linux-kernel - Re: [RFC][PATCH 0/3] vfs: Detach mounts on unlink.

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Message-ID: <20131008080303.GH14360@x2.net.home>
Date:	Tue, 8 Oct 2013 10:03:03 +0200
From:	Karel Zak <kzak@...hat.com>
To:	Rob Landley <rob@...dley.net>
Cc:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Miklos Szeredi <miklos@...redi.hu>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Linux-Fsdevel <linux-fsdevel@...r.kernel.org>,
	Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andy Lutomirski <luto@...capital.net>
Subject: Re: [RFC][PATCH 0/3] vfs: Detach mounts on unlink.

On Sat, Oct 05, 2013 at 06:42:44PM -0500, Rob Landley wrote:
> Oh, attached is a dumb "zapchroot" script I've been using for years to
> unlink all mount points under a given directory, taking advantage of the
> fact that mount points are appended to the end of the list so if you unlink
> from the end to the front you should get the sub-mounts before the parent
> mounts (modulo mount --move not reordering the list, but that's uncommon).

 util-linux umount supports --recursive, it uses /proc/self/mountinfo
 to compose the hierarchy. The important is that the mountinfo file
 contains Id and Parent_Id relations, so you don't rely on the order
 only.

> Recently I noticed some kernels where chroot does _not_ trim the paths so
> that the paths you see in /proc/mounts are relevant to the current chroot
> but instead have all sorts of crap you can't access with no way to know what
> it's talking about. That was sad, I need to go figure out if that was distro
> breakage or vanilla breakage...

 hmm..

    Karel


-- 
 Karel Zak  <kzak@...hat.com>
 http://karelzak.blogspot.com
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