[PATCH] knfsd: add svc_get

add svc_get() for those occasions when we need to temporarily bump up
svc_serv->sv_nrthreads as a pseudo refcount.

Signed-off-by: Greg Banks <gnb@melbourne.sgi.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/nfsd/nfssvc.c

@@ -200,7 +200,7 @@ int nfsd_create_serv(void)
 	int err = 0;
 	lock_kernel();
 	if (nfsd_serv) {
-		nfsd_serv->sv_nrthreads++;
+		svc_get(nfsd_serv);
 		unlock_kernel();
 		return 0;
 	}

include/linux/sunrpc/svc.h

@@ -70,6 +70,17 @@ struct svc_serv {
 						 */
 };
 
+/*
+ * We use sv_nrthreads as a reference count.  svc_destroy() drops
+ * this refcount, so we need to bump it up around operations that
+ * change the number of threads.  Horrible, but there it is.
+ * Should be called with the BKL held.
+ */
+static inline void svc_get(struct svc_serv *serv)
+{
+	serv->sv_nrthreads++;
+}
+
 /*
  * Maximum payload size supported by a kernel RPC server.
  * This is use to determine the max number of pages nfsd is