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Mon, 21 Jun 2021 03:25:12 -0400 Received: by smtp.corp.redhat.com (Postfix) id 6E76B1112840; Mon, 21 Jun 2021 07:25:12 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast04.extmail.prod.ext.rdu2.redhat.com [10.11.55.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 66DA0111286A for ; Mon, 21 Jun 2021 07:25:09 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-2.mimecast.com [205.139.110.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D6396108C0A0 for ; Mon, 21 Jun 2021 07:25:09 +0000 (UTC) Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-292-cEtyx5fDNpCXT92TLFV7TA-1; Mon, 21 Jun 2021 03:25:05 -0400 X-MC-Unique: cEtyx5fDNpCXT92TLFV7TA-1 Received: by verein.lst.de (Postfix, from userid 2407) id 7EA6368BEB; Mon, 21 Jun 2021 09:25:02 +0200 (CEST) Date: Mon, 21 Jun 2021 09:25:02 +0200 From: Christoph Hellwig To: Ming Lei Message-ID: <20210621072502.GC6651@lst.de> References: <20210617103549.930311-1-ming.lei@redhat.com> <20210617103549.930311-3-ming.lei@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210617103549.930311-3-ming.lei@redhat.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; 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charset="us-ascii" Content-Transfer-Encoding: 7bit > + struct gendisk *disk = bio->bi_bdev->bd_disk; > + struct request_queue *q = disk->queue; > blk_qc_t cookie = READ_ONCE(bio->bi_cookie); > int ret; > > - if (cookie == BLK_QC_T_NONE || !blk_queue_poll(q)) > + if ((queue_is_mq(q) && cookie == BLK_QC_T_NONE) || > + !blk_queue_poll(q)) > return 0; How does polling for a bio without a cookie make sense even when polling bio based? But if we come up for a good rationale for this I'd really split the conditions to make them more readable: if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) return 0; if (queue_is_mq(q) && cookie == BLK_QC_T_NONE) return 0; > + if (!queue_is_mq(q)) { > + if (disk->fops->poll_bio) { > + ret = disk->fops->poll_bio(bio, flags); > + } else { > + WARN_ON_ONCE(1); > + ret = 0; > + } > + } else { > ret = blk_mq_poll(q, cookie, flags); I'd go for someting like: if (queue_is_mq(q)) ret = blk_mq_poll(q, cookie, flags); else if (disk->fops->poll_bio) ret = disk->fops->poll_bio(bio, flags); else WARN_ON_ONCE(1); with ret initialized to 0 at declaration time. > struct block_device_operations { > void (*submit_bio)(struct bio *bio); > + /* ->poll_bio is for bio driver only */ I'd drop the comment, this is already nicely documented in add_disk together with the actual check. We also don't note this for submit_bio here. -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel 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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 8D22FC49EA4 for ; Mon, 21 Jun 2021 07:25:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74D0360240 for ; Mon, 21 Jun 2021 07:25:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230316AbhFUH1U (ORCPT ); Mon, 21 Jun 2021 03:27:20 -0400 Received: from verein.lst.de ([213.95.11.211]:40878 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230311AbhFUH1S (ORCPT ); Mon, 21 Jun 2021 03:27:18 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 7EA6368BEB; Mon, 21 Jun 2021 09:25:02 +0200 (CEST) Date: Mon, 21 Jun 2021 09:25:02 +0200 From: Christoph Hellwig To: Ming Lei Cc: Jens Axboe , Mike Snitzer , linux-block@vger.kernel.org, Jeffle Xu , dm-devel@redhat.com, Hannes Reinecke , Christoph Hellwig Subject: Re: [RFC PATCH V2 2/3] block: add ->poll_bio to block_device_operations Message-ID: <20210621072502.GC6651@lst.de> References: <20210617103549.930311-1-ming.lei@redhat.com> <20210617103549.930311-3-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210617103549.930311-3-ming.lei@redhat.com> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org > + struct gendisk *disk = bio->bi_bdev->bd_disk; > + struct request_queue *q = disk->queue; > blk_qc_t cookie = READ_ONCE(bio->bi_cookie); > int ret; > > - if (cookie == BLK_QC_T_NONE || !blk_queue_poll(q)) > + if ((queue_is_mq(q) && cookie == BLK_QC_T_NONE) || > + !blk_queue_poll(q)) > return 0; How does polling for a bio without a cookie make sense even when polling bio based? But if we come up for a good rationale for this I'd really split the conditions to make them more readable: if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) return 0; if (queue_is_mq(q) && cookie == BLK_QC_T_NONE) return 0; > + if (!queue_is_mq(q)) { > + if (disk->fops->poll_bio) { > + ret = disk->fops->poll_bio(bio, flags); > + } else { > + WARN_ON_ONCE(1); > + ret = 0; > + } > + } else { > ret = blk_mq_poll(q, cookie, flags); I'd go for someting like: if (queue_is_mq(q)) ret = blk_mq_poll(q, cookie, flags); else if (disk->fops->poll_bio) ret = disk->fops->poll_bio(bio, flags); else WARN_ON_ONCE(1); with ret initialized to 0 at declaration time. > struct block_device_operations { > void (*submit_bio)(struct bio *bio); > + /* ->poll_bio is for bio driver only */ I'd drop the comment, this is already nicely documented in add_disk together with the actual check. We also don't note this for submit_bio here.