> Ok, I am wondering why are we concerned about older kernels. I mean, > if we introduce new features, we don't provide compatibility with > older kernels. Say "metacopy", "redirect_dir". If you mount with > older kernel, they will see something which you don't expect. > True. We missed the opportunity to do the work/incompat trick with metacopy etc. > So why "volatile" is different. We seem to be bending backward and > using an unrelated behavior of overlay to provide this. > > Why not simply drop a file $workdir/volatile for volatile mounts > and check for presence of this file when mounting? > That's an option. But what's the problem with $workdir/work/incompat/volatile/dirty compared to: $workdir/volatile It's not more complicated to implement is it? So we get some extra protection with little extra cost. No? I don't feel strongly about it. But I must say, according to Giuseppe's description of the use case: "mount volatile overlay+umount overlay+syncfs upper dir..." looks like what he is looking for is "volatile,sync=shutdown", is it not? And if this is the case, I think it would be much preferred to implement "volatile,sync=shutdown", over documenting how to make a "volatile" overlay mountable from outside overlay. Don't you guys agree? Doesn't matter, either way, the same protection will be used. Thanks, Amir.
