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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 66A51C433F5 for ; Tue, 11 Jan 2022 08:48:03 +0000 (UTC) Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-292-s3GpenIRM9KI8TAF46PTcQ-1; Tue, 11 Jan 2022 03:47:53 -0500 X-MC-Unique: s3GpenIRM9KI8TAF46PTcQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CC94583DEA6; Tue, 11 Jan 2022 08:47:49 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3E1871F2F4; Tue, 11 Jan 2022 08:47:49 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 8868A1809CB8; Tue, 11 Jan 2022 08:47:48 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 20B8lkLn027912 for ; Tue, 11 Jan 2022 03:47:46 -0500 Received: by smtp.corp.redhat.com (Postfix) id 6C526141DED6; Tue, 11 Jan 2022 08:47:46 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast07.extmail.prod.ext.rdu2.redhat.com [10.11.55.23]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 68013141DED5 for ; Tue, 11 Jan 2022 08:47:46 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [205.139.110.120]) (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 4F1703C021A9 for ; Tue, 11 Jan 2022 08:47:46 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-384-XXTriTRCNIqRxra8LTGWPA-1; Tue, 11 Jan 2022 03:47:42 -0500 X-MC-Unique: XXTriTRCNIqRxra8LTGWPA-1 Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1n7Cbu-00FKhf-2T; Tue, 11 Jan 2022 08:34:30 +0000 Date: Tue, 11 Jan 2022 00:34:30 -0800 From: Christoph Hellwig To: Mike Snitzer Message-ID: References: <20211221141459.1368176-1-ming.lei@redhat.com> MIME-Version: 1.0 In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.85 on 10.11.54.7 X-loop: dm-devel@redhat.com Cc: Christoph Hellwig , Jens Axboe , dm-devel@redhat.com, linux-block@vger.kernel.org, Ming Lei Subject: Re: [dm-devel] [PATCH 0/3] blk-mq/dm-rq: support BLK_MQ_F_BLOCKING for dm-rq X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Tue, Dec 28, 2021 at 04:30:08PM -0500, Mike Snitzer wrote: > Yeah, people use request-based for IO scheduling and more capable path > selectors. Imposing bio-based would be a pretty jarring workaround for > BLK_MQ_F_BLOCKING. request-based DM should properly support it. Given that nvme-tcp is the only blocking driver that has multipath driver that driver explicitly does not intend to support dm-multipath I'm absolutely against adding block layer cruft for this particular use case. SCSI even has this: /* * SCSI never enables blk-mq's BLK_MQ_F_BLOCKING flag so * calling synchronize_rcu() once is enough. */ WARN_ON_ONCE(shost->tag_set.flags & BLK_MQ_F_BLOCKING); -- 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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0CEBC433EF for ; Tue, 11 Jan 2022 08:34:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348935AbiAKIei (ORCPT ); Tue, 11 Jan 2022 03:34:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346437AbiAKIeh (ORCPT ); Tue, 11 Jan 2022 03:34:37 -0500 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 589C3C06173F for ; Tue, 11 Jan 2022 00:34:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=idOVtxgn12323QLg3AYWDEU1cOGoJUWrTbf6WqVChm0=; b=HBub7cboe9T9RvoO0iD5LuuZEk Gaq1oZmKcaN6p4pmBb8CvLMW2fHxcu6hH2Axo4l2W1ZVy1svZqeJiprI+bMHe5UmwLfypYuLkOc4P zvTCJ70rnOdkl8nAepbE2hL2iV5Khtt+igShGZHfwCgrJux7rG7tXoO/AM/bxygQlRGWiKWER2TZ8 YbjCBkkkrR5V6GyFJgiuVsBnTdsCLIfSoJ5wXWsri+IO8M5YLZg1xRoELrI8R8ehUo8UBnmOafWxT 8vY1AjJ4ZmguZHUtWDiHw94kzo8AR1HHN9TWNM9qMASVwy2eP0/aQMkCG0TrXMe99eyxxOCUOmDya DUI7DArA==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1n7Cbu-00FKhf-2T; Tue, 11 Jan 2022 08:34:30 +0000 Date: Tue, 11 Jan 2022 00:34:30 -0800 From: Christoph Hellwig To: Mike Snitzer Cc: Ming Lei , Christoph Hellwig , Jens Axboe , dm-devel@redhat.com, linux-block@vger.kernel.org Subject: Re: [dm-devel] [PATCH 0/3] blk-mq/dm-rq: support BLK_MQ_F_BLOCKING for dm-rq Message-ID: References: <20211221141459.1368176-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, Dec 28, 2021 at 04:30:08PM -0500, Mike Snitzer wrote: > Yeah, people use request-based for IO scheduling and more capable path > selectors. Imposing bio-based would be a pretty jarring workaround for > BLK_MQ_F_BLOCKING. request-based DM should properly support it. Given that nvme-tcp is the only blocking driver that has multipath driver that driver explicitly does not intend to support dm-multipath I'm absolutely against adding block layer cruft for this particular use case. SCSI even has this: /* * SCSI never enables blk-mq's BLK_MQ_F_BLOCKING flag so * calling synchronize_rcu() once is enough. */ WARN_ON_ONCE(shost->tag_set.flags & BLK_MQ_F_BLOCKING);