linux-kernel - Re: [PATCH 3/4] autofs - make mountpoint checks namespace aware

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Message-ID: <20160916211457.GA18830@vader.DHCP.thefacebook.com>
Date:   Fri, 16 Sep 2016 14:14:57 -0700
From:   Omar Sandoval <osandov@...ndov.com>
To:     Ian Kent <raven@...maw.net>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        autofs mailing list <autofs@...r.kernel.org>,
        Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Al Viro <viro@...IV.linux.org.uk>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>, kernel-team@...com
Subject: Re: [PATCH 3/4] autofs - make mountpoint checks namespace aware

On Wed, Sep 14, 2016 at 02:14:45PM +0800, Ian Kent wrote:
> If an automount mount is clone(2)ed into a file system that is
> propagation private, when it later expires in the originating
> namespace subsequent calls to autofs ->d_automount() for that
> dentry in the original namespace will return ELOOP until the
> mount is manually umounted in the cloned namespace.
> 
> In the same way, if an autofs mount is triggered by automount(8)
> running within a container the dentry will be seen as mounted in
> the root init namespace and calls to ->d_automount() in that namespace
> will return ELOOP until the mount is umounted within the container.
> 
> Also, have_submounts() can return an incorect result when a mount
> exists in a namespace other than the one being checked.
> 
> Signed-off-by: Ian Kent <raven@...maw.net>
> Cc: Al Viro <viro@...IV.linux.org.uk>
> Cc: Eric W. Biederman <ebiederm@...ssion.com>
> Cc: Omar Sandoval <osandov@...ndov.com>

I can confirm that this fixes my repro and hasn't caused any other
problems as far as I can tell.

Tested-by: Omar Sandoval <osandov@...com>

-- 
Omar