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Subject: Re: [PATCH] ovl: introduce new "index=nouuid" option for inodes index
 feature
To:     Miklos Szeredi <miklos@szeredi.hu>
Cc:     Amir Goldstein <amir73il@gmail.com>,
        Vivek Goyal <vgoyal@redhat.com>, linux-unionfs@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20200923125014.181931-1-ptikhomirov@virtuozzo.com>
From:   Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
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Date:   Wed, 23 Sep 2020 16:31:25 +0300
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Please drop, I accidentally missed several hunks...

On 9/23/20 3:50 PM, Pavel Tikhomirov wrote:
> dd if=/dev/zero of=loopbackfile.img bs=100M count=10
> losetup -fP loopbackfile.img
> losetup -a
>    #/dev/loop0: [64768]:35 (/loop-test/loopbackfile.img)
> mkfs.ext4 /root/loopbackfile.img
> mkdir loop-mp
> mount -o loop /dev/loop0 loop-mp
> mkdir loop-mp/{lower,upper,work,merged}
> mount -t overlay overlay -oindex=on,lowerdir=loop-mp/lower,\
> upperdir=loop-mp/upper,workdir=loop-mp/work loop-mp/merged
> umount loop-mp/merged
> umount loop-mp
> e2fsck -f /dev/loop0
> tune2fs -U random /dev/loop0
> 
> mount -o loop /dev/loop0 loop-mp
> mount -t overlay overlay -oindex=on,lowerdir=loop-mp/lower,\
> upperdir=loop-mp/upper,workdir=loop-mp/work loop-mp/merged
>    #mount: /loop-test/loop-mp/merged:
>    #mount(2) system call failed: Stale file handle.
> 
> If you just change the uuid of the backing filesystem, overlay is not
> mounting any more. In Virtuozzo we copy container disks (ploops) when
> crate the copy of container and we require fs uuid to be uniq for a new
> container.

-- 
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.