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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, 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 CC76DC433DB for ; Tue, 30 Mar 2021 06:51:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D39561989 for ; Tue, 30 Mar 2021 06:51:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230415AbhC3Gu7 (ORCPT ); Tue, 30 Mar 2021 02:50:59 -0400 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]:35376 "EHLO out30-57.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229950AbhC3Guy (ORCPT ); Tue, 30 Mar 2021 02:50:54 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=alimailimapcm10staff010182156082;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0UTpnuEy_1617087051; Received: from admindeMacBook-Pro-2.local(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0UTpnuEy_1617087051) by smtp.aliyun-inc.com(127.0.0.1); Tue, 30 Mar 2021 14:50:52 +0800 Subject: Re: [PATCH V4 11/12] block: add poll_capable method to support bio-based IO polling To: Hannes Reinecke , Ming Lei , Jens Axboe Cc: linux-block@vger.kernel.org, Mike Snitzer , dm-devel@redhat.com References: <20210329152622.173035-1-ming.lei@redhat.com> <20210329152622.173035-12-ming.lei@redhat.com> <162f000f-7f86-8988-4a15-2c3bf70de1b7@suse.de> From: JeffleXu Message-ID: Date: Tue, 30 Mar 2021 14:50:51 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <162f000f-7f86-8988-4a15-2c3bf70de1b7@suse.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 3/30/21 2:26 PM, Hannes Reinecke wrote: > On 3/29/21 5:26 PM, Ming Lei wrote: >> From: Jeffle Xu >> >> This method can be used to check if bio-based device supports IO polling >> or not. For mq devices, checking for hw queue in polling mode is >> adequate, while the sanity check shall be implementation specific for >> bio-based devices. For example, dm device needs to check if all >> underlying devices are capable of IO polling. >> >> Though bio-based device may have done the sanity check during the >> device initialization phase, cacheing the result of this sanity check >> (such as by cacheing in the queue_flags) may not work. Because for dm >> devices, users could change the state of the underlying devices through >> '/sys/block//io_poll', bypassing the dm device above. In this case, >> the cached result of the very beginning sanity check could be >> out-of-date. Thus the sanity check needs to be done every time 'io_poll' >> is to be modified. >> >> Signed-off-by: Jeffle Xu >> --- >> block/blk-sysfs.c | 14 +++++++++++--- >> include/linux/blkdev.h | 1 + >> 2 files changed, 12 insertions(+), 3 deletions(-) >> >> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c >> index db3268d41274..c8e7e4af66cb 100644 >> --- a/block/blk-sysfs.c >> +++ b/block/blk-sysfs.c >> @@ -426,9 +426,17 @@ static ssize_t queue_poll_store(struct >> request_queue *q, const char *page, >> unsigned long poll_on; >> ssize_t ret; >> - if (!q->tag_set || q->tag_set->nr_maps <= HCTX_TYPE_POLL || >> - !q->tag_set->map[HCTX_TYPE_POLL].nr_queues) >> - return -EINVAL; >> + if (queue_is_mq(q)) { >> + if (!q->tag_set || q->tag_set->nr_maps <= HCTX_TYPE_POLL || >> + !q->tag_set->map[HCTX_TYPE_POLL].nr_queues) >> + return -EINVAL; >> + } else { >> + struct gendisk *disk = queue_to_disk(q); >> + >> + if (!disk->fops->poll_capable || >> + !disk->fops->poll_capable(disk)) >> + return -EINVAL; >> + } >> ret = queue_var_store(&poll_on, page, count); >> if (ret < 0) >> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h >> index bfab74b45f15..a46f975f2a2f 100644 >> --- a/include/linux/blkdev.h >> +++ b/include/linux/blkdev.h >> @@ -1881,6 +1881,7 @@ struct block_device_operations { >> int (*report_zones)(struct gendisk *, sector_t sector, >> unsigned int nr_zones, report_zones_cb cb, void *data); >> char *(*devnode)(struct gendisk *disk, umode_t *mode); >> + bool (*poll_capable)(struct gendisk *disk); >> struct module *owner; >> const struct pr_ops *pr_ops; >> }; >> > I really wonder how this would work for nvme multipath; but I guess it > doesn't change the current situation. I wonder, at least, md/dm, which is built upon other devices, or 'virtual device' in other words, should be distinguished from other 'original' bio-based device (e.g., nvme multipath) then. Maybe one extra flag or something. -- Thanks, Jeffle 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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, 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 464FEC433C1 for ; Tue, 30 Mar 2021 08:23:54 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8B63561919 for ; Tue, 30 Mar 2021 08:23:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8B63561919 Authentication-Results: mail.kernel.org; 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Tue, 30 Mar 2021 02:50:57 -0400 X-MC-Unique: DEAtM1quMCio2cp1drPOaA-1 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R121e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=alimailimapcm10staff010182156082; MF=jefflexu@linux.alibaba.com; NM=1; PH=DS; RN=6; SR=0; TI=SMTPD_---0UTpnuEy_1617087051 Received: from admindeMacBook-Pro-2.local(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0UTpnuEy_1617087051) by smtp.aliyun-inc.com(127.0.0.1); Tue, 30 Mar 2021 14:50:52 +0800 To: Hannes Reinecke , Ming Lei , Jens Axboe References: <20210329152622.173035-1-ming.lei@redhat.com> <20210329152622.173035-12-ming.lei@redhat.com> <162f000f-7f86-8988-4a15-2c3bf70de1b7@suse.de> From: JeffleXu Message-ID: Date: Tue, 30 Mar 2021 14:50:51 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <162f000f-7f86-8988-4a15-2c3bf70de1b7@suse.de> X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; 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