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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D286CC32771 for ; Mon, 26 Sep 2022 09:45:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234442AbiIZJp5 (ORCPT ); Mon, 26 Sep 2022 05:45:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50918 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234152AbiIZJpU (ORCPT ); Mon, 26 Sep 2022 05:45:20 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 43F18102C; Mon, 26 Sep 2022 02:44:36 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 6438422087; Mon, 26 Sep 2022 09:44:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1664185475; h=from:from:reply-to: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=aYfBxVLDKXRyCiZQ7+UvH4mxxp4XXerCm1q4/cpIXHU=; b=2p+BTxx+HjqmIk5/4mNduRmMMDjaKzg0la9AUsCspEoEPjVP1ZySGgkcgzv5kxdj8aYCdi GbFMFk7huSG9pQgeJoDVbVTeRECMPNa6saRsHNcse4REWEQcXea24FeBCkGXwO6cZgxzQ+ OVzVKWnj1U+Wnznf4CQTCvNGE9aDfWM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1664185475; h=from:from:reply-to: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=aYfBxVLDKXRyCiZQ7+UvH4mxxp4XXerCm1q4/cpIXHU=; b=iI4pLzcIHbiJOieLr/8DhQlpa13oAZeoiB2NObDSNXDrNC7x56vqgFDsioIQAwkqnikFal /h7fAxTr9V7JAcCQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 56060139BD; Mon, 26 Sep 2022 09:44:35 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id U9LxFIN0MWMMfwAAMHmgww (envelope-from ); Mon, 26 Sep 2022 09:44:35 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id D2977A0685; Mon, 26 Sep 2022 11:44:34 +0200 (CEST) Date: Mon, 26 Sep 2022 11:44:34 +0200 From: Jan Kara To: Yu Kuai Cc: jack@suse.cz, paolo.valente@linaro.org, axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai1@huaweicloud.com, yi.zhang@huawei.com Subject: Re: [PATCH v3 1/5] wbt: don't show valid wbt_lat_usec in sysfs while wbt is disabled Message-ID: <20220926094434.jrl6gnlbjqkex3wa@quack3> References: <20220922113558.1085314-1-yukuai3@huawei.com> <20220922113558.1085314-2-yukuai3@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220922113558.1085314-2-yukuai3@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu 22-09-22 19:35:54, Yu Kuai wrote: > Currently, if wbt is initialized and then disabled by > wbt_disable_default(), sysfs will still show valid wbt_lat_usec, which > will confuse users that wbt is still enabled. > > This patch shows wbt_lat_usec as zero and forbid to set it while wbt > is disabled. So I agree we should show 0 in wbt_lat_usec if wbt is disabled by wbt_disable_default(). But why do you forbid setting of wbt_lat_usec? IMHO if wbt_lat_usec is set, admin wants to turn on wbt so we should just update rwb->enable_state to WBT_STATE_ON_MANUAL. Honza > > Signed-off-by: Yu Kuai > Reported-and-tested-by: Holger Hoffstätte > --- > block/blk-sysfs.c | 9 ++++++++- > block/blk-wbt.c | 7 +++++++ > block/blk-wbt.h | 5 +++++ > 3 files changed, 20 insertions(+), 1 deletion(-) > > diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c > index e1f009aba6fd..1955bb6a284d 100644 > --- a/block/blk-sysfs.c > +++ b/block/blk-sysfs.c > @@ -467,10 +467,14 @@ static ssize_t queue_io_timeout_store(struct request_queue *q, const char *page, > > static ssize_t queue_wb_lat_show(struct request_queue *q, char *page) > { > + u64 lat; > + > if (!wbt_rq_qos(q)) > return -EINVAL; > > - return sprintf(page, "%llu\n", div_u64(wbt_get_min_lat(q), 1000)); > + lat = wbt_disabled(q) ? 0 : div_u64(wbt_get_min_lat(q), 1000); > + > + return sprintf(page, "%llu\n", lat); > } > > static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page, > @@ -493,6 +497,9 @@ static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page, > return ret; > } > > + if (wbt_disabled(q)) > + return -EINVAL; > + > if (val == -1) > val = wbt_default_latency_nsec(q); > else if (val >= 0) > diff --git a/block/blk-wbt.c b/block/blk-wbt.c > index a9982000b667..68851c2c02d2 100644 > --- a/block/blk-wbt.c > +++ b/block/blk-wbt.c > @@ -422,6 +422,13 @@ static void wbt_update_limits(struct rq_wb *rwb) > rwb_wake_all(rwb); > } > > +bool wbt_disabled(struct request_queue *q) > +{ > + struct rq_qos *rqos = wbt_rq_qos(q); > + > + return !rqos || RQWB(rqos)->enable_state == WBT_STATE_OFF_DEFAULT; > +} > + > u64 wbt_get_min_lat(struct request_queue *q) > { > struct rq_qos *rqos = wbt_rq_qos(q); > diff --git a/block/blk-wbt.h b/block/blk-wbt.h > index 7e44eccc676d..e42465ddcbb6 100644 > --- a/block/blk-wbt.h > +++ b/block/blk-wbt.h > @@ -94,6 +94,7 @@ void wbt_enable_default(struct request_queue *); > > u64 wbt_get_min_lat(struct request_queue *q); > void wbt_set_min_lat(struct request_queue *q, u64 val); > +bool wbt_disabled(struct request_queue *); > > void wbt_set_write_cache(struct request_queue *, bool); > > @@ -125,6 +126,10 @@ static inline u64 wbt_default_latency_nsec(struct request_queue *q) > { > return 0; > } > +static inline bool wbt_disabled(struct request_queue *q) > +{ > + return true; > +} > > #endif /* CONFIG_BLK_WBT */ > > -- > 2.31.1 > -- Jan Kara SUSE Labs, CR