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From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
To: Alexander Aring <aring@mojatatu.com>, netdev@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, kernel@mojatatu.com,
	David Howells <dhowells@redhat.com>
Subject: Re: [RFC iproute2 1/1] ip: netns: add mounted state file for each netns
Date: Thu, 27 Jun 2019 14:08:08 +0200
Message-ID: <293c9bd3-f530-d75e-c353-ddeabac27cf6@6wind.com> (raw)
In-Reply-To: <20190626190343.22031-2-aring@mojatatu.com>

Le 26/06/2019 à 21:03, Alexander Aring a écrit :
> This patch adds a state file for each generated namespace to ensure the
> namespace is mounted. There exists no way to tell another programm that
> the namespace is mounted when iproute is creating one. An example
> application would be an inotify watcher to use the generated namespace
> when it's discovers one. In this case we cannot use the generated
> namespace file in /var/run/netns in the time when it's not mounted yet.
> A primitiv approach is to generate another file after the mount
> systemcall was done. In my case inotify waits until the mount statefile
> is generated to be sure that iproute2 did a mount bind.
We (at 6WIND) already hit this problem. The solution was: if setns() fails, wait
a bit and retry the setns() and continue this loop with a predefined timeout.
netns may be created by other app than iproute2, it would be nice to find a
generic solution.

David Howells was working on a mount notification mechanism:
https://lwn.net/Articles/760714/
https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=notifications

I don't know what is the status of this series.


Regards,
Nicolas

  reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-26 19:03 [RFC iproute2 0/1] iproute2 netns mount race issue and solution? Alexander Aring
2019-06-26 19:03 ` [RFC iproute2 1/1] ip: netns: add mounted state file for each netns Alexander Aring
2019-06-27 12:08   ` Nicolas Dichtel [this message]
2019-06-28 16:26   ` David Howells
2019-06-28 17:06     ` Matteo Croce
2019-06-29 21:45       ` Matteo Croce
2019-07-01 12:34     ` Nicolas Dichtel

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