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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 8CCFCC433DF for ; Tue, 30 Jun 2020 06:26:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6F1F320759 for ; Tue, 30 Jun 2020 06:26:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729901AbgF3G0O (ORCPT ); Tue, 30 Jun 2020 02:26:14 -0400 Received: from mx2.suse.de ([195.135.220.15]:55068 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725845AbgF3G0O (ORCPT ); Tue, 30 Jun 2020 02:26:14 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id E1F99AAC3; Tue, 30 Jun 2020 06:26:12 +0000 (UTC) Subject: Re: [PATCH 3/3] blk-mq: centralise related handling into blk_mq_get_driver_tag To: Ming Lei , Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig References: <20200630022356.2149607-1-ming.lei@redhat.com> <20200630022356.2149607-4-ming.lei@redhat.com> From: Hannes Reinecke Message-ID: <49f8b5f5-e437-3bb7-ae5d-06f59fea5cfe@suse.de> Date: Tue, 30 Jun 2020 08:26:11 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200630022356.2149607-4-ming.lei@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 6/30/20 4:23 AM, Ming Lei wrote: > Move blk_mq_tag_busy(), .nr_active update and request assignment into > blk_mq_get_driver_tag(), all are good to do during getting driver tag. > > Meantime blk-flush related code is simplified and flush request needn't > to update the request table manually any more. > > Cc: Christoph Hellwig > Signed-off-by: Ming Lei > --- > block/blk-flush.c | 13 ++++--------- > block/blk-mq-tag.h | 12 ------------ > block/blk-mq.c | 33 +++++++++++++-------------------- > block/blk.h | 5 ----- > 4 files changed, 17 insertions(+), 46 deletions(-) > > diff --git a/block/blk-flush.c b/block/blk-flush.c > index 21108a550fbf..3b0c5cfe922a 100644 > --- a/block/blk-flush.c > +++ b/block/blk-flush.c > @@ -236,12 +236,10 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error) > error = fq->rq_status; > > hctx = flush_rq->mq_hctx; > - if (!q->elevator) { > - blk_mq_tag_set_rq(hctx, flush_rq->tag, fq->orig_rq); > + if (!q->elevator) > flush_rq->tag = -1; > - } else { > + else > flush_rq->internal_tag = -1; > - } > > running = &fq->flush_queue[fq->flush_running_idx]; > BUG_ON(fq->flush_pending_idx == fq->flush_running_idx); > @@ -315,13 +313,10 @@ static void blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq, > flush_rq->mq_ctx = first_rq->mq_ctx; > flush_rq->mq_hctx = first_rq->mq_hctx; > > - if (!q->elevator) { > - fq->orig_rq = first_rq; > + if (!q->elevator) > flush_rq->tag = first_rq->tag; > - blk_mq_tag_set_rq(flush_rq->mq_hctx, first_rq->tag, flush_rq); > - } else { > + else > flush_rq->internal_tag = first_rq->internal_tag; > - } > > flush_rq->cmd_flags = REQ_OP_FLUSH | REQ_PREFLUSH; > flush_rq->cmd_flags |= (flags & REQ_DRV) | (flags & REQ_FAILFAST_MASK); > diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h > index 3945c7f5b944..b1acac518c4e 100644 > --- a/block/blk-mq-tag.h > +++ b/block/blk-mq-tag.h > @@ -101,18 +101,6 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, > return atomic_read(&hctx->nr_active) < depth; > } > > -/* > - * This helper should only be used for flush request to share tag > - * with the request cloned from, and both the two requests can't be > - * in flight at the same time. The caller has to make sure the tag > - * can't be freed. > - */ > -static inline void blk_mq_tag_set_rq(struct blk_mq_hw_ctx *hctx, > - unsigned int tag, struct request *rq) > -{ > - hctx->tags->rqs[tag] = rq; > -} > - > static inline bool blk_mq_tag_is_reserved(struct blk_mq_tags *tags, > unsigned int tag) > { > diff --git a/block/blk-mq.c b/block/blk-mq.c > index cabeeeb3d56c..44b101757d33 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -277,26 +277,20 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data, > { > struct blk_mq_tags *tags = blk_mq_tags_from_data(data); > struct request *rq = tags->static_rqs[tag]; > - req_flags_t rq_flags = 0; > > if (data->flags & BLK_MQ_REQ_INTERNAL) { > rq->tag = BLK_MQ_NO_TAG; > rq->internal_tag = tag; > } else { > - if (data->hctx->flags & BLK_MQ_F_TAG_SHARED) { > - rq_flags = RQF_MQ_INFLIGHT; > - atomic_inc(&data->hctx->nr_active); > - } > rq->tag = tag; > rq->internal_tag = BLK_MQ_NO_TAG; > - data->hctx->tags->rqs[rq->tag] = rq; > } > > /* csd/requeue_work/fifo_time is initialized before use */ > rq->q = data->q; > rq->mq_ctx = data->ctx; > rq->mq_hctx = data->hctx; > - rq->rq_flags = rq_flags; > + rq->rq_flags = 0; > rq->cmd_flags = data->cmd_flags; > if (data->flags & BLK_MQ_REQ_PREEMPT) > rq->rq_flags |= RQF_PREEMPT; > @@ -380,8 +374,6 @@ static struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data) > retry: > data->ctx = blk_mq_get_ctx(q); > data->hctx = blk_mq_map_queue(q, data->cmd_flags, data->ctx); > - if (!(data->flags & BLK_MQ_REQ_INTERNAL)) > - blk_mq_tag_busy(data->hctx); > > /* > * Waiting allocations only fail because of an inactive hctx. In that > @@ -478,8 +470,6 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, > > if (q->elevator) > data.flags |= BLK_MQ_REQ_INTERNAL; > - else > - blk_mq_tag_busy(data.hctx); > > ret = -EWOULDBLOCK; > tag = blk_mq_get_tag(&data); > @@ -1131,7 +1121,6 @@ static bool __blk_mq_get_driver_tag(struct request *rq) > { > struct sbitmap_queue *bt = &rq->mq_hctx->tags->bitmap_tags; > unsigned int tag_offset = rq->mq_hctx->tags->nr_reserved_tags; > - bool shared = blk_mq_tag_busy(rq->mq_hctx); > int tag; > > if (blk_mq_tag_is_reserved(rq->mq_hctx->sched_tags, rq->internal_tag)) { > @@ -1146,19 +1135,23 @@ static bool __blk_mq_get_driver_tag(struct request *rq) > return false; > > rq->tag = tag + tag_offset; > - if (shared) { > - rq->rq_flags |= RQF_MQ_INFLIGHT; > - atomic_inc(&rq->mq_hctx->nr_active); > - } > - rq->mq_hctx->tags->rqs[rq->tag] = rq; > return true; > } > > static bool blk_mq_get_driver_tag(struct request *rq) > { > - if (rq->tag != BLK_MQ_NO_TAG) > - return true; > - return __blk_mq_get_driver_tag(rq); > + struct blk_mq_hw_ctx *hctx = rq->mq_hctx; > + bool shared = blk_mq_tag_busy(rq->mq_hctx); > + > + if (rq->tag == BLK_MQ_NO_TAG && !__blk_mq_get_driver_tag(rq)) > + return false; > + > + if (shared) { > + rq->rq_flags |= RQF_MQ_INFLIGHT; > + atomic_inc(&hctx->nr_active); > + } > + hctx->tags->rqs[rq->tag] = rq; > + return true; > } > > static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode, > diff --git a/block/blk.h b/block/blk.h > index 3a120a070dac..459790f9783d 100644 > --- a/block/blk.h > +++ b/block/blk.h > @@ -25,11 +25,6 @@ struct blk_flush_queue { > struct list_head flush_data_in_flight; > struct request *flush_rq; > > - /* > - * flush_rq shares tag with this rq, both can't be active > - * at the same time > - */ > - struct request *orig_rq; > struct lock_class_key key; > spinlock_t mq_flush_lock; > }; > Can you give some more explanation why it's safe to move blk_mq_tag_busy() into blk_mq_get_driver_tag(), seeing that it was called before blk_mq_get_tag() initially? Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer