[PATCH] Linux: Add test case for bug 33245

[Yury Khrustalev]

On Thu, Sep 25, 2025 at 01:08:11PM +0200, Florian Weimer wrote:
> * Yury Khrustalev:
> 
> > This comparison fails on Debian 13 with recent kernel 6.12.48+deb13-arm64
> > (it works fine on 6.12.43+deb13-arm64) for copy sizes like 0xfffff001,
> > for example:
> >
> > ../sysdeps/unix/sysv/linux/tst-copy_file_range-large.c:173: numeric comparison failure
> >    left: 4294963200 (0xfffff000); from: copied
> >   right: 4294963201 (0xfffff001); from: size
> 
> Is this a 64-bit build?

Yes, this is a 64-bit build. This happens when I build natively for
aarch64 or cross-build for this target.

> > I can't find changelog for 6.12.48+deb13 right now, but reading man page
> > for copy_file_range() I can see that it can copy less number of files than
> > requested and it should not be an error. Is there anything in this test
> > that should force copy_file_range() to always copy as many bytes as
> > requested?
> 
> Yes, the FUSE layer (or the VFS?) was changed after I reported this to
> the FUSE maintainers.  Previously the code path to the FUSE callback was
> completely clean and no such shortening could happen.

I see. I suppose test can be fixed to account for this?

Thanks,
Yury