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 0258EC11F78 for ; Mon, 12 Jul 2021 07:18:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EAC7E61480 for ; Mon, 12 Jul 2021 07:18:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245144AbhGLHTZ (ORCPT ); Mon, 12 Jul 2021 03:19:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:54182 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241124AbhGLGyl (ORCPT ); Mon, 12 Jul 2021 02:54:41 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id F1B41610CA; Mon, 12 Jul 2021 06:51:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626072708; bh=JTvUYKWUfQZKkQs/m0INxt4XbirfO+uD4+zGzmMgvC8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N/00ojUcqB9QwiYQAWF6V1z7a4q9gUlU6SxhFAPlSeQuyQOPSdtKaPrXBfOTLEuFc sb/aA96137IatWEZZEuYYQkYWDNfgEwbk7NdcfIEUTsK3oxIdLrTezliQxNtkIvHUp gIZ6Yffggj+uiQhFBOL+FYPnUDwTEo8x5b06Sqlo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jens Axboe , Johannes Thumshirn , Pavel Begunkov , Ming Lei , Tejun Heo , "Matthew Wilcox (Oracle)" , Jeffle Xu , Long Li , Christoph Hellwig Subject: [PATCH 5.10 588/593] block: return the correct bvec when checking for gaps Date: Mon, 12 Jul 2021 08:12:28 +0200 Message-Id: <20210712061000.264976350@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: Long Li commit c9c9762d4d44dcb1b2ba90cfb4122dc11ceebf31 upstream. After commit 07173c3ec276 ("block: enable multipage bvecs"), a bvec can have multiple pages. But bio_will_gap() still assumes one page bvec while checking for merging. If the pages in the bvec go across the seg_boundary_mask, this check for merging can potentially succeed if only the 1st page is tested, and can fail if all the pages are tested. Later, when SCSI builds the SG list the same check for merging is done in __blk_segment_map_sg_merge() with all the pages in the bvec tested. This time the check may fail if the pages in bvec go across the seg_boundary_mask (but tested okay in bio_will_gap() earlier, so those BIOs were merged). If this check fails, we end up with a broken SG list for drivers assuming the SG list not having offsets in intermediate pages. This results in incorrect pages written to the disk. Fix this by returning the multi-page bvec when testing gaps for merging. Cc: Jens Axboe Cc: Johannes Thumshirn Cc: Pavel Begunkov Cc: Ming Lei Cc: Tejun Heo Cc: "Matthew Wilcox (Oracle)" Cc: Jeffle Xu Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org Fixes: 07173c3ec276 ("block: enable multipage bvecs") Signed-off-by: Long Li Reviewed-by: Ming Lei Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/1623094445-22332-1-git-send-email-longli@linuxonhyperv.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- include/linux/bio.h | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -38,9 +38,6 @@ #define bio_offset(bio) bio_iter_offset((bio), (bio)->bi_iter) #define bio_iovec(bio) bio_iter_iovec((bio), (bio)->bi_iter) -#define bio_multiple_segments(bio) \ - ((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len) - #define bvec_iter_sectors(iter) ((iter).bi_size >> 9) #define bvec_iter_end_sector(iter) ((iter).bi_sector + bvec_iter_sectors((iter))) @@ -252,7 +249,7 @@ static inline void bio_clear_flag(struct static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv) { - *bv = bio_iovec(bio); + *bv = mp_bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); } static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv) @@ -260,10 +257,9 @@ static inline void bio_get_last_bvec(str struct bvec_iter iter = bio->bi_iter; int idx; - if (unlikely(!bio_multiple_segments(bio))) { - *bv = bio_iovec(bio); - return; - } + bio_get_first_bvec(bio, bv); + if (bv->bv_len == bio->bi_iter.bi_size) + return; /* this bio only has a single bvec */ bio_advance_iter(bio, &iter, iter.bi_size);