nfsd: make NFSd service boot time per-net

This is simple: an NFSd service can be started at different times in
different network environments. So, its "boot time" has to be assigned
per net.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/netns.h

@@ -94,6 +94,11 @@ struct nfsd_net {
 	time_t nfsd4_grace;
 
 	bool nfsd_net_up;
+
+	/*
+	 * Time of server startup
+	 */
+	struct timeval nfssvc_boot;
 };
 
 /* Simple check to find out if a given net was properly initialized */