From patchwork Mon Jan 25 12:13:37 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jingbo Xu X-Patchwork-Id: 12045463 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT 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 8E1A9C433DB for ; Tue, 26 Jan 2021 05:33:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5E160229C4 for ; Tue, 26 Jan 2021 05:33:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727883AbhAZFcu (ORCPT ); Tue, 26 Jan 2021 00:32:50 -0500 Received: from out30-44.freemail.mail.aliyun.com ([115.124.30.44]:36779 "EHLO out30-44.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727877AbhAYMTz (ORCPT ); Mon, 25 Jan 2021 07:19:55 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0UMqjSks_1611576822; Received: from localhost(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0UMqjSks_1611576822) by smtp.aliyun-inc.com(127.0.0.1); Mon, 25 Jan 2021 20:13:42 +0800 From: Jeffle Xu To: snitzer@redhat.com Cc: joseph.qi@linux.alibaba.com, dm-devel@redhat.com, linux-block@vger.kernel.org, io-uring@vger.kernel.org Subject: [PATCH v2 3/6] block: add iopoll method to support bio-based IO polling Date: Mon, 25 Jan 2021 20:13:37 +0800 Message-Id: <20210125121340.70459-4-jefflexu@linux.alibaba.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210125121340.70459-1-jefflexu@linux.alibaba.com> References: <20210125121340.70459-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org ->poll_fn was introduced in commit ea435e1b9392 ("block: add a poll_fn callback to struct request_queue") to support bio-based queues such as nvme multipath, but was later removed in commit 529262d56dbe ("block: remove ->poll_fn"). Given commit c62b37d96b6e ("block: move ->make_request_fn to struct block_device_operations") restore the possibility of bio-based IO polling support by adding an ->iopoll method to gendisk->fops. Elevate bulk of blk_mq_poll() implementation to blk_poll() and reduce blk_mq_poll() to blk-mq specific code that is called from blk_poll(). Signed-off-by: Jeffle Xu Suggested-by: Mike Snitzer Reviewed-by: Mike Snitzer --- block/blk-core.c | 70 +++++++++++++++++++++++++++++++++++++++ block/blk-mq.c | 74 ++++++------------------------------------ include/linux/blk-mq.h | 3 ++ include/linux/blkdev.h | 1 + 4 files changed, 84 insertions(+), 64 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 7663a9b94b80..3d93aaa9a49b 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1132,6 +1132,76 @@ blk_qc_t submit_bio(struct bio *bio) } EXPORT_SYMBOL(submit_bio); +/** + * blk_poll - poll for IO completions + * @q: the queue + * @cookie: cookie passed back at IO submission time + * @spin: whether to spin for completions + * + * Description: + * Poll for completions on the passed in queue. Returns number of + * completed entries found. If @spin is true, then blk_poll will continue + * looping until at least one completion is found, unless the task is + * otherwise marked running (or we need to reschedule). + */ +int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin) +{ + long state; + struct blk_mq_hw_ctx *hctx = NULL; + struct gendisk *disk = NULL; + + if (!blk_qc_t_valid(cookie) || + !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) + return 0; + + if (current->plug) + blk_flush_plug_list(current->plug, false); + + if (queue_is_mq(q)) { + /* + * If we sleep, have the caller restart the poll loop to reset + * the state. Like for the other success return cases, the + * caller is responsible for checking if the IO completed. If + * the IO isn't complete, we'll get called again and will go + * straight to the busy poll loop. If specified not to spin, + * we also should not sleep. + */ + hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)]; + if (spin && blk_mq_poll_hybrid(q, hctx, cookie)) + return 1; + hctx->poll_considered++; + } else + disk = queue_to_disk(q); + + state = current->state; + do { + int ret; + + if (hctx) + ret = blk_mq_poll(q, hctx); + else if (disk->fops->iopoll) + ret = disk->fops->iopoll(q, cookie); + + if (ret > 0) { + __set_current_state(TASK_RUNNING); + return ret; + } + + if (signal_pending_state(state, current)) + __set_current_state(TASK_RUNNING); + + if (current->state == TASK_RUNNING) + return 1; + if (ret < 0 || !spin) + break; + cpu_relax(); + } while (!need_resched()); + + __set_current_state(TASK_RUNNING); + return 0; +} +EXPORT_SYMBOL_GPL(blk_poll); + /** * blk_cloned_rq_check_limits - Helper function to check a cloned request * for the new queue limits diff --git a/block/blk-mq.c b/block/blk-mq.c index f285a9123a8b..d058b9cbdf76 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3801,8 +3801,8 @@ static bool blk_mq_poll_hybrid_sleep(struct request_queue *q, return true; } -static bool blk_mq_poll_hybrid(struct request_queue *q, - struct blk_mq_hw_ctx *hctx, blk_qc_t cookie) +bool blk_mq_poll_hybrid(struct request_queue *q, + struct blk_mq_hw_ctx *hctx, blk_qc_t cookie) { struct request *rq; @@ -3826,72 +3826,18 @@ static bool blk_mq_poll_hybrid(struct request_queue *q, return blk_mq_poll_hybrid_sleep(q, rq); } -/** - * blk_poll - poll for IO completions - * @q: the queue - * @cookie: cookie passed back at IO submission time - * @spin: whether to spin for completions - * - * Description: - * Poll for completions on the passed in queue. Returns number of - * completed entries found. If @spin is true, then blk_poll will continue - * looping until at least one completion is found, unless the task is - * otherwise marked running (or we need to reschedule). - */ -int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin) +int blk_mq_poll(struct request_queue *q, struct blk_mq_hw_ctx *hctx) { - struct blk_mq_hw_ctx *hctx; - long state; - - if (!blk_qc_t_valid(cookie) || - !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) - return 0; - - if (current->plug) - blk_flush_plug_list(current->plug, false); - - hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)]; - - /* - * If we sleep, have the caller restart the poll loop to reset - * the state. Like for the other success return cases, the - * caller is responsible for checking if the IO completed. If - * the IO isn't complete, we'll get called again and will go - * straight to the busy poll loop. If specified not to spin, - * we also should not sleep. - */ - if (spin && blk_mq_poll_hybrid(q, hctx, cookie)) - return 1; - - hctx->poll_considered++; - - state = current->state; - do { - int ret; - - hctx->poll_invoked++; - - ret = q->mq_ops->poll(hctx); - if (ret > 0) { - hctx->poll_success++; - __set_current_state(TASK_RUNNING); - return ret; - } - - if (signal_pending_state(state, current)) - __set_current_state(TASK_RUNNING); + int ret; - if (current->state == TASK_RUNNING) - return 1; - if (ret < 0 || !spin) - break; - cpu_relax(); - } while (!need_resched()); + hctx->poll_invoked++; + ret = q->mq_ops->poll(hctx); + if (ret > 0) + hctx->poll_success++; - __set_current_state(TASK_RUNNING); - return 0; + return ret; } -EXPORT_SYMBOL_GPL(blk_poll); +EXPORT_SYMBOL(blk_mq_poll); unsigned int blk_mq_rq_cpu(struct request *rq) { diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index d705b174d346..8062a2d046a9 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -607,6 +607,9 @@ static inline void blk_rq_bio_prep(struct request *rq, struct bio *bio, } blk_qc_t blk_mq_submit_bio(struct bio *bio); +int blk_mq_poll(struct request_queue *q, struct blk_mq_hw_ctx *hctx); +bool blk_mq_poll_hybrid(struct request_queue *q, + struct blk_mq_hw_ctx *hctx, blk_qc_t cookie); void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx, struct lock_class_key *key); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 2a802e011a95..bc540df197cb 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1853,6 +1853,7 @@ static inline void blk_ksm_unregister(struct request_queue *q) { } struct block_device_operations { blk_qc_t (*submit_bio) (struct bio *bio); + int (*iopoll)(struct request_queue *q, blk_qc_t cookie); int (*open) (struct block_device *, fmode_t); void (*release) (struct gendisk *, fmode_t); int (*rw_page)(struct block_device *, sector_t, struct page *, unsigned int);