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=-8.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 855AFC2D0A3 for ; Tue, 3 Nov 2020 14:49:16 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E28F42242F for ; Tue, 3 Nov 2020 14:49:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="NEMnwyMC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E28F42242F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=tempfail smtp.mailfrom=dm-devel-bounces@redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1604414954; h=from:from:sender:sender:reply-to:subject:subject: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:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=/V7OLYi7AM4omqHXgP0nXhYcGHmQ5QKhtcMNFLX+hB0=; b=NEMnwyMCbTMDpsMtWt7YX+Lykm3VVbCwoZjjqol/jpVCF3PWfoa0jPQUJ6oAeyu1miVmGY LnHXpychSugg2qT2f7qMgvFKf5NW+g4GCZOx+8l3OibLwqguVK7KLZ15QASXjk1cZ3JjJY +KUyA6qpcWbgAx9WCsHvrzYHmC2cJq0= 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-200-gIpc3YirM4-2BF7h1MPVoQ-1; Tue, 03 Nov 2020 09:49:12 -0500 X-MC-Unique: gIpc3YirM4-2BF7h1MPVoQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 62FA71842170; Tue, 3 Nov 2020 14:49:06 +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 1BC2E60BF1; Tue, 3 Nov 2020 14:49:05 +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 21D261826D35; Tue, 3 Nov 2020 14:49:02 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 0A3EmwXt032521 for ; Tue, 3 Nov 2020 09:48:58 -0500 Received: by smtp.corp.redhat.com (Postfix) id E17D7747C6; Tue, 3 Nov 2020 14:48:58 +0000 (UTC) Received: from localhost (unknown [10.18.25.174]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C297D75127; Tue, 3 Nov 2020 14:48:55 +0000 (UTC) Date: Tue, 3 Nov 2020 08:48:25 -0500 From: Mike Snitzer To: Jeffle Xu Message-ID: <20201103134824.GA26430@redhat.com> References: <20201103092329.17694-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 In-Reply-To: <20201103092329.17694-1-jefflexu@linux.alibaba.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-loop: dm-devel@redhat.com Cc: joseph.qi@linux.alibaba.com, dm-devel@redhat.com Subject: Re: [dm-devel] Why queue_work unneeded for REQUEUE bio 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 2.79 on 10.5.11.12 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, Nov 03 2020 at 4:23am -0500, Jeffle Xu wrote: > Hi Mike, > > Why queue_work() is unnecessary here for bio with BLK_STS_DM_REQUEUE > returned? > > Thanks > Jeffle Xu > > --- > drivers/md/dm.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > index c18fc2548518..ae550daa99b5 100644 > --- a/drivers/md/dm.c > +++ b/drivers/md/dm.c > @@ -908,9 +908,11 @@ static void dec_pending(struct dm_io *io, blk_status_t error) > * Target requested pushing back the I/O. > */ > spin_lock_irqsave(&md->deferred_lock, flags); > - if (__noflush_suspending(md)) > + if (__noflush_suspending(md)) { > /* NOTE early return due to BLK_STS_DM_REQUEUE below */ > bio_list_add_head(&md->deferred, io->orig_bio); > + queue_work(md->wq, &md->work); > + } > else > /* noflush suspend was interrupted. */ > io->status = BLK_STS_IOERR; > -- > 2.27.0 > For the case you highlighted (BLK_STS_DM_REQUEUE + __noflush_suspending) I think the missing queue_work is because we're actively dealing with the fact that we do _not_ want to flush IO. SO kicking the workqueue there isn't helpful because it just processes work that cannot be issued yet -- the workqueue will be kicked upon resume (see __dm_resume's dm_queue_flush). Mike -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel