On Thu, Apr 15, 2021 at 09:49:21AM +0200, Christian Brauner wrote: > Harsh words. :) > Christoph's right though I think for the xfstests we don't need it and > we're covered with what we have in the version I sent out last Sunday. Sorry, I had missed your v13 patch set and that it had included tests for the existence of idmapped. I had sent out the RFC patch because I was under the impression that we hadn't made forward progress on testing for the support idmapped mounts. If we have a way of doing this, and you're comfortable that it is reliable (e.g., that a bug might cause the test to be skipped because it thinks the file system doesn't support idmapped mount, when really it was caused by a regression), and I'm happy to just rely on the method you've used in the v13 fstests patch set. That being said, I still think it would be helpful to have a VFS-standard way for userspace to be able to test for the presence of a particular kernel feature/capability without having to do a test mount, possibly requiring setting up a test user_ns, etc., etc. But that isn't as urgent as making sure we can easily the feature without needing manual customization of the test suite as file systems add support for the feature, or as the feature gets backported to enterprise distro kernels. Cheers, - Ted
