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Date: Wed, 20 Jun 2012 19:27:14 +0200
Message-ID: <CAB9VWqB8z_faPNRJo8+9JWsQFDe507iTxwQK4sctUYGF9zCL4Q@mail.gmail.com>
Subject: Re: [PATCH] Allow cross subvolume reflinks (2nd attempt)
From: Alexander Block <ablock84@googlemail.com>
To: kreijack@inwind.it
Cc: linux-btrfs@vger.kernel.org, dave@jikos.cz, hch@infradead.org,
        linux-fsdevel@vger.kernel.org, chris.mason@fusionio.com,
        linux-kernel@vger.kernel.org
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On Wed, Jun 20, 2012 at 7:18 PM, Goffredo Baroncelli <kreijack@libero.it> wrote:
> Hi Alexander,
>
> On 06/20/2012 12:35 PM, Alexander Block wrote:
>> The patch also does proper vfs mount checks, so cross mount
>> point reflinks are not possible with this patch. It only allows cross
>> reflinks between two subvolumes which are in the same mount point.
>
> Thanks for working on that. What happens if two subvolumes of the same
> filesystem are mounted on two different places ?
>
> I usually do:
> ?mount -o subvol=__active /dev/sdX /
> ?mount -o subvol=. ? ? ? ?/dev/sdX /var/btrfs
>
> So two different subvolumes of the same filesystem (the one on /dev/sdX)
> are mounted on two different places.
>
> Is it possible to do
> ?cp --reflink /tmp/foo /var/btrfs/tmp/foo2
This will fail with -EXDEV. The patch explicitly forbids reflinks crossing vfs
mount boundaries.
>
> Thanks
> G.Baroncelli
>
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