I looked at this more closely. Here is the patch that added the sysctl to the kernel previously: https://lkml.org/lkml/2016/11/2/300. This was meant to be configurable earlier. That is why this made sense. But, now it is not. We unconditionally clamp to the fs limits. I looked around to see if we ever expose information about internal kernel changes to userspace. This is almost never done. And, this is always in the form of maybe a syscall failing. Given that we don't see any modified behaviour that the user can point out, I don't think we can expose the presence of clamping in the kernel. fsinfo though exposes a fs max and min that could be useful if we fill in an unknown pattern as default: https://lwn.net/ml/linux-api/153314004147.18964.11925284995448007945.stgit@xxxxxxxxxxxxxxxxxxxxxx/. I also spoke about this to Arnd, and he also suggested the fsinfo as an alternative. Is it easy to not run the test on older kernels? Otherwise, we just have to rely on fsinfo being merged? -Deepa
