NFS: Fake up 'wcc' attributes to prevent cache invalidation after write

NFSv2 and v4 don't offer weak cache consistency attributes on WRITE calls.
In NFSv3, returning wcc data is optional. In all cases, we want to prevent
the client from invalidating our cached data whenever ->write_done()
attempts to update the inode attributes.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 0303201..daab252 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -62,7 +62,8 @@
 #define NFS_ATTR_FATTR		0x0002		/* post-op attributes */
 #define NFS_ATTR_FATTR_V3	0x0004		/* NFSv3 attributes */
 #define NFS_ATTR_FATTR_V4	0x0008		/* NFSv4 change attribute */
-#define NFS_ATTR_FATTR_V4_REFERRAL	0x0010		/* NFSv4 referral */
+#define NFS_ATTR_WCC_V4		0x0010		/* pre-op change attribute */
+#define NFS_ATTR_FATTR_V4_REFERRAL	0x0020		/* NFSv4 referral */
 
 /*
  * Info on the file system