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_fs.h b/include/linux/nfs_fs.h
index 63850a8..9449286 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -293,6 +293,7 @@
 				struct nfs_fattr *);
 extern int nfs_refresh_inode(struct inode *, struct nfs_fattr *);
 extern int nfs_post_op_update_inode(struct inode *inode, struct nfs_fattr *fattr);
+extern int nfs_post_op_update_inode_force_wcc(struct inode *inode, struct nfs_fattr *fattr);
 extern int nfs_getattr(struct vfsmount *, struct dentry *, struct kstat *);
 extern int nfs_permission(struct inode *, int, struct nameidata *);
 extern int nfs_open(struct inode *, struct file *);