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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 647EAC38A2A for ; Sat, 9 May 2020 02:05:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 36CA0218AC for ; Sat, 9 May 2020 02:05:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="dSQ72+nf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728415AbgEICFn (ORCPT ); Fri, 8 May 2020 22:05:43 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:45890 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728158AbgEICFn (ORCPT ); Fri, 8 May 2020 22:05:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588989941; 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: in-reply-to:in-reply-to:references:references; bh=FelGRuv5Frlg3E3AJBKqFDXYnuGaIALB63acDeC1q2E=; b=dSQ72+nfAdNnylNJNPBKmoaUrJw2yZleP1uf9qfpnDsuLVfweuanAMiOW7PTeAYbrcWa7g Gc39FuY+XH+JWYrIcJV/T2NmXVZ56JrY5FWt0IMX0zqDzgkBDN3VsOFk+CBTuWHmTRzwN4 aWBE+2njbxQUfYZe9Qd8BcLN8+x+OQ4= 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-15-mq0W2nIjMxSdbm4trTC7sw-1; Fri, 08 May 2020 22:05:37 -0400 X-MC-Unique: mq0W2nIjMxSdbm4trTC7sw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 05DF8464; Sat, 9 May 2020 02:05:36 +0000 (UTC) Received: from T590 (ovpn-8-32.pek2.redhat.com [10.72.8.32]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B381C6AD09; Sat, 9 May 2020 02:05:27 +0000 (UTC) Date: Sat, 9 May 2020 10:05:22 +0800 From: Ming Lei To: Bart Van Assche Cc: Jens Axboe , linux-block@vger.kernel.org, John Garry , Hannes Reinecke , Christoph Hellwig , Thomas Gleixner Subject: Re: [PATCH V10 05/11] blk-mq: support rq filter callback when iterating rqs Message-ID: <20200509020522.GA1392681@T590> References: <20200505020930.1146281-1-ming.lei@redhat.com> <20200505020930.1146281-6-ming.lei@redhat.com> <8d7a14f8-b36c-4f5c-a4af-d5904d3e9ea1@acm.org> <51888b96-1e3b-9810-fb64-47a965b83711@acm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51888b96-1e3b-9810-fb64-47a965b83711@acm.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Fri, May 08, 2020 at 05:18:56PM -0700, Bart Van Assche wrote: > On 2020-05-08 16:32, Bart Van Assche wrote: > > On 2020-05-04 19:09, Ming Lei wrote: > >> @@ -310,19 +313,30 @@ static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt, > >> /** > >> * blk_mq_all_tag_busy_iter - iterate over all started requests in a tag map > >> * @tags: Tag map to iterate over. > >> - * @fn: Pointer to the function that will be called for each started > >> - * request. @fn will be called as follows: @fn(rq, @priv, > >> - * reserved) where rq is a pointer to a request. 'reserved' > >> - * indicates whether or not @rq is a reserved request. Return > >> - * true to continue iterating tags, false to stop. > >> + * @fn: Pointer to the function that will be called for each request > >> + * when .busy_rq_fn(rq) returns true. @fn will be called as > >> + * follows: @fn(rq, @priv, reserved) where rq is a pointer to a > >> + * request. 'reserved' indicates whether or not @rq is a reserved > >> + * request. Return true to continue iterating tags, false to stop. > >> + * @busy_rq_fn: Pointer to the function that will be called for each request, > >> + * @busy_rq_fn's type is same with @fn. Only when @busy_rq_fn(rq, > >> + * @priv, reserved) returns true, @fn will be called on this rq. > >> * @priv: Will be passed as second argument to @fn. > >> */ > >> -static void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, > >> - busy_tag_iter_fn *fn, void *priv) > >> +void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, > >> + busy_tag_iter_fn *fn, busy_rq_iter_fn *busy_rq_fn, > >> + void *priv) > >> { > > > > The name 'busy_rq_fn' is not ideal because it is named after one > > specific use case, namely checking whether or not a request is busy (has > > already been started). How about using the name 'pred_fn' ('pred' from > > predicate because it controls whether the other function is called)? > > Since only the context that passes 'fn' can know what data structure > > 'priv' points to and since 'busy_rq_fn' is passed from another context, > > can 'busy_rq_fn' even know what data 'priv' points at? Has it been > > considered not to pass the 'priv' argument to 'busy_rq_fn'? > > Thinking further about this, another possible approach is not to modify > blk_mq_all_tag_busy_iter() at all and to introduce a new function that > iterates over all requests instead of only over busy requests. I think > that approach will result in easier to read code than patch 5/11 because > each of these request iteration functions will only accept a single > callback function pointer. Additionally, that approach will make the > following function superfluous (from patch 7/11): > > +static bool blk_mq_inflight_rq(struct request *rq, void *data, > + bool reserved) > +{ > + return rq->tag >= 0; > +} Fine, then we can save one callback, how about the following way? diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 586c9d6e904a..5e9c743d887b 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -257,6 +257,7 @@ struct bt_tags_iter_data { busy_tag_iter_fn *fn; void *data; bool reserved; + bool iterate_all; }; static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) @@ -274,8 +275,10 @@ static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) * test and set the bit before assining ->rqs[]. */ rq = tags->rqs[bitnr]; - if (rq && blk_mq_request_started(rq)) - return iter_data->fn(rq, iter_data->data, reserved); + if (rq) { + if (iter_data->iterate_all || blk_mq_request_started(rq)) + return iter_data->fn(rq, iter_data->data, reserved); + } return true; } @@ -294,13 +297,15 @@ static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) * bitmap_tags member of struct blk_mq_tags. */ static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt, - busy_tag_iter_fn *fn, void *data, bool reserved) + busy_tag_iter_fn *fn, void *data, bool reserved, + bool iterate_all) { struct bt_tags_iter_data iter_data = { .tags = tags, .fn = fn, .data = data, .reserved = reserved, + .iterate_all = iterate_all, }; if (tags->rqs) @@ -321,8 +326,30 @@ static void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, busy_tag_iter_fn *fn, void *priv) { if (tags->nr_reserved_tags) - bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, true); - bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, false); + bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, true, + false); + bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, false, false); +} + +/** + * blk_mq_all_tag_iter - iterate over all requests in a tag map + * @tags: Tag map to iterate over. + * @fn: Pointer to the function that will be called for each + * request. @fn will be called as follows: @fn(rq, @priv, + * reserved) where rq is a pointer to a request. 'reserved' + * indicates whether or not @rq is a reserved request. Return + * true to continue iterating tags, false to stop. + * @priv: Will be passed as second argument to @fn. + * + * It is the caller's responsility to check rq's state in @fn. + */ +void blk_mq_all_tag_iter(struct blk_mq_tags *tags, busy_tag_iter_fn *fn, + void *priv) +{ + if (tags->nr_reserved_tags) + bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, true, + true); + bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, false, true); } /** diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h index 2b8321efb682..d19546e8246b 100644 --- a/block/blk-mq-tag.h +++ b/block/blk-mq-tag.h @@ -34,6 +34,8 @@ extern int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, extern void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool); void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, void *priv); +void blk_mq_all_tag_iter(struct blk_mq_tags *tags, busy_tag_iter_fn *fn, + void *priv); static inline struct sbq_wait_state *bt_wait_ptr(struct sbitmap_queue *bt, struct blk_mq_hw_ctx *hctx) thanks, Ming