The follow_link() interface was retired in favor of get_link().
In the process of phasing in get_link() the Linux kernel went
through two different versions. The first of which depended
on put_link() and the final version on a delayed done function.
- Improved configure checks for .follow_link, .get_link, .put_link.
- Interfaces checked from newest to oldest.
- Strict checking for each possible known interface.
- Configure fails when no known interface is available.
- Both versions .get_link are detected and supported as well
two previous versions of .follow_link.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Issue #4228
