> > > I see no feature detection logic, so test just fails on old kernels
> > > without this feature? I tried with v5.7-r4 kernel, test fails because
> > > each whiteout file has only one hardlink.
> >
> > That's true.
>
> I'd like to see it _notrun on old kernels where the feature is not
> available. But that seems hard to do.. Do you have any better ideas?
>
I've got a few.
1. LTP has the concept of require minimum kernel version.
This would mean that functionality will be not be tested if feature
is backported to old kernels.
2. We could add to overlayfs advertising of supported features, like
/sys/fs/ext4/features/, but it already does "advertise" the configurable
features at /sys/module/overlay/parameters/, and we were already
asking the question during patch review:
/* Is there a reason anyone would want not to share whiteouts? */
ofs->share_whiteout = true;
and we left the answer to "later" time.
So a simple solution would be to add the module parameter (without adding
a mount option), because:
- It doesn't hurt (?)
- Somebody may end up using it, for some reason we did not think of
- We can use it in test to require the feature
The one non-trivial thing that this will require is to add Documentation
of the module parameter in the section about Whiteouts and opaque directories.
Thanks,
Amir.
