Re: [PATCH] fstests: disable generic duperemove tests for NFS and others

[Christoph Hellwig <hch@infradead.org>]

On Mon, Dec 09, 2024 at 10:00:58AM -0500, Chuck Lever wrote:
> 2. How to disable this test on filesystems (like NFS) where duperemove
> is not supported or where the test is not meaningful. The current check
> for the presence of the duperemove executable is IMO inadequate.

I've not looked at dupremove, but the name suggested it's de-duplicating
and thus needs a working FIDEDUPERANGE ioctl.  So the test should check
for that using the _require_test_dedupe / _require_scratch_dedupe
helpers. generic/{559,560,561} do that, so something either in these
helpers is probably broken given that NFS rejects remap_file_range
with REMAP_FILE_DEDUP, although a bit of tracing would be useful if
there actually is something broken in NFS or the VFS.