From patchwork Thu Aug 3 15:55:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 1816539 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=XY1/il34; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4RGtkd3KLkz1ybS for ; Fri, 4 Aug 2023 01:56:41 +1000 (AEST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qRagD-0006pr-Tc; Thu, 03 Aug 2023 11:56:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qRagA-0006pd-0n for qemu-devel@nongnu.org; Thu, 03 Aug 2023 11:55:58 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qRag8-0004oa-G4 for qemu-devel@nongnu.org; Thu, 03 Aug 2023 11:55:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1691078155; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vuhqgQawoFar29iDZgHO95xXm2Ku6g+zYEg0foUzyKc=; b=XY1/il34oUpKYP/CDAyUWXokhNpaTAEXa/HZ+oHaWCQujX4tcIWm2WiYsWSDa+rohH1ACp TxUil8/isJ54S0EcwOz65lzUzGeY03Kczw3uIc6D3ylmO6OZVquaqyrLNsHuBfkq5OTgi5 BMbNZbSEE39It29VUCYgWmXMGjrVrwU= Received: from mimecast-mx02.redhat.com (66.187.233.73 [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-13-03VoesUdPH-dmPVq28NMQg-1; Thu, 03 Aug 2023 11:55:52 -0400 X-MC-Unique: 03VoesUdPH-dmPVq28NMQg-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C360A29AA38B; Thu, 3 Aug 2023 15:55:51 +0000 (UTC) Received: from localhost (unknown [10.39.194.215]) by smtp.corp.redhat.com (Postfix) with ESMTP id 28861403162; Thu, 3 Aug 2023 15:55:50 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: Kevin Wolf , Fam Zheng , Stefan Hajnoczi , Hanna Reitz , qemu-block@nongnu.org, Richard Henderson , Stefano Garzarella Subject: [PULL for-8.1 2/2] block/blkio: add more comments on the fd passing handling Date: Thu, 3 Aug 2023 11:55:45 -0400 Message-ID: <20230803155545.2349984-3-stefanha@redhat.com> In-Reply-To: <20230803155545.2349984-1-stefanha@redhat.com> References: <20230803155545.2349984-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Stefano Garzarella As Hanna pointed out, it is not clear in the code why qemu_open() can fail, and why blkio_set_int("fd") is not enough to discover the `fd` property support. Let's fix them by adding more details in the code comments. Suggested-by: Hanna Czenczek Reviewed-by: Hanna Czenczek Signed-off-by: Stefano Garzarella Message-id: 20230803082825.25293-3-sgarzare@redhat.com Signed-off-by: Stefan Hajnoczi --- block/blkio.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/block/blkio.c b/block/blkio.c index baba2f0b67..1dd495617c 100644 --- a/block/blkio.c +++ b/block/blkio.c @@ -713,6 +713,12 @@ static int blkio_virtio_blk_connect(BlockDriverState *bs, QDict *options, */ fd = qemu_open(path, O_RDWR, NULL); if (fd < 0) { + /* + * qemu_open() can fail if the user specifies a path that is not + * a file or device, for example in the case of Unix Domain Socket + * for the virtio-blk-vhost-user driver. In such cases let's have + * libblkio open the path directly. + */ fd_supported = false; } else { ret = blkio_set_int(s->blkio, "fd", fd); @@ -741,9 +747,12 @@ static int blkio_virtio_blk_connect(BlockDriverState *bs, QDict *options, } /* - * If the libblkio driver doesn't support the `fd` property, blkio_connect() - * will fail with -EINVAL. So let's try calling blkio_connect() again by - * directly setting `path`. + * Before https://gitlab.com/libblkio/libblkio/-/merge_requests/208 + * (libblkio <= v1.3.0), setting the `fd` property is not enough to check + * whether the driver supports the `fd` property or not. In that case, + * blkio_connect() will fail with -EINVAL. + * So let's try calling blkio_connect() again by directly setting `path` + * to cover this scenario. */ if (fd_supported && ret == -EINVAL) { /*