On Fri, Oct 26, 2018 at 10:16:40AM -0400, Vivek Goyal wrote: > On Fri, Oct 26, 2018 at 04:10:27PM +0200, Miklos Szeredi wrote: > > On Fri, Oct 26, 2018 at 3:43 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > > > Assume a user wanted to enable metadata only copy-up and passes metacopy=on. > > > If this feature can't be enabled, we disable metacopy=off and just leave > > > a warning in logs. metacopy=on requires redirect_dir=on (for upper dir) > > > or redirect_dir=follow (for non-upper mount). > > > > What's the reason we can't enable these for metacopy=on automatically? > > > > I mean, the simplest and least surprising behavior would be if > > metacopy would simply imply redirect_dir, no? > > redirect_dir=on is a significant change. And it might be better if > users passes it in (instead of enabling it automatically). > > For example, when redirect_dir is enabled, container runtime software > (docker, podman), their logic to generate image does not work and > they have to fall back to *slower* method of diff. > > https://github.com/moby/moby/pull/34342 Having said that, metacopy=on will have same issue and user need to fall back to slower naivediff interface for image generation. So enabling redirect_dir automatically probably is good. We could just drop a message in logs that it has been enabled automatically. IOW, I can go either way depending on how others feel about it. Thanks Vivek
