staging/lustre/llite: don't add to page cache upon failure

Reading directory pages may fail on MDS, in this case client should
not cache a non-up-to-date directory page, because it will cause
a later read on the same page fail.
Signed-off-by: Lai Siyao <lai.siyao@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5461
Reviewed-on: http://review.whamcloud.com/11450Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/llite/dir.c

@@ -183,7 +183,10 @@ static int ll_dir_filler(void *_hash, struct page *page0)
 	op_data->op_offset = hash;
 	rc = md_readpage(exp, op_data, page_pool, &request);
 	ll_finish_md_op_data(op_data);
-	if (rc == 0) {
+	if (rc < 0) {
+		/* page0 is special, which was added into page cache early */
+		delete_from_page_cache(page0);
+	} else if (rc == 0) {
 		body = req_capsule_server_get(&request->rq_pill, &RMF_MDT_BODY);
 		/* Checked by mdc_readpage() */
 		LASSERT(body != NULL);