From patchwork Mon Jul 12 06:09:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 474533 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=-19.4 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=ham 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 B091DC11F66 for ; Mon, 12 Jul 2021 06:22:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9F25B610CD for ; Mon, 12 Jul 2021 06:22:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234858AbhGLGZM (ORCPT ); Mon, 12 Jul 2021 02:25:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:40462 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235121AbhGLGYd (ORCPT ); Mon, 12 Jul 2021 02:24:33 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A7B49611AF; Mon, 12 Jul 2021 06:21:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626070871; bh=Yi5NytIE9J3gmo0GWWAKPRo90xCSBXEVAHL4emG5zCE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X7Gw5LXRH+hgEQrlJOtd4JPlCqVFfJ0JRWAjwiwuYho+xhO9rxGjPtZLtlbhUHXT3 BPHrul5pez5s4Cu4K99coQVtoVJCDR4O15Cq0hFliH9WR+cqyvwf66QSnghWZn/nHw YGSJxLgcSXok9vQEjTkU/eAjm3Qmq9ysDYKV7Of0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zhang Yi , Jens Axboe , Sasha Levin Subject: [PATCH 5.4 177/348] blk-wbt: introduce a new disable state to prevent false positive by rwb_enabled() Date: Mon, 12 Jul 2021 08:09:21 +0200 Message-Id: <20210712060724.385474539@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060659.886176320@linuxfoundation.org> References: <20210712060659.886176320@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Zhang Yi [ Upstream commit 1d0903d61e9645c6330b94247b96dd873dfc11c8 ] Now that we disable wbt by simply zero out rwb->wb_normal in wbt_disable_default() when switch elevator to bfq, but it's not safe because it will become false positive if we change queue depth. If it become false positive between wbt_wait() and wbt_track() when submit write request, it will lead to drop rqw->inflight to -1 in wbt_done(), which will end up trigger IO hung. Fix this issue by introduce a new state which mean the wbt was disabled. Fixes: a79050434b45 ("blk-rq-qos: refactor out common elements of blk-wbt") Signed-off-by: Zhang Yi Link: https://lore.kernel.org/r/20210619093700.920393-2-yi.zhang@huawei.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-wbt.c | 5 +++-- block/blk-wbt.h | 1 + 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/block/blk-wbt.c b/block/blk-wbt.c index 8641ba9793c5..7c7dd5c14391 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -77,7 +77,8 @@ enum { static inline bool rwb_enabled(struct rq_wb *rwb) { - return rwb && rwb->wb_normal != 0; + return rwb && rwb->enable_state != WBT_STATE_OFF_DEFAULT && + rwb->wb_normal != 0; } static void wb_timestamp(struct rq_wb *rwb, unsigned long *var) @@ -710,7 +711,7 @@ void wbt_disable_default(struct request_queue *q) rwb = RQWB(rqos); if (rwb->enable_state == WBT_STATE_ON_DEFAULT) { blk_stat_deactivate(rwb->cb); - rwb->wb_normal = 0; + rwb->enable_state = WBT_STATE_OFF_DEFAULT; } } EXPORT_SYMBOL_GPL(wbt_disable_default); diff --git a/block/blk-wbt.h b/block/blk-wbt.h index 8e4e37660971..d8d9f41b42f9 100644 --- a/block/blk-wbt.h +++ b/block/blk-wbt.h @@ -34,6 +34,7 @@ enum { enum { WBT_STATE_ON_DEFAULT = 1, WBT_STATE_ON_MANUAL = 2, + WBT_STATE_OFF_DEFAULT }; struct rq_wb {