On Thu, Jun 20, 2013 at 10:47:53AM +0200, Clemens Eisserer wrote: > Hi, > > I've observed a rather strange behaviour while trying to mount two > identical copies of the same image to different mount points. > Each modification to one image is also performed in the second one. > > Example: > dd if=/dev/sda? of=image1 bs=1M > cp image1 image2 > mount -o loop image1 m1 > mount -o loop image2 m2 > > touch m2/hello > ls -la m1 //will now also include a file calles "hello" > > Is this behaviour intentional and known or should I create a bug-report?
It's known, and not desired behaviour. The problem is that you've ended up with two filesystems with the same UUID, and the FS code gets rather confused about that. The same problem exists with LVM snapshots (or other block-device-layer copies). The solution is a combination of a tool to scan an image and change the UUID (offline), and of some code in the kernel that detects when it's being told about a duplicate image (rather than an additional device in the same FS). Neither of these has been written yet, I'm afraid. > I've deleted quite a bunch of files on my production system because of this... Oops. I'm sorry to hear that. :( Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- Welcome to Rivendell, Mr Anderson... ---
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