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=-16.5 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 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 EC05DC4338F for ; Thu, 29 Jul 2021 09:18:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF7BC60F6F for ; Thu, 29 Jul 2021 09:18:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235488AbhG2JSm (ORCPT ); Thu, 29 Jul 2021 05:18:42 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:47743 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235462AbhG2JSj (ORCPT ); Thu, 29 Jul 2021 05:18:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1627550316; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PI9JUHXs4GaYR/G3v16SHbU7oaOyoHc0jk0Afcy60+U=; b=MhtsXZX9i1ns+tm2dJKHlTEe731LcQeouwYS6T95oX4xxKsAS5kLkdUY4rR8u3BwE2ryvX wPCdp/eLg3vR7Mmke3sHfLje9dv3xNEZe//6LIBkqI4BEFdlRINIfsQ5vi5cVXPWztd2tW Kgx8zsHk+g9fNmbPSqdYkK9JxTpcwjg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-580-kihY6MXWN8CeeVt6c4AhZQ-1; Thu, 29 Jul 2021 05:18:33 -0400 X-MC-Unique: kihY6MXWN8CeeVt6c4AhZQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BE8E0801AE3; Thu, 29 Jul 2021 09:18:31 +0000 (UTC) Received: from T590 (ovpn-12-146.pek2.redhat.com [10.72.12.146]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3847760BF1; Thu, 29 Jul 2021 09:18:24 +0000 (UTC) Date: Thu, 29 Jul 2021 17:18:26 +0800 From: Ming Lei To: Oleksandr Natalenko Cc: Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig Subject: Re: [PATCH] block: return ELEVATOR_DISCARD_MERGE if possible Message-ID: References: <20210729034226.1591070-1-ming.lei@redhat.com> <67816551.sp8fIUDole@natalenko.name> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <67816551.sp8fIUDole@natalenko.name> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Jul 29, 2021 at 09:17:28AM +0200, Oleksandr Natalenko wrote: > On čtvrtek 29. července 2021 5:42:26 CEST Ming Lei wrote: > > When merging one bio to request, if they are discard IO and the queue > > supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE > > because both block core and related drivers(nvme, virtio-blk) doesn't > > handle mixed discard io merge(traditional IO merge together with > > discard merge) well. > > > > Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation, > > so both blk-mq and drivers just need to handle multi-range discard. > > > > Reported-by: Oleksandr Natalenko > > Signed-off-by: Ming Lei > > --- > > block/bfq-iosched.c | 3 +++ > > block/blk-merge.c | 16 ---------------- > > block/elevator.c | 3 +++ > > block/mq-deadline-main.c | 2 ++ > > include/linux/blkdev.h | 16 ++++++++++++++++ > > 5 files changed, 24 insertions(+), 16 deletions(-) > > > > diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c > > index 727955918563..673a634eadd9 100644 > > --- a/block/bfq-iosched.c > > +++ b/block/bfq-iosched.c > > @@ -2361,6 +2361,9 @@ static int bfq_request_merge(struct request_queue *q, > > struct request **req, __rq = bfq_find_rq_fmerge(bfqd, bio, q); > > if (__rq && elv_bio_merge_ok(__rq, bio)) { > > *req = __rq; > > + > > + if (blk_discard_mergable(__rq)) > > + return ELEVATOR_DISCARD_MERGE; > > return ELEVATOR_FRONT_MERGE; > > } > > > > diff --git a/block/blk-merge.c b/block/blk-merge.c > > index a11b3b53717e..f8707ff7e2fc 100644 > > --- a/block/blk-merge.c > > +++ b/block/blk-merge.c > > @@ -705,22 +705,6 @@ static void blk_account_io_merge_request(struct request > > *req) } > > } > > > > -/* > > - * 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; > > - return false; > > -} > > - > > static enum elv_merge blk_try_req_merge(struct request *req, > > struct request *next) > > { > > diff --git a/block/elevator.c b/block/elevator.c > > index 52ada14cfe45..a5fe2615ec0f 100644 > > --- a/block/elevator.c > > +++ b/block/elevator.c > > @@ -336,6 +336,9 @@ enum elv_merge elv_merge(struct request_queue *q, struct > > request **req, __rq = elv_rqhash_find(q, bio->bi_iter.bi_sector); > > if (__rq && elv_bio_merge_ok(__rq, bio)) { > > *req = __rq; > > + > > + if (blk_discard_mergable(__rq)) > > + return ELEVATOR_DISCARD_MERGE; > > return ELEVATOR_BACK_MERGE; > > } > > > > diff --git a/block/mq-deadline-main.c b/block/mq-deadline-main.c > > index 6f612e6dc82b..294be0c0db65 100644 > > --- a/block/mq-deadline-main.c > > +++ b/block/mq-deadline-main.c > > @@ -677,6 +677,8 @@ static int dd_request_merge(struct request_queue *q, > > struct request **rq, > > > > if (elv_bio_merge_ok(__rq, bio)) { > > *rq = __rq; > > + if (blk_discard_mergable(__rq)) > > + return ELEVATOR_DISCARD_MERGE; > > return ELEVATOR_FRONT_MERGE; > > } > > } > > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h > > index 3177181c4326..87f00292fd7a 100644 > > --- a/include/linux/blkdev.h > > +++ b/include/linux/blkdev.h > > @@ -1521,6 +1521,22 @@ static inline int > > queue_limit_discard_alignment(struct queue_limits *lim, sector return > > offset << SECTOR_SHIFT; > > } > > > > +/* > > + * 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; > > + return false; > > +} > > + > > static inline int bdev_discard_alignment(struct block_device *bdev) > > { > > struct request_queue *q = bdev_get_queue(bdev); > > Tested-by: Oleksandr Natalenko > > Also, > > Fixes: ? Fixes: 2705dfb20947 ("block: fix discard request merge") In theory, the fixes should be 1e739730c5b9 ("block: optionally merge discontiguous discard bios into a single request"). The reason why it isn't be triggered before 2705dfb20947 is that the nr_segment of each bio is exactly 1 for multi-range device. > > and possibly: > > CC: stable@ # v5.x? CC: stable@ # v5.13 Thanks, Ming