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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,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 A55E1C4338F for ; Thu, 19 Aug 2021 18:00:19 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 27BD36109F for ; Thu, 19 Aug 2021 18:00:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 27BD36109F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; 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bh=SebhoJzxtK52qncBsoNztkY6rroMQUoPMbpJH9xxz3Y=; b=GOQGLSjhzBZ+ravoL7RFQDrrcNBg+7MjEICOYOy2we5mdMPjQA1di60qGucIxW0nRQll4t P0lDrpgycfX3MRau+CeE8JazICI5p18Iiee9KQA9+IJLpCDtM+UlZWvrASd9UqqarCdgXe AiS5OvHn1kI/Zo4Zlu2uR2lPV2iWOsk= 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-559-R6T3X9_jMkGT9Vmg9jzrGA-1; Thu, 19 Aug 2021 13:58:58 -0400 X-MC-Unique: R6T3X9_jMkGT9Vmg9jzrGA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 589318A6BFF; Thu, 19 Aug 2021 17:58:44 +0000 (UTC) Received: from redhat.com (ovpn-114-146.phx2.redhat.com [10.3.114.146]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2CF5469280; Thu, 19 Aug 2021 17:58:19 +0000 (UTC) Date: Thu, 19 Aug 2021 12:58:18 -0500 From: Eric Blake To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH 2/3] qcow2: refactor handle_dependencies() loop body Message-ID: <20210819175818.v4i4hgdmwknvjp2k@redhat.com> References: <20210724133846.64614-1-vsementsov@virtuozzo.com> <20210724133846.64614-3-vsementsov@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: <20210724133846.64614-3-vsementsov@virtuozzo.com> User-Agent: NeoMutt/20210205-732-28786f X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -15 X-Spam_score: -1.6 X-Spam_bar: - X-Spam_report: (-1.6 / 5.0 requ) DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, den@openvz.org, qemu-devel@nongnu.org, qemu-block@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Sat, Jul 24, 2021 at 04:38:45PM +0300, Vladimir Sementsov-Ogievskiy wrote: > No logic change, just prepare for the following commit. > > Signed-off-by: Vladimir Sementsov-Ogievskiy > --- > block/qcow2-cluster.c | 49 ++++++++++++++++++++++++------------------- > 1 file changed, 28 insertions(+), 21 deletions(-) > > diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c > index bd0597842f..967121c7e6 100644 > --- a/block/qcow2-cluster.c > +++ b/block/qcow2-cluster.c > @@ -1400,29 +1400,36 @@ static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset, > > if (end <= old_start || start >= old_end) { > /* No intersection */ > - } else { > - if (start < old_start) { > - /* Stop at the start of a running allocation */ > - bytes = old_start - start; > - } else { > - bytes = 0; > - } > + continue; > + } > > - /* Stop if already an l2meta exists. After yielding, it wouldn't Pre-existing, but... > - * be valid any more, so we'd have to clean up the old L2Metas > - * and deal with requests depending on them before starting to > - * gather new ones. Not worth the trouble. */ > - if (bytes == 0 && *m) { > - *cur_bytes = 0; > - return 0; > - } > + /* Conflict */ > > - if (bytes == 0) { > - /* Wait for the dependency to complete. We need to recheck > - * the free/allocated clusters when we continue. */ > - qemu_co_queue_wait(&old_alloc->dependent_requests, &s->lock); > - return -EAGAIN; > - } > + if (start < old_start) { > + /* Stop at the start of a running allocation */ > + bytes = old_start - start; > + } else { > + bytes = 0; > + } > + > + /* > + * Stop if already an l2meta exists. After yielding, it wouldn't ...might as well fix the grammar: Stop if an l2meta already exists. > + * be valid any more, so we'd have to clean up the old L2Metas > + * and deal with requests depending on them before starting to > + * gather new ones. Not worth the trouble. > + */ > + if (bytes == 0 && *m) { > + *cur_bytes = 0; > + return 0; > + } > + > + if (bytes == 0) { > + /* > + * Wait for the dependency to complete. We need to recheck > + * the free/allocated clusters when we continue. > + */ > + qemu_co_queue_wait(&old_alloc->dependent_requests, &s->lock); > + return -EAGAIN; So the change adds a short-circuiting 'continue', then reduces the indentation of the rest of the loop body. Reviewed-by: Eric Blake -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org