From patchwork Fri Jun 30 20:42:51 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Eric Wheeler X-Patchwork-Id: 9820421 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 66B0660224 for ; Fri, 30 Jun 2017 20:43:55 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 58CF1271BC for ; Fri, 30 Jun 2017 20:43:55 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4B73528437; Fri, 30 Jun 2017 20:43:55 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B4B2A271BC for ; Fri, 30 Jun 2017 20:43:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752645AbdF3Unx (ORCPT ); Fri, 30 Jun 2017 16:43:53 -0400 Received: from mx.ewheeler.net ([66.155.3.69]:43776 "EHLO mail.ewheeler.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752506AbdF3Unw (ORCPT ); Fri, 30 Jun 2017 16:43:52 -0400 Received: from localhost (localhost [127.0.0.1]) by mail.ewheeler.net (Postfix) with ESMTP id EED30A0694; Fri, 30 Jun 2017 20:43:51 +0000 (UTC) X-Virus-Scanned: amavisd-new at ewheeler.net Received: from mail.ewheeler.net ([127.0.0.1]) by localhost (mail.ewheeler.net [127.0.0.1]) (amavisd-new, port 10024) with LMTP id XGInPQVuil0P; Fri, 30 Jun 2017 20:43:51 +0000 (UTC) Received: from el7-dev.ewi (c-24-20-122-25.hsd1.or.comcast.net [24.20.122.25]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.ewheeler.net (Postfix) with ESMTPSA id 5158EA029F; Fri, 30 Jun 2017 20:43:51 +0000 (UTC) From: bcache@lists.ewheeler.net To: linux-block@vger.kernel.org Cc: linux-bcache@vger.kernel.org, hch@infradead.org, axboe@kernel.dk, Tang Junhui , stable@vger.kernel.org Subject: [PATCH 02/19] bcache: fix sequential large write IO bypass Date: Fri, 30 Jun 2017 13:42:51 -0700 Message-Id: <1498855388-16990-2-git-send-email-bcache@lists.ewheeler.net> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1498855388-16990-1-git-send-email-bcache@lists.ewheeler.net> References: <20170629134510.GA32385@infradead.org> <1498855388-16990-1-git-send-email-bcache@lists.ewheeler.net> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Tang Junhui Sequential write IOs were tested with bs=1M by FIO in writeback cache mode, these IOs were expected to be bypassed, but actually they did not. We debug the code, and find in check_should_bypass(): if (!congested && mode == CACHE_MODE_WRITEBACK && op_is_write(bio_op(bio)) && (bio-＞bi_opf & REQ_SYNC)) goto rescale that means, If in writeback mode, a write IO with REQ_SYNC flag will not be bypassed though it is a sequential large IO, It's not a correct thing to do actually, so this patch remove these codes. Signed-off-by: tang.junhui Reviewed-by: Kent Overstreet Reviewed-by: Eric Wheeler Cc: stable@vger.kernel.org Reviewed-by: Christoph Hellwig --- drivers/md/bcache/request.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c index 019b3df..958072a 100644 --- a/drivers/md/bcache/request.c +++ b/drivers/md/bcache/request.c @@ -400,12 +400,6 @@ static bool check_should_bypass(struct cached_dev *dc, struct bio *bio) if (!congested && !dc->sequential_cutoff) goto rescale; - if (!congested && - mode == CACHE_MODE_WRITEBACK && - op_is_write(bio->bi_opf) && - op_is_sync(bio->bi_opf)) - goto rescale; - spin_lock(&dc->io_lock); hlist_for_each_entry(i, iohash(dc, bio->bi_iter.bi_sector), hash)