From patchwork Fri Oct 26 09:28:36 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "jianchao.wang" X-Patchwork-Id: 10657123 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1678D14BB for ; Fri, 26 Oct 2018 09:26:25 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0720B2C0C4 for ; Fri, 26 Oct 2018 09:26:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EE1592C21E; Fri, 26 Oct 2018 09:26:24 +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=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY 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 8792A2C0C4 for ; Fri, 26 Oct 2018 09:26:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726006AbeJZSCl (ORCPT ); Fri, 26 Oct 2018 14:02:41 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:52148 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725914AbeJZSCl (ORCPT ); Fri, 26 Oct 2018 14:02:41 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w9Q9J8Vo017699; Fri, 26 Oct 2018 09:26:17 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id; s=corp-2018-07-02; bh=DVsT1P9EQbgOncA6VVOziLLOZzf4VL5zAOb/i3z2x5w=; b=NLYF7NtUL1IzafXcyGj6hjXd3H1f7KA8nM52rmZRprA1diBx8kuYMhYeF/nQzcktPy+6 hPfsNJpl5apLbG+MD2oVL/tD8Mp7Jq1lHh+sxutf82FiU4+t+9U05RWstJaXo9bra4C2 WqDgpu2qW6ZFZeLEf+pPPEjXyw0IybXuHGCfhQf+PnRt5Wf1ImK/gwg1Gj5R/HihHGgR Xf/SR8mpowSgQXu7e7q4dsSLLuEEUml5cZAYFj1EfRhNSb3CjdqjwqrPcAs/nCsQ0zFe HIJqVezire8UgMo/lSxYVfDOYnAyFTCCfz/U+Nt+Oq6Q1hQz5JwecoXID6I0M/FTJiR4 5Q== Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by userp2120.oracle.com with ESMTP id 2n7w0r673r-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 26 Oct 2018 09:26:17 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w9Q9QH2Y010066 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 26 Oct 2018 09:26:17 GMT Received: from abhmp0016.oracle.com (abhmp0016.oracle.com [141.146.116.22]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id w9Q9QGTF031051; Fri, 26 Oct 2018 09:26:17 GMT Received: from will-ThinkCentre-M910s.cn.oracle.com (/10.182.70.254) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 26 Oct 2018 02:26:16 -0700 From: Jianchao Wang To: axboe@kernel.dk Cc: martin.petersen@oracle.com, tom.leiming@gmail.com, hch@lst.de, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH V4] block: fix the DISCARD request merge Date: Fri, 26 Oct 2018 17:28:36 +0800 Message-Id: <1540546116-1620-1-git-send-email-jianchao.w.wang@oracle.com> X-Mailer: git-send-email 2.7.4 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9057 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=1 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1810260083 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 There are two cases when handle DISCARD merge. If max_discard_segments == 1, the bios/requests need to be contiguous to merge. If max_discard_segments > 1, it takes every bio as a range and different range needn't to be contiguous. But now, attempt_merge screws this up. It always consider contiguity for DISCARD for the case max_discard_segments > 1 and cannot merge contiguous DISCARD for the case max_discard_segments == 1, because rq_attempt_discard_merge always returns false in this case. This patch fixes both of the two cases above. Signed-off-by: Jianchao Wang --- V4: - introduce blk_try_req_merge as suggestion of Christoph. V3: - Introduce blk_discard_mergable into attempt_merge and blk_try_merge. - Some comment changes. V2: - Add max_discard_segments > 1 checking in attempt_merge. - Change patch title and comment. - Add more comment in attempt_merge block/blk-merge.c | 47 +++++++++++++++++++++++++++++++++++++---------- 1 file changed, 37 insertions(+), 10 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index 42a4674..cf817c7a 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -714,6 +714,32 @@ static void blk_account_io_merge(struct request *req) part_stat_unlock(); } } +/* + * Two cases of handling DISCARD merge: + * If max_discard_segments > 1, the driver takes every bio + * as a range and send them to controller together. The ranges + * needn't to be contiguous. + * Otherwise, the bios/requests will be handled as same as + * others which should be contiguous. + */ +static inline bool blk_discard_mergable(struct request *req) +{ + if (req_op(req) == REQ_OP_DISCARD && + queue_max_discard_segments(req->q) > 1) + return true; + else + return false; +} + +enum elv_merge blk_try_req_merge(struct request *req, struct request *next) +{ + if (blk_discard_mergable(req)) + return ELEVATOR_DISCARD_MERGE; + else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) + return ELEVATOR_BACK_MERGE; + + return ELEVATOR_NO_MERGE; +} /* * For non-mq, this has to be called with the request spinlock acquired. @@ -731,12 +757,6 @@ static struct request *attempt_merge(struct request_queue *q, if (req_op(req) != req_op(next)) return NULL; - /* - * not contiguous - */ - if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next)) - return NULL; - if (rq_data_dir(req) != rq_data_dir(next) || req->rq_disk != next->rq_disk || req_no_special_merge(next)) @@ -760,11 +780,19 @@ static struct request *attempt_merge(struct request_queue *q, * counts here. Handle DISCARDs separately, as they * have separate settings. */ - if (req_op(req) == REQ_OP_DISCARD) { + + switch (blk_try_req_merge(req, next)) { + case ELEVATOR_DISCARD_MERGE: if (!req_attempt_discard_merge(q, req, next)) return NULL; - } else if (!ll_merge_requests_fn(q, req, next)) + break; + case ELEVATOR_BACK_MERGE: + if (!ll_merge_requests_fn(q, req, next)) + return NULL; + break; + default: return NULL; + } /* * If failfast settings disagree or any of the two is already @@ -888,8 +916,7 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio) enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) { - if (req_op(rq) == REQ_OP_DISCARD && - queue_max_discard_segments(rq->q) > 1) + if (blk_discard_mergable(rq)) return ELEVATOR_DISCARD_MERGE; else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) return ELEVATOR_BACK_MERGE;