unable to mount using overlayfs.v22 on kernel 3.15.5

unable to mount using overlayfs.v22 on kernel 3.15.5

[Klaus A. Kreil]

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

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

[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

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

[Klaus A. Kreil]

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@vger.kernel.org.

But: There is already a discussion about this issue going on at 
linux-unionfs@vger.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@vger.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