual
device maybe, adding an IP address, setting a default route or whatever.
None of that is done by udev rules (is it)?
Setting the NFS identity is just another part of configuring the new
network namespace.

udev is great when we don't know exactly when an event will happen, but
we want to respond when it does.
That doesn't match the case of creating a new network namespace.  Some
code deliberately creates it and is perfectly positioned to then
configure it.

udev is async.  How certain can we be that the udev event will be fully
handled before the first mount attempt?

NeilBrown