linux-kernel - Re: unable to mount using overlayfs.v22 on kernel 3.15.5

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Date:	Thu, 24 Jul 2014 15:48:51 +0200
From:	"Klaus A. Kreil" <klaus.kreil@...vie.ac.at>
To:	Woody Suwalski <terraluna977@...il.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: unable to mount using overlayfs.v22 on kernel 3.15.5

Woody,
my message obviously ended up in the wrong list due to a mistake of 
mine. I originally thought it got lost until your reply as I am not 
subscribed to linux-kernel@...r.kernel.org.

But: There is already a discussion about this issue going on at 
linux-unionfs@...r.kernel.org with Miklos Szeredi, the author of overlayfs.

He has kindly pointed me towards the correct list when I sent him a PM 
about the problem and he rightly has taken the issue to 
linux-unionfs@...r.kernel.org. I think it would be good if you joined us 
there to keep related things together.

Thanks,

Klaus

Am 24.07.14 14:14, schrieb Woody Suwalski:
> Klaus A. Kreil wrote:
>> Hello list,
>> I have just found out about this mailing list which obviously also
>> takes care of overlayfs.
>>
>> I have been a happy user of overlayfs for quiet some time using it to
>> propagate a shared r/o LVM ext4 lowerdir rootfs with a small r/w ext4
>> upperdir for a number of XEN domU guests. I started with overlayfs on
>> kernel version 3.11.7 (all on gentoo-hardened). Recently I have
>> switched from 3.13.10 (using overlayfs.v21) to 3.15.5 with overlayfs.v22.
>>
>> overlayfs.v22 seems to have changed insofar as there's a new parameter
>> workdir=/dir with dir required to be an empty directory on the same
>> filesystem as upperdir. So I have changed my initramfs to include that
>> parameter and have also created my /dir directory (named /.work, owned
>> by root:root and 0755 mode) on all my individual upperdir filesystems
>> for all of my XEN domUs.
>>
>> Now when I start the new kernel 3.15.5 with the modified init script
>> from the newly created initramfs, I am ending up in a rescue shell.
>> Both the upper and lower filesystem are (as expected) mounted
>> appropriately to /mnt/root_ro and /mnt/root_rw amd /mnt/root exists.
>> Howeverm, trying to combine those two filesystems on /mnt/root (as
>> before and regardless of whether used with or without the workdir=
>> parameter) fails with an error message as follows:
>>
>> # mount -t overlayfs overlayfs -o
>> lowerdir=/mnt/root_ro,upperdir=/mnt/root_rw,workdir=/.work /mnt/root
>> mount: mounting overlayfs on /mnt/root failed: Invalid argument
>>
>> The error message stays the same regardless of where on the command
>> line the overlayfs "device" parameter appears. I can't see what's
>> wrong with the command line given that - with the exception of the
>> workdir=/.work part - the command has not changed from 3.13.10
>> (overlayfs.v21), therefore currently leaving me at loss.
>>
>> I would very much appreciate any help and support in tracking down
>> this unexpected issue.
>>
>> Regards Atom2
> Klaus, I have run into similar problems...
> What works for me:
> Once you mount the upperdir /mnt/root_rw, create /mnt/root_rw/root and
> /mnt/root_rw/workdir and use these for overlayfs mountpoints.
>
> Woody
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