On Tue, Apr 12, 2016 at 08:21:59PM +0200, Stanislav Brabec wrote:
> As it was discussed in LKML[1], kernel has no way to detect backing
> file data changes if multiple loop devices have the same backing file.
>
> Exactly this happened if -oloop is used multiple times with the same
> source.
>
> It could not happen in past, but with introduction of btrfs sub-volumes
> it has a perfectly legal use cases.
>
> This patch set introduces a new behavior of -oloop:
>
> First check, whether the same backing file with the same offset is
> already used. If yes, reuse already initialized loop device.
>
> If not, initialize another loop device.
Applied, thanks.
> - If the same backing file is already used for a loop device with
> correct offset, but incorrect sizelimit, there is no solution. The
> current implementation does not check for it.
We need a warning/error for this.
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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