From patchwork Mon Apr 4 18:09:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 12800724 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F472C433EF for ; Mon, 4 Apr 2022 21:18:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379651AbiDDVU1 (ORCPT ); Mon, 4 Apr 2022 17:20:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1379822AbiDDSLR (ORCPT ); Mon, 4 Apr 2022 14:11:17 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A601122B27 for ; Mon, 4 Apr 2022 11:09:20 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 5F8CEB818D3 for ; Mon, 4 Apr 2022 18:09:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 197AAC2BBE4 for ; Mon, 4 Apr 2022 18:09:18 +0000 (UTC) Subject: [PATCH v1 3/6] SUNRPC: Cache deferral injection From: Chuck Lever To: linux-nfs@vger.kernel.org Date: Mon, 04 Apr 2022 14:09:17 -0400 Message-ID: <164909575709.3716.7317334286489397904.stgit@manet.1015granger.net> In-Reply-To: <164909503892.3716.8666091898179474248.stgit@manet.1015granger.net> References: <164909503892.3716.8666091898179474248.stgit@manet.1015granger.net> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Cache deferral injection stress-tests the cache deferral logic as well as upper layer protocol deferred request handlers. This facility is for developers and professional testers to ensure coverage of the rqst deferral code paths. To date, we haven't had an adequate way to ensure these code paths are covered during testing, short of temporary code changes to force their use. A file called /sys/kernel/debug/fail_sunrpc/ignore-cache-wait enables administrators to disable cache deferral injection while allowing other types of sunrpc errors to be injected. The default setting is that cache deferral injection is enabled (ignore=false). To enable support for cache deferral injection, CONFIG_FAULT_INJECTION, CONFIG_FAULT_INJECTION_DEBUG_FS, and CONFIG_SUNRPC_DEBUG must all be set to "Y". Signed-off-by: Chuck Lever --- net/sunrpc/cache.c | 18 +++++++++++++++++- net/sunrpc/debugfs.c | 3 +++ net/sunrpc/fail.h | 2 +- 3 files changed, 21 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index bb1177395b99..c3c693b51c94 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -33,7 +33,9 @@ #include #include #include + #include "netns.h" +#include "fail.h" #define RPCDBG_FACILITY RPCDBG_CACHE @@ -688,16 +690,30 @@ static void cache_limit_defers(void) discard->revisit(discard, 1); } +#if IS_ENABLED(CONFIG_FAIL_SUNRPC) +static inline bool cache_defer_immediately(void) +{ + return !fail_sunrpc.ignore_cache_wait && + should_fail(&fail_sunrpc.attr, 1); +} +#else +static inline bool cache_defer_immediately(void) +{ + return false; +} +#endif + /* Return true if and only if a deferred request is queued. */ static bool cache_defer_req(struct cache_req *req, struct cache_head *item) { struct cache_deferred_req *dreq; - if (req->thread_wait) { + if (!cache_defer_immediately()) { cache_wait_req(req, item); if (!test_bit(CACHE_PENDING, &item->flags)) return false; } + dreq = req->defer(req); if (dreq == NULL) return false; diff --git a/net/sunrpc/debugfs.c b/net/sunrpc/debugfs.c index 7dc9cc929bfd..a176d5a0b0ee 100644 --- a/net/sunrpc/debugfs.c +++ b/net/sunrpc/debugfs.c @@ -262,6 +262,9 @@ static void fail_sunrpc_init(void) debugfs_create_bool("ignore-server-disconnect", S_IFREG | 0600, dir, &fail_sunrpc.ignore_server_disconnect); + + debugfs_create_bool("ignore-cache-wait", S_IFREG | 0600, dir, + &fail_sunrpc.ignore_cache_wait); } #else static void fail_sunrpc_init(void) diff --git a/net/sunrpc/fail.h b/net/sunrpc/fail.h index 69dc30cc44b8..4b4b500df428 100644 --- a/net/sunrpc/fail.h +++ b/net/sunrpc/fail.h @@ -14,8 +14,8 @@ struct fail_sunrpc_attr { struct fault_attr attr; bool ignore_client_disconnect; - bool ignore_server_disconnect; + bool ignore_cache_wait; }; extern struct fail_sunrpc_attr fail_sunrpc;