From: Pavel Emelyanov <xemul@parallels.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>,
Daniel Lezcano <dlezcano@fr.ibm.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
Miklos Szeredi <mszeredi@suse.cz>
Subject: Re: [PATCH] vfs: Add setns support for the mount namespace
Date: Sat, 12 May 2012 15:41:36 +0400 [thread overview]
Message-ID: <4FAE4C70.5000804@parallels.com> (raw)
In-Reply-To: <87mx5e5tho.fsf_-_@xmission.com>
On 05/12/2012 12:54 AM, Eric W. Biederman wrote:
>
> setns support for the mount namespace is a little tricky as an arbitrary
> decision must be made about what to set fs->root and fs->pwd to, as
> there is no expectation of a relationship between the two mount
> namespaces. Therefore I arbitrarily find the root mount point, and
> follow every mount on top of it to find the top of the mount stack.
> Then I set fs->root and fs->pwd to that location. The topmost root of
> the mount stack seems like a reasonable place to be.
>
> Bind mount support for the mount namespace inodes has the possibility of
> creating circular dependencies between mount namespaces. Circular
> dependencies can result in loops that prevent mount namespaces from
> every being freed. I avoid creating those circular dependencies by
> adding a sequence number to the mount namespace and require all bind
> mounts be of a younger mount namespace into an older mount namespace.
>
> Add a helper function proc_ns_inode so it is possible to detect when we
> are attempting to bind mound a namespace inode.
>
> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
next prev parent reply other threads:[~2012-05-12 11:41 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-11 12:25 [PATCH 1/2] proc: Show ns-based inode numbers for /proc/pid/ns/* files Pavel Emelyanov
2012-05-11 12:25 ` [PATCH 2/2] ns: Add proc_ns_operations for mount namespaces Pavel Emelyanov
2012-05-11 17:05 ` Eric W. Biederman
2012-05-12 11:42 ` Pavel Emelyanov
[not found] ` <87mx5e5tho.fsf_-_@xmission.com>
2012-05-12 11:41 ` Pavel Emelyanov [this message]
2012-05-18 19:44 ` [PATCH] vfs: Add setns support for the mount namespace Serge E. Hallyn
2012-05-18 22:47 ` Eric W. Biederman
2012-05-11 17:07 ` [PATCH 1/2] proc: Show ns-based inode numbers for /proc/pid/ns/* files Eric W. Biederman
2012-05-12 11:40 ` Pavel Emelyanov
2012-05-26 15:14 ` Eric W. Biederman
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