ceph: add feature bits to connection handshake (protocol change)

Define supported and required feature set.  Fail connection if the server
requires features we do not support (TAG_FEATURES), or if the server does
not support features we require.

Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/ceph_fs.h

@@ -50,6 +50,12 @@
 #define CEPH_MAX_MON   31
 
 
+/*
+ * feature bits
+ */
+#define CEPH_FEATURE_SUPPORTED  0
+#define CEPH_FEATURE_REQUIRED   0
+
 
 /*
  * ceph_file_layout - describe data layout for a file/inode