NFS: Fix up nfs_readdir_inode_mapping_valid()

The check for duplicate readdir cookies should only care if the change
attribute is invalid or the data cache is invalid.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Tested-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>

fs/nfs/dir.c

@@ -411,7 +411,8 @@ static int nfs_readdir_search_for_pos(struct nfs_cache_array *array,
 static bool
 nfs_readdir_inode_mapping_valid(struct nfs_inode *nfsi)
 {
-	if (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))
+	if (nfsi->cache_validity & (NFS_INO_INVALID_CHANGE |
+				    NFS_INO_INVALID_DATA))
 		return false;
 	smp_rmb();
 	return !test_bit(NFS_INO_INVALIDATING, &nfsi->flags);