From patchwork Thu Feb 1 20:31:57 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Keith Busch X-Patchwork-Id: 10195995 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 72BB660380 for ; Thu, 1 Feb 2018 21:15:15 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 611A4288C6 for ; Thu, 1 Feb 2018 21:15:15 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5FED428958; Thu, 1 Feb 2018 21:15:15 +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 E05AD28AF9 for ; Thu, 1 Feb 2018 20:36:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754952AbeBAU2W (ORCPT ); Thu, 1 Feb 2018 15:28:22 -0500 Received: from mga14.intel.com ([192.55.52.115]:15517 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754956AbeBAU2V (ORCPT ); Thu, 1 Feb 2018 15:28:21 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 01 Feb 2018 12:28:21 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,444,1511856000"; d="scan'208";a="14677836" Received: from unknown (HELO localhost.lm.intel.com) ([10.232.112.44]) by fmsmga007.fm.intel.com with ESMTP; 01 Feb 2018 12:28:21 -0800 From: Keith Busch To: Linux Block , Linux NVMe , Christoph Hellwig , Jens Axboe Cc: Keith Busch Subject: [PATCHv2 1/2] block: Merge discard requests as a special case Date: Thu, 1 Feb 2018 13:31:57 -0700 Message-Id: <20180201203158.24761-2-keith.busch@intel.com> X-Mailer: git-send-email 2.13.6 In-Reply-To: <20180201203158.24761-1-keith.busch@intel.com> References: <20180201203158.24761-1-keith.busch@intel.com> 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 Discard requests operate under different constraints than other operations and have different rules for merging. This patch will handle such requests as a special case, using the same criteria and segment accounting used for merging a discard bio into a reqseut. Signed-off-by: Keith Busch --- block/blk-merge.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index 8452fc7164cc..e36462bc90f3 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -550,6 +550,25 @@ static bool req_no_special_merge(struct request *req) return !q->mq_ops && req->special; } +static int req_attempt_discard_merge(struct request_queue *q, struct request *req, + struct request *next) +{ + unsigned short segments = blk_rq_nr_discard_segments(req); + + if (segments >= queue_max_discard_segments(q)) + goto no_merge; + if (blk_rq_sectors(req) + bio_sectors(next->bio) > + blk_rq_get_max_sectors(req, blk_rq_pos(req))) + goto no_merge; + + req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); + return 1; + +no_merge: + req_set_nomerge(q, req); + return 0; +} + static int ll_merge_requests_fn(struct request_queue *q, struct request *req, struct request *next) { @@ -564,6 +583,13 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req, if (req_no_special_merge(req) || req_no_special_merge(next)) return 0; + /* + * Merging discard requests use different constraints than other + * operations. + */ + if (req_op(req) == REQ_OP_DISCARD) + return req_attempt_discard_merge(q, req, next); + if (req_gap_back_merge(req, next->bio)) return 0; @@ -715,7 +741,8 @@ static struct request *attempt_merge(struct request_queue *q, req->__data_len += blk_rq_bytes(next); - elv_merge_requests(q, req, next); + if (req_op(req) != REQ_OP_DISCARD) + elv_merge_requests(q, req, next); /* * 'next' is going away, so update stats accordingly