From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: buildroot@busybox.net
Subject: [Buildroot] Obscure bug in Util-Linux umount?
Date: Tue, 10 Mar 2015 18:59:37 +0100 [thread overview]
Message-ID: <20150310185937.280f8497@free-electrons.com> (raw)
In-Reply-To: <54FF18D4.2030709@ou.edu>
Dear Steve Kenton,
On Tue, 10 Mar 2015 11:16:20 -0500, Steve Kenton wrote:
> Further testing revealed that it only occurs if the embedded root filesystem is read-only
> which I forgot to mention (blush) so it's probably an interaction with a stale /etc/mtab
> or something, but only for the root filesystem and only if the mount point directory names
> are the same, yada etc. Much less likely to bite anyone else so I guess a heads up is not needed.
>
> Any way, not really a bug but rather a feature with undefined behaviour and most importantly
> a case of 'it hurts if I do this' soooo 'don't do that'!
Interesting. After reading your e-mail, I had a very quick look at the
kernel side and util-linux side, looking for code using the
s_last_mounted field of the superblock which indeed contains the last
location where it was mounted. But I couldn't spot any place where it
is specifically used to prevent something from happening. But I didn't
spend a lot of time, so I may very well have missed something.
Thomas
--
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
next prev parent reply other threads:[~2015-03-10 17:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <54FE7E8E.20306@ou.edu>
2015-03-10 5:25 ` [Buildroot] Obscure bug in Util-Linux umount? Steve Kenton
2015-03-10 16:16 ` Steve Kenton
2015-03-10 17:59 ` Thomas Petazzoni [this message]
2015-03-10 18:05 ` Steve Kenton
2015-03-12 0:50 ` [Buildroot] Obscure bug in Util-Linux umount? - Solved Steve Kenton
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