From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C224CC433E0 for ; Mon, 8 Feb 2021 17:18:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D1E064E5A for ; Mon, 8 Feb 2021 17:18:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234820AbhBHRRz (ORCPT ); Mon, 8 Feb 2021 12:17:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:36034 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231687AbhBHP0Q (ORCPT ); Mon, 8 Feb 2021 10:26:16 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8ABF364F31; Mon, 8 Feb 2021 15:15:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1612797335; bh=9ssLXoxktnkifxFHN8BZERPbYjyLxBGVshfK2BtaSuw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sSk/YkK9sqaJwOoLOrOntBWRviUZviDDwgRf884HEyl7qJydJqXu0DB/asxqtlkbb DnAh5Q5J70zDOygVZyTmrB5Khftav0VQx/45bDXmFG9srZ1hcuVqKLVzKO6SSZOD9R 65QTHE8O88EapYX7E7v3/ceYsVpuCo4kSNRxdEFM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pavel Shilovsky , Tom Talpey , Shyam Prasad N , Steve French Subject: [PATCH 5.10 074/120] smb3: fix crediting for compounding when only one request in flight Date: Mon, 8 Feb 2021 16:01:01 +0100 Message-Id: <20210208145821.364490485@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210208145818.395353822@linuxfoundation.org> References: <20210208145818.395353822@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pavel Shilovsky commit 91792bb8089b63b7b780251eb83939348ac58a64 upstream. Currently we try to guess if a compound request is going to succeed waiting for credits or not based on the number of requests in flight. This approach doesn't work correctly all the time because there may be only one request in flight which is going to bring multiple credits satisfying the compound request. Change the behavior to fail a request only if there are no requests in flight at all and proceed waiting for credits otherwise. Cc: # 5.1+ Signed-off-by: Pavel Shilovsky Reviewed-by: Tom Talpey Reviewed-by: Shyam Prasad N Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/cifs/transport.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -655,10 +655,22 @@ wait_for_compound_request(struct TCP_Ser spin_lock(&server->req_lock); if (*credits < num) { /* - * Return immediately if not too many requests in flight since - * we will likely be stuck on waiting for credits. + * If the server is tight on resources or just gives us less + * credits for other reasons (e.g. requests are coming out of + * order and the server delays granting more credits until it + * processes a missing mid) and we exhausted most available + * credits there may be situations when we try to send + * a compound request but we don't have enough credits. At this + * point the client needs to decide if it should wait for + * additional credits or fail the request. If at least one + * request is in flight there is a high probability that the + * server will return enough credits to satisfy this compound + * request. + * + * Return immediately if no requests in flight since we will be + * stuck on waiting for credits. */ - if (server->in_flight < num - *credits) { + if (server->in_flight == 0) { spin_unlock(&server->req_lock); return -ENOTSUPP; }