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=-19.4 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=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 C42A1C11F67 for ; Mon, 12 Jul 2021 06:52:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE9AF61263 for ; Mon, 12 Jul 2021 06:52:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239502AbhGLGz0 (ORCPT ); Mon, 12 Jul 2021 02:55:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:36538 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238545AbhGLGkU (ORCPT ); Mon, 12 Jul 2021 02:40:20 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D8FA761004; Mon, 12 Jul 2021 06:37:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626071851; bh=c3SFVdmEk6tJ/l3rcpQazKWLZA/z4lJGSSec1g2FU14=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MnLjxzreh0H5tCbak4f6nIqRRqIY9IOqV6wo98ywlJgYa6Fphze1KOVUgaDzxUpZ6 pDXejsd6UC1afxcnchRj05gvqYeFkP+nRdKgAdsLdHDSssSvKezQf859r1GIu75HvF Z75maaTaUMb3IdPTMsoFdUeO3r+CsOUCUqV/0wzg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christoph Hellwig , Wang Shanker , Ming Lei , Jens Axboe , Sasha Levin Subject: [PATCH 5.10 205/593] block: fix discard request merge Date: Mon, 12 Jul 2021 08:06:05 +0200 Message-Id: <20210712060905.546106797@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060843.180606720@linuxfoundation.org> References: <20210712060843.180606720@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: Ming Lei [ Upstream commit 2705dfb2094777e405e065105e307074af8965c1 ] ll_new_hw_segment() is reached only in case of single range discard merge, and we don't have max discard segment size limit actually, so it is wrong to run the following check: if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req)) it may be always false since req->nr_phys_segments is initialized as one, and bio's segment count is still 1, blk_rq_get_max_segments(reg) is 1 too. Fix the issue by not doing the check and bypassing the calculation of discard request's nr_phys_segments. Based on analysis from Wang Shanker. Cc: Christoph Hellwig Reported-by: Wang Shanker Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20210628023312.1903255-1-ming.lei@redhat.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-merge.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index 7cdd56696647..349cd7d3af81 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -552,10 +552,14 @@ static inline unsigned int blk_rq_get_max_segments(struct request *rq) static inline int ll_new_hw_segment(struct request *req, struct bio *bio, unsigned int nr_phys_segs) { - if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req)) + if (blk_integrity_merge_bio(req->q, req, bio) == false) goto no_merge; - if (blk_integrity_merge_bio(req->q, req, bio) == false) + /* discard request merge won't add new segment */ + if (req_op(req) == REQ_OP_DISCARD) + return 1; + + if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req)) goto no_merge; /* -- 2.30.2