follow_link has been replaced by get_link() which can be
called in RCU mode.

see commit: commit 6b255391 ("replace ->follow_link() with
new method that could stay in RCU mode")
Signed-off-by: Fox Chen <foxhlchen@gmail.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20210527091618.287093-8-foxhlchen@gmail.comSigned-off-by: Jonathan Corbet <corbet@lwn.net>