From: Al Viro <viro@ZenIV.linux.org.uk>
To: Phillip Susi <psusi@ubuntu.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: mount --move and shared namespaces
Date: Tue, 10 May 2016 16:48:26 +0100 [thread overview]
Message-ID: <20160510154826.GL2694@ZenIV.linux.org.uk> (raw)
In-Reply-To: <5731132A.7040801@ubuntu.com>
On Mon, May 09, 2016 at 06:46:02PM -0400, Phillip Susi wrote:
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> It seems that mount --move does not work on a shared namespace ( now
> the default under systemd ), yet you can mount --bind and then umount
> the original, which seems to amount to exactly the same thing. Why is
> the direct move not allowed?
You have something mounted on /foo and events from /foo propagated to
/bar. You move the instance on /foo to /baz; what to do with one on
/bar? Propagation from /baz might have nothing whatsoever in common
with that on /foo, so "move to the corresponding recepients of events
for /baz" is not an answer...
Move *into* shared is allowed - the one you move ends up relocated and
cloned, with clones attached to the places where events propagate to.
Move *from* shared... No sane semantics.
And no, mount --move is *not* mount --bind + umount - it really moves
the vfsmount, so anything sitting in that subtree will find itself at
the new location.
prev parent reply other threads:[~2016-05-10 15:48 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-09 22:46 mount --move and shared namespaces Phillip Susi
2016-05-10 15:48 ` Al Viro [this message]
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