From patchwork Thu Mar 26 15:36:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 11460555 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 76F7913A4 for ; Thu, 26 Mar 2020 15:38:11 +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 05B5820714 for ; Thu, 26 Mar 2020 15:38:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GNLj7mC6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 05B5820714 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:55542 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jHUa9-0006xR-La for patchwork-qemu-devel@patchwork.kernel.org; Thu, 26 Mar 2020 11:38:09 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54459) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jHUYn-0005Vo-Bx for qemu-devel@nongnu.org; Thu, 26 Mar 2020 11:36:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jHUYk-0002re-OY for qemu-devel@nongnu.org; Thu, 26 Mar 2020 11:36:44 -0400 Received: from us-smtp-delivery-74.mimecast.com ([216.205.24.74]:37985) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jHUYk-0002qd-JY for qemu-devel@nongnu.org; Thu, 26 Mar 2020 11:36:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585237001; h=from:from: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; bh=Nfo30rj6FM0R7h4c2RpNlC8JzNBVqLhSr60I3x2Ghys=; b=GNLj7mC64P4yXbpPmQXFGcxNxxhHz7J8C9AGRtkcp/luPoQe98vG71LDtEchr0KbIadgjy PH+POunPCCffTbIkN0iMADKW4GP+VPEeDvJ+eGw5WLt944WSjAvcghPfIPwiBTd+SRmxhD 3HbCm1SUm6mYnLoaGpA4w3EriHi4M/E= 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-289-lH5Q5k4JM9GLuxaWldwAPg-1; Thu, 26 Mar 2020 11:36:39 -0400 X-MC-Unique: lH5Q5k4JM9GLuxaWldwAPg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8A167192D785; Thu, 26 Mar 2020 15:36:38 +0000 (UTC) Received: from linux.fritz.box.com (ovpn-112-205.ams2.redhat.com [10.36.112.205]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4233F5C1BA; Thu, 26 Mar 2020 15:36:37 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PATCH v2 2/2] mirror: Wait only for in-flight operations Date: Thu, 26 Mar 2020 16:36:28 +0100 Message-Id: <20200326153628.4869-3-kwolf@redhat.com> In-Reply-To: <20200326153628.4869-1-kwolf@redhat.com> References: <20200326153628.4869-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 216.205.24.74 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, jsnow@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" mirror_wait_for_free_in_flight_slot() just picks a random operation to wait for. However, a MirrorOp is already in s->ops_in_flight when mirror_co_read() waits for free slots, so if not enough slots are immediately available, an operation can end up waiting for itself, or two or more operations can wait for each other to complete, which results in a hang. Fix this by adding a flag to MirrorOp that tells us if the request is already in flight (and therefore occupies slots that it will later free), and picking only such operations for waiting. Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1794692 Signed-off-by: Kevin Wolf --- block/mirror.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/block/mirror.c b/block/mirror.c index 393131b135..88414d1653 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -102,6 +102,7 @@ struct MirrorOp { bool is_pseudo_op; bool is_active_write; + bool is_in_flight; CoQueue waiting_requests; Coroutine *co; @@ -293,7 +294,9 @@ mirror_wait_for_any_operation(MirrorBlockJob *s, bool active) * caller of this function. Since there is only one pseudo op * at any given time, we will always find some real operation * to wait on. */ - if (!op->is_pseudo_op && op->is_active_write == active) { + if (!op->is_pseudo_op && op->is_in_flight && + op->is_active_write == active) + { qemu_co_queue_wait(&op->waiting_requests, NULL); return; } @@ -367,6 +370,7 @@ static void coroutine_fn mirror_co_read(void *opaque) /* Copy the dirty cluster. */ s->in_flight++; s->bytes_in_flight += op->bytes; + op->is_in_flight = true; trace_mirror_one_iteration(s, op->offset, op->bytes); ret = bdrv_co_preadv(s->mirror_top_bs->backing, op->offset, op->bytes, @@ -382,6 +386,7 @@ static void coroutine_fn mirror_co_zero(void *opaque) op->s->in_flight++; op->s->bytes_in_flight += op->bytes; *op->bytes_handled = op->bytes; + op->is_in_flight = true; ret = blk_co_pwrite_zeroes(op->s->target, op->offset, op->bytes, op->s->unmap ? BDRV_REQ_MAY_UNMAP : 0); @@ -396,6 +401,7 @@ static void coroutine_fn mirror_co_discard(void *opaque) op->s->in_flight++; op->s->bytes_in_flight += op->bytes; *op->bytes_handled = op->bytes; + op->is_in_flight = true; ret = blk_co_pdiscard(op->s->target, op->offset, op->bytes); mirror_write_complete(op, ret); @@ -1318,6 +1324,7 @@ static MirrorOp *coroutine_fn active_write_prepare(MirrorBlockJob *s, .offset = offset, .bytes = bytes, .is_active_write = true, + .is_in_flight = true, }; qemu_co_queue_init(&op->waiting_requests); QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next);