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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 C3EF9C433E9 for ; Wed, 3 Mar 2021 11:41:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8CFCB64EF6 for ; Wed, 3 Mar 2021 11:41:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357953AbhCCLhX (ORCPT ); Wed, 3 Mar 2021 06:37:23 -0500 Received: from mail.synology.com ([211.23.38.101]:37154 "EHLO synology.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1351597AbhCCDXT (ORCPT ); Tue, 2 Mar 2021 22:23:19 -0500 Received: from localhost.localdomain (unknown [10.17.210.104]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) by synology.com (Postfix) with ESMTPSA id F1D19CE781B5; Wed, 3 Mar 2021 11:22:37 +0800 (CST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=synology.com; s=123; t=1614741758; bh=xgbf6WZCaD/FFIaA3Mp4FPHSkXy9rxV+ldX5NyY3vEA=; h=From:To:Cc:Subject:Date; b=NRkkX1SdcFPOTAJK1DDZbDb4N8NJ9nEPoLKHMNd+OxBA6DVJRsTrVXFnj+qssv2ZJ UeGATxekQtR6iTZdty0Az+OeBXevMpDNx5/9zfCYXqY44z6TfcX/0tvp22v9NQu7T1 40hxIajkCGd1Q+dUewYACnzsaN20+zzl2TWMRckA= From: edwardh To: axboe@kernel.dk, neilb@suse.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, s3t@synology.com, bingjingc@synology.com, cccheng@synology.com, Edward Hsieh Subject: [PATCH v2] block: fix trace completion for chained bio Date: Wed, 3 Mar 2021 11:22:06 +0800 Message-Id: <1614741726-28074-1-git-send-email-edwardh@synology.com> X-Mailer: git-send-email 2.7.4 X-Synology-MCP-Status: no X-Synology-Spam-Flag: no X-Synology-Spam-Status: score=0, required 6, WHITELIST_FROM_ADDRESS 0 X-Synology-Virus-Status: no Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Edward Hsieh For chained bio, trace_block_bio_complete in bio_endio is currently called only by the parent bio once upon all chained bio completed. However, the sector and size for the parent bio are modified in bio_split. Therefore, the size and sector of the complete events might not match the queue events in blktrace. The original fix of bio completion trace ("block: trace completion of all bios.") wants multiple complete events to correspond to one queue event but missed this. md/raid5 read with bio cross chunks can reproduce this issue. To fix, move trace completion into the loop for every chained bio to call. Fixes: fbbaf700e7b1 ("block: trace completion of all bios.") Reviewed-by: Wade Liang Reviewed-by: BingJing Chang Signed-off-by: Edward Hsieh --- block/bio.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/block/bio.c b/block/bio.c index a1c4d29..2ff72cb 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1397,8 +1397,7 @@ static inline bool bio_remaining_done(struct bio *bio) * * bio_endio() can be called several times on a bio that has been chained * using bio_chain(). The ->bi_end_io() function will only be called the - * last time. At this point the BLK_TA_COMPLETE tracing event will be - * generated if BIO_TRACE_COMPLETION is set. + * last time. **/ void bio_endio(struct bio *bio) { @@ -1411,6 +1410,11 @@ void bio_endio(struct bio *bio) if (bio->bi_bdev) rq_qos_done_bio(bio->bi_bdev->bd_disk->queue, bio); + if (bio->bi_bdev && bio_flagged(bio, BIO_TRACE_COMPLETION)) { + trace_block_bio_complete(bio->bi_bdev->bd_disk->queue, bio); + bio_clear_flag(bio, BIO_TRACE_COMPLETION); + } + /* * Need to have a real endio function for chained bios, otherwise * various corner cases will break (like stacking block devices that @@ -1424,11 +1428,6 @@ void bio_endio(struct bio *bio) goto again; } - if (bio->bi_bdev && bio_flagged(bio, BIO_TRACE_COMPLETION)) { - trace_block_bio_complete(bio->bi_bdev->bd_disk->queue, bio); - bio_clear_flag(bio, BIO_TRACE_COMPLETION); - } - blk_throtl_bio_endio(bio); /* release cgroup info */ bio_uninit(bio); -- 2.7.4