linux-kernel - Re: [PATCH] Revert "__d_unalias() should refuse to move mountpoints"

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Message-ID: <50615268.1040805@canonical.com>
Date:	Tue, 25 Sep 2012 08:42:48 +0200
From:	Maarten Lankhorst <maarten.lankhorst@...onical.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	al viro <viro@...iv.linux.org.uk>, linux-fsdevel@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Revert "__d_unalias() should refuse to move mountpoints"

Hey,

Op 25-09-12 05:39, Eric W. Biederman schreef:
> Maarten Lankhorst <maarten.lankhorst@...onical.com> writes:
>
>> This reverts commit ee3efa91e240f513898050ef305a49a653c8ed90.
>>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@...onical.com>
>>
>> My thread about the regression seemed to have been ignored, so I can only
>> conclude nobody objects against a full revert of this patch.
>>
>> My testcase is simply booting through netboot with / and ~/nfs as separate
>> nfs filesystems, then doing 'ls ~/nfs' followed by 'ls ~' in a gnome-terminal
>> window, then I get:
> Do I read your description correctly:  Without using a bind mount you
> have the same nfs filesystem mounted on / and on ~/nfs?
>
> Something is definitely off with your configuration but if to work you
> need to move mount points around then that something seems much deeper
> than the __d_unalias change.
>
> What filesystems do you have mounted where?
>
/ is a nfs filesystem, ~/nfs is a different nfs filesystem. Just doing ls / is enough
to make all filesystems mounted on / return -EBUSY and disappear.

I also have a subdir of ~/nfs/ bind mounted to /lib/modules/$(uname -r)/kernel
for easy debugging so just doing 'make' in the kernel tree is enough to get the
new modules + bzImage, but I don't know if it is a factor in reproducing this bug
or not.

~Maarten
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