On 06/23/2015 03:23 PM, David Howells wrote:
Jan Olszak <j.olszak@xxxxxxxxxxx> wrote:
Why not just say: "rename causes copy" and leave everything as it is now.
That's another option - but your whole proposal was that we specifically don't
copy up these files IIRC.
Yes, so let's modify the proposal:
Overlayfs checks xattr "trusted.overlay.cow" to switch COW off whenever
it's possible.
1. This would be an optimization/convenience option, not a security option
2. By default overlayfs uses COW like it does now
3. trusted.overlay.cow=="n" means:
- Unlink, open, setattr etc. use the original inode from lowerdir
- Unmodifying operations also use inode from lowerdir
- Other operations (rename) may copy the file if it's required by the
implementation of overlayfs
Thanks,
Jan
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