copy_file_range.2: Document the COPY_FILE_RANGE_CLONE flags argument

[rmacklem]

Summary

Commit 37b2cb5ecb0f added support for the
COPY_FILE_RANGE_CLONE flags argument to
copy_file_range(2).

This patch documents this flags argument.

This is a content change.

[kib]

The first paragraph of the DESCRIPTION becomes too heavy IMO.

Can we split it into a paragraph per arg. I do not think it would require anything but a bunch of .Pps.

lib/libsys/copy_file_range.2

136

142

I do not see a need to list a differences with other OSes in the main description. You might add a COMPATIBILITY section if you think that this is important enough for the FreeBSD manpage.

227

BTW, ENOSYS feels somewhat out of place there. Is there a reason the error cannot be ENOTSUPP?

ENOSYS means that the (whole) syscall is not implemented.

[rmacklem]

Thanks for the feedback. I'm off doing other things for
a few days, but will update this next weekend.

lib/libsys/copy_file_range.2

227

Sure, I can change it. The only reason I used ENOSYS
was that that was what zfs_copy_file_range() already
uses to indicate it cannot block clone. But, that ENOSYS
does not become a syscall return because the code just
calls vn_generic_copy_file_range() for ENOSYS.

I put up the one liner patch to change it to ENOTSUPP.

[rmacklem]

Made changes suggested by kib@.

[kib]

lib/libsys/copy_file_range.2

228