nfsd: only register cld pipe notifier when CONFIG_NFSD_V4 is enabled

Otherwise, we get a warning or error similar to this when building with
CONFIG_NFSD_V4 disabled:

    ERROR: "nfsd4_cld_block" [fs/nfsd/nfsd.ko] undefined!

Fix this by wrapping the calls to rpc_pipefs_notifier_register and
..._unregister in another function and providing no-op replacements
when CONFIG_NFSD_V4 is disabled.

Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index eaaf9482c7f5..4767429264a2 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -1032,3 +1032,15 @@ rpc_pipefs_event(struct notifier_block *nb, unsigned long event, void *ptr)
 struct notifier_block nfsd4_cld_block = {
         .notifier_call = rpc_pipefs_event,
 };
+
+int
+register_cld_notifier(void)
+{
+        return rpc_pipefs_notifier_register(&nfsd4_cld_block);
+}
+
+void
+unregister_cld_notifier(void)
+{
+        rpc_pipefs_notifier_unregister(&nfsd4_cld_block);
+}